Abstract: In order to predict the service life of ultra-high-pressure vessels more accurately, the influence of the initial crack size on the fatigue life of ultra-high-pressure vessels was studied. Firstly, the fatigue crack life of the surface crack in the ultra-high-pressure vessel was calculated by the fracture mechanics analysis method in ASME. Secondly, the stress intensity factor and the number of fatigue propagation cycles under different initial crack sizes were calculated by the method. Finally, the influence of initial cracks on stress intensity factor and fatigue crack growth life was comparatively analyzed. The results show that this method can calculate the fatigue crack propagation life of the corresponding surface crack of ultra-high-pressure vessels, and the number of first propagation cycles of different initial crack sizes varies from 9.379% to 28.057% of the total fatigue propagation cycles, which is relatively large. Combining with the results of stress intensity factor calculation, it is found that the size of the initial crack depth has a great influence on the overall fatigue crack growth life, and the size of the crack depth direction has a greater influence than the size of the crack length direction in the fatigue crack growth.

Key words:  high-pressure vessel;fatigue life;initial cracks; ASEM specification; fracture mechanics; life calculation

GAO Yao-dong, WANG Zhuang-zhuang, GUO Zhong-liang. Influence of initial cracks on fatigue life of ultra-high-pressure vessels［J］.Journal of Mechanical & Electrical Engineering, 2021,38(11):1506-1512.