Additive Manufacturing and Mechanical Behaviors of Carbon–Kevlar Intralayer Hybrid Continuous Fiber Composite Corrugated Sandwich Structures

Hybrid continuous fiber-reinforced composite structures are widely used in aerospace, but they show poor printing quality and unstable performance. Thus, the additive manufacturing process and mechanical behaviors of carbon–Kevlar intralayer hybrid continuous fiber composite corrugated sandwich structures are experimentally investigated. All samples are fabricated using an in-situ impregnation method based on the one-stroke path planning. The inherent intralayer fiber hybridization mechanism and the effects of 3D printing parameters (layer thickness, temperature, and speed) on printing quality and mechanical performance are focused. The protection mechanism based on intralayer hybridization, meso-structural characteristics, and failure modes is analyzed. Results reveal that Kevlar fibers protect carbon fibers during printing, reducing nozzle friction and preventing brittle fractures. However, parameter mismatches (e.g., extrusion amount and temperature) between carbon and Kevlar fibers lead to surface defects and uneven impregnation. Quasi-static crushing tests demonstrate that hybrid samples exhibit superior energy absorption and load stability compared to single-fiber samples, attributed to the synergy effect of high-strength carbon and tough Kevlar fibers. Optimal printing parameters enhance impregnation and interlayer bonding, minimizing the defects. This study provides valuable exploration for the 3D-printing and mechanics of intralayer hybrid fiber composite structures.