ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (449)
  • Chemical Engineering  (389)
  • Civil and Mechanical Engineering  (60)
  • Cell & Developmental Biology
  • General Chemistry
  • 1995-1999  (449)
  • 1945-1949
  • 1940-1944
  • 1930-1934
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (449)
Collection
  • Articles  (449)
Source
Keywords
Publisher
Years
Year
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Assessment of some failure criteria for strongly anisotropic geomaterials (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 1-26 
    Details
    ISSN: 1082-5010
    Keywords: anisotropy ; failure criterion ; schist ; sedimentary rock ; rock joints ; laboratory testing ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper is devoted to the assessment of some representative failure criteria in the framework of modelling the failure behaviour of strongly anisotropic geomaterials. Experimental data concerning the failure behaviour of a typical strongly anisotropic rock; the schist of Angers are first presented. Nine widely used failure criteria are then selected and classified into three groups, the mathematical continuous models, the empirical continuous models and the discontinuous weakness planes based models. This classification is made up according to the main assumptions and techniques used in each criterion to describe the strength anisotropy. The calibration of each one is carried out with respect to the laboratory data of Angers schist. Qualitative and quantitative comparisons between the selected criteria and with the experimental data are provided. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    A new anisotropic failure criterion for transversely isotropic solids (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 89-103 
    Details
    ISSN: 1082-5010
    Keywords: transversely isotropic material ; elliptic paraboloid failure surface ; strength differential effect ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A coordinate-free formulation of a failure criterion for transversely isotropic solids is proposed. In the three-dimensional stress space the criterion is represented by an elliptic paraboloid. The anisotropic form of the proposed criterion is based on generalization of the second invariant of the deviatoric stress and of the mean stress obtained through the introduction of a unique fourth-order tensor. For isotropic conditions, the criterion reduces to the Mises-Schleicher failure condition. It is shown that the criterion satisfactorily predicts the strength anisotropy of transversely isotropic rocks subjected to an axisymmetric stress state. The procedure for the identification of the parameters of the criterion from a few simple laboratory tests is outlined. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    A model for ageing visco-elastic tension softening materials (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 27-39 
    Details
    ISSN: 1082-5010
    Keywords: creep ; effective spring concept ; Kelvin chain model ; load bearing volume ; micromechanical model ; relaxation ; softening spring ; solidification ; tension softening ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An analytical constitutive model similar to the Kelvin chain rheological model associated with solidification theory, is developed for time-dependent tension softening of ageing materials like concrete. The stiffness of spring elements is allowed to vary with time via a function of load bearing volume fraction as in the solidification theory. The development of cracks reduces the load bearing volume fraction with time, so that the overall behaviour of springs is a softening type. A reduction in the load bearing volume with time ensures a gradual reduction in the spring stiffness without violating prescribed retardation times. In some circumstances, depending on the boundary conditions, the stress in a structure can remain unchanged over a period of time. During this period, any cracks in the structure will continue to experience an increased opening due to creep. In other parts of the structure, again depending on the boundary conditions, the crack opening displacements may remain unchanged over a period of time, so that the stress will relax over these parts of the structure. In a large concrete structure, creep and relaxation may be taking place simultaneously in different parts or in the same part but at different times. There is thus a need for a visco-elastic tension softening model for ageing concrete that will cater for both creep and relaxation. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    A constitutive model coupling elastoplasticity and damage for cohesive-frictional materials (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 41-63 
    Details
    ISSN: 1082-5010
    Keywords: elastoplasticity ; damage ; bonded geomaterials ; triaxial testing ; intact and remoulded specimen ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In order to model the various phenomena which govern the mechanical response of bonded geomaterials under monotonic loadings, an elastoplastic model coupled with an elastic model with damage was developed, taking into account both the frictional and cohesive aspects of these materials. First, the principles at the base of the model are presented, as well as the physical meaning of the parameters which were used in the elastic model with damage. In order to illustrate the capabilities of the model to reproduce the mechanical behaviour of bonded geomaterials, we simulated triaxial tests on various materials: a deep cemented clay, whose heterogeneity from one specimen to another appeared mainly due to the calcium carbonate content; an assembly of sintered glass balls; and an artificially cemented sand. In this last example, various initial mean stresses allowed us to enlighten the brittle-ductile transition which was modelled by introducing the mean confining pressure in the damage evolution law. We demonstrated that the parameters of each part of the model could be adapted to reproduce the observed general trends. For weak bonds, the elastoplastic part played the predominant role, whereas for strong bonds, the elastic part with damage governed the mechanical behaviour. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    An investigation on the uniqueness of the incremental response of elastoplastic models for virgin sand (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 65-87 
    Details
    ISSN: 1082-5010
    Keywords: elastoplasticity ; sand ; constitutive modelling ; controllability ; instability ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The paper investigates the possibility of the occurrence of a multiplicity of homogeneous responses of soil specimens under the same incremental loading, and the associated non-controllability of the imposed loading path.It is shown that for non-associated elastoplastic strain-hardening constitutive laws, such a possibility exists even in the hardening regime. Only when the stiffness matrix is positive-definite is the incremental solution unique for any loading programme.A particular constitutive model is chosen and the shape of the loci of non-uniqueness is calculated for various loading programmes. It is shown that the conditions for the occurrence of a shear band and of a peak of the deviator stress in a triaxial undrained test can be seen as special cases of the theory presented. Accordingly, the so-called ‘instability line’ concept in undrained conditions is generalized. © 1998 by John Wiley & Sons, Ltd.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    ALE analyses of localization in wave propagation problems (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 105-125 
    Details
    ISSN: 1082-5010
    Keywords: localization ; non-local damage ; Perzyna viscoplasticity ; mesh adaptivity ; Arbitrary Lagrangian-Eulerian technique ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The computational modelling of localization of deformation in cohesive-frictional materials must be carried out in a proper, accurate and efficient manner. A proper solution can be obtained by using an enriched material description such as a non-local damage model or Perzyna's viscoplasticity model. However, still a large number of finite elements is needed for an accurate description of the localization zone. To improve efficiency, mesh adaption is applied here by means of the Arbitrary Lagrangian-Eulerian (ALE) technique. The ALE technique must typically be applied in combination with an enriched material model. Otherwise, the use of a standard model gives a zero-width solution of the localization zone and therefore remeshing results in a continuing decrease of finite element size. Implementation of this method requires the addition of convective forces in the equations of motion, transport of the state variables and the formulation of a remeshing strategy. The remeshing strategy heavily determines the success of the ALE method. Three examples of wave propagation have been treated and it is shown that a suitable remeshing strategy in combination with an enriched material model leads to proper, accurate and efficient analyses of the localization process. © 1998 John Wiley & Sons. Ltd.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Daphnis: a new model for the description of post-localization behaviour: application to sands (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 127-153 
    Details
    ISSN: 1082-5010
    Keywords: constitutive equations ; post-localization behaviour ; large strain ; interface model ; bifurcation ; shear band ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper addresses developments on a constitutive model able to describe the post-localized behaviour of structures composed by geomaterials. The behaviour of the shear band is defined by means of a specific non-linear constitutive equation in the framework of large strain. Concept of ‘consistency’ of this model with the CLoE model from which it is derived at the onset of localization is discussed. During the post-localization regime this model evolves in a specific way by introducing the concept of critical void ratio. After some recalls about the CLoE framework and about a Rice bifurcation analysis involving CLoE models, the basic concepts of the Daphnis model are introduced. The last part of this paper is devoted to numerical results on an initially homogeneous frictionless biaxial test. The behaviour of the sample is modelled by means of a plane Mohr Coulomb model defined in the CLoE framework and its associated Daphnis model is used to characterize the specific behaviour of the shear band in the post-localization regime. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    Development of a plasticity bond model for steel reinforcement (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 155-180 
    Details
    ISSN: 1082-5010
    Keywords: reinforced concrete ; bond model ; plasticity ; interface ; yield surface ; modelling ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The development of an interface, non-associative, plasticity model for bond between ribbed, steel bars and concrete is discussed. The model relates average local slip and radial dilation to average bond shear stress and radial confinement stress. The model partially accounts for the response of the damaged, finite-thickness region around the bar - the bond zone. The model is developed for standard steel bars that are initially unstrained. With simplifying assumptions, data for the components of a plasticity law are extracted from a key set of experimental results. In this paper, we emphasize the development of an expression for the yield surface for monotonic loading. While the forms of the model's components are empirically derived, they qualitatively reflect the mechanics of the mechanical interaction of ribbed bars with the adjacent concrete. A characteristic length, related to the rib pattern, helps quantify this interaction. The mechanics of the bond are difficult to characterize in a simple form, but the calibrated model only requires four physical properties and reproduces with acceptable accuracy experimental results with various levels of radial confinement stress. Model refinements are suggested for future work. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    FE-Simulation of compaction and solid-state sintering of cemented carbides (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 181-205 
    Details
    ISSN: 1082-5010
    Keywords: cemented ; carbide ; finite ; element ; compaction ; sintering ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: We have developed a tool for simulating the press cycle and the sintering cycle of cemented carbides. A constitutive model for compaction and tensile fracture has been implemented in the explicit FE programme LS-DYNA2D, and it has been tuned to experiments of hydrostatic compression, uniaxial strain and conventional triaxial compression. The programme simulates the complete compaction cycle in a robust manner. Friction against the tooling is properly taken into account. We have further developed a constitutive model for the stress-free solid-state sintering to also account for a mechanical stress field. The sintering model is based on physical concepts, diffusion parameters, free surface energy, dimensions of carbide grains, etc. of the constituents, and was tuned to successfully simulate the unloaded and loaded sintering of simple specimens. The models of compaction and sintering have a common set of state variables, such that after the compaction cycle, and at raising the temperature the sintering starts out with proper account of the residual stress field. Finally, the potential of the model is demonstrated by simulating the production cycle of a simple WC-Co tool piece until sintering to 75% of full density. The final geometrical shape of the specimen is compared to experimental data. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 10
    Electronic Resource
    Electronic Resource
    A superstable time-discrete scheme for the numerical integration of viscous constitutive equations (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 229-256 
    Details
    ISSN: 1082-5010
    Keywords: finite element method ; viscous constitutive equations ; time-discrete scheme ; stability ; superstability ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The general framework of the paper deals with the finite element modelling of mechanical problems involving viscous materials such as bitumen or bituminous concrete. Its aim is to present a second-order-accurate discrete scheme which remains unconditionally superstable when used for the time discretization of the linear and non-linear viscoelastic constitutive equations considered. After stating the space- and time-continuous mechanical problem we focus on the time discretization of these equations, considering three different schemes. For both of them sufficiently small values of the time step are required in order to ensure the superstability, whereas the third remains unconditionally superstable. Eventually, some numerical results are presented. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 11
    Electronic Resource
    Electronic Resource
    Numerical simulations of impacts using a discrete element method (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 257-276 
    Details
    ISSN: 1082-5010
    Keywords: impacts ; structural damage ; discrete element method ; dynamic loading ; scabbing ; perforation ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Impacts of rigid spherical nose shaped missiles on concrete beams are simulated with a discrete element method. The history of the structural damage of the beam is followed from the very first crushing and fracturing processes to the ultimate fragmentation step. Spalling, scabbing, penetration and perforation events are characterized and compared with real test cases of the civil engineering industry. It is found that these phenomena depend not only on the kinetic energy of the missile as predicted by some recent empirical laws but also on its momentum. This means that the dynamic impact loading time is determinant in the scabbing and perforation thicknesses. When the numerical data is plotted against the empirical rules determined from experimental data, the fit is good although the model is two dimensional. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 12
    Electronic Resource
    Electronic Resource
    Failure design of jointed rock structures by means of a homogenization approach (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 207-228 
    Details
    ISSN: 1082-5010
    Keywords: jointed rock masses ; stability ; failure ; yield design ; homogenization ; strength anisotropy ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Conceived as a potential alternative to the methods usually employed for evaluating the stability of jointed rock masses, the homogenization approach developed in this paper stems from the intuitive idea that, from a macroscopic point of view, a rock mass intersected by a regular network of joint surfaces may be perceived as a homogeneous continuum. The failure criterion of such an equivalent medium is theoretically determined from the knowledge of the failure conditions of the individual constituents, namely the intact rock matrix and joint interfaces. Owing to the existence of privileged material directions associated with the joint orientation distribution, this criterion turns out to be of the anisotropic frictional type, as shown by the closed-form expression obtained in the particular case of two mutually orthogonal joint sets. This criterion is then applied to the investigation of two illustrative engineering problems: the calculation of the load-bearing capacity of a shallow foundation on a jointed rock half-space and the stability analysis of an excavation. Both problems are handled by means of the kinematic method of yield design, making use of the previously determined macroscopic failure condition. The upper bound estimates thus derived appear to be significantly better than those obtained from a direct analysis in which the intact rock matrix and joints are considered separately. In spite of some limitations regarding its range of applicability, which are underlined throughout the paper, the homogenization approach may constitute an appropriate general framework for the design of densely jointed rock structures. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 13
    Electronic Resource
    Electronic Resource
    Experimental behaviour of fibre concrete slabs on soil (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 277-290 
    Details
    ISSN: 1082-5010
    Keywords: experimental analysis ; slabs on soil ; reinforced concrete ; steel fibres ; fracture energy ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The cracking control of plain concrete slabs on soil foundation requires the execution of joints with mechanisms of load transfer between adjacent panels. These joints increase the construction costs and, often, are the source of local damage and loss of service performance. Slabs reinforced with steel wire mesh have been used in order to increase the load-carrying capacity and to enhance the cracking control. However, the use of this conventional reinforcement increases the costs, mainly due to labour time spent on the arrangement and positioning of the reinforcement.Fibre-reinforced concrete is a recent material well fitted for applications in industrial floors on soil foundation. The cost of fibres is compensated by a faster construction process and a reduction in the number of expansion joints. The fatigue, impact and flexural strength are significantly improved when steel fibres are added to the concrete mix.The work developed aims to contribute to the on going research effort to clarify the behaviour of fibre-reinforced concrete slabs on soil foundation. For this purpose, an experimental and numerical investigation were carried out. The present article deals basically with the experimental work developed, describing the tests performed and discussing the main results obtained. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 14
    Electronic Resource
    Electronic Resource
    Enhanced consolidation in brittle geomaterials susceptible to damage (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 291-303 
    Details
    ISSN: 1082-5010
    Keywords: poroelasticity ; isotropic damage ; brittle geomaterials ; enhanced consolidation ; saturated geomaterials ; computational modelling ; indentation of geomaterials ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper examines consolidation behaviour of saturated geomaterials with a matrix component which is susceptible to damage. Finite-element-based computational model accounts for the alteration in both the deformability and permeability characteristics of the porous material due to damage evolution. The isotropic damage criteria governing the evolution of elastic stiffness and hydraulic conductivity parameters are characterized by the dependency of the damage variable on the distortional strain invariant. The computational procedure is utilized to evaluate the extent to which the time-dependent axisymmetric indentation behaviour of a rigid circular punch on a poroelastic half-space can be influenced by the damage evolution in the porous skeleton. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 15
    Electronic Resource
    Electronic Resource
    A multilayered mixed beam element in gradient plasticity for the analysis of localized failure modes (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 305-322 
    Details
    ISSN: 1082-5010
    Keywords: strain localization ; finite element ; mesh sensitivity ; regularization ; gradient plasticity ; multilayered concrete beams ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A gradient-dependent plasticity theory is applied to finite element solutions of static strain localization problems. Assuming weak satisfaction of constitutive equations, a multilayered beam finite element with a mixed character is developed. The plastic strain field is discretized in addition of the displacement field. A consistent Newton-Raphson algorithm for this approach is presented. Some examples are carried out in order to illustrate the approach and verify the performances of the element. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 16
    Electronic Resource
    Electronic Resource
    Sliding friction, Physical Principles and Applications by Bo N. J. Persson, Springer, Berlin, 1998 (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 365-365 
    Details
    ISSN: 1082-5010
    Keywords: Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: No Abstract
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 17
    Electronic Resource
    Electronic Resource
    Gradient-enhanced damage modelling of concrete fracture (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 323-342 
    Details
    ISSN: 1082-5010
    Keywords: concrete fracture ; computational modelling ; continuum damage mechanics ; localization ; regularization ; gradient enhancement ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Classical continuum damage theory for quasi-brittle fracture exhibits an extreme sensitivity to the fineness and orientation of the spatial discretization in finite element simulations. This sensitivity is caused by the fact that the mathematical description becomes ill-posed at a certain level of accumulated damage. The ill-posedness can be removed by the use of a gradient-enhanced damage model. In this model, higher-order deformation gradients give rise to a non-local effect, which regularizes the localization of deformation and thus renders numerical analyses mesh-objective.The mesh objectivity of the gradient-enhanced damage approach is demonstrated by the application to two concrete fracture experiments: a double-edge notched bar subjected to a uniaxial, tensile load and a single-edge notched beam under anti-symmetric four-point loading. Both the initiation and the propagation of damage can be simulated. Particularly the latter aspect calls for an appropriate definition of the strain measure which governs the evolution of damage. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 18
    Electronic Resource
    Electronic Resource
    On the linearization of the microplane model (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 3 (1998), S. 343-364 
    Details
    ISSN: 1082-5010
    Keywords: concrete modelling ; microplane model ; anisotropic damage ; consistent linearization ; localization analysis ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The paper addresses the microplane model in the context of localization analysis. Capable of reproducing experimental results of concrete specimens, the microplane model includes anisotropic damage in a natural and conceptually simple and explicit way. However, the efficiency of former microplane implementations suffers from the expense of the solution procedure being based on the secant stiffness method. Within this paper, the macroscopic constitutive equation derived by kinematically constraining the microplane strains to the macroscopic strain tensor is consistently linearized resulting in quadratic convergence of the Newton-Raphson iteration for the equilibrium equations. A fully three-dimensional model will be presented and linearized incorporating the two-dimensional case in a natural fashion. Furthermore, the localization criterion is analysed, indicating locally the onset of localization in terms of the acoustic tensor. Several examples demonstrate the features of the microplane model in predicting the material behaviour of concrete in tension and compression as well as in shear. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 19
    Electronic Resource
    Electronic Resource
    Book Review: Computational Mechanics of Reinforced Concrete Structures, Günter Hofstetter and Herbert A. Mang. Vieweg, Weisbaden, Germany, 1995. 366pp. (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 357-357 
    Details
    ISSN: 1082-5010
    Keywords: Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 20
    Electronic Resource
    Electronic Resource
    On shear band localization phenomena of liquid-saturated granular elastoplastic porous solid materials accounting for fluid viscosity and micropolar solid rotations (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 301-320 
    Details
    ISSN: 1082-5010
    Keywords: theory of porous media ; micropolar grain rotations ; liquid-saturated cohesive-frictional granular elastoplastic skeleton materials ; single-surface yield function ; non-associated flow ; shear band localization ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Elastoplastic deformations of cohesive-frictional liquid-saturated granular solid materials can be described by use of a macroscopic continuum mechanical approach within the well-founded framework of the theory of porous media (TPM). In the present contribution, the TPM formulation of the skeleton material is extended by micropolar degrees of freedom in the sense of the Cosserat brothers. Proceeding from two basic assumptions, material incompressibility of both constituents (skeleton material and pore liquid) and geometrically linear solid deformations, the non-symmetric effective skeleton stress and the couple stress tensor are determined by linear elasticity laws. In the framework of the ideal plasticity concept, the plastic yield limit is governed by a smooth and closed single-surface yield function together with non-associated flow rules for both the plastic strain rate and the plastic rate of curvature tensor. Fluid viscosity is taken into account by the drag force.The inclusion of micropolar degrees of freedom, in contrast to the usual continuum mechanical approach to the TPM, allows, on the one hand, for the determination of the local average grain rotations and, on the other hand, additionally yields a regularization effect on the solution of the strongly coupled system of governing equations when shear banding occurs. However, in the framework of the original TPM formulation of fluid-saturated porous materials, the inclusion of the fluid viscosity alone also yields a certain regularization on shear band computations. The numerical examples are solved by use of finite element discretization techniques, where, in particular, the computation of shear band localization phenomena is carried out by the example of the well-known base failure problem of geotechnical engineering. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 21
    Electronic Resource
    Electronic Resource
    Closed-form solution on the thermoplastic behaviour of a deep tunnel in a thermal-softening material (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 321-337 
    Details
    ISSN: 1082-5010
    Keywords: thermal-softening behaviour ; transient evolution ; corner flow ; analytical solution ; convergence-confinement concept ; thermomechanical interaction ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A closed-form solution of deep tunnel subject to an internal pressure and to an axisymmetrical time-dependent temperature field is presented. The material is supposed to have a thermal-softening behaviour, the cohesion decreasing with the temperature. The thermal expansion generates plastic zones with face flow and corner flow, which can coexist and interact. The explicit character of the solution allows rigorous demonstrations of the evolution of such plastic zones, as well as other interesting and fundamental properties of the thermoplastic behaviour of deep tunnels. On the other hand, the causal relationship between the thermomechanical loading and the structural response (convergence, extension of rupture zones) is rendered transparent, thanks to the simplicity of the analytical solution. The consequence of thermal-softening is clearly shown by comparison with the analytical solution for a constant cohesion previously established. Quantitatively, its importance is illustrated by a restricted parametric study, to which the analytical solution is ideally suited. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 22
    Electronic Resource
    Electronic Resource
    Modelling the strengths of engineering materials in three dimensions (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 339-356 
    Details
    ISSN: 1082-5010
    Keywords: biaxial tests ; combined stresses ; compressive strength ; engineering materials ; failure ; failure surfaces ; mathematical models ; tensile strength ; triaxial tests ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A general, three-dimensional failure criterion is presented. This criterion is formulated in terms of the first and third stress invariants of the stress tensor, and it involves only three independent material parameters. Although these parameters interact with one another, each parameter corresponds to one of three failure characteristics of material behaviour. These material parameters may be determined from any type of strength test, including the simplest possible, such as uniaxial compression and tension tests or biaxial tests for materials with cohesion and tensile strength, and by triaxial compression tests for materials without tensile strength. The procedure for determination of the three material parameters is demonstrated and comparisons between the failure criterion and experimental results are presented for different types of engineering materials. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 23
    Electronic Resource
    Electronic Resource
    A continuum model for periodic two-dimensional block structures (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 31-46 
    Details
    ISSN: 1082-5010
    Keywords: block structure ; elasticity ; homogenization ; Cosserat continuum ; dynamics ; large deformation ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A continuum model for regular block structures is derived by replacing the difference quotients of the discrete equations by corresponding differential quotients. The homogenization procedure leads to an anisotropic Cosserat Continuum. For elastic block interactions the dispersion relations of the discrete and the continuous models are derived and compared. Yield criteria for block tilting and sliding are formulated. An extension of the theory for large deformation is proposed. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 24
    Electronic Resource
    Electronic Resource
    Implicit integration of elastoplastic constitutive models for frictional materials with highly non-linear hardening functions (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 1-29 
    Details
    ISSN: 1082-5010
    Keywords: numerical integration ; constitutive modelling ; frictional materials ; highly non-linear hardening functions ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Constitutive relations in elastoplasticity may be formulated in a variety of ways, and different update algorithms may be employed to solve the resulting equations. Several implicit integration schemes, although some not widely used, have been suggested in the last years. Among them, the closest point projection method (CPPM) has proven to be an effective and robust integration scheme. In order to gain maximum control of the stress projection, a two-level CPPM iteration scheme is proposed. The hardening variables are fixed during the stress projection onto consequently fixed yield surfaces, and after the stress projection, new values of the hardening variables are calculated defining new yield surfaces. The update of the hardening parameters which, in general, may be highly nonlinear functions, may be determined by a combination of a Picard Iteration (PI) on the hardening variables and an adaptative order inverse interpolation (AOII) on the difference of subsequent iterations of the hardening variables.The integration scheme has been implemented in a general constitutive driver which has been formulated independent of the selected constitutive model and easily linked to finite element codes. A third stress invariant dependent, cone-cap elastoplastic constitutive model, referred to as the MRS-Lade, with a highly non-linear hardening function has been used to show the applicability of the proposed iteration scheme. Error analyses and accuracy assessment are presented along with some representative test results. © 1997 by John Wiley & Sons, Ltd
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 25
    Electronic Resource
    Electronic Resource
    Undrained instability of very loose Hostun sand in triaxial compression and extension. Part 2: theoretical analysis using an elastoplasticity model (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 71-92 
    Details
    ISSN: 1082-5010
    Keywords: undrained instability ; static liquefaction ; non-associated plasticity ; loss of uniqueness ; model validations ; very loose sand ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The characteristics of the loss of stability associated with the initiation of the static liquefaction phenomenon is obtained using the CJS model within the elastoplasticity framework. This model is based on the characteristic line concept. The determining factors involved in the prediction of this phenomenon and in the modelling process are identified. The importance of the elastic components is highlighted, in particular its non-linearity. The possibilities and the limits of the proposed model to describe the undrained behaviour of very loose sand are examined, taking into consideration the effects of the more or less complex stress history. Finally, the conditions leading to the appearance of the uniqueness domain are indicated. The findings of this theoretical study rely entirely on the experimental data presented in a companion paper, with emphasis on the triaxial tests on anisotropically consolidated samples. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 26
    Electronic Resource
    Electronic Resource
    Experimental analysis and theoretical interpretation of triaxial load controlled loose sand specimen collapses (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 93-120 
    Details
    ISSN: 1082-5010
    Keywords: loose sands ; load-controlled triaxial tests ; creep tests ; instability ; theoretical interpretation ; strain-rate sensitivity ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A series of triaxial load-controlled tests is performed.Finite load increments are imposed. The single load-steps are followed by a time period during which the axial load is kept constant.At low stress levels the mechanical response is stable and characterized by a continuous decrease in strain rate with time. At higher stress levels, the mechanical response changes and, subsequently, the collapse takes place.The collapse is unexpected and occurs at a stress level less than that associated with the steady state, experimentally observed by performing strain triaxial controlled tests.In order to interpret such a behaviour, a theoretical discussion is introduced. This is based on a dynamical reinterpretation of the micromechani cal fabric rearrangement of granular assembly.In particular, the role played by the kinetic energy of the system, as well as that played by the anisotropy of the microstructure, have been analysed. © 1997 by John Wiley & Sons, Ltd. Mech. cohesive-frictional mater. 2, 93-120 (1997)
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 27
    Electronic Resource
    Electronic Resource
    Undrained instability of very loose Hostun sand in triaxial compression and extension. Part 1: experimental observations (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 47-70 
    Details
    ISSN: 1082-5010
    Keywords: instability ; liquefaction ; laboratory tests ; undrained ; triaxial ; loose sand ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The undrained behavior of very loose Hostun RF sand in triaxial compression and extension tests is described. The samples are consolidated isotropically or anisotropically along constant effective stress ratio paths. Very loose sand exhibits partial liquefaction, deviator peak stress at relatively low to very low axial strain, gradual post-peak stress reduction to a small residual value at large strains, sharp loss of effective mean pressure due to generation of large pore pressure and overall volume reduction. The instability line of Lade is examined in the case of extension tests and extended for anisotropic samples. It is shown that monotonic and anisotropic consolidation strongly influences the instability concept. A higher positive anisotropic consolidation level produces a greater slope of the instability line in compression and a reverse trend can occur in extension. Complex stress history can develop a fossilized instability line depending on the amount of axial strain attained. Effective strain ratio increment at peak has an asymptotic stabilization effect. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 28
    Electronic Resource
    Electronic Resource
    Experimental micromechanical analysis of a 2D granular material: relation between structure evolution and loading path (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 121-163 
    Details
    ISSN: 1082-5010
    Keywords: granular materials ; micromechanics ; biaxial tests ; complex loading paths ; micro-macro relations ; fabric anisotropy ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper is concerned with micromechanics of Schneebeli material specimens composed of wooden roller stacks. Several laboratory tests are carried out to analyse the material behaviour under complex loading conditions, involving loading-unloading cycles and principal axes rotations. In order to characterize micromechanical deformation features and structure evolution, a series of pictures is taken during loading. Pictures are then digitized using a stereo device, obtaining the position of each roller. Starting from these data a number of computer programs, conceived for the purpose, allow us to measure micromechanical variables and to analyse their evolution.In the following, after the description of the devices employed in this research, macromechanical results are analysed to evaluate the reliability of the laboratory model. Then, local variables are introduced and the use of continuum mechanics to describe granular materials behaviour is discussed. Finally, the evolution of local kinematic variables is described, focusing interest on the evolution of specimen anisotropy. © 1997 by John Wiley & Sons, Ltd. Mech. cohesive-frictional mater. 2, 121-163 (1997)
    Additional Material: 35 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 29
    Electronic Resource
    Electronic Resource
    Implicit integrations in elastoplastic geotechnics (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 165-183 
    Details
    ISSN: 1082-5010
    Keywords: elastoplasticity ; pressure sensitive materials ; constitutive modelling ; dilatancy ; implicit integrations ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The paper presents the derivation of a fully implicit Newton algorithm for direct integration of constitutive equations, in extended stress-internal variable space, involving hardening or softening of a general dilatant isotropic elastoplastic geomaterial. All relevant derivatives are provided in tensor notation, thus facilitating implementation. The consistent, algorithmic tangent stiffness tensor is derived. The relative accuracy of a template algorithm is assessed on a number of examples by means of iso-error maps. We present a rather simple, one-increment example concerning convergence properties of the Newton iterative scheme at the global, finite element level, associated with the consistent tangent stiffness tensor for integrating the weak form of the equilibrium equations. © 1997 by John Wiley & Sons, Ltd. Mech. Cohesive-frictional mater. 2, 165-183 (1977)
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 30
    Electronic Resource
    Electronic Resource
    Enhanced finite element formulation for geometrically linear fluid-saturated porous media (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 185-203 
    Details
    ISSN: 1082-5010
    Keywords: fluid-saturated porous media ; enhanced element technology ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This contribution is concerned with a new mixed finite element formulation for geometrically linear Terzaghi-Biot type fluid-saturated porous media. To this end, an extended Hu-Washizu type mixed variational principle is presented for fluid-saturated porous continua. Then, a suitable discretization and its implementation are discussed, resulting in an improved element behaviour especially in numerical localization analyses. The intriguing element performance is firstly demonstrated for the case of localization within an elastoplastic compression problem. Finally, an elastoplastic slope stability problem is examined, whereby the new element formulation proves to render more pronounced failure modes as compared with a standard element expansion. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 31
    Electronic Resource
    Electronic Resource
    Modelling of pollutant migration in porous media with interfacial transfer: local equilibrium/non-equilibrium (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 205-221 
    Details
    ISSN: 1082-5010
    Keywords: pollutant diffusion ; advection ; porous media ; surface transfer resistance ; physical modelling ; homogenization ; model classification ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In the paper, an attempt to model local equilibrium and local non-equilibrium in pollutant migration in porous media is presented. Diffusion is assumed to occur in the pores as well as in the solid porous matrix. The macroscopic models are developed using the homogenization method (asymptotic expansion technique). The resulting macroscopic equations show either a one-concentration field or two-concentration fields or memory effects. The domains of validity of all the presented models are also determined. Local cell problems are provided to compute the effective diffusion tensors. The conditions for the local mass equilibrium assumption to be valid are derived in terms of the dimensionless characteristic parameters. The effect of pollutant source distributions is also investigated. © 1997 John Wiley & Son, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 32
    Electronic Resource
    Electronic Resource
    Coherent vortex structures in deforming granular materials (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 223-236 
    Details
    ISSN: 1082-5010
    Keywords: granular materials ; vortices ; discrete element method ; coherent structures ; proper orthogonal decomposition ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Discrete element models are used to investigate the formation of coherent structures within a deforming granular material. The numerical models predict the formation of coherent vortex-like structures, even when the boundary deformations introduce zero vorticity. We name these structures circulation cells because the particles instantaneously translate and rotate as a rigid body about a common centre. They occur for all the particle shapes and material properties tested. The size of these coherent structures range from approximately 20 to 600 particles, with the largest structures being limited by the test boundaries. Circulation cells are seen to play an important role in granular deformations including the formation of shear bands. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 33
    Electronic Resource
    Electronic Resource
    Dilation characteristics of confined concrete (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 237-249 
    Details
    ISSN: 1082-5010
    Keywords: concrete ; confinement ; dilation ; fibres ; plastics ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Confinement of concrete enhances it strength and ductility by restraining lateral dilation. The accuracy of a confinement model depends on how well it captures the dilation tendency of concrete. In recent years, external confinement of concrete by fibre composites has become increasingly popular for civil infrastructure applications. This includes fibre-wrapping of existing columns or encasement of concrete in a fibre reinforced plastics (FRP) shell. A total of 54-concrete-filled FRP tubes were tested in uniaxial compression under displacement control mode. Full instrumentation of the specimens has allowed the variation of tangent Poisson's ratio for concrete to be captured. The dilation trend of confined concrete is shown to be a function of jacket stiffness. In steel-encased members, once steel yields, confining pressure becomes constant and the jacket renders itself ineffective in containing the dilation of concrete. On the other hand, for linear-elastic materials such as fibre composites, a strain reversal occurs that results in containment of dilation. A method for predicting the dilation is developed that can be easily adopted in any active confinement model. Moreover, a new confinement model for FRP-encased concrete is discussed. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 34
    Electronic Resource
    Electronic Resource
    Hypoplastic model for cohesionless soils with elastic strain range (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 279-299 
    Details
    ISSN: 1082-5010
    Keywords: constitutive model ; hypoplasticity ; plasticity ; grain contacts ; intergranular strain ; strain-space plasticity ; recent history ; small strain ; ratcheting ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In order to eliminate ratcheting a so-called intergranular strain has been added to a hypoplastic constitutive model. This additional state variable represents the deformation of the interface layer between the grains. The new concept is outlined and comparisons with and without intergranular strain are presented. Some comments on numerical implementation and determination of material constants are made. A discussion on the uniqueness of the solution and objectivity of the rate of intergranular strain is added. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 35
    Electronic Resource
    Electronic Resource
    An experimental and theoretical study of a partially saturated collapsible rock (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 251-278 
    Details
    ISSN: 1082-5010
    Keywords: Pietra Leccesse chalk ; laboratory tests ; constitutive modelling ; capillary forces ; partial saturation ; collapsible rocks ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Experiments on Pietra Leccese chalk revealed that many of the material parameters describing its mechanical behaviour, such as the Young's modulus, the uniaxial compressive strength and the plastic yield stress, depend strongly on the water saturation and the ensuing capillary suction. The experimental results show that Bishop's generalized effective stress is not by itself adequate to explain the observed behaviour and in particular the spontaneous collapse which may occur upon water injection under stress. An elastoplastic constitutive model for partially-saturated collapsible rocks is proposed where the capillary suction is assumed to affect primarily the material properties related to the intergranular cohesion, such as the elastic stiffness, the plastic tension cut-off and pressure cap parameters. The model builds upon the well- established Mohr-Coulomb theory of elastoplasticity by including a pressure cap and considering the water saturation as an internal variable. In low levels of water saturation, as is often the case in oil reservoir formations, the experimental and theoretical results demonstrate the potential significance of capillary effects on the response of reservoir rocks, a mechanism that has been largely underestimated in the petroleum industry. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 36
    Electronic Resource
    Electronic Resource
    Three-dimensional yield strength properties of jointed rock mass as a homogenized medium (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 1-24 
    Details
    ISSN: 1082-5010
    Keywords: jointed rocks ; strength criterion ; homogenization method ; yield design ; anisotropy ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A comprehensive three-dimensional formulation for the strength criterion of regular jointed rocks is derived in this paper. The approach is based upon the implementation of the homogenization method of periodic media within the framework of the yield design theory. A rigorous explicit expression of the macroscopic criterion is given as a function of the strength properties of the intact rock and of the joints modelled as interfaces. Attention is focused on the particular case of an infinitely resistance intact rock. It is shown in particular how the relevant velocity jumps for the homogenized medium can be characterized from the introduction of the set of admissible stress vectors acting upon an elementary surface. The results make it possible to perform the static and kinematic approaches in order to address the stability analysis of rock masses cut by sets of regular joints, even for the three-dimensional geometries.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 37
    Electronic Resource
    Electronic Resource
    Time dependent mechanical behaviour of loose sands (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 45-73 
    Details
    ISSN: 1082-5010
    Keywords: loose sand ; load controlled triaxial tests ; creep tests ; time dependency delayed mechanical response ; elasto viscoplasticity ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The time dependency of loose sands mechanical behaviour has been experimentally analysed and theoretically interpreted. A series of load controlled triaxial tests, by imposing finite load increments, has been performed. The single load increments are followed by variable time periods, in order to carry out many classical creep tests.According to the authors, the considered time dependency is due to the internal fabric rearrangement of the granular assembly, i.e. to the plastic strain development with time.This mechanical peculiarity is theoretically interpreted by means of an elastoviscoplastic constitutive model. This is a very simple extension of a previous incremental elastoplastic constitutive model and appears to be capable to reproduce experimental data quite well.Finally, the importance of the considered time dependency is underlined, both by considering numerical solutions and in analysing unstable natural and experimental phenomena.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 38
    Electronic Resource
    Electronic Resource
    Plane shear waves and loss of stability in a saturated granular body (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 25-44 
    Details
    ISSN: 1082-5010
    Keywords: shear waves ; spontaneous liquefaction ; stability ; hypoplasticity ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A theoretical study of plane shear waves in a fully saturated granular medium is presented using a hypoplastic constitutive relation for the solid constituent. Dynamic equations for small disturbances about an initial state are derived and analysed with constitutive parameters for Karlsruhe sand. Permanent changes in stresses during the propagation of waves are shown to result in the liquefaction of the material. As follows from the equations, in the general case the propagation is characterized by two different wave speeds, corresponding to the plus or minus sign of the velocity gradient, i.e. to different directions of an instantaneous shear. The values of the wave speeds depend on the initial state (stresses and void ratio) as well as on the orientation of the wave with respect to the principal stresses of the initial stress tensor. If the granular material is loose enough and the initial stress state differs from the hydrostatic one, it is possible that one of the wave speeds becomes imaginary, i.e. physically does not exist. This case means a loss of stability of the body in the sense that a small boundary disturbance results in a flow of the whole mass which cannot be prevented by a boundary control. Such a solution can be viewed as a model of spontaneous liquefaction. The condition obtained for stability is compared with the one derived from the analysis of the second-order work.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 39
    Electronic Resource
    Electronic Resource
    Computational aspects of a softening plasticity model for plain concrete (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 75-94 
    Details
    ISSN: 1082-5010
    Keywords: concrete modelling ; softening plasticity ; fracture energy models ; stress return ; five parameter model ; improved predictors ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Several computational aspects of the fracture energy based softening plasticity model for plain concrete are considered. A need for a more robust stress return strategy is identified, as the basic closest point projection algorithm leads to regions of nonconvergence, associated with zones of high curvature near the compressive meridian close to the apex. The use of an intermediate stress return to an auxiliary surface to establish an improved predictor is proposed, in conjunction with a controlled scaling of stress return increments, ensuring convergence and providing an efficient and robust stress return strategy.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 40
    Electronic Resource
    Electronic Resource
    Editorial (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. iii 
    Details
    ISSN: 1082-5010
    Keywords: Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cfm.1600010101
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    A multiphase medium model for localisation and postlocalisation simulation in geomaterials (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 95-114 
    Details
    ISSN: 1082-5010
    Keywords: multiphase material ; strain localisation ; averaging theories ; pore pressure ; cavitation ; finite element method ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: It is recalled that negative water pressures are of importance in localisation phenomena of fully saturated, undrained samples of dilatant geomaterials. A model to simulate cavitation phenomena connected with such pore water tractions is developed and implemented in a simplified form in a dynamics code for partially saturated porous media. A case of localisation is studied from the onset of the instability up to the full developed shear band. The weak mesh dependence of the maximum effective plastic strain, due to the employed physical model, is also shown.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 42
    Electronic Resource
    Electronic Resource
    Experimental investigation of concrete fracture under uniaxial compression (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 115-127 
    Details
    ISSN: 1082-5010
    Keywords: concrete ; fracture ; uniaxial compression tests ; boundary restraint ; slenderness ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Localization of deformations has been investigated in a series of displacement controlled uniaxial compression experiments. Of main interest are the effects of specimen slenderness and friction between loading platen and specimen. Both effects have a direct influence on the development of localized fracture zones in the specimen. The results indicate that the use of a double layer of teflon with an intermediate layer of grease yields size-independent results as far as the pre-peak stress-strain behaviour and the peak strength are concerned. However, in terms of stress and strain, a significant influence of both the specimen slenderness and the amount of boundary restraint has been observed in the post-peak regime. It is found that the post-peak curves become almost completely identical when they are plotted in terms of nominal stress and post-peak displacement. For any type of loading platen used, the post-peak relative stress-displacement curves are found to be independent of the specimen height. Furthermore, since during post-peak localization relative sliding and movements of larger parts of the specimen are observed, the definition of a unique Poisson's ratio is virtually impossible.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 43
    Electronic Resource
    Electronic Resource
    Damage and localisation in elastic materials with voids (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 129-144 
    Details
    ISSN: 1082-5010
    Keywords: damage ; void growth ; softening ; localisation ; bifurcation ; rupture ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An extension of the theory of elastic material with voids to the case where the material undergoes an irreversible void growth is presented. The particularity of this theory is that the continuum is described by two kinematic variables: the displacements and the variation of the volume fraction of material in the porous continuum. Motion is controlled by two governing equations, the classical one involving the displacement or stresses and another one that involves the other kinematic variable, similar to the governing equation in heat conduction problems. The degradation of the elastic moduli is described in the model by a damage scalar variable. A simplified model where the damage variable is proportional to the irreversible variation of volume fraction of material is discussed. From the governing equations, it is deduced that the equation which governs the growth of damage involves the second gradient of damage and a material parameter which plays the role of an internal length according to the analysis of strain localisation. The finite element implementation of the theory is briefly presented. The two variables are discretised separately and the form of the equations to be solved is similar to those obtained in coupled thermoelasticity. One dimensional finite element results of strain localisation show that a proper convergence upon mesh refinement is obtained. The equation which governs the irreversible variation of volume fraction (or the damage growth) acts as a localisation limiter.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 44
    Electronic Resource
    Electronic Resource
    Failure criterion, flow rule and dissipation function derived from hypoplasticity (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 145-163 
    Details
    ISSN: 1082-5010
    Keywords: constitutive model ; hypoplasticity ; failure criterion ; flow rule ; dissipation function ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Failure criterion, flow rule and dissipation function derived from a class of incrementally non-linear, so-called hypoplastic, constitutive equations are presented. Although the hypoplastic model is developed without recourse to some concepts pertinent to pasticity theory, such as failure surface, plastic potential, flow rule and decomposition of deformation into elastic and plastic parts, it is shown how these concepts may be obtained as natural outcomes of the constitutive model. A connection of the hypoplastic model to Truesdell's hypoelasticity theory and of the derived failure criterion and flow rule to their hypoelastic counterparts is made. By defining the plastic strain rate properly, the dissipation surface is obtained based on the principle of maximum entropy production. Furthermore, the plastic potential is constructed with reference to the direction of plastic strain rate. Finally, the failure surface, flow rule and dissipation surface obtained with a specific hypoplastic constitutive equation are presented and compared with experimental results in the literature.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 45
    Electronic Resource
    Electronic Resource
    Homogenization for Granular Materials: non reversible behaviour (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 199-218 
    Details
    ISSN: 1082-5010
    Keywords: homogenization ; granular material ; yield surface ; elasticity ; plasticity ; modelling ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Using a homogenization framework, this paper proposes a description of the non-reversible behaviour of granular materials. First the basic equations are reviewed and some general elasticity results are presented with a comparison to DEM simulations. The global non-reversible behaviour is introduced by the definition of local conditions of contact stability: loss of contact and sliding. The first consequence is the possible definition of global yield surfaces and thus failure surfaces. These surfaces are compared to the usual plastic criteria. The influence of the different homogenization parameters introduced by the definition of localization and averaging operators is also studied. In the last section, a simulation of non-reversible behaviour is presented. Comparisons to experimental data are made in the case of simple loading paths (isotropic compression, triaxial test) as well as in complex loading histories.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 46
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996) 
    Details
    ISSN: 1082-5010
    Keywords: Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cfm.1600010201
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Validity and Limits of the Effective Stress Concept in Geomechanics (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 219-234 
    Details
    ISSN: 1082-5010
    Keywords: effective stress ; theory of mixture ; compressibility ; pore-water pressure ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The effective stress concept in geomechanics advocated by Terzaghi is historically reviewed and the mechanical interpretation of this concept is clarified based on the theory of mixtures. In the interpretation of the effective stress concept, both the compressibility of the constituents and the balance of force are taken into consideration. The effectiveness of the effective stress comes from the fact that the descriptions of the effective stress in undrained and unjacketed conditions are approximately equal, although the role of the pore-water pressure under different test conditions is not the same. It is shown that the effective stress concept is also applicable to soft rock. Finally, classical interpretations and various definitions of the effective stresses are critically examined.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 48
    Electronic Resource
    Electronic Resource
    Creep, damage and failure around large rectangular-like caverns and galleries (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 165-197 
    Details
    ISSN: 1082-5010
    Keywords: creep ; dilatancy ; damage ; stability ; failure ; galleries ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An analysis of stability of rectangular-like galleries or caverns is developed from the point of view of creep, creep failure and short-time failure. The initial stress distribution around the cavern just after excavation is obtained with an exact elastic solution. Further this solution is used in conjunction with an elastic/viscoplastic non-associated constitutive equation to determine first the domains around the excavation where the rock becomes dilatant, where compressible, and where a short-time failure is expected. This constitutive equation is further used to determine the creep of the rock around the opening, and where and when a creep failure is to be expected due to excessive dilatancy. It is shown that the location of the incipient creep failure depends on the stress concentration due to the presence of the ‘corners’, on the possible elongated shape of the cavern, and also to the stress concentration induced by the far field stresses. This location also depends on the internal pressure and on depth, and it can be determined quite accurately. Thus the location of incipient creep damage depends on a variety of parameters and the determination of this exact location is very important, and is described in this paper. It is shown that the evolutive damage is spreading mainly in the direction of minimum far field stresses or in the direction of greater elongation of the cross-section. The same constitutive equation allows us to determine the creep convergence (or divergence) of the walls, where this creep is quite fast and when for the first time the incipient creep failure due to dilatancy is to be expected. This timing depends primarily on the magnitude of octahedral shear stress. The time up to creep failure is shorter if this stress is larger (close to the short-term failure value), but tends towards infinity if the stress is relatively small (close but still above the compressibility/dilatancy boundary). Once the various failure modes are well understood the orientation and magnitude of far field stresses can be determined by this analysis if not known a priori. Also, once the location of losing the stability and that of the volume of rock involved in fast creep and creep failure are determined, one can suggest the optimal design of a support. The way in which the stress variation is influencing the above mentioned problem will be discussed in forthcoming papers. While the authors recognize the importance of the pre-existing rock discontinuities in the overall cavern stability, it was thought that a better understanding of this stability starts from analyzing a rock without such pre-existing discontinuities. The examples are given for rock salt.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 49
    Electronic Resource
    Electronic Resource
    Announcement (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. i 
    Details
    ISSN: 1082-5010
    Keywords: Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cfm.1600010202
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Boundary element analysis of the pullout behaviour of an anchor bolt embedded in concrete (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 235-249 
    Details
    ISSN: 1082-5010
    Keywords: boundary element method ; concrete ; fracture mechanics ; fictitious crack model ; crack growth ; contact mechanics ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A boundary element formulation for the analysis of pullout behaviour of an anchor bolt embedded in concrete is presented. The pullout analysis involves modelling two different bodies (i.e. anchor head and concrete) which are in contact over a certain region. The fracture of concrete is represented by the fictitious crack model (FCM) in which the fracture zone is replaced by applying closing forces on both crack surface. The FCM in conjunction with the boundary element method (BEM) allows the simulation of crack growth in concrete in a straight forward manner without remeshing. The crack path need not be known in advance as it is calculated during the iteration process. The numerical results obtained are compared with the round-robin analysis of pullout test proposed by RILEM TC 90-FMA.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 51
    Electronic Resource
    Electronic Resource
    A hypoplastic relation for granular materials with a predefined limit state surface (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 251-271 
    Details
    ISSN: 1082-5010
    Keywords: constitutive law ; plasticity ; hypoplasticity ; asymptotic state ; limit surface ; sand ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A hypoplastic theory for granular materials developed by Gudehus and Bauer is discussed. The description of asymptotic states is of particular interest. Three forms of asymptotic states are defined. Useful criteria to describe the tensorial part of the constitutive relation is developed for one of them, namely for the critical states. The terms proposed by Wu are correlated to the well-known formulations of elastic plastic theory: the Drucker/Prager model and the yield condition by Matsuoka/Nakai. The suitability of the Matsuoka/Nakai criterion for critical states is discussed.Specification of tensorial functions follows in two steps. First the hypoplastic Drucker/Prager model is developed, and then the limit condition by Matsuoka/Nakai is implemented. The resulting tensorial functions require the critical friction angle as the only material constant. The limit condition in critical states obtained from the hypoplastic law coincide with the one by Matsuoka/Nakai. A more comprehensive hypoplastic constitutive relation based on these new tensorial functions is discussed and applied to simulations of element tests. These numerical results are compared with experimental results for sand.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 52
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996) 
    Details
    ISSN: 1082-5010
    Keywords: Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cfm.1600010301
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    A matrix formulation for the elastoplastic homogenisation of layered materials (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 273-294 
    Details
    ISSN: 1082-5010
    Keywords: homogenisation ; layered media ; non-linear analysis ; plasticity ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this article attention is given to the homogenisation of periodic layered materials. Based on the assumption of a homogeneous state of stress and strain in each layer, a novel matrix formulation capable of representing the elastic behaviour of the composite material is established. The matrix formulation yields a much clearer implementation of linear elastic homogenisation algorithms and a relatively straightforward extension to inelastic behaviour. The theory of plasticity, which is adopted to describe the inelastic behaviour, follows modern concepts, including a unconditionally stable implicit Euler backward return mapping, a local Newton-Raphson method and a consistent tangent stiffness matrix. A comparison between the homogenised continuum and the standard continuum with an exact discretisa tion of the geometry of the composite shows excellent agreement, both in the presence of elastic and inelastic material behaviour.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 54
    Electronic Resource
    Electronic Resource
    Time-dependent tension softening (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 295-304 
    Details
    ISSN: 1082-5010
    Keywords: creep ; effective spring concept ; micromechanical model ; relaxation ; rheological model ; softening-type spring ; tension softening ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A methodology that combines a rheological model for viscoelastic behaviour with a micromechanical model for tension softening through the effective spring concept is developed for materials exhibiting both tension softening and time-dependent behaviour. Spring elements with softening characteristics and dashpot with varying viscosity are used for this purpose. The characteristics of the spring elements and dashpot are obtained from a micromechanical model which relates the microstructure of the material to its tension softening response. The softening-type springs ensure gradual reduction in stiffness, whereas the dashpot with varying viscosity ensures that the retardation and relaxation times equal prescribed values. In this way, both the stress and crack opening are allowed to vary with time to reflect the real behaviour of a time-dependent tension softening material. The methodology is illustrated on the simple Poynting- Thompson rheological model, without restricting its application to more sophisticated models.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 55
    Electronic Resource
    Electronic Resource
    Numerical analysis of concrete structures subjected to alkali-aggregate reaction (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 305-319 
    Details
    ISSN: 1082-5010
    Keywords: concrete structures ; alkali-aggregate reaction ; plasticity ; finite elements ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper a simple continuum theory, as recently proposed by Pietruszczak (Int. J. Computers Struct., 58, 1093-1099 (1996)), is applied to describe the mechanical effects of the alkali-aggregate reaction in concrete structures. The formation of alkali- silica gel leads to a progressive expansion of the material. The progress in the reaction is assumed to be coupled with the degradation of mechanical properties, the latter described within the framework of elastoplasticity. The paper discusses the details of the numerical implementation of the constitutive model, including an implicit integration scheme and the computation of an updated tangent operator. Numerical examples are provided to assess the performance of the proposed algorithm. The formulation is then used to analyse the junction between the right-wing dam and the water intake structure of the Beauharnois powerhouse situated in Quebec (Canada). A non-linear 3D finite element analysis is performed simulating the time history of the deformation due to continuing reaction.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 56
    Electronic Resource
    Electronic Resource
    A unilateral damage model for masonry based on a homogenisation procedure (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 349-366 
    Details
    ISSN: 1082-5010
    Keywords: damage ; fracture energy ; homogenisation ; masonry ; mesh dependence ; unilateral effect ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: By considering masonry as a composite material, its mechanical properties are obtained by taking into account the properties of the components (bricks and mortar) through a homogenisation technique. To describe the behaviour of the material components a unilateral damage model is proposed. This model, based on the introduction of three damage variables, describes the behaviour of brittle materials subjected to alternating tensile-compressive cyclic loads. The model is applied to the simulation of tests on masonry panels and miniaturised walls; numerical results are discussed and successfully compared with experimental data.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 57
    Electronic Resource
    Electronic Resource
    Crush-crack': a non-local damage model for concrete (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 321-347 
    Details
    ISSN: 1082-5010
    Keywords: damage ; dilatancy ; failure-modes ; fractures ; localization ; shear ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A model is presented based on the non-local damage theory. It sets out to describe the behavior of concrete under free-variable loads, which are constant in sign. Its purpose is to analyze shear behavior and high strain-gradient localized problems, and it takes Mazar's model as a starting point with reference to the basic idea of a scalar isotropic non-local damage controlled by principal tensile strains. In addition, the other two main features are an internal variable denoted to the control or reversible volumetric expansion in compression, and irreversible strains aimed at modelling crushing in compression and cracks both in tension and compression. As a consequence, induced-anisotropy, dilatancy and path-dep endency can be reproduced. In particular, the modelling of micro- and macrocracks makes it possible to capture mixed-mode cracking as well as aggregate interlock, which requires a residual stiffness to guarantee the transmission of transversal and normal stresses for assigned slips. The model requires the knowledge of the material response in uniaxial tension and compression, and biaxial compression tests which can be introduced directly by adopting experimental curves, or by means of a reduced number of parameters. The effectiveness of the model is shown through comparisons with several sets of experimental tests on both small specimens, assumed to be homogeneous, and boundary value problems.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 58
    Electronic Resource
    Electronic Resource
    Implicit integration and consistent linearization for yield criteria of the Mohr-Coulomb type (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 367-383 
    Details
    ISSN: 1082-5010
    Keywords: plasticitity ; isotropy ; Mohr-Coulomb ; consistent linearization ; algorithmic tangent stiffness ; multisurface plasticity ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper, we discuss the efficient treatment of yield criteria that are of the Mohr-Coulomb type for elastic and plastic isotropy. On the basis of the fully implicit method, we derive the explicit expression for the integrated stress along with a flow rule that represents volumetric non-associativity. The integration algorithm covers all the possible cases of regular, corner and apex solutions including the suitable indicator for each case. We also establish the consequent consistently linearized tangent stiffness modulus tensor, which is shown to appear in the form of an additive modification of the continuum tangent stiffness tensor. The convergence properties of the consistent tangent stiffness tensor are compared with its feasible approximations. The results indicate the strongly sensitivity to the proper treatment of the corner conditions at the establishment of the ATS-tensor.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 59
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996) 
    Details
    ISSN: 1082-5010
    Keywords: Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cfm.1600010401
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Examination of the possibility of a fluid-mechanics treatment of dense granular flows (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 1 (1996), S. 385-403 
    Details
    ISSN: 1082-5010
    Keywords: granular flow ; constitutive equation ; simple fluid ; friction ; collision ; microstructural model ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The aim of this paper is to examine the possibility of a simple fluid-mechanics treatment of rapid dense granular flows. In other words, we examine whether the constitutive equation can be sought in a simple relationship between the strain-rate and stress tensors. With this aim, we first show that an inclined channel is an appropriate device for providing rheological data. Here we provide a complete rheometrical treatment, which allows to infer the shear-stress/shear-rate curve (for simple shear flows) from the flow-depth/mass-flow-rate curve. Experi-ments performed with glass beads and sand grains revealed an apparent decrease in the shear stress with increasing shear rate. We then demonstrate that this result, although paradoxical, is not unphysical. Moreover, more detailed theoretical analysis shows that the main issues raised by our experiments may be overcome by ‘microstructural’ models. We finally give two examples of models including a single microstructural parameter, which are able to qualitatively account for the main features of our experiments.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 61
    Electronic Resource
    Electronic Resource
    Compatibility of poly(ethylene 2,6-naphthalate) and poly(butylene 2,6-naphthalate) blends (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1807-1810 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends prepared from poly(ethylene 2,6-naphthalate) (PEN) and poly(butylene 2,6-naphthalate) (PBN) show only partial miscibility judged from their glass transition temperatures. Two distinct mechanical behaviors are observed: brittle for the blends 〈 20 wt% of PBN, while ductile 〉 20 wt% of PBN. The experimental modulus and strength values of the blends are within the predicted values according to Kleiner and Paul models, respectively. This means that PEN/PBN blends are somewhat compatible based on their tensile properties. Especially for 20 wt% of PBN blend, the high modulus and strength are observed. The viscosity of the blend is high, which may imply a somewhat entangled morphology in the amorphous state.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352210
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Masthead (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352301
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Effects of mixing porcedures on properties of compatibilized polypropylene/nylon 6 blends (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1821-1833 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The paper consides the effects of compatibilization with maleic anhydride grafted polypropylene (PP-g-MAH) on the propertie of immiscible blends of polypropylene (PP) and nylon 6 (N6). We prepared the blends by three different mixing processes; single-step blending, two-step blending with reactive premixing, and two-step blending with nonreactive premixing, to determine the effective mixiing process for fine morphological structure thermal stability, and mechanical properties. Dynamic melt reheological properties were measured to examine the modification of elastic properties by the compatibilizer. In addtion, thermal analysis was also carried out to detect the change in crystallization and thereby to probe the degree of compatibilizaton. The results show that compatibilized blends prepared by teh single-step process exhibit improved phase morphology, thermal stability, and mechanical properties for dried conditions, compared with other blend types. Finally, the water absorption test indicates that the added compatibilizer yields enhanced water resistance in spite of the strong intrinsic hydrophilicity of N6. In particular, two-step blending with reactive premixing is most effective in improving water resistance and reducing degradation of mechanical properties after moisture absorption.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352302
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    A hybrid numerical technique to model 3-D flow fields in resin transfer molding processes (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1834-1851 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A hybrid two-/three-dimensional solution technique is presentedto model 3-D flow fields in resin transfer moeling using Darcy's low. The 3-D flow field is only solved for regions where all three velocity components are significant, thus largely reducing the number of unknowns. Elsewhere, the commonly used 2-D approximation for flow in thin gaps between plates is employe.d The method is applied to regions where the flow splits, such as T-joints. Because of the uncertainties associated with an accurate determination of the permeability in these regions, a simplified decompled procedure is procesed, which reduces the computational complexity. In this procedure, the flow front is advanced using the 2-D formulation. The 2-D formulation also provides the boundary conditions for the subsequent computation of the 3-D flow field without feedback of flow field information to the 2-d model. The governing equations are solved using boundary fitted coordinate systems (BFCS) together with the finite difference method (FDM). Numerical as well as algebraic grid generation and domain decomposition are employe dto generate grids that always concide with the continuously deforming and enlarging flow domain. Results that include the trackingof numerical tracer particles to visualize the three-dimensionality of the flow field are presented for isothermal flow of a Newtonian fluid through a T-joint. This detailed flow field description is expected to form the basis for a rather accurate simulation of quantitities that largely depend on the fluid particle pathlines, such as the degree of cure. The method is also extendable to shear-thinning fluids as well as to 3-D flow in the vicinity of the flow front.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352303
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Theory of competition between breakup and coalescence of droplets in flowing polymer blends (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1872-1877 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The Smoluchowski equation for the breakup and coalescence of dispersed droplets has been solved for flowing polymer blends. A scaling form for the distribution of droplet sized derived and published for a system of clusters with fragmentation and coagualation was used in our dervation. Equations are developed here for the average droplet size and for the characteristic time of transition to steady state flow of blends with a high content of the dispersed phase. Expressions reasonably describing the average size of droplets for all concentrations were obtained by a theory modification. Measured dependences of droplet size on the blend composition can be matched only if simultaneous collisions of three and more droplets are considered. The results of the theory indicate that the mechanism of droplet breakup (formation of pieces with the same or different volumes) has only a small effect on their average size in concentrated systems. The dependence of droplet size on the shear rate in flow is determined by properties of the blend components, and is generally nonmonotonic.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352306
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Performance of reprocessed multilayer LDPE/nylon-6 film (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1878-1883 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Multilayer LDPE/nylon-6 films with an overall content of 71 wt% LDPE, 24 wt% nylon-6, and 5 wt% PE-based tie-layer adhesive were reprocessed under both minimal and extensive mixing conditions. Thermal and mechanical properties, oxygen and water vapor permeability, and morphology of the reprocessed samples were determined. The modulus and yield stress of the reprocessed films fell between those of the pure homopolymers, whereas percent elongation at break and energy-to-break for all reprocessed films were less than those of the homopolymers. In minimally reprocessed film, layering of LDPE (low-density polyethylene) and nylon-6 was retained, whereas in extensively mixed samples, nylon-6 domains were spherical and ranged from 0.2 to 7 μm. Minimally reprocessed film exhibited good O2 and H2O vapor barrier properties, whereas extensively-mixed samples had poor barrier properties. Properties of well-mixed blends prepared both with and without adhesive showed that 5 wt% adhesive did not compatibilize the LDPE and nylon-6 components.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352307
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Assessment of residual stresses during cure and cooling of epoxy resins (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1895-1898 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new stress monitoring technique, a stress-tracking device, is described here. It has been used to study some important properties of epoxy resin. Residual stresses, including a curing shrinkage stress and a cooling shrinkage stress, were measured automatically and continuously during curing and cooling. Simultaneously, information such as an apparent gelation time and glass transition temperature were obtained directly during the experiment. These epoxy resin properties were related to the extent of cure. Varying cure temperature produced changes of cure behavior, which resulted in different residual stresses.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352309
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Study of reaction injection molding of polyurethane microcellular foam (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1899-1906 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Processing of microcellular foam was investigated for the feasibility of production of tough and lightweight polyurethanes. To increase the nucleation rate in a gas-supersaturated resin, ultrasonic excitation was applied to the mixture of polyol(polyether-based polyol) and isocyanate(diphenyl methane diisocyanate). A microcellular structure was produced by two sequential steps, i.e., supersaturationof the polyol resin with nitrogen gas at elevated pressure and ultrasonic bubble nucleation right after the impingement mixing of two components of the polyurethane system. Theoretical analyses based on nucleation theories were employed to predict the rate of nucleation in the gas-supersaturated polyurethane. The rate of nucleatio in the resin was predicted by classical nucleation and cluster theories. In the experimental investigation, ultrasonic excitation was applied to increase the nucleation rate in the resin that had been saturated by nitrogen at a saturation pressure 〈 2.0 MPa.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352310
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Modeling the mechanical properties in polypropylene/polyamide-6 blends with core shell morphology (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1917-1922 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polypropylene/Polyamide-6 (PP.PA) blends containing maleic anhydride grafted elastomers were prepared by reactive blending. Three different types of core shell morphologies were obtained and characterized by transmission electron microscopy (TEM). The midulus of these elastomer midified PP/PA (70/30) blends with core shell type morphology is compared to predictions derived from the Kerner model. The multiphase morphology of these blends could be modeled by sequential application of the Kerner equation to two-phase subinclusions. Using morphological data ontained by TEM, good agreement between experimental and calculated values was ontained. The results are used to tailor PP/Pa-6 blends combining stiffness and toughness.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352402
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Creep analysis of thermiplastics using stress relaxation data (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1931-1937 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: One of the major factors limiting the use of thermoplastics in engineeing applications is the inadequacy of existing design data. Much of the data do not span appropriate ranges of stress, strain, time, or temperature. This study addresses the need to develop an accelerated method for generating long-time design data to support the innovative use of engineering thermoplastics. In particular, stress relaxation tests (SRT) were performed on polycarbonate (PC) and midified poly(phenylene oxide)(PPO), and used to generate time-dependent design data through the short-time measurement of the material's current state without dependence on elastic modulus. The test results and analyses reported here indicate the SRT method to be an efficeint means of generating accurate and repeatable creep and secant modulus data which may be directly used in design. Therefore, SRT shows great potential both as a design parameter development tool, and as a quality control instrumetn for assessing batch-to-batch variability.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352404
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Blockiness of olefin copolymers and possible microphase separation in the melt (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 18-27 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Solid-catalyzed copolymerization reactions of ethylene and α-olefins can produce complex mixtures generally regarded as “polyethylenes” (including linear low-density polyethylene). The selective nature of those catalysts can lead to block-like character in segments of polymer molecules, and these segments are sufficiently dissimilar (from a thermodynamic viewpoint) to allow for the possibility of microphase separation in the melt. Such a molecular-level phase separation would substantially alter the melt rheology, the crystallization process, and hence the mechanical and optical properties of the resulting product. It would, in principle, be identical to those occurring in conventional well-defined block copolymers, allowing the thermodynamic models developed for those systems to be extended to block-like polyolefins.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350104
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Influence of processing history on the properties of a thermotropic copolyester/polycarbonate blend (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 52-63 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Relationships between the rheological, morphological, and tensile properties of an immiscible blend of 25 wt% of a thermotropic liquid crystalline polymer (LCP) with polycarbonate are presented. The shear viscosity of the blend is intermediate between the two constituent materials, and indicates immiscibility in the melt. Extrudate swell behavior is examined and found to be closely related to that of polycarbonate. The morphology of the dispersed LCP phase varies between droplets and oriented fibrils, and is highly correlated with changes in tensile properties. Fibrils are associated with increased tensile modulus, and their development is favored in the elongation flow fields present in the spinline and in the die convergence section. In all cases, blend stiffness is less than that predicted for a continuous fiber-reinforced composite. Enhanced tensile modulus is associated with both extrusion from shorter length dies and increases in spinline draw ratio, with the latter proving the most important in fibril formation.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350108
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Masthead (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350101
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Preamble (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1-1 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350102
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    History of commercial polymer alloys and blends (from a perspective of the patent literature)Based on: encyclopaedic dictionary of commercial polymer blends, L. A. Utracki, ed., ChemTech Pub., Toronto, Canada (1994). (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 2-17 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer blends are defined as mixtures of at least two polymeric species. Thus, the first patent polymer blend was a mixture of natural rubber, NR, with gutta percha patented by Alexander Parkes, an artist of Birmingham, in 1846. The first man-made polymer, nitrocellulose, NC was prepared by Braconnot in 1833. The resin was commercialized in 1868, but its first blends (with NR) were patented three years earlier. The first patent on blends of two synthetic polymers was granted in 1928 for poly(vinylchloride)/poly(vinylacetate), PVC/PVAc (latex blending). During the intervening 65 years, the polymer blend patent literature grew at an exponential rate; since 1983 the annual output has doubled, to exceed 3000 patents/year in 1993.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350103
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    Instrumented impact evaluation of a toughened carbon fiber epoxy composite (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 129-136 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Instrumented impact testing and analysis were performed on an interlaminartoughened carbon fiber epoxy composite (Toray 3900-2/T800H) and a conventional (untoughened) epoxy composite (Fiberite 934/T300). Severity of impact was varied by using a wide range of impact energy. The effect of difference in the tup of the impact instrument was discussed. The residual compressive strengths after compact (CAI's) were measured by using a universal mechanical tester. The impact damage and delamination resistance of the toughened and conventional composites were quantitatively compared. At the same impact energy, the extent of damage was much less severe and the CAI was higher for the toughened composite. Relationships between the CAI's, the state of impact damage, and impact energy were investigated. Impact damage mechanisms for these two composites were not exactly the same. The impact damage of the conventional composite exhibited much greater extents of delamination. By contrast, interlaminar delamination in the toughened composite was found to be significantly suppressed, and the impact damage was more dominated by controlled matrix cracking/fiber damage, instead of catastrophic delamination. As a result, the CAI's of the toughened composite exhibited a monotonous decrease with increase in the impact energy and in the linear dimension of extents of damage.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350202
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Melting behavior and thermal properties of high density polythylene (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 151-156 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Thermal diffusivity of high density polyethylene (HDPE) was studied over a wide range of temperatures (25 to 200°C) by melting powdered HDPE in a cylindrical mold at several pressures (101.3 to 5065 KPa gage) and recording the temperature profiles at several radial positions. The energy equation was solved numerically for cylindrical geometry. The thermal diffusivity of HDPE was fit as a function of temperature, porosity, and pressure.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350205
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Re-examination of a proposed model for nonisothermal crystallization kinetics (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 170-172 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This communication is a theoretical re-examination of the model proposed by Choe and Lee for the nonisothermal crystallization kinetics of semicrystalline polymers.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Crosslinking in halogen containing novolac electron beam negative resists (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 180-183 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Halogenophenol novolac (HPN)-based negative resists exhibit excellent sensitivity and pattern resolution properties. The HPNs act as synergists for crosslinking with other irradiation labile compounds such as naphthoquinone diazide and bisazide vs. hydrogen halide (HX) elimination reaction, resulting in additional crosslinking, probably by aryl radical recombination and/or addition. We describe a new resist formulation based on HPN binder and melamine crosslinker (Cymel 303). In this case the irradiation induced HX elimination additionally catalyzes the melamine crosslinking.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350210
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    Morphology and mechanical properties of virgin and recycled polyethylene/polyvinyl chloride blends (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 64-71 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this study, blends of virgin and recycled polyethylene (PE) and poly(vinyl chloride) (PVC), with a methylmethacrylate-ethylacrylate copolymer as a processing aid, were prepared in the molten state. Different additives such as ethylenevinylacetate copolymers, ethylene-methacrylic acid ionomer, and two peroxides (dibenzoyl and dicumyl), in the presence of a coupling agent, were used to compatibilize the blend or possibly induce graft structures. The blends' morphologies, tensile properties, and impact properties were studied. For blends with low copolymer concentration (below 3 wt%) the mechanical test data indicated a good performance. In the case of blends with ethylene methacrylic acid ionomer, improvements in the mechanical properties were obtained also at higher additive concentrations. Of the two peroxides, better results were obtained using the dibenzoyl one. The morphological studies indicated that the blends that showed good mechanical properties were better dispersed and had improved interphase adhesion.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350109
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Performance blends based on recycled polymers (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 72-78 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The recent growth in the post-consumer recycling of plastics presents an opportunity for developing new, value-added blend products from the recycled polymers. However, in order to develop blends with useful performance characteristics, suitable techniques of compatibilization and impact modification must be employed. In this study, reactive toughening and compatibilization techniques have been found to be particularly useful in achieving high thermal embrittlement resistance in the blends of recycled poly(ethylene terephthalate) containing functionalized ethylene copolymers and polycarbonate. Reactive compatibilization of recycled polyolefin blends with poly(ethylene terephthalate) and polyamide has also been investigated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350110
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Masthead (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350201
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Development of polymer blend morphology during compounding in a twin-screw extruder. Part IV: A new computational model with coalescence (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 115-127 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In Part II of this series of publications, the first generation model of morphology evolution during polymer blending in a twin-screw extruder was presented. The model was based on a simplified flow analysis, and an assumption that dispersion occurs via drop fibrillation followed by disintegration. In the present Part IV, several modifications of the model are discussed. (i) The flow analysis was refined by computing the pressure profiles. (ii) The flow paths and strain history of the dispersed droplets within the screw elements are computed directly, which makes it possible to determine the drop susceptibility to deformation and break. (iii) Besides the fibrillation mechanism, a drop-splitting mechanism for low supercritical capillary numbers is incorporated. (iv) The choice of breakup mechanism is based on micro-rheological criteria. (v) The coalescence effects are taken into account. (vi) The theoretical model is self-consistent, without adjustable parameters. The validity of theoretical assumptions was evaluated by comparing the model predictions with the experimental droplet diameters at different positions in the twin-screw extruder.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350114
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Water sorption in a novel liquid crystalline epoxy resin (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 137-143 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Water sorption tests have been carried out for a novel epoxy resin having liquid crystalline character. The sorption isotherm. Relative to the expoxy resin cured in the nematic phase, does not indicate any substantial difference from the resin cured in the isotropic state. This is an indication that, as far as this class of thermosets is considered, the liquid crystalline order does not affect mechanism and equilibrium values of water uptake.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350203
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Microwave processing of two-phase systems: Composites and plymer blends (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 144-150 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The objective of the current paper was to extend the relationships between complex polymer structures and microwave absorptivity that were formulated in the first three papers of this series (1-3). The microwave processing of composite and polymeric blends via a cylindrical resonance wave cavity and a rectangular standing wave applicator is described. These polymeric materials were irradiated in a low power (〈 100W) electric field at 2.45 GHz. Graphite-epoxy laminates were processed in both standing and traveling wave applicators. Rapid heating and curing were achieved in both cases. An observation of significance was that, with proper tuning of the traveling wave device (the precursor of a protable repair tool), it proved to be highly effective in processing. Additionally, a compatible blend of poly(methyl methacrylate) and poly(vinylidene fluoride) was heated in and applicator and the rates of temperature rise were demonstrated to depend upon morphology.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350204
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Stress-strain behavior and dynamic mechanical properties of poly(1,1-dimethyl-1-sila-cis-pent-3-ene), poly(1-methyl-1-phenyl-1-sila-cis-pent-3-ene) and of these polymers after crosslinking with sulfur (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 157-164 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Mechanical properties of polymers can be described by their stress/strain curves and by their behavior under dynamic mechanical thermal analysis (DMTA). The purpose of this paper is to report such mechanical properties for two unsaturated polycarbosilanes: poly(1, 1-dimethyl-1-sila-cis-pent-3-ene) (I) and poly(1-methyl-1-phenyl-1-sila-cis-pent-3-ene) (II). Tensile strength, elongation at break, modulus, bending modulus, Tg, and tan δ for I, II and for sulfur crosslinked I and II have been measured. The influence of polymer molecular weight, quantity of crosslinking agent, cure time, presence of carbon black filler, the effect of crosshead speed, and frequency on these properties was investigated.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350206
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    The effects of physical aging on the brittle fracture behavior of polymers (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 165-169 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects of physical aging on the failure behavior of a typical brittle polymer, polystyrene, have been studied. Properties examined were creep rupture lifetimes, fatigue lifetimes, and environmental stress cracking in ethanol. Fractured samples were examined both optically and by scanning electron microscopy to determine the degree of crazing. It was found that a longer physical aging time produced shorter lifetimes in all cases. The main reason for this is the reduction in craze strength caused by a reduced toughness due to physical aging. A long aging time was found to delay craze formation, but once formed, these crazes were much less stable than those formed with a short aging time. The effects of aging are important on failure prediction criteria and on testing methodologies, and the implications are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350207
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Investigation of cure in epoxy acrylate resins using rheological and dielectric measurements (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 184-189 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dielectric and rheological measurements are reported for the cure in a series of mixtures of an epoxy-acrylate with n-butyl methacrylate. The level of the initiator and properties of the epoxy acrylate and n-butyl methacrylate influence the cure characteristics and morphology of the film formed. Analysis of the rheological data indicates that during the curing process, microphase separation occurs within the mixture. The changes in the dielectric relaxation behavior with composition of the completely cured material is also consistent with microphase separation occurring in these resins while they are cured.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350211
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Monomer chain cross-transfer constants and cross termination factor evaluations on styrene-acrylonitrile copolymerization (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 195-201 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Using low conversion bulk copolymerization experimental data and the apparent rate constant model, the monomer chain cross-transfer rate constants and the cross-termination coefficient were evaluated. It was found that the dependence of the cross-termination coefficient on composition is a function of initiator efficiency and that monomer chain cross-transfer rate constant are relevant for the theoretical estimation of the molecular weights and molecular weight distributions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350213
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Rheology of thermoplastic starch: Effects of temperature, moisture content, and additives on melt viscosity (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 202-210 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The melt viscosity of thermoplastic starch has been investigated as a function of temperature, moisture content, and processing conditions. The effects of various low molecular weight additives have also been studied. Starch melts exhibit power law behavior over the range of shear rates studied. Melt viscosity decreased with increasing temperature and moisture content (MC). The power law index m increased with increasing temperature. The consistency K decreased with increasing temperature and increasing moisture content. Moisture content during the pelletizing step influenced melt viscosities measured after equilibration to different MCs. All additives studied except glycerol monostearate (GMS) significantly lowered the melt viscosity of starch, some more effectively than water relative to starch with 15% MC. Starch with GMS had viscosities essentially the same as, or slightly higher than, starch/water. This behavior may be due to the presence of unmelted helical inclusion complexes of starch and GMS. Starch formulations at 160°C exhibited melt visocosities similar to an LDPE of melt index 1.8.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350214
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Review of stabilization of polyolefin insulated conductors. Part II: Characteristics of good stabilizers and methods of evaluation (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 218-221 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In a previous paper, the theory of polylefin stabilization and the major factors contributing to degradation were discussed. This paper reviews the methods of test employed to date, the characteristics of a good stabilization system, and the experimental work we propose to use to study the problem. The characteristics of a stabilizer which are reviewed are: color, melt temperature, solubility, resistance to extraction, migration, phase state, structural arrangement, energy considerations, and thermodynamic potential. The methods of test reviewed include: pedestal testing, oven aging, oxygen uptake, testing under stress, melt flow testing, thermal analysis by DSC, thermal analysis by TGA, color change, torque rheometry, and aged elongation. Our approach will be to quantify the effects of antioxidant, metal deactivator, and blowing agent on stability by doing differential scanning calorimetry (DSC); to study fracture surfaces with scanning electron microscopy (SEM) to study diffusion rate of the stabilizer and reaction rate of the degradation process; and to use dynamic mechanical analysis (DMA) to measure the change in loss modulus with aging.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350216
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Comparison of microwave and thermal cure of an epoxy/amine matrix (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 233-239 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An investigation was carried out into the effect ofa microwave cure on an epoxy prepolymer with a cycloaliphatic diamine mixture, as compared to a standard thermal cure. The microwave waveguide and process (propagation mode TE01) were adjusted to obtain large homogeneous samples. The extent of reaction, x, was measured during the microwave processing by size exclusion chromatography and differential scanning calorimetry. A good estimate of x was found using a modified DiBenedetto equation correlating x and the glass transition temperature Tg. The homogeneity of the samples was checked during the last steps of cure, showing the efficiency of the microwave processing and waveguide. The influence of the nature of the mold (metallic or dielectric) on the reaction kinetic was also investigated. Samples cured by both thermal and microwave processing were characterized by dynamic and static mechanical properties and then compared with those of fully crosslinked networks, i.e., postcured at a high temperature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350303
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Effects of inserts on the injection molding process (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 247-251 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Injection molds often contain blocks of dissimilar material for improved cooling; they may also contain blocks of movable metal as a means of ejecting large parts from the mold. In this case, the blocks of metal are made of the same material, but the resistance at the interface between them has a marked influence on the cooling in the local area near the interface. In many other cases, inserts may be required because of wear in a particular mold section, or because efficient mold design is needed to produce similar parts. Hence, any mathematical model for analysis of heat transfer in injection molds must be general enough to apply to interfaces with and without gaps (i.e., with and without resistance to the flow of heat at the interface) for similar, as well as dissimilar, materials. A new and accurate model for prediction of heat transfer in heterogeneous (zoned) molds is presented in this paper. Through the solution of real problems with this model, the effects of differing material properties and interfacial thermal resistance are studied and the results are reported. It is observed that inserts have both local and global effects on the injection molding process; the overall ejection time for a part may be shortened, and the surface appearance of a part may be improved by correct placement of inserts.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350305
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    A simple approach to determining three-dimensional screw characteristics in the metering zone of extrusion processes using a total shape factor (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 274-283 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is of great importance in designing extruders to predict the screw characteristics, that is, the throughput in terms of the screw speed and the pressure gradient along the down-channel direction. The screw characteristics depend on the extruder geometry, the operating conditions, and material properties of non-Newtonian fluids. This paper suggests a simple approach to determining the screw characteristics for a three-dimensional flow in a channel with a finite aspect ratio (ratio of a width to a depth, W/H) by introducing a Total Shape Factor (Ft) to correct a two-dimensional flow analysis for a channel with an infinite aspect ratio. In the present study, the Total Shape Factor (Ft) was defined as a ratio of a net flow rate obtained by the three-dimensional analysis to that by the two-dimensional analysis. In the proposed approach, the quantity, ∂Ft/∂(H/W), which turns out to be almost constant, offers important information for understanding the effects of the flights. Threfore, ∂Ft/∂(H/W) is extensively reported in this paper in terms of several dimensionless parameters. This simple approach with such a database will be very useful for extruder designers to predict screw characteristics.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350308
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Masthead (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350401
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Modeling the dielectric response of unsaturated polyester resin during cure (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 284-288 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dielectric relaxation of unsaturated polyester resin during cure was modeled using a modified Williams-Watts decay function. The dielectric response was studied using dielectric measurements coupled with two dynamic mechanical measurement methods. It was found that the variation of the relaxation time during cure is a WLF process using Tg (α) (α-conversion) as the varied temperature. It was shown that this process fits the Williams-Watts decay function Φ(t)=exp(-(t/τ)β) where τ-relaxation time and β-empirical parameter are time dependent. It was found that τ obeys a time dependent power law rule and β depends linearly on log(time). Using this modified decay function, it was shown that the experimental dielectric response measured during cure agrees well with the computed response. Relaxation times above and below the dielectric measurement system capability were computed thus, demonstrating the capability of yielding the entire relaxation times spectrum during cure, out of a single limited frequency dielectric measurement.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350309
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Cold-drawing (necking) behavior of polycarbonate as a double glass transition (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 304-309 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The thermomechanical behavior of poly(bisphenol A carbonate) (PC) undergoing cold-drawing (necking) over a large range of temperature and strain rate has been studied. The cold-drawing of PC has been described from a material particle perspective in terms of true stress and strain relationships. The isothermal draw stress is shown to be a material parameter, and the true stress-strain behavior of necked material above the true drawing stress follows conventional treatment by rubber elasticity. Cold-drawing is described as a double glass transition: first, a transition from an isotropic glass to an isotropic rubber at the yield point, then, on unloading after stretching of a rubbery mesophase, a transition from an oriented rubber to an oriented glass.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350404
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    A state variable model for high strength polymers (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 310-316 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Displacement controlled experiments on nylon 66, poly(etherether ketone), and poly(ether imide) at room temperature suggest that nonlinear elastcity is not a good model for these polymers. Rather, qualitative evidence is presented that a state variable model shows promise. In this model, the rate of deformation is the sum of the elastic and the inelastic rates of deformation. The elastic rate of deformation is given by an objective formulation of Hooke's law, and the inelastic deformation is an increasing function of the overstress, the difference between the Cauchy stress and the equilibrium stress. The equilibrium stress is a state variable, and represents the stress that can be sustained at rest following deformation. Load controlled tests, intended to verify or falsify the model, show that the creep rate at the same stress level can be different on loading and unloading, and that the creep rate need not increase with an increase in creep stress level. These anomalous results can easily be explained by the introduction of the overstress concept, and by proper evolution of the equilibrium stress. They confirm the usefulness of the overstress concept for the modeling of these polymers.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350405
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    A constitutive model for the nonlinear viscoelastic viscoplastic behavior of glassy polymers (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 331-344 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Two features of the glassy state of an amorphous polymer, which play a key role in determining its mechanical properties, are the distributed nature of the microstructural state and the thermally activated (temporal) evolution of this state. In this work, we have sought to capture these features in a mechanistically motivated constitutive model by considering a distribution in the activation energy barrier to deformation in a thermally activated model of the deformation process. We thus model what is traditionally termed the nonlinear viscoelastic behavior as an elastic-inelastic transition, where the energetically distributed nature of inelastic events and their evolution with straining is taken into account. The thermoreversible nature of inelastic deformation is modeled by invoking the notion of strain energy stored by localized inelastic shear transformations. The model results are compared to experimental data for constant true strain rate uniaxial compression tests (nonmonotonic) at different rates and temperatures; its predictive capabilities are further tested by comparison with compressive creep tests at different stress levels and temperatures.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350407
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Solidification of thermoviscoelastic melts. Part I: Formulation of model problem (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 351-364 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The solidification of a molten layer of amorphous thermoplastic between cooled parallel plates is used to model the mechanics of part shrinkage and warpage and the buildup of residual stresses in the injection molding process. Flow effects are neglected, and a thermorheologically simple thermoviscoelastic material model is assumed. The equilibrium thermomechanical properties of the material and the shift function can be temperature- and pressure-dependent. The model allows material to be added to fill the space created by the packing pressure applied during solidification; therefore, this model can be used to assess packing-pressure effects in injection molding. The model also accounts for freeze-off effects in which the cavity pressure is controlled by the solidification process and must therefore be determined as a part of the solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760350409
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...