Design and mechanical performance of gradient lattice structures based on triply periodic minimal surface

Due to its strong editability and parametric advantages, functionally graded lattice structures based on TPMS (triply periodic minimal surface, TPMS) have been widely used in fields such as lightweight high strength and high energy absorption. In this study, we propose an IW-P (I-Wrapped Package, IW-P) graded lattice structure based on TPMS, and four different types of graded lattice structures were designed using implicit functions to explore the effect of gradient direction on the mechanical properties of IW-P lattice structures. In addition, structural samples with two different volume fractions were fabricated using stereolithography (SLA) technology, and quasi-static compression tests were conducted to evaluate the mechanical properties of the designed porous structures. The results indicate that lattice structures with a gradient along the Y direction exhibit higher equivalent elastic modulus, initial peak stress, and energy absorption characteristics. Notably, the lattice structures designed in this study demonstrate different excellent performances in different gradient directions, providing more options for the optimized design of mechanical properties in lattice structures with varying directions.