Fatigue Life Predictions based on a New Stress Field Intensity Approach

This work is to introduce a new model for fatigue life prediction. At first, considering the weakening speed of weight function in the stress field of intensity method is too fast, a modification is presented to make it more suitable for the calculation of the fatigue life of the key components. In this model the stress contour line was proposed as the boundary of the damage zone and a new mathematical model for stress gradient was constructed. Then, the determination of the damage zone and the direction angle were given. Numerical simulations were performed to analyze the proposed new method. On the basis of the new stress field of intensity method, two examples were analyzed and calculated. Compared with the traditional method, the damage zone determined by the improved stress field method can change with the load amplitude, and it is closer to the shape and size of the real damage zone. The experiment effectively verifies the rationality of the new mathematical model and the feasibility of this new approach. With the small error and good stability, this new approach can be well used in the fatigue life prediction of notched specimen.