An integrated software tool for fatigue life prediction in large additive manufactured metallic structures under multi-axial loading

Additive Manufacturing (AM) offers unprecedented design freedom but also introduces challenges for fatigue life prediction, including surface roughness variability, microstructural defects, and complex stress states. Conventional fatigue assessment methods, which rely on equivalent stress parameters and assume uniform surface conditions, often fall short when applied to AM components with intricate geometries and localized surface features. This work presents a fatigue post-processing framework that integrates three key modeling strategies: (i) the Modified Wöhler Curve Method for critical-plane-based multiaxial fatigue assessment, (ii) the Theory of Critical Distances to account for stress concentrations near geometric features, and (iii) surface-orientation-dependent material properties to reflect roughness variations induced by the build process. The post-processor operates on finite element (FE) results, supports large-scale three-dimensional meshes, and is applicable to metallic components in general, not limited to those produced by AM. The framework is demonstrated on a bearing housing produced by Laser Powder Bed Fusion in Ti–6Al–4V. The FE model comprises over one million quadratic tetrahedral elements, and the predicted fatigue life and crack initiation site show good agreement with experimental results. Total computation time remains under 50 min, despite the full-field critical-plane search and subsurface stress evaluation, making the tool practical for industrial use.