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Abstract Establishing a more realistic contact model of joint surfaces is one of the key way to explore the variation law of stiffness characteristics. Firstly, according to the anisotropic fractal geometry theory, this paper equates the micro-convex body on the joint surface to an ellipsoid; Secondly, the two-dimensional joint distribution density function of the micro-contact area and eccentricity of the elliptical contact point was obtained by combining the micro-contact area distribution function and the related theory of probability theory; Finally, based on the Hertz theory, the elliptic elastoplastic normal contact stiffness model of the joint surface was established, and the related factors affecting the normal stiffness of the joint surface were numerically simulated and analyzed using MATLAB software. The results show that the eccentricity distribution of the elliptical micro-contact points on the joint surface has a significant effect on the total rigidity of the joint surface. The total stiffness of the joint surface increases with the increase of the shape parameter , but decreases with the increase of the shape parameter ; The normal stiffness of the joint surface increases with the increase of the normal load. When the load is constant, the normal contact stiffness of the joint surface increases with the increase of the plastic index and decreases with the increase of the fractal roughness, but increases first and then decreases with the increase of the fractal dimension. This model provides a certain theoretical basis for model optimization to improve calculation accuracy.
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Received: 06 May 2020
Published: 22 February 2021
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2021, Vol. 42 
