Strengthening mechanisms of minimal surface lattices with CT deviation

Abstract

Lattice structure based on triply periodic minimal surface (TPMS) has received increasing interests due to exceptional lightweight and excellent performance. Recent studies are focusing on improving geometric efficiency of TPMS lattice structures. This paper presents an optimization approach of shell offset to improve mechanical and energy absorption of TPMS lattices. Additive manufactured lattices with four TPMS units were detected by Micro-CT to evaluate the micro-pores and manufacturing deviation of Ti6Al4V parts. Mean deviation was novelty loaded into simulation models to reveal the enhancement mechanisms of lattice structures, confirmed by experimental tests. The simulation results reproduce the experimental process including the elastic region, stress drop and plateau, indicating its good predictability. Shell offset design leads to a significant improvement on mechanical properties and energy absorption by maximum values of 244.9% and 312.7% respectively. This is due to the increase of second moment of area by shell offset, contributing to successive and stable layer-by-layer deformation mechanism of Diamond, Gyroid and I-WP lattices in which bending moment and torque are dominant. But excessive shell offset should be avoided for sheet Primitive due to the weakening effect of plastic hinge.