Abstract
The contact calculation of three-dimensional real rough surfaces is the frontier field of tribology and surface science. In this study, we consider the interaction and elastic-plastic deformation characteristics of asperities and further, propose an analytical contact calculation method for rough surfaces considering the interaction of asperities. Based on the watershed algorithm, the rough surface is segmented and the asperities are reconstructed into ellipsoids. According to the height relationship between the asperities, the definition of the deformation reference height of the matrix between each couple of asperities is provided. Subsequently, the calculation formula of the substrate deformation is provided according to the local contact pressure considering the elastic-plastic deformation of the asperity, and the contact state under a specific load is determined using the iterative correction method. The results correspond with those of finite element numerical calculation and the study reveals the following: (1) compared with the results obtained without considering the asperity interaction, contact area, distance, and stiffness will be reduced by 6.6%, 19.6%, and 49.5%, respectively, when the influence of asperity interaction is considered; (2) the interaction of the asperities has the greatest influence on the surface contact distance and stiffness. Under the same load, the existence of asperity interaction will reduce the contact distance, area, and stiffness; (3) considering the interaction of the asperities, the higher asperity will bear more load, but it will simultaneously reduce the contact of the surrounding area and increase that of the distant area. The calculation method proposed in this study has the advantages of high calculation efficiency and accuracy, thus, providing the calculation basis and method for subsequent studies on service performance of rough surfaces, such as the calculation of contact stiffness and fatigue performance analysis of rough surfaces.
Highlights
The surface of mechanical parts is rough and uneven on the micro level, making the real contact area of the surface far smaller than the nominal contact area
Based on the analysis of the above research status and aimed at the determined surface topography, we propose a rough surface contact calculation model considering the interaction of asperities
To verify the correctness of the method proposed in this study, the contact calculation and verification analysis are performed based on measured data of rough surface topography, and the results are compared with those of Zhao’s [24], KE [6], Chandrasekar’s [27], and the finite element models
Summary
The surface of mechanical parts is rough and uneven on the micro level, making the real contact area of the surface far smaller than the nominal contact area. To realize the contact calculation and analysis promptly and stably, the researchers simplified and reconstructed the asperities on the deterministic surface, and proposed the relevant rough surface contact calculation model by combining with the mechanical deformation model of the asperity [22, 23]. Ciavarella et al [25] calculated the average height change of asperities according to the deformation of Hertz pressure in the elastic half space, and further studied the influence of the interaction of asperities on the calculation results of the GW model. All of the above-mentioned models are based on the simplified calculation model for studying the interaction between the asperities, which is helpful in solving the average contact state of the rough surface efficiently. Based on the analysis of the above research status and aimed at the determined surface topography, we propose a rough surface contact calculation model considering the interaction of asperities. Based on the calculation model, the influence of the interaction of asperities on the surface contact state is further studied
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