A micromechanical model for fatigue prediction of laminated composite structures ; Sur un modèle micro pour le calcul des structures en composites stratifiés

Laminated composites are increasingly involved in vital parts for the aeronautical industry. Degradation phenomenology is very complex, so that predicting the evolution of damage is a crucial research topic. In this context, a semi-discrete approach called the computational damage micromodel is developped at the LMT-Cachan. Transverse microcracking and microdelamination are described through discrete cracks (micromechanics), whereas the cracked ply's behaviour is described through the "Damage Mesomodel of Laminated" (mesomechanics). In the first part of the work, the semi-discrete model has been completed with pertinent behaviours under static loading. Plastic deformations, viscosit and fiber breaking has been added throught adapted scales. Thus, it constitutes a "virtual reference material" combining information from a whole family of materials rather than from only a single material. It can be viewed as a database containing the most important information about the material Then, this hybrid model has been numerically implemented on a high-performance parallel numerical platform, based on the multiscale LaTin method. Considering the high computing cost necessary to perfoml calculations, the code had to be paralellized in order to perfonn simulations on realistIC coupons. Finally, a first stage of validation with the comparison between experimental and numerical results has been done, leading to accurate description of damage evolution up to fracture, on different stacking sequences. ; La proportion de matériaux composites stratifiés ne cesse d'augmenter dans les structures aéronautiques, et notamment dans les zones vitales de ces dernières. Ces matériaux présentent des mécanismes de dégradation très complexes, ce qui limite la confiance dans les modèles actuellement utilisés. C'est dans ce cadre qu'un modèle micro innovant pour les matériaux composites stratifiés est développé au LMT. Ce modèle dit "hybride", réconcilie micromécanique et mésomécanique des stratifiés. Les mécanismes tels que la microfissuration ...