Abstract
The present study investigated dynamic sliding friction of polyurethane (PU) rubber samples on an inclined smooth transparent polymethylmethacrylate (PMMA) surface with a thin layer of silicone oil. The two samples with different contact areas were used to study the sliding velocity as a function of the inclined angle. The results showed that the sliding velocity increased in the early stages of sliding and approached a constant value in the later stages. To understand the observed changes of the velocities, we proposed an analytical model, and found that the model can predict important changes of the velocities. Our findings suggest that the dynamic friction force can be dependent on both the sliding velocity and the contact area, and the similarity between the dynamic sliding friction and Stokes' law which describes the falling velocity of a small particle in a viscous fluid.
