A New Method for Modeling Mechanical Joint Surface Contact Stiffness

Abstract

：Establishing an accurate and effective joint contact stiffness model is the basis for further modeling and analysis of machine tool dynamics characteristics. A new elastic contact stiffness model is proposed, which considers the bulk substrate deformation and modifies the Greenwood and Williamson microcontact model (GW model) of rough surfaces. In order to analyze the influence of the bulk substrate on the contact deformation, a single asperity contact model containing the bulk substrate is first established, and the contact parameters of the joint surface are obtained based on the Hertz contact theory. Then, the new elastic contact stiffness model is proposed by introducing a triangular distribution function and making up for the defects of the GW model. The effects of distribution function, bulk substrate deformation and surface roughness on the contact characteristics of the joint surface are analyzed. The research shows that the triangular distribution function can effectively characterize asperity heights distribution. The influence of the bulk substrate deformation is caused by the interaction between the bulk substrate and the asperity, which is obvious as the normal load increases. In addition, surface roughness is the main factor affecting the contact stiffness. When the joint surface is applied with the same load, the surface roughness is larger, the contact deformation is larger, and the contact stiffness is smaller.

Research on Non-contact Bolt Preload Monitoring Based on DIC

“…It is mainly calculated by the graphic correlation of the displacement field. In this test, the head and end of the bolt are respectively equipped with stickers to optimize the speckle characteristics, and DIC monitors the total elongation of the bolt [15] .…”