Impact Analysis of Polymeric Additive Manufactured Lattice Structures

This work was sponsored by the US Army’s Natick Soldier Systems Center to investigate additively manufactured lattice structures for improved blunt impact protection for helmets. The idea is simple enough, modern helmets are designed to deflect or mitigate the impact forces due to bullets (high velocity) but not so much for blunt force impacts (lower velocity). In military operations, blunt force impacts are common, albeit sometimes accidently, due to falls or in the rush to enter-exit buildings and vehicles. In combat, flying debris also present challenges to helmet designers where the impacts can be both high- and low-velocity. Our work was to set the foundation for the exploration of polymeric 3D lattice structures to create the next generation of energy-absorbing helmet liners for military applications. Current foam liners, whether multi-layer or sculptured, all exhibit more-or-less the same energy-absorbing response which is fine for high-energy impacts but lacks the sensitivity for low-energy impacts. If one can move away from the use of foam and toward that of a 3D polymeric lattice structures, then it should be possible to engineer a helmet liner to have a more variable or tailored energy-absorbing response. To create such structures, the additive manufacturing process was used.