Simulated effect of defect volume and location on very high cycle fatigue of laser beam powder bed fused AlSi10Mg

• The effects of defect size and location on VHCF behavior in LB-PBF AlSi10Mg were simulated. • A CPFEM, calibrated with monotonic and cyclic data, was used to investigate fatigue crack formation. • Surface-adjacent and irregularly shaped defects were shown to significantly amplify fatigue crack driving forces. • Samples with multiple small defects exhibited lower fatigue susceptibility than those with single large defects under cyclic loading. This study quantifies the interaction between volumetric defect location and size on the very high cycle fatigue (VHCF) of laser beam powder bed fused (LB-PBF) AlSi10Mg. Crystal plasticity finite element method (CPFEM) simulations were used to investigate the effects of defect location and size on the driving force for crack initiation. The CPFEM model was calibrated against uniaxial and cyclic experimental data of LB-PBF AlSi10Mg. Defect characteristics were informed by experimental data from the specimens produced in various geometries to create realistic representative volume elements (RVEs) with equivalent volume fractions of defects. By embedding defects of varying sizes and locations within the RVEs, fatigue indicator parameters (FIPs) were calculated to analyze the impact of defects’ characteristics on fatigue performance. Different combinations of defect volume and locations were generated for various microstructure instantiations, providing insight into extreme value fatigue responses. Larger defect volumes located on free surfaces consistently generated the highest FIPs, suggesting defect size and boundary proximity intensify stress concentration effects. RVEs with multiple smaller defects produced lower FIPs than those with single large critical defects. These findings underscore the critical role of defect characteristics on fatigue life, providing a foundation for future predictive modeling in fatigue-sensitive AM applications.