Investigation on stress microcycles and mild wear mechanism in gear contact fatigue

Abstract

AbstractGear contact fatigue is becoming a primary limitation for the growing demand of power density and service life in gear‐driven equipment. The unchecked surface fatigue crack could further cause premature failure and put a serious risk to the safety and reliability of mechanical systems. In this work, an attempt is made to investigate the effects of rolling‐sliding and mild wear on contact fatigue behavior. A contact model is developed to capture the variation of instantaneous pressure and stress field, which are calculated with the transient mixed elastohydrodynamic lubrication (EHL) approach. Rolling‐sliding contact is simulated with the time‐varying roughness topography, which is updated by Archard wear equation. The stress cycles are extracted, and the relative contact fatigue life is obtained by using the Zaretsky criterion. Results suggest that in rolling‐sliding contact, the contact fatigue life is obviously lower compared with pure rolling. The increases in the number and amplitude of stress microcycles is found to be the main contributors to the reduction of fatigue life. Mild wear tends to smooth the surface, subsequently mitigates the stress concentration, and reduces stress cycles, and then decreases the risk of surface contact fatigue.