Investigation of effects of fractal dimension and sliding speed on deformation of semi-infinite medium by using multiply asperity contact

The effects of surface roughness, sliding speed and indentation dept on deformation and temperature rise of elastic-plastic semi-infinite medium in contact with fractal rough surface were analyzed by using the finite element method. A 2-dimensional finite element model that rigid rough surface which is sliding over semi-infinite medium was used. Initially, an optimum element edge was determined by analyzing mesh densities. In this study fractal geometry was used to model rough surface due to ability of representing multiscale real surfaces. Because, traditional methods which were used to model surface roughness depend on sensitivity of measuring device, the vibrations in the environment etc. In order to determine effects of surface roughness on deformation and temperature rise, fractal rough surfaces were obtained by using fractal dimensions such as 1.41, 1.43, 1.45 ve 1.47. Sliding distance was fixed by changing sliding time to obtain effect of sliding speed. Also, 1.5, 1.6, 1.7, 1.8 nm indentations which are displacement distances to the semi-infinite medium by rough surface were used to get effects on deformation and temperature rise. It is obtained that increasing fractal dimension reduces surface roughness, temperature rise and stresses.