Optimization of contact parameters of bolted joint surfaces based on fractal theory

Abstract

The contact characteristics of bolted joint surfaces are the key to affect the dynamic and static characteristics of mechanical systems. When the joint surface is in the vibration fatigue state, the damping will increase and the resonance frequency will decrease. Therefore, it is very important to establish an accurate contact model of the bolted joint surface to study the dynamic characteristics of the whole machine tool. Firstly, the contact model of a single asperity on rough surface is established based on Herz contact theory. On this basis, the contact stiffness and contact damping model of the whole bolted joint surface are obtained by integrating the asperity on the surface based on fractal theory; The influence of assembly load F, fractal dimension D and fractal rough ness coefficient G on contact stiffness K and contact damping C is obtained through the numerical analysis of the stiffness damping model by writing a Matlab program; Through finite element modal simulation, the mapping relationship between contact stiffness, damping and natural frequency of assembly structure is explored; The research results show that the contact stiffness and contact damping can not meet the improvement of the dynamic characteristics of the assembly at the same time. In this paper, the contact parameters of the bolted joint surface were optimized by the method of theoretical modeling, numerical simulation and finite element analysis, which improved the assembly performance and machining accuracy of the whole machine, and provided a theoretical basis for the realization of intelligent manufacturing