THE DAMAGE MECHANICS APPROACH IDENTIFYING FATIGUE LIMIT BY FATIGUE
以成组疲劳试验确定疲劳极限的损伤力学方法

Based on irreversible thermodynamics,the damage evolution equation is constructed by introducing the damage driving force,in order to reduce the work of the up-down method in identifying the fatigue limit. The theoretical relationship between fatigue life and stress or strain can be obtained by integrating the damage evolution equation. For smooth members of structure, according to the results of fatigue experiment with group method,the material parameters of damage evolution equation,including the fatigue limit,are determined by the least squares technique.The curves of fatigue life in high stress area are obtained by the damage mechanics. And then,the fatigue life and fatigue limit in low stress area are deduced.The results of theoretical fatigue limit agree well with the fatigue experimental results of up-down method.By using this method,a lot of time, cost and manpower in fatigue experiment can be saved.