Design optimization of multimorphology surface-based lattice structures with density gradients

Graded structure design based on triply periodic minimal surface (TPMS) structures can effectively improve the stiffness of lightweight structures. To further improve the structural stiffness of these lattice structures, a novel optimization method combing performance characteristics of various morphology lattice structures is proposed. First, a discrete homogenization method based on the ABAQUS software is proposed to rapidly obtain the effective elastic properties of the TPMS structures. Then the effective elastic properties of three typical types of TPMS (iWp [W], IW, and primitive [P]) structures are studied for later design optimization. The size effect of TPMS structures is also studied, and the validity of effective compression modulus of three TPMS structures is verified by experiments. Third, density mapping, based on topology optimization (TO), and interpolation approaches are used to obtain the optimized lattice structure with a density gradient. The selective filling function of unit cells is given to obtain a suitable cell topology distribution across the design space. Finally, the effectiveness of the optimized results is verified by finite element analysis (FEA) and experiments.