Numerical prediction for effects of fiber orientation on perforation resistance behaviors of patch-repaired composite panel subjected to projectile impact

To improve the resistance capacity of repaired composite structures, effects of fiber orientation on perforation mechanisms of bonding- and scarf-patch repaired panel under impact loading are predicted. To this end, the linear-exponential intraply damage model and bi-linear interface debonding damage model are adopted to capture various damage modes occurring both in composite patch and laminate. The adopted damage model is validated with available experimental data. Then, the perforation resistance mechanisms of repaired panel with different fiber orientations are predicted and analyzed. Four types of layups including [0](3)+[theta](4), [theta](3)+[theta /90-](2), [theta](3)+[0](4) and [theta](3)+[theta](4) ([...](3)+[...](4) represents '[laminate](3)+[patch](4)') are considered. Results show that numerical residual velocity, energy absorption and damage modes corresponding to three impact locations respectively agree well with experimental results. Through numerical analysis for proposed layups, significant insights into perforation resistance mechanism, energy dissipation mechanism and stress distribution law are gained. Conclusions drawn from such predictions contribute to layup design of repaired aircraft panel.