Abstract:

：Based on the statistical contact theory and the assumption of equivalent joint surface, and the asperity deformation characteristics are considered under the loading, the unloading and the dynamic loading. Then, the static and dynamic contact model can be established, and the basic characteristic parameter can be obtained, which include the static and dynamic contact stiffness and contact damping in the unit area. Firstly, based on the Kadin’s and Etsion’s unloading model of rough surfaces in elastic plastic stage, the relationship of residual deformation and maximum deformation and maximum contact load is introduced. Then the static loading and unloading contact model can be created. Secondly, aimed at the dynamic harmonic displacement between contact surfaces, the static contact load and contact stiffness are expanded by using Taylor's formula. The dynamic load, the contact stiffness increment and the energy dissipation in the dynamic loading can be obtained. Then the model of dynamic contact stiffness and damping is built. Thirdly, influences of the combined surface pressure, dynamic displacement amplitude and vibration frequency on the dynamic contact stiffness and contact damping are analyzed. The research shows that the normal dynamic contact stiffness is slightly offset compared with the static contact stiffness, and the dynamic contact stiffness increment and contact damping increase with the increase of normal pressure and dynamic displacement amplitude, and the dynamic contact stiffness increases linearly with the increase of the vibration frequency, and the contact damping decreases with the increase of the vibration frequency. Lastly, through the comparison of theoretical calculation and experimental results, it is proved that the theoretical model of the combined surface method of the static and dynamic contact stiffness and contact damping is correct.

Key words: asperity, contact damping, contact stiffness, loading and unloading, mechanical joint