Prediction of the influence of flaws on the fatigue strength under biaxial loading

A method for the prediction of the fatigue strength of flaw-containing components subjected to in-phase biaxial loading is presented based upon a knowledge of the materials fatigue strength in bending. A key aspect of the method is the relationship between stress concentration factors and stress intensity factors. The fatigue strength is taken to be that stress needed to overcome a materials resistance to crack propagation, and a material constant, re, is used to relate fatigue strength and the threshold for crack propagation. Continuous crack growth in components containing flaws occurs when the driving force for crack propagation exceeds the resistance to crack growth which is created by the need to exceed the threshold level as well as to overcome the effects of crack closure. Good agreement between the predictions and experimental results was obtained.