An Evaluation of the Compressive Properties of Helmet Pads Pre- and Post-Shock Wave Overpressure Exposure
Final rept. Jul 2012-Oct 2013
ARMY NATICK SOLDIER RESEARCH DEVELOPMENT AND ENGINEERING CENTER MA
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This report documents a study of the compressive properties between pre- and post-shock tube treated helmet pads under the on-going Headborne Equipment Shock Tube Methods Program in support of TeCD1b Force Protection-Soldier and Small Unit. The goal of this study was to determine whether the composite pad protection, designed for low velocity impacts in the Advanced Combat Helmet ACH, exhibits measurable damage in compression performance after being loaded by an overpressure shock wave. Ultimately, this information will be used to determine whether the helmet pads can be re-used or if they need to be replaced after every exposure from a pressure loading in a shock tube or live fire blast. Rectangular and trapezoidal helmet pads were subjected to shock tube tests with the pads mounted inside a helmet set on a mannequin headform. The tests were conducted inside of a 28-inch x 28-inch shock tube with two overpressure durations and outside of a 9-inch x 9-inch shock tube at two distances from the exit of the tube for modified load profiles. The headform was oriented in four configurations with respect to the incoming shock front facing, right side facing, back facing, and front facing at a 30 deg angle. The pads were removed from the helmet and subjected to either a dynamic impact drop tower assessment 305 cms or a quasi-static compression test with an Instron materials test machine 8 mms. New helmet pads were subjected to the same compression tests, and the conditions of the two sets of pads were compared. No conclusions could be drawn from the drop tower assessment due to problems encountered with the data collection methods. No conclusive difference in compressive strength was observed from the quasi-static compression tests between the helmet pads subjected to an overpressure shock wave and the new pads.
- Protective Equipment