Composite shock-absorbing devices can dissipate a large amount of energy, thanks to the combined action of delamination and fragmentation of the plies in compression. The latter failure mode is due to kinking, which naturally arises at the scale of the fibers. This Ph.D. is a contribution to the multiscale modeling of this phenomenon for the simulation of composite structures. Therefore, three-step-strategy is adopted. The first step deals with the design of a microscopic model able to represent the kinematics and kinetics of kinking. The difficulty is to include all relevant parameters in terms of ultimate stress and dissipated energy, particularly defects and shear. The second step deals with the nonlinear homogenization of the micromodel reponse for several load paths. This is done by postulating an original constitutive model with a parametric influence of defects. It includes deterministic constitutive laws which are identified through numerical tests on the microstructure. Finally, the third step deals with the introduction of this micromechanics-based behavior in an existing and validated model at the scale of the plies. It is implemented in the framework of a hybrid continuous/discrete computation code, in order to perform sample-scale simulations and observe interactions between kinking and other failure mechanisms.
