Finite-Element Modeling and Optimization of 3D-Printed Auxetic Reentrant Structures with Stiffness Gradient under Low-Velocity Impact

Abstract

Additive manufacturing technologies such as fused filament fabrication (FFF) allow the production of metastructures with global properties that can be tailored to their specific application. This study simulated and optimized an auxetic re-entrant structure with a stiffness gradient for enhanced energy absorption with low acceleration peaks under different low-velocity impact conditions. The finite-element method (FEM) was used, and appropriate constitutive models were fitted to static and dynamic tensile and compressive data of acrylonitrile butadiene styrene (ABS) tested under various strain rates. A Johnson–Cook plasticity model demonstrated the best compromise between accuracy and computational efficiency. A simulation strategy using explicit FEM was developed to simulate additively manufactured auxetic metastructures under impact conditions. There was good agreement between the model prediction and the experimentally observed structural response. A parametric optimization was implemented to enhance the energy absorption capability with low acceleration peaks of a graded auxetic re-entrant structure for different impact velocities.