Seidi, M., Hajiaghamemar, M., Ferguson, J., and Caccese, V., "Injury Mitigation Performance of a Head Protection Wear with Polyurethane Honeycomb," SAE Technical Paper 2015-01-1443, 2015, doi:10.4271/2015-01-1443.
Falls in the elderly population is an important concern to individuals and in the healthcare industry. When the head is left unprotected, head impact levels can reach upwards of 500 g (gravitational acceleration), which is a level that can cause serious injury or death. A protective system for a fall injury needs to be designed with specific criteria in mind including energy protection level, thickness, stiffness, and weight among others. The current study quantifies the performance of a protective head gear design for persons prone to falls. The main objective of this paper is to evaluate the injury mitigation of head protection gear made from a patented system of polyurethane honeycomb and dilatant materials. To that end, a twin wire fall system equipped with a drop arm that includes a Hybrid-III head/neck assembly was used. The head was instrumented with an accelerometer array. The test apparatus captures impact velocity and translational acceleration components simultaneously. Tests were performed on two different material systems for frontal, side and rear impact cases. The honeycomb-dilatant system for each design consists of a cast 6mm thick, polyurethane honeycomb in the front section and a 6mm thick, honeycomb in the rear, that are nominally 55 Shore A and 40 Shore A durometer, respectively and the outer shell was a dilatant material. The peak translational acceleration at the head center of gravity (C. G.) and the Head Injury Criterion (HIC) were captured to evaluate the performance of two material systems. A reduction of the peak translational acceleration and HIC during impact was observed. Dropping the head/neck assembly equipped with the protection system from 45cm height (rear impact) resulted in translational acceleration and HIC reduction from 308g to 82g and 879 to 136, respectively for the thicker material system.