Peridynamic modeling of low-velocity impact damage in laminated composites reinforced with z-pins

In this study, a new approach for predicting damage and specific failure modes in laminated fiber reinforced composites is presented. The new method is based on the peridynamic theory and models individual plies, and represents fiber and matrix materials in each ply explicitly. These features enable analysis of laminates with arbitrary fiber orientation in a convenient manner. Additionally, a new failure mode identification algorithm has been developed and implemented. Instead of the conventional peridynamic damage parameter, the new algorithm works with individual broken bonds, which makes identification of different failure modes including matrix cracking, fiber breakage, and delamination straight-forward and unambiguous. The new peridynamic approach is demonstrated by considering the low-velocity impact damage on composite laminates with and without translaminar reinforcements. The translaminar reinforcement technique considered in this study is z-pinning; two different geometric configurations of z-pins are explored. The impact testing and the post-impact nondestructive evaluations with ultrasonic c-scans are performed at the Air Force Research Laboratory to characterize the delaminations. The impact tests on different samples are simulated using the current peridynamic approach. The predicted impact damage failure modes are compared against the experimental measurements. The new approach is shown to capture low-velocity impact damage both quantitatively and qualitatively.