Mechanical properties and deformation behavior of functionally graded TPMS structures under static and dynamic loading

Two types of triply periodic minimal surface structures (TPMS), Diamond and Gyroid structures with uniform and gradient characteristics are designed and fabricated by the fused deposition modeling(FDM) method. Quasi-static and drop-hammer experiments were conducted to investigate the mechanical response and deformation behavior of the structures. The global deformation processes of the structures were captured by a digital camera. Meanwhile, numerical simulations were also performed by ABAQUS according to the experimental arrangement. The numerical predictions were compared with the experimental results to reveal the deformation modes of the structures. Subsequently, the influences of the relative density and loading velocity on the mechanical properties and deformation behavior of the structures were analyzed. The experimental and numerical simulation results demonstrated that the specific modulus and strength of the Diamond structure were evidently higher than the Gyroid structure with the relative density increased. The strength of the Diamond and Gyroid structure under dynamic loading was apparently higher than the static results, which indicated that the structures present certain strain rate sensitivity. The characteristic of mechanical response and deformation modes of the graded structures are not influenced by the loading speed, while obvious softening behavior can be detected in the uniform structures. Finally, the specific energy absorption(SEA) of the structures in this work was found to be superior to some traditional honeycombs and lattice structures, and the Diamond structure with density gradient exhibited the highest specific energy absorption.