Research on extraction method of roughness parameters of relay circular contacts

Currently, the calculation of the surface roughness parameter is mainly based on the surface height data of the rectangular region, which results in the nonrectangular relay contact surface topography acquisition being limited to a certain local area, and it is difficult to characterize the overall topography state of contacts. In this paper, a method of fitting the rotation roughness parameter is proposed, which is to fit the roughness parameter of the largest inscribed square of contact surface under different rotation angles, and finally, a comprehensive roughness parameter value characterizing the whole circular contact surface is obtained. The Tamura feature analysis method is used to calculate the rotation roughness parameters of the circular contact at various angles. The effective area for calculating the surface roughness of circular contacts is increased from 63.66 to 99.14%. By calculating the moving Hurst index, the rotation roughness parameters of each angle are proven to conform to the fractional Brownian motion, and the rotation roughness parameters are fitted accordingly. Finally, the validity of the fitting parameters is verified by a neural network, which provides a feasible method for comprehensively characterizing the overall topography of circular contact. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.