The Mechanism Research On Rolling-Sliding Fretting Fatigue

Fretting fatigue damage widely lies in machine components which interfaces bear alternating load,such as bolts,axletrees,slots and tenors. Fretting fatigue will accelerate the crack initiation and growth on the surface and the sub-surface of the fretting contact components. In the early stages, fretting fatigue crack growes fast, which leads to early failure of metal components and cause a significant reduction on the working life. Therefore, the study of fretting fatigue crack initiation and growth behavior is significantly important. In this study,the fretting fatigue numerical analysis and simulation is performed,the fretting crack initiation process and the influence factors on fretting fatigue life is analyzed systemically.Firstly,according to the important factors of the fretting fatigue crack initiation, a numerical analysis method is adopted to calculate the stress and strain of the contact bodies. Then, a prediction model is proposed to predict the location of crack initiation. The model introduce a control parameter W, which conbine the determinant factors on sliding fretting and rolling fretting, and predict the location of the crack initiation according to the control parameter W.Secondly, the fretting fatigue life is predicted by employing the average strain method in fracture mechanics. Then, in accordance with the geometry characteristics of a typical "rolling-sliding" contact, a finite element model is established, by which the distributions of the the stress and strain on the contact surfaces are analyzed. Combined with the corresponding parameters,the fretting fatigue crack initiation life and the total fretting fatigue life are calculated under three working conditions : pure rolling, pure sliding, as well as pure "rolling - sliding" contact . Further analysis of the influence of these parameters on the fretting crack initiation life and fretting fatigue life is studied according to the FEA results.Finally, three typical "rolling-sliding" fretting fatigue examples: dovetail tenon connection fretting fatigue, steel ball bearings fretting fatigue, and cylindrical / flat contact fretting fatigue,are analyzed by employing the numerical analysis and FEA methods in this thesis. The fatigue life, rupture location, the crack propagation life and location are found,and the results agree actual results. And based on the comparison of the above three analysis results, are aggregated.The thesis analyzes the influences of the fretting amplitude, normal pressure and friction coefficient on fretting fatigue Systematically.