Fatigue life prediction model for welded stainless steel connections considering mean stress under random vibration

Abstract

For vibration response signals with mean stress, a Rayleigh function with a multiplier was used to fit the probability distribution of stress amplitude corrected to vibration response signals with zero mean stress. An equation was developed by the obtained S-N curves for welded 1Cr18Ni9Ti stainless steel connections with stress ratios of −1, 0.1, and 0.5, respectively, to convert the stress amplitudes of cyclic loadings with different mean stress to stress amplitudes with zero mean stress for the same fatigue life. Based on the S-N curve of material with a stress ratio of −1 and the Miner linear damage accumulation theory, a vibration fatigue life prediction method was proposed. The results of the random vibration fatigue test with non-zero mean stress on the pipeline of the launch vehicle have verified the accuracy of the proposed method.