Stick-slip in sliding systems with tangential contact compliance

Sliding systems with a flexible body (i.e., a soft material) in the contact zone were modeled as a general two-degrees-of-freedom system that includes tangential contact compliance, and a series of dimensionless governing equations was derived. Based on the equations, a numerical simulation was conducted to study the stick-slip characteristics of the modeled system. By using six dimensionless parameters included in the equations, we obtained criteria for preventing stick-slip that can be applied to the design of sliding systems, such as the selection of soft materials for contact surfaces. In addition, some unusual phenomena caused by tangential contact compliance were observed. Even if the supporting section is overdamped, stick-slip motion can be promoted by the inertia of the mass of the contact zone; moreover, tangential contact compliance can cause serious errors in the measurement of the static and kinetic friction coefficients that uses the elongation of the supporting spring.