Abstract
According to the common characteristics of elastic mechanics and plastic mechanics expressions, a new model of asperity elastic–plastic contact is developed. The proposed model can solve the problem of discontinuous, leap, and non-monotone contact load and mean contact pressure and contact area in three separate phases, i.e., a perfectly elastic phase, elastoplastic phase, and fully plastic phase. The analytical model of normal contact stiffness considering the influence of the contact area distribution of the asperity and the elastoplastic deformation mechanism on the characteristics of the joint surface is further established by the fractal theory. In addition, the input energy of the asperity in the elastoplastic deformation stage is separated into stored energy and dissipated energy by introducing the loading and unloading model of the asperity. The analytical model of normal contact damping considering the deformation process of asperities and the elastoplastic deformation mechanism is further established. The effects of normal contact load, fractal dimension, fractal roughness, and plastic index on the normal contact stiffness and damping of the joint surface are studied by numerical simulation. The comparison of different models shows that the elastoplastic contact deformation mechanism has an obvious effect on the normal contact stiffness and damping. The normal contact stiffness and damping considering the elastoplastic deformation mechanism are greater than the normal contact stiffness and damping considering only the elastic and plastic states. Finally, the rationality of the present model is verified through model comparison and experimental comparison.
Highlights
A mechanical joint surface is composed of surfaces of mechanical parts in contact with each other and is widely found in machine tools and other mechanical equipment
By introducing the single load and unload model of the asperity, the input energy of the asperity in the elastoplastic deformation stage is separated into stored energy and dissipated energy
The simulation results show that the normal contact stiffness of the joint surface increases with the increase in the normal contact load and the plastic index and with the decrease in the fractal roughness
Summary
A mechanical joint surface is composed of surfaces of mechanical parts in contact with each other and is widely found in machine tools and other mechanical equipment. Wan et al. and Xueliang et al. ignored the elastoplastic deformation mechanism and established a contact damping fractal model related to the quality of the joint surface substrate This model reveals the influence of normal contact load and fractal parameters on the contact damping of the joint surface. Aiming at the above-mentioned shortcomings, based on the continuous and monotonous characteristics of the contact load, mean contact pressure and contact area of the asperity in the deformation process, and the common characteristics of elastic mechanics and plastic mechanics expressions, a new asperity elastoplastic model is proposed On this basis, considering the influence of the contact area distribution of the asperity on the characteristics of a joint surface, a normal stiffness model of the joint surface considering the continuous monotonic elastoplastic contact is established. Considering the deformation process of the asperity, a normal damping model of the joint surface, which is independent of the quality of the joint surface substrate, is established
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