Enhanced mechanical performance of re-entrant structures using carbon fiber/polyamide composites by dual-material 3D printing

Multi-component 3D printing has become a reliable and feasible strategy with complex shape and colorful appearance. However, the overall mechanical performance is greatly dependent on the material components and printing pattern design. This study fabricated dual-component laminates and re-entrant structures by using polyamide (PA) and 20 wt% carbon fiber (CF)/PA composites through a dual-material feeding 3D printer. Effects of CF/PA volume fraction ( V CF/PA ), stacking sequence and bonding mode on the tensile, compressive and three-point bending properties were comprehensively investigated. The results showed that the mechanical performance could be enhanced by increasing V CF/PA in the dual-component laminates and re-entrant structures with good PA-CF/PA interfacial boundary zone. However, frequent alternatively stacking of PA and CF/PA components was not favorable for the compressive performance of re-entrant structures. Moreover, an interlocking bonding mode between PA and CF/PA was utilized to further enhance the interconnection. The mechanical anchoring effect contributed to an enhanced tensile and compressive properties on dual-component samples and re-entrant structures. This modified re-entrant core with skin panels was proved to have excellent load-carrying capacity. Therefore, the study of dual-component 3D printing provides meaningful information and guidance for fabrication of lightweight, multi-functional and energy absorbed components, which could be used as energy absorbers, shock-resistant components and biomedical implants.