Structural Optimization of the Novel 3D Graded Axisymmetric Chiral Auxetic Structure

Abstract

A recently introduced novel 3D auxetic axisymmetric chiral structure (ACS) with a periodic structure exhibits nonuniform stress distribution, with stresses concentrated primarily on the inner part of the structure. The structural optimization of one unit cell of the validated computational model is conducted to determine the optimal geometrical configuration of the unit cell, considering the target strain energy density as the optimization objective function. The results of the unit cell optimization are then used to build the parametric computational model of the whole ACS structure, where the areas of the significantly different strut thicknesses are defined as a separate section to control the thickness of the struts discretely. The parametric computational model is then optimized. This results in a new, spatially graded ACS with a stiffer structure, providing 4.25 times higher energy absorption capability than regular ACS, with one of the highest specific energy absorption (SEA) values in the strut-based metamaterial class and thus ideal for future crash absorption applications.