Abstract：The solid-liquid contact state widely exists in the contact kinematic pairs of the key parts of the machine tool core unit. To acquisition of normal contact stiffness and damping parameters of solid-liquid interface is a key theoretical and technical problem in the research and development stage of high-end CNC machine tools, and it is still not fundamentally solved. The interface is the contact between two rough surfaces at the mesoscopic level, while it is the contact between asperities and at the micro level. Asperities of rough surfaces may produce elastic/elastic-plastic/plastic deformation under the medium/heavy loads. In order to reveal the influence of static and dynamic external load on the contact stiffness and damping of solid-liquid interface, the elastic/elasto-plastic/plastic deformation of contact asperity is studied based on the GW model, the KKE model and the AF model, respectively. And then, the contact stiffness and damping models of solid-liquid interface considering elastic/elasto-plastic/plastic deformation of contact asperity are established by combining with the Reynolds equation of hydrodynamic lubrication. Finally, it is verified by experiments. It is found that: the normal dynamic contact stiffness of solid-liquid mechanical joints decreases quickly and then increases with the increase of preload. The dynamic contact stiffness is smaller than the static contact stiffness when the contact load is over a certain threshold value. The normal dynamic contact stiffness increases with the increase of the amplitude of normal relative displacement. The normal dynamic contact stiffness increases linearly with the increase of excitation frequency. The normal contact damping increases nonlinearly with the increase of normal relative displacement amplitude and the contact load, but it’s almost unchanged with the increase of excitation frequency. There is great theoretical significance for the analysis, design, optimization and static and dynamic performance control of mechanical system to accurately obtain the normal contact stiffness and damping of solid-liquid mechanical joint and the key influencing factors.
2021, Vol. 42 
