Modeling the short fatigue crack growth in additively manufactured notched parts

This work numerically assessed the synergistic effects of volumetric defects and macroscopic notches on the short fatigue crack growth behavior in metallic materials. The effective stress intensity factor (SIF), proposed by El Haddad to quantify a crack’s driving force, was utilized to assess the tendency of crack arrest for short cracks initiating from defects in notched specimens. Notch-defect configurations with defects of varying shapes and sizes at different locations (notch-surface, corner, sub-surface, and lateral-surface) were analyzed using linear elastic finite element analysis. Features such as notch root radii, defect’s size, shape, and location (proximity to notch and free lateral surfaces) influenced the effective SIF of cracks. A fatigue notch factor-based approach, incorporating the effective SIF of cracks, was employed to predict the fatigue lives of notched specimens. Predicted fatigue lives were validated using the experimentally observed fatigue lives of additively manufactured AlSi10Mg and 17-4 precipitation hardening (PH) stainless steel (SS) flat notched specimens with varying geometries from the authors’ previous work. For AlSi10Mg, 86 % of all fatigue life predictions fell within the scatter band of 3—most of them were conservative, and 100 % fell within the same scatter band for 17-4 PH SS.