Study on normal contact stiffness characteristics in non-Gaussian rough surfaces under mixed lubrication

This study aims to investigate the mechanical characteristics of contact between mating surfaces in the state of mixed lubrication, with a specific focus on the distribution of surface asperity heights in mechanical precision machining parts, which deviates from a Gaussian distribution. To achieve this, a normal contact model is developed for mating surfaces experiencing mixed lubrication, incorporating the non-Gaussian contribution nature of surface asperities and accounting for relative motion between mating surfaces. This model allows us to derivate the stiffness information in both solid and liquid domains to comprehend the contact behavior of mating surfaces under mixed lubrication conditions. The investigation results reveal that several key factors including normal load, viscosity, relative motion velocity, and non-Gaussian roughness parameters influence the normal contact stiffness of non-Gaussian rough surfaces in mixed lubrication mating surfaces significantly. These findings provide valuable insights that enhance our understanding of the performance of mating surfaces under mixed lubrication, and serve as a reference for the optimization design of mechanical equipment.