Normal contact stiffness of rough surfaces considering oblique asperity contact

Kai Zhang,Jing Zhong Gong,Guoxi Li,Meng Zhang

doi:10.1177/1687814018824471

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.

Highlights

The contact stiffness of joint surface in a complex mechanical product is a vital component of overall stiffness.[1,2] At the same time, it shows that contact stiffness varies with contact load, contact state, material, processing method, surface roughness, and surface structure
The stiffness of experiment is lower than the modified models at the beginning, higher after certain point. It indicates that the actual contact angle and size distribution of the shoulder–shoulder contact are more complicated than the assumed distributions
A modified fractal model was raised based on WK model

Summary

Introduction

The contact stiffness of joint surface in a complex mechanical product is a vital component of overall stiffness.[1,2] At the same time, it shows that contact stiffness varies with contact load, contact state, material, processing method, surface roughness, and surface structure. Keywords Fractal model, oblique asperity contact, normal stiffness, elastic–plastic force, contact angle According to the experiments and conclusions of these publications, a modified WK fractal model is proposed based on shoulder-shoulder asperity contact.

Results

Conclusion