Study on Friction Behaviors of Soft Materials Considering Sliding-Caused Deformation

Accurate and quantitative characterization of friction behavior is of critical importance for material design and manufacture, especially for soft materials. It is mainly because the sliding-caused deformation of soft materials has always been neglected during characterization. Here, a modified model considering sliding-caused deformation was proposed to characterize the friction behavior between a spherical glass indenter and silicon rubber. A novel friction apparatus consisting of a transparent spherical indenter connected with a camera was used in real-time to measure the friction contact status. The contact shape and area during friction were then extracted by a proposed shape function. Experimental results show that shrinking and expanding of the contact area occur simultaneously when a spherical-rigid indenter slides on a soft substrate due to sliding-caused deformation of soft materials. Based on these results, this study built a modified model considering the shape change and the accompanying deformation component of friction, which is an effective method for evaluating the friction behavior of soft materials.