Probabilistic fatigue strength assessment method for maglev train levitation frames based on P-S-N curves and modified Goodman-Smith diagram

Authors:
Preprint
Publisher website
Google Scholar
Abstract
Fatigue assessment of maglev train levitation frames lacks dedicated criteria, and deterministic methods cannot account for the dispersion of fatigue life. This study proposes a probabilistic fatigue strength assessment methodology that integrates P-S-N curves with Goodman-Smith (GS) fatigue limit diagram, and applies it to a maglev train levitation frame. Fatigue test data of ZL101A base metal and 6005A aluminium alloy butt and corner welded joints were fitted with P-S-N curves at survival probabilities of 50%, 90%, 95% and 99% by combining a three-parameter Weibull distribution, maximum likelihood estimation and the Stromeyer model. The octagonal GS diagram was modified with probability-dependent symmetrical cyclic fatigue strengths corrected for stress concentration and welding residual stress. A refined finite element model of the frame was verified by mesh convergence and full-scale bench tests, with a maximum stress error of about 14%, and provided the stress states under 17 operational load cases. Case analysis results show that all critical locations lie within the probabilistic safety envelopes, and that the safety margins of the butt joint, corner joint and base metal exceed those of the traditional deterministic method by 44.32%, 6.33% and 46.11%, respectively.

This publication has 32 references indexed in Scilit: