Compressive properties and energy absorption of honeycomb filled square tubes produced by selective laser melting

Abstract

Honeycomb core structure used as filling material requires high out-of-plane compression stiffness and good energy absorption performance. The regular honeycomb core structure can be produced by selective laser melting (SLM) and can offer better compressive performance than that of most traditional methods, and the square tube filled with honeycomb core structure may have good performance. In order to study the properties of honeycomb filled square tube, 316 L stainless steel powder was selected as raw material to prepare honeycomb filled square tube with different aperture sizes by SLM. The compression performance and energy absorption efficiency were studied by compression experiments. The collapse mode was analyzed by both experiments and simulation. The results show that the honeycomb filled square tubes have regular structures and no obvious defects. Compression experiments agree well with the simulation results. Comprehensive behavior presents three stages: elastic stage I, yield (platform) stage Ⅱ and densification stage Ⅲ. With the increase of porosity, Young's modulus and yield strength decrease. The honeycomb filled square tube produced by SLM has a higher relative Young's modulus in comparison to other topological structures. When the porosity increases from 73.5% to 87.9%, the energy absorption efficiency in the yield stage is higher than 70%, and the energy absorption per unit volume varies from 13.44 MJ/m3 to 76.41 MJ/m3 at 50% strain. Increasing aperture size of honeycomb single tube will results in the collapse mode changing from global to progressive buckling.