Modeling For Contact Characteristics Of Joint Surface Considering Friction And Asperity Interaction

The joint surface widely exists in the mechanical structure,and its contact characteristics such as contact stiffness,contact damping and contact thermal conductance have an important influence on the structure.This paper mainly focused on the modeling of contact stiffness,contact damping and contact thermal conductance of mechanical joint surface.Firstly,the asperity contact model considering Friction and Asperity Interaction(FAI)was built,and combined with the distribution density function of asperity area,fractal models of the normal contact stiffness and damping of plane joint surface considering FAI were established.Furthermore,the plane joint surface was extended to the cylinder joint surface by considering the distribution density function of asperity area of the cylindrical contact coefficient.Thus,fractal models of the normal contact stiffness,contact thermal conductance and tangential contact damping of cylindrical joint surface considering FAI were further established,and the built models were simulated and verified.The main work was as follows:(1)On the basis of establishing the asperity contact model considering FAI,three-dimensional fractal models of normal contact stiffness and contact damping of plane joint surface considering FAI were established.The simulation results of the model show that the normal contact damping and stiffness increase with the increase of fractal dimension and normal load.The contact stiffness decreases as the friction factor and fractal roughness parameter increase,while the contact damping first increases and then decreases as the fractal roughness parameter and friction factor increase.The case where only the asperity interaction is considered and the case where FAI are not considered are compared,and it is found that the normal contact damping and stiffness decrease when the asperity interaction is considered.(2)By introducing the contact coefficient of the cylindrical surface,the area distribution density function of asperities on the plane joint surface was extended to the cylindrical joint surface.The three-dimensional fractal models of normal contact stiffness,contact thermal conductance and tangential contact damping of the cylindrical joint surface considering FAI were established,and the simulation analysis of the built models was carried out respectively.The results show that the normal contact stiffness,contact thermal conductance and tangential contact damping of the cylindrical joint surface increase as the normal load,fractal dimension,material characteristic parameter and the smaller cylinder radius increase,but decrease with the increase of fractal roughness parameter and friction factor.The tangential contact damping of the cylindrical joint surface increases as the ratio of tangential load to normal load increase,and also increases due to the asperity interaction.The normal contact stiffness and contact thermal conductance of the cylindrical joint surface are smaller than those of the plane joint surface,and the normal stiffness,contact thermal conductance and tangential contact damping of the internal contact of the cylindrical joint surface are larger than those of the external contact.(3)The correctness of the established models and the necessity of considering FAI were verified by the simulation of the built models and experimental and example data.