An Experimental Investigation of a Rubber Sponge Padded Motorcycle Helmet Subjected to Impact

Abstract

This research has aimed to improve the impact absorption capacity of motorcycle helmet by installing rubber sponge pads underneath its comfort foam. Three types of Thai commercial helmets have been used in this study, namely the Shorty, Open-face and Full-face. A number of off-the-shelf helmets and padded-helmets have been us as experimental specimens. The thicknesses of the rubber sponge pads have been 1.0 cm and 1.6 cm and they have been installed to the helmets with two different patterns, i.e. Full Area (FA) and Oregon Aero (OA). Two series of test, the impact and the drop test, have been carried out. Time-histories of the transmitted load and of acceleration have been considered. The peak load, the peak acceleration, and the HIC have been investigated and discussed. The experimental results have indicated that the padding technique could significantly improve the impact absorption capacity of the helmet. The maximum peak load reduction has been 55.21% in the case of the padded-helmet at the at impact height of 1.2 m. However, the peak load reduction has decreased with an increase in the impact height. The values of the peak acceleration and the HIC of commercial helmets have been found to exceed the standard value of ECE22.05, particularly for the Shorty helmet. By padding the helmet with a rubber sponge, the peak acceleration and the HIC have been also significantly decreased. The highest reduction of peak acceleration and the HIC were approximately 70% for the Shorty with 1.6 cm pad. In the case of the Open-face and the Full-face, the reductions have ranged in between approximately 12-35%. In addition, this study has revealed that the influence of rubber sponge thickness has been more prominent than the one of the pad patterns. Therefore, the OA pattern may be preferable since it is lighter and uses less material.