Research on influence parameters and fatigue life prediction method of weld with undercut imperfection

ISO5817 standard is widely used to define the quality levels of undercut in engineering, and the fatigue life is evaluated by traditional fatigue assessment method, which has some limitations such as difficulty in parameter matching and high modeling accuracy. The structural stress method based on fracture mechanics and crack growth law has overcome the limitations. In this paper, the simulation method and formula method based on equivalent structural stress are put forward firstly, and the fatigue life prediction ability of these methods for undercut imperfection is verified. Then, the influence parameters of undercut are summarized and analyzed. Based on the stress distribution at the notch, a new method for predicting fatigue life with undercut imperfection, i.e., zero-point characteristic structural stress method, is put forward, and its ability and accuracy are verified by test data.