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  • 1985-1989  (35)
  • 1
    Electronic Resource
    Electronic Resource
    Internal material damping of polymer matrix composites under off-axis loading (1985)
    Springer
    Journal of materials science 20 (1985), S. 2575-2585 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The objective of this paper is to determine theoretically the material damping of short fibre-reinforced polymer matrix composites. The major damping mechanism in such composites is the viscoelastic behaviour of the polymer matrix. The analysis was carried out by developing a finite-element program which is capable of evaluating the stress and strain distribution of short fibre composites under axial loading (see Fig. 1a). Using the concept of balance of force we can express the modulusE x along the loading direction as a function of the mechanical properties of the fibre and matrix materials, fibre aspect ratio,l/d, loading angle,θ, and fibre volume fraction,V f. Then we apply the elastic-viscoelastic correspondence principle to replace all the mechanical properties of the composite, fibre and matrix materials such asE x,E f,E m,G m, by the corresponding complex moduli such asE x ′ +iE x ″ , andE f ′ +iE f ″ . After separation of the real and imaginary parts, we can expressE ' x/t' andE x t" as functions of the fibre aspect ratio,l/d, loading angle,θ, stiffness ratio,E f/E m, fibre volume fraction,V f, and damping properties of the fibre and matrix materials such asη f andη m. Numerical results of the composite storage modulus,E x ′ , loss modulus,E x ″ , and loss factor (damping),η C, are plotted as functions of parameters such asl/d,θ,V f, and are discussed in terms of variations ofl/d,θ, andE f/E m, in detail. It is observed that for a given composite, there exist optimum values ofl/d andθ at whichE x ″ andη c are maximized. The results of this paper can be used to optimize the performance of composite structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00556089
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Prediction of material damping of laminated polymer matrix composites (1987)
    Springer
    Journal of materials science 22 (1987), S. 1006-1012 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this study the material damping of laminated composites is derived analytically. The derivation is based on the classical lamination theory in which there are eighteen material constants in the constitutive equations of laminated composites. Six of them are the extensional stiffnesses designated by [A] six of them are the coupling stiffnesses designated by [B] and the remaining six are the flexural stiffnesses designated by [D]. The derivation of damping of [A], [B] and [D] is achieved by first expressing [A], [B] and [D] in terms of the stiffness matrix [Q](k) andh k of each lamina and then using the relations ofQ ij (k) in terms of the four basic engineering constantsE L,E T, GLT andv LT. Next we apply elastic and viscoelastic correspondence principle by replacingE L,E T...by the corresponding complex modulusE L *,E T *,..., and [A] by [A]*, [B] by [B]* and [D] by [D]* and then equate the real parts and the imaginary parts respectively. Thus we have expressedA ij ′,A y ″,B ij ′,B ij ″, andD ij ″ in terms of the material damping ηL (k) and ηT (k)...of each lamina. The damping ηL (k), ηT (k)...have been derived analytically by the authors in their earlier publications. Numerical results of extensional damping lη ij =A ij ″/A ij ′ coupling dampingcη ij =B ij ″/B ij ′ and flexural damping Fη ij =D ij ″/D ij ″ are presented as functions of a number of parameters such as fibre aspect ratiol/d, fibre orientation θ, and stacking sequence of the laminate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01103543
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  • 3
    Electronic Resource
    Electronic Resource
    The influence of fiber length and fiber orientation on damping and stiffness of polymer composite materials (1986)
    Springer
    Experimental mechanics 26 (1986), S. 175-184 
    Details
    ISSN: 1741-2765
    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 describes the theoretical analysis, the experimental results and the curve-fitting of the analytical model to the experimental results on the influence of fiber length and fiber orientation on damping and stiffness of polymer-composite materials. The experimental results show that, as predicted, very low fiber aspect ratios are required to produce significant improvements in damping. Measurements and predictions also indicate that the control of lamina orientation in a continuous fiber-reinforced laminate may be a better approach to the improvement of damping than the control of the fiber aspect ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02320012
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  • 4
    Electronic Resource
    Electronic Resource
    Determining transverse impact force on a composite laminate by signal deconvolution (1989)
    Springer
    Experimental mechanics 29 (1989), S. 414-419 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Dynamic impact forces on a composite structure were recovered by using experimentally generated Green's functions and signal deconvolutions. The signal processing is straightforward. Extra windowing and filtering the recorded signals are unnecessary. The Green's functions account for boundary conditions, material properties and structure geometry. This approach can be applied to linearly elastic structures with different boundary conditions. It is realistic and convenient to use for the recovery of impact force on anisotropic or isotropic solid structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02323860
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  • 5
    Electronic Resource
    Electronic Resource
    On the completeness of the Westergaard stress functions (1989)
    Springer
    International journal of fracture 40 (1989), S. 73-77 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé La méthode de Westergaard conduit à une solution succincte pour les problèmes de fissuration en condition linéaire élastique. On montre ici qu'en superposant les fonctions de Westergaard et un champ de contraintes uniformes uniaxiales, on est conduit à une solution complète des équations d'élasticité linéaire à deux dimensions dans le cas d'un plan infini.
    Notes: Abstract The Westergaard method yields a succinct solution to linear elastic crack problems. Here it is shown that the superposition of the Westergaard functions with a uniform uniaxial stress field provides a complete solution to the equations of two-dimensional linear elasticity for the infinite plane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01150867
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  • 6
    Electronic Resource
    Electronic Resource
    Application of a hybrid finite element method to determine stress intensity factors in unidirectional composites (1986)
    Springer
    International journal of fracture 31 (1986), S. 37-51 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé On applique, dans la présente étude, une méthode d'éléments finis hybrides à l'évaluation des facteurs d'intensité de contrainte KI et KII pour des composites renforcés de fibres unidirectionnelles. Pour tenir compte de la singularité de la contrainte à l'extrémité de la fissure, on développe un super élément singulier en se basant sur un principe modifié d'énergie complémentaire. Les champs de contraintes et de déplacements dans le super-élément sont exprimés sous forme polynormale de deux variables complexes ξ1, et ξ2 dans le plan de la transformée. La matrice de rigidité du super élément est, quant à elle, définie en utilisant une intégrale linéaire le long du contour de l'élément. Le vecteur de déplacement est exprimé par un vecteur (9) de déplacement nodal de l'élément, et par une fonction de forme appropriée, définie le long du contour de l'élément. On évalue les résultats numériques pour KI et KII, correspondant à des composites à fibres unidirection-nelles de types verre-epoxy et graphite-epoxy, oú des fissures se situeraient sur le diamètre de découpes circulaires et elliptiques
    Notes: Abstract In this paper a hybrid finite element method is applied in evaluation of the stress intensity factors K I and K II of unidirectional fiber reinforced composites. In order to satisfy the stress singularity at the crack tip a singular super-element based on a modified complementary energy principle is developed. The stress and displacement fields in the super-element are expressed in terms of polynomials of two complex variables ξ1 and ξ2 in the transformed ξ-plane. The stiffness matrix of the super-element was determined by using a line integral along the boundary of the super-element. The displacement vector was expressed in terms of the element nodal displacement vector {q} and a properly selected shape function defined along the element boundary. Numerical results for K I and K II of glass-epoxy and graphite-epoxy unidirectional composites with cracks along the diameter of a circular cut out as well as elliptical cut outs were evaluated
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033928
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  • 7
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    Unknown
    Determining transverse impact force on a composite laminate by signal deconvolution (1989)
    Springer
    Details
    Publication Date: 1989-12-01
    Print ISSN: 0014-4851
    Electronic ISSN: 1741-2765
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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  • 8
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    The influence of fiber length and fiber orientation on damping and stiffness of polymer composite materials (1986)
    Springer
    Details
    Publication Date: 1986-06-01
    Print ISSN: 0014-4851
    Electronic ISSN: 1741-2765
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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  • 9
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    Unknown
    On the completeness of the Westergaard stress functions (1989)
    Springer
    Details
    Publication Date: 1989-05-01
    Print ISSN: 0376-9429
    Electronic ISSN: 1573-2673
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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  • 10
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    Unknown
    Application of a hybrid finite element method to determine stress intensity factors in unidirectional composites (1986)
    Springer
    Details
    Publication Date: 1986-05-01
    Print ISSN: 0376-9429
    Electronic ISSN: 1573-2673
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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