Multiscale failure analysis of fiber-reinforced composite structures via a hybrid cohesive/volumetric nonlinear homogenization strategy

In this work, a novel multiscale model for softening periodic microstructures is proposed, relying on a nonlinear homogenization method combined with a cohesive/volumetric finite element model. This strategy is able to overcome the mesh sensitivity issues usually experienced by purely volumetric homogenization techniques in presence of strain localization. As the main ingredient of the proposed approach, a microscopically informed traction-separation law for the embedded interfaces is extracted, starting from the homogenized bulk behavior obtained for a suitably chosen Repeating Unit Cell (RUC) subjected to different macro-strain paths. The present approach has been fully validated by performing several numerical simulations of the main damage phenomena experienced by fiber-reinforced composite structures, with special reference to transverse micro-cracking. Finally, to investigate the reliability and the accuracy of the proposed model, a comparison with direct simulations performed on fully meshed specimens has been presented, in terms of both load-displacement curves and associated crack patterns.