Stick-slip behaviour in sliding rubber contacs

The stick-slip phenomena play an important role in sliding contacts. The presence of that dynamic phenomena indicates that a sliding system can be regarded as a dynamic system consisting of masses, dampers and springs. To describe stick-slip behavior of a sliding system, modelling is needed. This research focuses on investigating the stick-slip occurrence by modelling the rubber sliding system. The sliding system is designed as a moving rubber surface which experiences a friction force from a single rigid indenter. Three sliding system models are proposed here. The first model is a tangential compliance system. It considers the rubber specimen and indenter move or oscillate in the tangential direction only. The second model is a fixed load system or full compliance system. It considers the rubber specimen to be able to oscillate in both tangential and normal direction. In this case, besides moving relatively in the tangential direction, the indenter and its frame can also oscillate in the normal direction. The third model is a fixed depth system. It considers the rubber specimen to be able to oscillate in the tangential as well as in the normal direction, but the indenter moves relatively in the tangential direction only.
Experimentally, rubber abrasion tests are conducted using the pin on disc tribometer with a specified or fixed indenter load (deadweight). This study investigates the stick-slip frequency and periodic wear pattern of an abraded surface. The results show that the wear pattern spacing of the wavy wear track correlates to the stick-slip frequency. Based on the sliding system model, the stick-slip frequency is the natural frequency of the normal oscillation of the indenter system. The indenter system includes the loaded indenter and its frame which oscillate together in the normal direction during sliding. Based on the experimental results, the proposed sliding system is suitable for describing the stick-slip phenomenon in sliding contact.