The FEM analysis of rolling-sliding contact under boundary lubrication's

The Boundary Lubrication (BL) in rolling contact appears different properties in contrast to Elasto-Hydrodynamic Lubrication (EHL). The. surface and subsurface of contact bodies are subjected to extremely high and complex loads, which can give rise to radically changed microstructures and to marked micro-structural gradients. The surface roughness is certainly an important factor that can't be neglected if mechanisms of rolling-sliding wear are investigated and shall be included in the calculation of the local deformation and stress state. This can be modeled as that water fill in the crack or between the crest and trough of corrugation. A two dimensional finite element study is carried out when a small region of a wheel is rolled onto a block. In this study block and wheel are assumed to be flat and to have a certain surface roughness with water respectively. The simplified numerical calculating method is applied to investigate the influence of water on rough surface and crack by the coupling fluid-structure analysis. The area around the crack front satisfies the assumptions of linear elastic fracture mechanics (LEFM). From this result, it can be concluded that water is essential for the fatigue micro-cracks to develop into defects.