Experimental study of the importance of fiber breakage on the strength of thermoplastic matrix composites subjected to compression after impact

Abstract

Post-impact strength and damage tolerance of composite structures stands as a paramount design consideration in the aeronautical industry. In the event of a low velocity impact, a set of damage manifestations within laminated structures are induced, including matrix cracking, delamination and fiber breakage. Despite the critical importance of discerning the influence of each damage type on post-impact compression strength, only a limited number of studies have endeavored to quantify these effects comprehensively. In response to this research gap, we have developed a novel methodology capable of mimicking damage extension and shape caused by a low-velocity impact, while preserving fiber integrity. This innovation is achieved through the application of induced electrical currents, thereby facilitating controlled damage simulation without compromising fiber structural integrity. Our investigation compares the residual stiffness and strength of AS4/PEEK laminates subjected to low velocity impacts and induction currents, under conditions of equivalent damage. Our findings reveal that fiber breakage significantly influences the loss of stiffness in the laminate, but not its strength. Moreover, our results confirm the role of delamination as the primary determinant of strength degradation in the damaged material.