滚动和滑动接触疲劳多裂纹萌生和扩展特性研究

In rolling contact fatigue, the damage of contact surfaces and sub-surfacesare often occurred by the initiation and propagation of multi-cracks and theircombination. The study on behavior of multi-cracks in ontact fatigue does notdevelop enough in theory and experiment to suit engineering needs. Investigations ofthis subject are possessed of important values of theories and applications.The aim of this study is to investigate the behavior of surface and sub-surfacemulti-crack initiation and propagation under rolling cyclic loading, to analyze theinfluence of rolling and fretting compression and speed on the crack distribution andits growth direction, to obtain the interaction of the distance and direction between.cracks and also the inclination and combination of cracks in mixed-mode stress field.The physical model, mathematical method and evaluation criterion should be.developed with respect to approximation to the real engineering problems.In this study, with respect to linear elasticity assumption, an Airy function series is.applied to approximate the stress field of one crack or multi-cracks, and the conditionof stability and convergence is investigated. In the case of elastic plastic contactbetween the metal materials and rubber by compressing of multi-layers, a non-linearstress and strain distribution is calculated. A boundary element method has introducedto obtain the stress field under three-dimensional surface crack and sub-surface crackcondition. The behavior of inclining of mixed-mode crack has also investigated byexperimental mechanics method.The results of the study are obtained as conclusions as: the stress in the neighborhoodof the crack by combination of contact mechanics and fracture mechanics; influenceand reaction between multi-cracks; numerical simulation of contact stresses for ighnon-linearelastic material; stress and strain resolutions of three-dimensioncrack bodyby the boundary element method; crack inclination behavior in the mixed-mode tressfield.The research successes in the study are of applying value to transport vehicle,mechanical product and aeronautical engineering, especially in the case of complexcontact and multi-crack systems. In the scientific cooperation with the KeyLaboratory of Mechanics of Lille in France, Some research results have beendeveloped to the study on the crack delay technique by using residual stress and onthe fretting fatigue of interface.

研究滚动和滑动循环载荷下，接触疲劳裂纹萌生和扩展的规律。建立接触面在混合应力状态下，多个三维裂纹相互耦合的损伤力学模型。开展实验研究，对复杂环境下接触疲劳数值模拟技术的影响进行分析。发展接触疲劳数值模拟技术，完成有实用价值的计算实例。接触疲劳的研究在理论和实用价值上都处于科学技术的先进领域。适合我国经济和科技发展的迫切需要。