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
  • 1
    Electronic Resource
    Electronic Resource
    A smoothing scheme for a minimum weight problem in structural plasticity (1999)
    Springer
    Structural optimization 17 (1999), S. 279-285 
    Details
    ISSN: 0934-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We revisit an important and challenging class of minimum weight structural plasticity problems, the feature of which is the presence of complementarity constraints. Such relations mathematically express the perpendicularity of two sign-constrained vectors and mechanically describe an inherent property of plasticity. The optimization problem in point is referred to in the mathematical programming literature as a Mathematical Program with Equilibrium Constraints (MPEC). Due to its intrinsic complexity, MPECs are computationally very hard to solve. In this paper, we adopt recent ideas, proposed by mathematical programmers, on smoothing to develop a simple scheme for reformulating and solving our minimum weight problem as a standard nonlinear program. Simple examples concerning truss-like structures are also presented for illustrative purpose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01207004
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Cyclic moment-curvature characteristics of mild steel (1980)
    Springer
    Materials and structures 13 (1980), S. 371-382 
    Details
    ISSN: 1359-5997
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Description / Table of Contents: Résumé Trois séries d'essais ont été effectuées sur des poutres en acier doux à section rectangulaire de dimensions 19.1×6.3 mm et 20×6 mm. On a soumis ces poutres à des cycles quasi statiques de flexion pure. On est parvenu à obtenir des courbures lorsque les fibres extrêmes sont dans le champ de durcissement. Les caractéristiques expérimentales des courbes cycliques comportent des particularités distinctes qui peuvent être élaborées par des modèles mathématiques. Ceci rend possible l'analyse numérique du comportement des structures suivant toute évolution de charge prescrite. Ces essais montrent que: 1. les caractéristiques prévisibles de la courbe moment-courbure sont la courbe vierge de charge initiale, la dimension et la forme des boucles hystérétiques, et l'influence des charges cycliques sur la longueur du palier de moment plastique; 2. sous une variation de moment-fléchissant essentiellement unilatérale, les boucles hystérétiques sont étroites, quoiqu'un phénomène de fluage cyclique puisse se produire; 3. l'influence de l'effet Baüschinger en ce qui concerne les grandes variations de moment alterné est significative, toutes les caractéristiques élastoplastiques du comportement sous charge monotonique étant absentes de la courbe cyclique; 4. le phénomène de durcissement sous charge cyclique suit étroitement un modèle d'écrouissage essentiellement cinématique contenant un certain degré de durcissement isotropique. La boucle hystérétique est définie aux figures 8 et 9. Si la variation de courbure est suffisamment grande, on constate que la courbe peut se diviser en trois parties: une partie élastique (BB′et CC′), une partie inélastique, type Baüschinger (B′B″ et C′C″), et une partie d'écrouissage cinématique (B″C et C″D). En l'absence de fluage cyclique et d'écrouissage isotropique, D et B coïncident.
    Notes: Abstract An experimental study of the moment-curvature behaviour of mild steel under essentially quasistatic cyclic loading is presented. A simple and efficient test rig which allows the testing to be extended into the strain hardening range was developed and is briefly described. In all, seventeen tests were conducted on rectangular mild steel sections to enable various features of the cyclic behaviour to be observed and highlighted. In particular, it was found that the main characteristics of the cyclic moment-curvature curves are predictable, and amenable to mathematical modelling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02476534
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    On the numerical solution of a class of unilateral contact structural optimization problems (1999)
    Springer
    Structural optimization 17 (1999), S. 155-161 
    Details
    ISSN: 0934-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper deals with a special class of structural optimization problems in nonsmooth mechanics. More precisely, it is required to minimize the weight of a structure subject to frictionless unilateral contact conditions and constraints on the magnitudes of contact forces, displacements, stresses and cross-sectional areas. This problem, as is well-known, can be formulated as a special and challenging optimization problem known as a Mathematical Program with Equilibrium Constraints (MPEC), a key feature of which is the presence of complementarity conditions, involving the orthogonality of two sign-constrained vectors. In spite of its inherent nonsmoothness, we attempt to solve the problem using standard nonlinear programming techniques. In particular, we investigate numerically the application of two simple algorithms, both based on the use of the general-purpose nonlinear programming code CONOPT accessed via the powerful GAMS modelling language, for solving the suitably reformulated problem. Application is illustrated by means of three numerical examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01195940
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    On multiplicity of solutions in quasi-brittle fracture computations (1997)
    Springer
    Computational mechanics 19 (1997), S. 511-516 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The analysis of quasi-brittle fracture processes is formulated as a linear complementarity problem either in finite increments or in rates. Some time-stepping solution procedures and mathematical programming algorithms are discussed as for their ability to capture the whole set of possible alternative equilibrium paths. Potentialities and limitations of the proposed approach and of the relevant procedures are pointed out also by means of a numerical example.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004660050201
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    A smoothing scheme for a minimum weight problem in structural plasticity (1999)
    Springer
    Structural and multidisciplinary optimization 17 (1999), S. 279-285 
    Details
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We revisit an improtant and challenging class of minimum weight structural plasticity problems, the feature of which is the presence of complementarity constraints. Such relations mathematically express the perpendicularity of two sign-constrained vectors and mechanically describe an inherent property of plasticity. The optimization problem in point is referred to in the mathematical programming literature as a Mathematical Program with Equilibrium Constraints (MPEC). Due to its intrinsic complexity, MPECs are computationally very hard to solve. In this paper, we adopt recent ideas, proposed by mathematical programmers, on smoothing to develop a simple scheme for reformulating and solving our minimum weight problem as a standard nonlinear program. Simple examples concerning truss-like structures are also presented for illustrative purposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01207004
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Optimum shakedown design under residual displacement constraints (2000)
    Springer
    Structural and multidisciplinary optimization 19 (2000), S. 130-139 
    Details
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract. We consider the minimum weight design of suitably discretized elastoplastic structures subjected to variable repeated loads and constraints on the amount of residual (or permanent) deflections. The optimization problem is formulated on the basis of the classical lower bound theorem of shakedown, supplemented by appropriate constraints on deflections obtained from existing bounding results. The primary purpose of the paper is to show that, even for large size structures, this important and challenging problem can be modeled and solved directly as a mathematical programming problem within the industry standard modeling framework GAMS. Examples concerning truss-like structures are presented for illustrative purposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001580050093
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    On the numerical solution of a class of unilateral contact structural optimization problems (1999)
    Springer
    Structural and multidisciplinary optimization 17 (1999), S. 155-161 
    Details
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper deals with a special class of structural optimization problems in nonsmooth mechanics. More precisely, it is required to minimize the weight of a structure subject to frictionless unilateral contact conditions and constraints on the magnitudes of contact forces, displacements, stresses and cross-sectional areas. This problem, as is well-known, can be formulated as a special and challenging optimization problem known as a Mathematical Program with Equilibrium Constraints (MPEC), a key feature of which is the presence of complementarity conditions, involving the orthogonality of two sign-constrained vectors. In spite of its inherent nonsmoothness, we attempt to solve the problem using standard nonlinear programming techniques. In particular, we investigate numerically the application of two simple algorithms, both based on the use of the general-purpose nonlinear programming code CONOPT accessed via the powerful GAMS modelling language, for solving the suitably reformulated problem. Application is illustrated by means of three numerical examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01195940
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    LARGE DISPLACEMENT ELASTOPLASTIC ANALYSIS OF SEMIRIGID STEEL FRAMES (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 741-762 
    Details
    ISSN: 0029-5981
    Keywords: elastoplastic analysis ; mathematical programming ; plasticity ; semirigid connections ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A mathematical programming approach for the large displacement analysis of elastoplastic plane frames with flexible, partial-strength beam-to-column connections is proposed. The incremental formulation is developed within the framework of a discrete model, piecewise linear yield surfaces and large displacement theory. It is based on the fundamental relations of equilibrium, compatibility and constitutive laws, all expressed in incremental form. The irreversible plasticity laws are used in a stepwise holonomic format. A feature of the final mathematical programming problem, known as a non-linear complementarity problem, is that the governing relations exhibit symmetry as a result of the use of fictitious quantities and non-linear residuals. The iterative predictor-corrector computational scheme adopted has the ability of tracing historically a sequence of plastic hinge activations and/or unloadings well beyond any critical point. Numerical examples are presented to illustrate and validate the accuracy of the approach.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 9
    facet.materialart.
    Unknown
    MOKE setup exploiting a nematic liquid crystal modulator (2018)
    American Institute of Physics
    Details
    Publication Date: 2018-10-01
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Sardinia Radio Telescope wide-band spectral-polarimetric observations of the galaxy cluster 3C 129 (2016)
    Oxford University Press
    Details
    Publication Date: 2016-07-21
    Description: We present new observations of the galaxy cluster 3C 129 obtained with the Sardinia Radio Telescope in the frequency range 6000–7200 MHz, with the aim to image the large-angular-scale emission at high-frequency of the radio sources located in this cluster of galaxies. The data were acquired using the recently commissioned ROACH2-based backend to produce full-Stokes image cubes of an area of 1° x 1° centred on the radio source 3C 129. We modelled and deconvolved the telescope beam pattern from the data. We also measured the instrumental polarization beam patterns to correct the polarization images for off-axis instrumental polarization. Total intensity images at an angular resolution of 2.9 arcmin were obtained for the tailed radio galaxy 3C 129 and for 13 more sources in the field, including 3C 129.1 at the galaxy cluster centre. These data were used, in combination with literature data at lower frequencies, to derive the variation of the synchrotron spectrum of 3C 129 along the tail of the radio source. If the magnetic field is at the equipartition value, we showed that the lifetimes of radiating electrons result in a radiative age for 3C 129 of t syn ~= 267 ± 26 Myr. Assuming a linear projected length of 488 kpc for the tail, we deduced that 3C 129 is moving supersonically with a Mach number of M  =  v gal / c s  = 1.47. Linearly polarized emission was clearly detected for both 3C 129 and 3C 129.1. The linear polarization measured for 3C 129 reaches levels as high as 70 per cent in the faintest region of the source where the magnetic field is aligned with the direction of the tail.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...