Effect of roughness on surface stress concentration factor and fatigue life

The surface topography of plate was simplified as micro semi-ellipse notches. Finite element method was used to analyze the stress field of the plate with different roughness and obtain the effect of roughness on surface stress concentration factor. Fatigue life of the plate was predicted with given survivability and the effect of roughness on fatigue life was discussed. Empirical equation that relates distance between notches and roughness to stress concentration factor was established by linear regression method. An approximate quadratic curve has been found to suit the relationship between the roughness and logarithmic fatigue lives plate with given survivability.