응력 구배 효과를 고려한 구름 접촉 모델의 피로수명해석

Abstract

Recently, Luu suggested fatigue life equation that uses every term of the Crossland equation with stress gradient effect. Luu's model, however, has a limit of being unable to coverage small radii that are less than a specified length. Furthermore, rolling model has a very small contact area compared to the rolling element size, and fatigue failure occurs on the small radius such as surface asperity by cyclic loading. Therefore, it is necessary to modify fatigue life equation in order to enable fatigue analysis for a small radius. In this paper, the fatigue life considering a stress gradient effect in rolling contact was obtained using Luu's modified equation. Fatigue analysis was performed to study the effect of stress gradient on the fatigue life using newly adopted equation and to compare the results with pervious models. In order to do this, a series of simulation such as surface stress anal- ysis, subsurface stress analysis, and fatigue analysis are conducted for two rolling balls of same size that contact each other. Through such a series of processes, the fatigue life can be calculated and equation that is proposed in this paper evaluates the fatigue life in case the contact area is small. Keywordsstress gradient effect(응력 구배 효과), stress invariant(응력 불변량), rolling contact fatigue(구름 접촉 피로), hertz contact(헤르츠 접촉), fatigue life(피로수명)