Interacting and coalescing Hertzian asperities: A new multiasperity contact model

Starting from the multiasperity contact theory, firstly addressed by Greenwood and Williamson [1] and Bush et al. [2], in the present paper we suggest a new methodology to take into account the lateral interaction between the asperities and their coalescing, neglected in the first formulation of the theory. When two opposing rough surfaces approach, the number and the size of the contacts grow, and some contacts spots may merge to form larger contact areas.This phenomenon is modeled, in this paper, in a simple way replacing the overlapping contact spots with a single ‘appropriate’ equivalent asperity.The method has been then utilized to analyse the contact between an elastic half-space and a numerically generated self-affine fractal rigid surface. The fractal surface has been generated by employing spectral methods. Results predict linearity between contact area and load and are in good agreement with numerical and experimental investigations.

► A new multiasperity model is presented to study the contact of rough surfaces.
► Interaction and coalescing effects between asperities are taken into account.
► Results predict linearity between contact area and load according to experimental data.
► The slope parameter κ of the area–load relation is almost insensitive to H, N and hrms.