The Mechanics of Frictional Sliding at the Elastomer/Rigid Surface Interface

It is widely accepted that there are two principal factors commonly considered to give rise to a frictional force during the sliding of a rigid surface on a flexible elastomer. The first being due to the work of adhesion at the interface; the second to the viscoelastic energy required to deform the rubber materials. A finite element analysis (FEA) investigation into the mechanics of rubber friction is reported here. An additional third geometric factor is identified that relates just to the deformation of the rubber can also contribute to the frictional force. This entirely geometric contribution under certain conditions increases the frictional force considerably above that expected from a consideration of the interfacial friction coefficient alone. This will therefore make a significant contribution to many every day frictional sliding applications such as tyres on a road surface. This contribution is dependent on the depth of penetration of the rigid surface into the elastomer and is therefore perhaps comparable to the frictional behaviour found when wrapping a rope around a capstan.