Normal contact stiffness of rough surfaces considering oblique asperity contact

Abstract

The contact stiffness of the machined surface has an important effect on the performance of the complex mechanical product. A modified fractal model based on oblique asperity contact is proposed in this research. First, the contact radius and the critical contact area are analyzed based on oblique contact condition. The normal contact stiffness and elastic–plastic force are calculated. The ratio of the actual contact area and a new parameter related to the current contact angle are introduced. Second, numerical simulations indicate the difference. The results show that the stiffness of the oblique contact is smaller, and with the increment of the fractal dimension, the extent of the stiffness reduction is larger. In contrast, the uniform distribution has the lower proportion of the elastic force in the total normal contact force. Finally, experiments including specimen surface observation and load-deformation measurement are utilized to obtain contact stiffness of the machined surface. To some extent, the modified fractal stiffness model is more reasonable and accurate from the result.