Simulation of buckling and delamination propagation of composite laminates with fiber bridging

Fiber reinforced composite laminates are susceptible to delamination damage due to relatively weak inter-laminar mechanical properties. The growth of delamination is always accompanied by fiber bridging, which can significantly increase the resistance of delamination propagation, especially in the case of multidirectional lami-nates. Compared with the traditional bilinear model, a trilinear cohesive zone model with fiber bridging effects can describe the R curve characteristic of the fracture toughness shown in the delamination test, and consequently better characterize the delamination propagation behavior of composite laminates. In order to evaluate the effects of fiber bridging on the behaviors of delamination growth and post-buckling in composite laminates, a trilinear cohesive zone model was built to investigate the compressive behavior of composite laminates with a circular delamination. The results demonstrate that, fiber bridging has little effect on the buckling load of the laminates. The relative deflection between the upper and lower sub-laminate predicted by the trilinear model is much smaller than that predicted by the bilinear model under mixed buckling mode. The buckling mode predicted by the trilinear model transits to global buckling earlier than that predicted by the bilinear model at identical delamination depth. The post-buckling modes change from local buckling mode to mix mode buckling and finally global buckling with the increase of delamination depth. For shallow delamination, mode I delamination is prominent. With the increase of delamination depth, the mode I delamination gradually disappears, while the mode II and III delamination propagation increases significantly. For delamination close to the mid-plane of the laminate, the delamination propagation is dominated by mode II and mode III, without mode I growth. Copyright ©2022 Acta Materiae Compositae Sinica. All rights reserved.