A new method for constructing three dimensional rough surface topography with expected bearing capacity

Abstract

Surface bearing ratio tp(c) or tp curve is often used to evaluate the bearing contact performance of rough surfaces, but currently it is difficult to invert the surface topography with the expected surface bearing ratio tp(c). Combining the definition of tp curve and the key coefficients in random process theory, roughness characteristic parameters (RCP) that directly regulate tp curve are found out to provide parameters for the active design model with expected tp(c). By calculating the surface height matrix satisfying the expected tp(c) and RCP with genetic algorithm, the active design method of surface topography gets constructed. Surface tp curves of grinding, shot peening, barrel finishing and active design are compared to verify the reliability of the method and the versatility of RCP. The results show: 1) RCP of tp curve are Sa (arithmetic mean height), Sq (root mean square height), Ssk (skew), Sku (kurtosis), Sp (maximum peak height) and Sv (maximum pit depth); 2) The surface topography of the expected tp(c) is basically consistent with the measured tp curve. The maximum relative errors of tp(c) and Sa are 5%, 1%, respectively. And the average relative errors are only 1.4% and 0.5%. The regulatory parameters influence in RCP on the surface bearing capacity is ranked as follows: Sa, Ssk, Sku, Sv, Sp. The new active design model provides method for constructing the expected bearing capacity surface and roughness interface mechanics’ study.