Machine joint surface has an important impact on the performance of mechanical systems. Based on fractal theory, joint surface is assumed to be the contact between absolute smooth surface and rough surface. Through the analysis of the contact process, the contact mechanics model, the contact stiffness model and the three-dimensional surface micro-contact model are studied. To obtain fractal characteristic, the factors and laws affecting the contact characteristics are indicated through digital simulation. The concept of micro-convex body hierarchy is proposed. The critical values are related to the scale of micro-convex bodies and affected by the property parameters of the material. It is proved that the critical point is smooth and continuous, the parameter characteristics of the critical point are determined and the error between prediction and practice is reduced. In the integral calculation of the model, the experimental constants are also established to facilitate the calculation. The results show that the contact process of rough surface is consistent with the actual contact. It makes up the deficiency of KE model by considering the interaction between micro-convex bodies.

中文翻译：

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粗糙表面接触模型的分形特征和域扩展因子研究

机械接合面对机械系统的性能有着重要的影响。基于分形理论，关节面被假定为绝对光滑表面和粗糙表面之间的接触。通过对接触过程的分析，研究了接触力学模型、接触刚度模型和三维表面微接触模型。为获得分形特性，通过数字模拟表明影响接触特性的因素和规律。提出了微凸体层次的概念。临界值与微凸体的尺度有关，受材料性能参数的影响。证明临界点是平滑连续的，确定了临界点的参数特征，减少了预测与实践的误差。在模型的积分计算中，还建立了实验常数以方便计算。结果表明，粗糙表面的接触过程与实际接触是一致的。它通过考虑微凸体之间的相互作用弥补了KE模型的不足。