Static and dynamic mechanical behavior of self-supporting lattice with symmetric gradients

Abstract

Self-supporting lattice structures (s-LS) have shown great potential in various applications such as energy absorption. However, conventional s-LS designs solely rely on uniform structural configurations, limiting their mechanical properties. In this study, we present gradient lattice structures (GLS) by incorporating a size-graded design strategy. Both bending- and stretching-dominated GLS are fabricated using the Selective Laser Melting (SLM) technique. A comprehensive investigation of their mechanical properties, failure modes, and energy absorption is conducted under both quasi static and dynamic impact loading. It is observed that the stretching-dominated GLS exhibits significantly higher load-carrying capacity and energy absorption efficiency compared to the bending-dominated GLS. The gradient design enabled GLS to manifest different internal stress distribution, deformation processes, and failure modes in response to loadings. Furthermore, GLS also displays significant strain-rate dependent mechanical behavior, leading to improved energy absorption efficiency while maintaining a high material utilization rate. Our gradient-based design strategy may pave the way for more applications in energy absorption using lattice structures.