Tailored deformation modes and enhanced energy absorption in TPMS structures with 2D gradient surface density distribution

Functionally graded triply periodic minimal surface (TPMS) structures utilizing three distinct density mapping strategies parabolic, trigonometric, and hyperbolic paraboloid were designed and fabricated via Fused Deposition Modeling (FDM). Quasi-static and dynamic compression tests were conducted to investigate the mechanical response and deformation behaviors of these structures. Corresponding numerical simulations were performed using ABAQUS to validate the experimental findings, and the effects of gradient pattern and strain rate on the structural mechanical properties were analyzed. Results indicate that, compared to uniform TPMS structures at an equivalent relative density, the gradient structures exhibit significantly enhanced plateau stress and energy absorption capabilities. The specific energy absorption (SEA) and specific plateau stress of the gradient structure increased by up to 34.4% and 21.8% compared to the uniform structure, respectively. Among the investigated designs, the hyperbolic paraboloid gradient structure demonstrated superior mechanical performance because of the uniform deformation within the structure. Although the structures demonstrated significant strain rate sensitivity with elevated dynamic strength, the macroscopic deformation modes remained consistent across loading speeds. Furthermore, the gradient design strategy effectively mitigated the softening behavior observed in uniform structures. However, the mechanical behavior showed notable anisotropy with respect to loading direction. The results further demonstrated that incorporating a gradient design into TPMS structures significantly improves energy absorption capabilities without compromising the energy absorption efficiency, suggesting their suitability as load-bearing components and impact energy absorbers.