Analyse par éléments finis de la dégradation des propriétés thermomécaniques des stratifiés croisés.

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Résumé (Français et/ou Anglais) : Components manufactured from composite materials are frequently subjected to superimposed mechanical and thermal loadings during their operating service. Both types of loadings may cause fracture and failure of composite structures. When composite cross-ply laminates of type [0m / 90n]s is subjected to uni-axial tensile loading, different types of damage are set-up and are developed such as matrix cracking: transverse and longitudinal cracks, delamination between disoriented layers and broken fibers. The development of these modes of damage can be detrimental for the stiffness of the laminates. From the experimental point of view, transverse cracking is known as the first mode of damage. In this regard, the objective of the present paper is to investigate the effect of transverse cracking in cross-ply laminate on the distribution of the stress filed and thermo-mechanical degradation. A Finite Element (FE) simulation of damage evolution in composite cross-ply laminates of type [0m / 90n]s subjected to uni-axial tensile loading is carried out. The effect of transverse cracking on the cross-ply laminate strength under thermo-mechanical degradation is investigated numerically. The results obtained by prediction of the numerical model developed in this investigation demonstrate the influence of the transverse cracking on the bearing capacity and resistance to damage as well as its effects on the variation of the mechanical properties such as Young’s modulus, Poisson’s ratio and coefficient of thermal expansion. The effect of the number n of 90° plies and the number m of 0° plies on the degradation of the longitudinal elasticity modulus and the variation of the normal stress , with different density of transverse cracks, was also studied. The results obtained are in good agreement with those predicted by the shear lag analytical model as well as with the obtained experimental results available in the literature.
Doctorat en Sciences