Failure mechanisms of 3D printed continuous fiber reinforced thermoplastic composites with complex fiber configurations under impact

3D printing of continuous fiber reinforced thermoplastic matrix composites has been increasingly used in manufacturing high-performance prototypes or even functional parts. It has allowed engineers and researchers to produce composites with custom design on their fiber configurations besides geometries. This work focuses on studying the printability of continuous fiber reinforced thermoplastic composites with different fiber configurations, including cross-ply, unidirectional, and complex helicoidal structures with different fiber angles, as well as evaluating their impact performance and failure mechanisms from impact. It was found that main failure mechanisms at the filament level included filament fracture, in-plane debonding and through-thickness debonding of continuous fiber composite filaments at the impact site. Interlaminar delamination occurred to some samples and both fiber configuration and sample thickness affected its occurrence. The impact testing results also showed that printed continuous glass fiber composite had better impact performance than printed continuous Kevlar fiber composite. The findings of this work can provide guidelines in both geometry and fiber configuration design to achieve different failure mechanisms for 3D printed continuous fiber composites under impact.