Energy absorption characteristics of additively manufactured plate-lattices under low- velocity impact loading

Abstract This study is focused on the low-velocity impact response of 3D plate-lattices fabricated via stereolithography additive manufacturing (AM). Elementary (SC, BCC and FCC) and hybrid (SC-BCC, SC-FCC and SC-BCC-FCC) configurations were tested and the effects of impact energy, relative density, plate-thickness, multiple impacts and impact angle on the dynamic crushing behavior and energy absorption characteristics were analyzed. The experimental results reveal that the hybrid lattices, due to the existence of larger number of open and closed sub-cells, were able to attenuate the peak impact stress transmitted to the structure and extend the duration of the load pulse (high toughness). A significant energy dependency of contact force-displacement characteristics of hybrid structures was noticed with increase in impact energy. The SC-BCC-FCC hybrid plate-lattices depicted a 70% increase in toughness and their specific energy absorption capacity is higher than the conventional aluminum lattices and other practical metamaterials. Experimental observations also revealed that the distribution of plates in each elementary structure in hybrid configuration plays an important role in mitigating the deleterious failure mode by transforming the brittle mode fracture into progressive damage of the plate-lattices. This paper, believed to be the first comprehensive experimental study, discusses the role of relative density, plate-thickness, multiple impacts, impact energy and oblique impact on the low velocity impact response of geometrically hybridized plate-lattice structures. The results of this investigation suggest that the concept of hybridization of plate-lattice architectures in conjunction with AM will enable development of lightweight high impact energy absorbing structures for a wide variety of applications.