Normal contact stiffness model considering 3D surface topography and actual contact status

A normal contact stiffness model considering 3D topography and elastic-plastic contact of rough surfaces is presented in this paper. The asperities are generated from the measured surfaces using the watershed segmentation and a modified nine-point rectangle. The topography parameters, including the asperity locations, heights, and radii of the summit, are obtained. Asperity shoulder-shoulder contact is considered. The relationship of the contact parameters, such as the contact force, the deformation, and the mean separation of two surfaces, is modelled in the three different contact regimes, namely elastic, elastic-plastic and fully plastic. The asperity contact state is determined, and if the contact occurs, the stiffness of the single asperity pair is calculated and summed as the total normal stiffness of two contact surfaces. The developed model is validated using experimental tests conducted on two types of specimens and is compared with published theoretical models.