Continuum damage mechanics-based fatigue life prediction of L-PBF Ti-6Al-4V

The fatigue behavior and life of additively manufactured Ti-6Al-4V are very dependent on its heterogeneous microstructure, which in turn results from its fabrication process. In this paper, a fatigue damage model based on continuum damage mechanics was proposed to predict the high-cycle and very-high-cycle fatigue life at various stress ratios of Ti-6Al-4V fabricated by laser powder bed fusion (L-PBF). Model predictions were found to be in good agreement with experimental results for the different stress ratios considered. The model was found to be sufficiently robust to predict the fatigue life of other titanium alloys over a range of mean stress. The primary novelty is the incorporation of a tensorial formulation for anisotropic fatigue properties and the nonlinear effect of mean stress, which extended the model applicability to a wide range of stress ratio from -1 to 0.5. The results provide new insight into mean stress effects on fatigue of L-PBF Ti-6Al-4V up to the very-high-cycle fatigue regime.