Fatigue Behavior of LB-PBF Ti-6Al-4V Parts Under Mean Stress and Variable Amplitude Loading Conditions

Additively manufactured components are intended for use in load bearing applications, which are often accompanied by fluctuating external loadings. Therefore, understanding the fatigue behavior of AM materials under variable amplitude loadings is necessary for ensuring reliable in-service component performance. This research focuses on the fatigue behavior of Ti-6Al-4V, fabricated via laser beam powder bed fusion process, under mean stress and variable amplitude loadings. Mean stress effects are investigated under strain-controlled constant amplitude loading under fully-reversed, Rε = -1, and tension-release, Rε = 0, strain ratios. The generated data is used to compare two mean stress models including Morrow and Smith-Watson-Topper. Variable amplitude loading conditions include fully reversed high-low and low-high loading to investigate load sequence and history effects. Finally, cumulative fatigue damage and life predictions are made using the linear damage accumulation model (i.e., Miner’s rule).