Investigating the effect of notch size on critical distance and fatigue limit by coupling the theory of critical distance and finite fracture mechanics

Abstract

The energy based failure criterion Finite Fracture Mechanics is transformed into a stress based failure criterion and expressed by an effective stress similar with Line Method. After coupling the two criterions, the theoretical critical distance expression is derived based on notch stress distribution, stress intensity factor function and material characteristic length. The effect of notch size and material characteristic length on the critical distance and fatigue limit prediction was analyzed for a group of V-shaped notches. Then, the coupled method was validated by a large number of experimental results. It is revealed that the Line Method and coupled method are the same except that they employ different critical distances. The validity of Line Method was discussed based on the difference of critical distances and fatigue limit predictions between the Line Method and coupled method.