From small wrinkles to Schallamach waves during rubber friction: In situ experiment and 3D simulation

Rubber-like materials are widely used in mechanical systems. Schallamach waves appear in friction process due to their small elastic modulus and relatively large surface adhesion energy, which may cause some negative influences, such as additional vibration and singular wear. In-depth researches into the characteristics and mechanism of Schallamach waves are of great significance to development and application of rubber-like materials. Therefore, the nucleation and propagation law of Schallamach waves are investigated by using in-situ experiments and 3D finite element simulation method. Results indicate that small wrinkles appear firstly at the edges of contact regions. Here, the small wrinkles propagate towards the centers of the contact regions in a spiral manner, which is analyzed by using elastic theory. The first Schallamch wave forms on the sides of the contact region, while the subsequent waves nucleate at the front of the contact region. Then, In-situ experiments are carried out to study the influences of materials ratios and sliding velocity on the behaviors of Schallamach waves. Based on the finite element model, analysis results reveal the law of propagation speed, wave length and wave amplitude of Schallamach waves, and the relationship between contact area and force (frictional and vertical force). There is basically no sliding exiting in the contact interface during friction process, and in some extent the Schallamach waves play a lubricating role.