Investigation into the contact characteristics of rough surfaces with surface tension

Abstract

Surface tension is a kind of force that exists between the molecules of the material surface, which has a significant influence on the contact characteristics of rough surfaces. Therefore, the Nayak’s random process model is introduced to describe the height and curvature distribution of asperity on isotropic rough surfaces, and a single conical asperity system considering surface tension is established. Then, the single conical asperity system is extended to the entire rough surface, and a new contact model of the rough surface is presented based on statistical methods. The contact stiffness from the proposed model is added to the finite element model for comparison with experimental results. The effects of surface tension and semi-cone angle of conical asperity on the contact load, the contact area, and the contact stiffness of rough surfaces are revealed. The results show that the new model has larger normal load and contact stiffness, and a smaller real contact area than the classical elastic model where the dimensionless separation is constant. In addition, the contact load and contact stiffness between rough surfaces increase with increasing surface tension, but the real contact area decreases. When the surface tension is constant, the larger the semi-cone angles of the conical asperity, the greater the load, the real contact area, and the stiffness will be.