Analysis Method for Both Internal Stresses and Microstructural Effect Under Pure Rolling Fatigue Conditions

Abstract

For pure rolling fatigue conditions, the effect of microstructural changes and internal stresses due to grinding and fatigue processes itself was studied. Using Sachs’ method, the field of internal stresses was determined and it has been shown that its evolution is correlated with microstructural changes. These microstructural changes lead to changes in mechanical properties, especially to the reversible strain limit stress (R.S.L.S.) which has been determined in each point of the subsurface contact. Assuming a given relation between R.S.L.S. and fatigue limit, and using fatigue criterion which includes R.S.L.S., the effect of internal stresses, microstructural evolution, and Hertz stresses was analyzed. It has been found that the grinding internal stresses have no significant effect. On the contrary, the R.S.L.S. value was strongly reduced by grinding thermal effect in subsurface region, and was also strongly changed by the fatigue process. Finally, this analysis method was used to determine the best field of internal stresses necessary to minimize the fatigue damage.