PANTHER's Stelios Koumlis and Leslie Lamberson of CO School of Mines have published their work on the compressive response of a strongly rate dependent open cell polyurethane foam. The foam is manufactured by Team Wendy and used in the US Military's Advanced Combat Helmet. In completing this work, they also developed a new measurement technique that leverages high-speed full-field imaging to extract the dynamic stress-strain response.
This work allows the stress-strain response of the foam to be inferred at any strain rate, only by knowing the response at a reference strain rate. This expression could prove valuable, for extrapolating the stress-strain response to the intermediate strain rate regime which is challenging to obtain experimentally, but is crucial for modeling blunt impact traumatic brain injury scenarios.
Koumlis S, Lamberson L. Strain Rate Dependent Compressive Response of Open Cell Polyurethane Foam. Experimental Mechanics. 2019:1-17.