Micromechanical modelling of matrix cracks effect on shear and transverse response for unidirectional composites with a full field approach

Modelling the damage of composite materials is not an easy task because different modes of ruins coexist: Fiber matrix decohesion,matrix cracks, delamination, and fiber cracks. In the case of laminated composites, the matrix cracks have the particularity to remain parallel to the fibers. As a consequence of the orientation of this crack network, only shear and transverse moduli in the plane of the ply are degraded in proportion to the increase of the crack density. The main point of this work is to characterize the relation linking transverse and shear damage with respect to the crack density. Following this objective, full field calculations are run using CraFT, a software developed at the LMA. The modeling is done in two steps: first the undamaged composite is homogenized, then, as a second step, the damaged behavior is determined by introducing cracks into the healthy composite. The behavior is calculated from an optimal size of RVE (Representative Volume Element) in order to determine numerically the relation between transverse and shear moduli variables.