Normal contact stiffness model of mixed lubrication joint surface

In practical work, lubricating medium is generally added to mechanical joint surface to reduce wear. Here, a micro convex body of joint surface was equivalent to a conical micro convex body, and a 3-D fractal model for normal contact stiffness of joint surface under mixed lubrication was established based on the fractal theory and improved W-M function. The model was used to perform simulation. The simulation results showed that the non-dimensional normal contact total stiffness of joint surface firstly increases and then decreases with increase in fractal dimension, and the maximum value is obtained when fractal dimension is around 2. 6; with increase in fractal roughness parameter, it decreases; with increase in acoustic impedance of lubricating medium, it increases; the non-dimensional normal contact total stiffness of joint surface under mixed lubrication is larger than that without lubricating medium; compared with other models and experimental data, the model established here is more consistent with experimental data to verify its correctness; the proposal of the normal contact stiffness model for mixed lubrication rough surface can provide a good basis for predicting joint surface stiffness, optimizing performance of mechanical equipment and improving its structure. © 2023 Chinese Vibration Engineering Society. All rights reserved.