Fractographic Analysis and Particle Filter-Based Fatigue Crack Propagation Prediction of Q550E High-Strength Steel

Fatigue damage has become one of the key issues affecting the service safety of steel bridges with the continuous increase of vehicle load and traffic volume. In this paper, fatigue crack growth (FCG) tests were performed on the base metal and butt-welded specimens of Q550E high-strength steel with various stress conditions. The fatigue crack propagation model parameters and fatigue life of Q550E steel compact tensile specimens under four stress ratios were discussed, and the fractographic analysis of the fatigue fracture of the specimens was also executed. The fatigue fracture mechanisms of Q550E steel under different stress ratios were revealed. Based on the experimental results, a particle filter-based FCG behavior prediction method of Q550E high-strength steel was developed considering the uncertainty of the FCG process. The results showed that the FCG behavior of the butt-welded specimen is more sensitive to stress ratio than that of the base metal specimen. The particle filter-based algorithm reduced the uncertainty of physical model parameters. The theoretical results were in good agreement with the experimental observations. This study can provide a basis for the antifatigue design of high-strength steel.