Abstract:

Background: The appearance of smooth pit defect brings considerable difficulties to the prediction of fatigue life of structure whilst the traditional approach of fatigue analysis hardly meets the requirements of engineering applications. Purpose: This study aims to find a fast approach for fatigue life estimation of structure with pit defeat for engineering applications. Methods: Based on Miner linear cumulative damage rule, the quantitative relation between usage factor of structure with pit defect and that of structure without pit defect is determined. Based on the data fitting of the S-N curve, the expressions of ratio of the permissible number of cycles are deduced, and the range of application is given for common materials of nuclear pressure vessel. Results: Computional results using above mentioned approach provide the codomain of undetermined constants and sphere of application. Conclusion: The approach for fatigue life estimation of structure with pit defect meets the requirements of engineering applications, thus is suitable to fast estimation of fatigue life for nuclear pressure vessel.

Key words: Pit defect, Fatigue life, S-N curve, Power function, Three parameter function