COMPUTATIONAL MICRO-MESO MODELING FOR LAMINATES UNDER THERMOMECHANICAL FATIGUE AND AN OXIDIZING ATMOSPHERE

Summary One computational approach for studying damage in laminated composites is the damage mesomodel for laminates, which has been developed for more than fifteen years, particularly at LMT-Cachan. Recently, we introduced micro-meso relations which prove that this mesomodel is compatible with classical micromechanical analysis and, therefore, can be viewed as a homogenization of classical theories on the microscale. Consequently, basic material quantities on the microscale can be easily interpreted on the mesoscale. Here, we propose to use these micro-meso relations as a tool for studying the degradation of laminates under fatigue in an oxidizing atmosphere. The reason why we are interested in this specific topic is that carbon-epoxy laminated composites are candidate materials for the construction of the future European civil supersonic aircraft. Our approach is rather simple: first, the influence of fatigue or oxidation on basic material characteristics is studied on the microscale; then, the equivalent damage evolution law on the mesoscale is obtained thanks to the micro-meso relations. THE COMPUTATIONAL MICRO-MESO APPROACH FOR LAMINATES The micro-meso relations for laminates One of the computational approaches applicable to laminated composites is based on what we call a damage mesomodel for laminates, whose characteristic length is the thickness of the elementary ply ([1]). In such an approach, one assumes that the behavior of any laminated composite can be constructed using two elementary constituents which are continuous media: the ply and the interface ([3],[4]). The ply takes into account diffuse damage (quasi-homogeneous debonding o