Fretting fatigue of rough surfaces

This paper presents a numerical model that maps the evolution of fretting fatigue life of Hertzian rough contacting bodies in fretting wear. Effect of surface roughness parameters (i.e. root mean square, skewness and orientation) on fretting fatigue life is reported. Fretting fatigue life is calculated as the crack initiation period predicted by the Smith Watson Topper multiaxial fatigue theory. Fretting wear is also accommodated in the analysis and is calculated by local application of Archard's wear law. The results from this investigation indicate that wear initially improves resistance to fatigue cracking, and reduces fatigue life as it becomes dominant. The approach developed in this study allows for implementation of real rough surfaces and study the effects of various statistical surface properties on fretting fatigue life. The presence of surface roughness in the analytical model reduces predicted fatigue life significantly. Other statistical surface parameters such as skewness and orientation also have a major impact on fretting fatigue life calculations.