The delamination performance of composite laminates with bionic high toughness regions

Inspired by the composite structure of soft and hard phases found in biological materials, this paper prepares the CF/PPS woven composite laminates with bionic high toughness regions to improve the delamination resistance. The optimal bionic high toughness regions can increase the flexural strength by 75% compared to Baseline. These bionic regions improve the delamination resistance via two mechanisms. i) The paths of crack change from interlaminar to intralaminar because of crack deflection, branching, and convergence. ii) The singular concentrations of interlaminar stress are improved by producing tiny cracks. Finally, the damage mode is investigated in details. It shows that the pure mode II failure is transformed into a mixture of mode I and mode II failures. The cracks are more likely to transition from interlaminar to intralaminar when the distribution of bionic regions is more dispersed. As a result of these regions, the catastrophic delamination failure is improved effectively.