Comportement viscoélastique des materiaux orthotropes.

Abstract

The composites materials with organic matrix and glass fiber or carbon are finding more important applications in the areas of engineering and specially in the realization of structural pieces of various dimensions in many industrial sectors. The objective of this study is to valid the rhéological model, such as the Maxwell model, for orthotropic materials using the visco elastic theory in order to predict the creep and the relaxation responses of theses materals. Consequently, it is necessary to develop an analytical model which can pedict exactly the structural behavior of these materials under the creep and the relaxation effects. The the visco elastic behaviour law of these materials have been determinated based on the Boltzmann superposition, and the characteristic equations thus obtained are solved by two methods: the first one is based on the Carson-Laplace transformation and the author isbased on the Fourier transformation. A visco elastic behavior application for three types of orthotropic materials in the area of Carson-Laplace has been considered. The first is an unidirectional glass/vinylester, and the two others are symmetric laminated materials [(± 45° / CSM)2]S and [(90°± 45° / CSM)3]S . The compliance and relaxation coefficients of these materials are calculated using the Maxwell model in time fu nction. While the Fourier method has been used to fined the relaxation modulus and the longitudinal and transversal stresses for the unidirectional verre/vinylester in function of the frequencies pulsations; and good results have been founds.