Abstract：Abstract: In this article, the asperity of joint surface is equivalent to the micro ellipsoid. According to the KE finite element model and the elastic Hertz contact theory of ellipsoid, the relationship between normal load, contact area and deformation was obtained by analogy with the elastoplastic contact deformation mechanism of the spherical asperity. Combined with the theory of three-dimensional anisotropic fractal geometry, the strict effective interval of the eccentricity of the contact point of the joint surface is [0,0.7374]. Assuming that the eccentricity of the contact point of the joint surface obeys the exponential distribution in the effective range, and is independent with the area distribution, Using probability theory and the area size distribution function of the contact point, the two-dimensional joint distribution density function of the area of the contact point and the eccentricity of the joint surface was obtained. Furthermore, the fractal model of the normal contact stiffness of the joint surface including the complete elasticity, elastoplasticity and complete plasticity of the ellipsoidal asperities was established. The comparison between the theoretical stiffness of the model and the experimental data shows that: the model can better predict the normal contact stiffness of the joint surface. Especially under light load conditions, the model has a higher prediction accuracy.
2021, Vol. 42 
