The Research On Contact Stiffness Of Joint Surface

In order to meet a variety of functions and properties and processing requirements and convenience of transportation, machine tools as well as various types of machinery is generally not a continuous whole, but by the various parts in accordance with certain requirements of combinations together. The parts and the components between the contact surfaces is called mechanical joint surface. It can be said that in the mechanical structure the joint surface is exist everywhere. The mechanical properties of joint surface were researched by theoretical, numerical simulation and experimental measurement. At last, schematically show the practical application of the contact stiffness of joint surface.With considering the change of elastic-plastic critical deformation of asperities contact, a calculation model of normal contact stiffness of joint surfaces was presented. The surface topography of joint surfaces was described based on fractal geometry. According to the plastic-elastic contact theory, the contact deformation characteristic of asperities was analyzed, and the critical deformation estimation model was presented, which expressed critical deformation as the function of fractal parameters and contact deformation, the contact stiffness calculation model of single asperity was brought forward with considering the change of critical deformation. Additionally, combining the surface topography description function and the elastic-plastic critical deformation calculation model of asperities, the asperity statistical distribution function was presented, and the calculation model of contact stiffness of joint surfaces was built.The thesis proposed a new model of real rough surfaces based on 3D measured method and reverse engineering method. First of all, shape and morphology with four different coarseness of turning surfaces is obtained by the surface topography measuring instrument, secondly,3D solid models of real rough surface is captured by reverse modeling, and its finite elements contact model is established, which is prepare for the Posterior finite element analysis. Eventually, the actual contact surfaces were analyzed by finite element analysis. The residual stress and contact stiffness of the joint obtained by the he finite element analysis.In this paper, independently complete the experiment about the static stiffness of joint interfaces. Firstly, the experimental model of the static stiffness is established, and combined with the theoretical analysis. Completely extract the characteristic curve of the load and displacement, and then obtain the contact stiffness of the joint surface.Finally, the research finished practical application based on the research projects. The joint contact stiffness is currently mainly used in the dynamic dimension chain and the finite element analysis of dynamic and static characteristics of the machine.