Abstract: The orthogonal shear stress was selected as the key stress controlling the subsurface rolling contact fatigue damage. The influence of friction coefficient on the subsurface orthogonal shear stress under rolling contact was analyzed. Based on the linear fatigue accumulation rule and a modified equation for the stress rang of unsymmetrical cycling stress， the relationship between the subsurface stress and fatigue life was established to assess the subsurface rolling contact fatigue damage of backup rolls. An instance was implemented to analyze the influence of friction coefficient on the subsurface rolling contact fatigue damage of backup rolls. The result shows that the subsurface rolling contact fatigue damage of backup rolls increase with the increase of stress ratio and friction coefficient. So the fatigue damage of backup roll can be lessened by decreasing its friction coefficient.

Key words: backup roll, orthogonal shear stress, subsurface contact fatigue, friction coefficient, stress amplitude, stress ratio