Computational Studies of Porous Head Protection Structures for Human Cranium under Impact Loading

Abstract

This paper looks into the effects of various porous structures used in the construction of the shell of a protective helmet on the energy absorption capacity and their efficacy in protecting the head/skull against impact force. It is well known that porous structures are very effective for energy absorption; hence, they have been widely used to reduce the negative effects of impact and explosion loads on the human skull. Porous shell structures, made from titanium alloy (Ti–6Al–4V) and, comprised of several periodic topological configurations, namely the more common rectangle and hexagonal honeycomb, as well as those having auxetic properties, namely the concave honeycomb and double-arrow, are studied by means of numerical modeling. The reliability of the numerical model is validated with the published experimental results. For the double-arrow configurations, the study involves three different densities, and the structural energy absorption capacity of the double-arrow shells increases with density. For the same density, the energy absorption capacity of the rectangular shell is the best, and that of the honeycomb is the worst. The superior performance of the rectangular configuration is partly derived from the fact that the orientation of the struts in this structure is aligned along the direction of the impact force. Further comparison of energy absorption capacity is made between the porous shell and a shell having a traditional titanium monolayer. The severe plastic deformation in the solid titanium shell (traditional monolayer shell) is detrimental to the overall effectiveness of head protection gear. Apart from this, compared with the Kevlar composite laminated shell of the same mass, both the solid and porous titanium shells provide considerable protection to the human head. The comprehensive comparisons show that the porous design on the titanium shell is beneficial for mitigating the risks of traumatic brain injuries (TBIs).