Motorcycle clothing fabric burst failure during high speed impact with an abrasive surface

High energy is involved when a rider impacts a road surface in a crash. Rider speed, height of fall and road surface morphology all contribute to the level of initial impact energy. Impact can cause fabrics and seams of protective garments to burst rendering their protective value void. The Cambridge abrasion tester tests protective clothing with a fall height of 50mm and abrasive belt speed of 28km/hr, far below what can happen in a “high side” motorcycle crash at 100km/hr. This work addresses the mechanics of what occurs in the first few microseconds of an impact and provides insight into the effect that speed has on fabric burst. This work used a Cambridge impact abrasion test to evaluate two different protective motorcycle clothing fabrics (a denim and brushed fleecy fabric over a p-aramid protective liner). It measured their abrasion resistance at an abrasion speed of 28km/hr and standard impact height. It used a high speed camera to measure the impact displacement of the test head. Fabrics with high stretch were more prone to burst failure on initial impact. Fabric burst is caused by a high speed tensile stress between the fabric coupled with the abrasion surface and the inertia of the body dragging against it. Stretch fabrics are pushed into the abrasion surface for a longer period by the body before the tensile stress occurs so the coupling force is higher. If the transition to abrasion occurs early in the impact then a fabric is less likely to burst.