Design of a Helmet Liner for Improved Low Velocity Impact Protection

Abstract

Abstract : This report documents a 2012 Natick Soldier Research, Development and Engineering Center (NSRDEC) study that used material testing and modeling tools to design and test a helmet liner prototype for increased low velocity impact protection. Basic theory of energy absorption and packaging were used to estimate material requirements for the helmet application. Foam materials were tested with an impact test device and characterized based on foam compression strength and energy absorbing efficiency. A helmet was measured for low velocity impact protection with a helmeted headform drop test. A finite element model of the drop test was developed to incorporate different materials and configurations. Material test data was imported to the drop test model, and the LS-DYNA model was used to simulate the response of the helmet in the impact test. Based on material test and model simulation results, helmet liner prototypes were fabricated and tested. The effectiveness of crushable foam was demonstrated for a one time use application. A prototype helmet liner combining high density polyethylene (HDPE) foam and viscoelastic comfort foam showed an improvement in impact protection over the current Army Combat Helmet (ACH) system at 4.3 m/s (14 ft/s), although the results were mixed at higher impact velocities.