A Prediction Model for Low Cycle Fatigue Crack Initiation under Axial Loading

摘要

A prediction model for low cycle fatigue crack initiation was proposed,based on damage mechanics theory,which indicated the relation of equivalent value d of low cycle fatigue crack initiation to stress attenuation percentage △S/S.Then,parameter d will be calculated if △S/S is given,and the corresponding cyclic life is initiation life of fatigue crack.To validate the model,a group of 10CrNiMo structural steel specimens with a round-section were tested through low cycle fatigue test controlled by constant strain under axial loading,and the results manifested that the model is dependable and applicable; and the error of d to really measured value is not more than 5.0％; when the total strain amplitude is 0.6％,d is close to 2.0mm and the initiation life is approximately 900 cycles,which is nearly 80％ of the entire life.