Increased Sliding Friction of a Lubricated Soft Solid Using an Embedded Structure

Controlling the lubricated sliding friction of compliant contacts is important for many mechanical and biological systems. Multiphase materials have been shown to exhibit varied lubricated friction responses when compared to controls of just one phase of the material. In this work, we describe a structured two-phase material composed of a plastic mesh embedded in a compliant elastomer matrix. This embedded mesh structure (EMS) exhibits increased lubricated sliding friction for a number of load, velocity, and lubricant viscosity conditions. The observed friction enhancement appears to be a result of the EMS sample transitioning to the mixed lubrication regime under conditions in which the control is in the elastohydrodynamic lubrication regime. Simulations suggest that the difference in lubrication regimes for the EMS sample compared to the unstructured control comes from areas of high contact pressure induced by the increased local contact stiffness of the material near the embedded mesh. We hypothesize that these areas of high pressure can lead to the destabilization of lubricant films under conditions where the control films are stable, leading to the difference in lubrication regime behaviors observed. Graphical Abstract