A new method for predicting the fatigue strength at various stress ratios based on damage of metallic materials

Abstract The prediction of fatigue strength for metallic materials in a wide range of stress ratios is a crucial engineering challenge. To pursue a more accurate method, the dependence of fatigue strength on stress ratio for 35CrMo steel and other materials was investigated in detail. It was found that as the stress ratio increases, the damage mechanism changes, and the errors of the conventional models in predicting the fatigue strength increase. The reason is that those models fail to describe the fatigue damage evolution of metallic materials under some special conditions. Based on the variational fatigue damage, a new prediction method was proposed by introducing the damage parameter. Through the validation with fatigue strength covering a variety of metallic materials and loading conditions, the method exhibits higher universality. And then the corresponding parameter of the formula is further analyzed to elucidate the influences of various loading conditions on fatigue damage of materials.