Criteria for crack initiation during rubber abrasion

The crack initiation process during blade abrasion of a rubber surface has been investigated both experimentally and using a FEA simulation. At first the crack initiates at the location of the maximum tensile stress, yielding a crack growth angle of between 30° and 50° with the rubber surface, with the angle increasing with the normal load applied on the blade. The crack growth angle reduces as the initial crack propagates. It passes through several steps, each with a reduced crack growth angle and eventually reaches a much smaller angle generally observed at the steady state of abrasion. This initial crack growth process is predicted well by the FEA simulation. Both the experimental and the calculated results suggest that the initial cracks in rubber abrasion originate from micro-vibrations generated during the slip stage of stick-slip motion, which arises during the frictional contact between a soft rubber and hard abrader.