Determination of wear coefficient in mixed lubrication using FEM

In a line or point contact with an elastohydrodynamic lubricant oil film, solid-to-solid contacts are common and wear will occur at these places. Given that there is only a portion of the load is supported by the direct interaction of roughness asperities, the wear coefficient should be less than that for dry contacts and account for the effect of surface roughness and oil film. Since it is difficult to obtain the wear coefficient value at different oil film thickness by experiments, this paper presents the methodology of determination of wear coefficient in mixed lubrication using finite element method (FEM). In this method, the roughness of contact surfaces is characterized as fractal surfaces by the Weierstrass–Mandelbrot (W–M) function, the sliding wear in mixed lubrication is simulated by the Coupled-Eulerian–Lagrangian (CEL) method and the wear volume is calculated according to the solid–solid contact load. Then the wear coefficient can be determined and the simulation example shows that the wear coefficient decreases nonlinearly with the increasing of oil film thickness and dynamic viscosity in mixed lubrication.