A hybrid cohesive/volumetric multiscale finite element model for the failure analysis of fiber-reinforced composite structures

Several multiscale approaches have been introduced in the last decades, aimed at investigating the failure behavior of composite materials with reduced computational costs and a high accuracy level at the same time. This is due to their capability to account for the effect of microstructural details on the overall mechanical behavior of such materials. Among the existing multiscale approaches, continuous/discontinuous models have gained increasing interest, by virtue of their ability to overcome the main limitation of purely volumetric approaches, consisting in a spurious mesh sensitivity in the presence of strain localization phenomena. In this work, a novel continuous/discontinuous multiscale model is proposed, used in combination with a hybrid cohesive/volumetric finite element approach for the accurate numerical simulation of pervasive fracture propagation at both the micro- and macro-scales. This approach allows a microscopically informed traction-separation law for the embedded interfaces to be extracted from the homogenized bulk response, derived with reference to a suitably defined Repeating Unit Cell (RUC). The present model is applied to the numerical simulation of microscopic damage phenomena in composite structures. Finally, comparisons with direct numerical simulations on fully meshed specimens are presented for validation purposes, in terms of both loading curves and associated crack patterns.