Low-cycle fatigue life prediction of spot welds based on hardness distribution and finite element analysis

Elasto-plastic finite element analysis was carried out for single spot tensile shear spot welds with software ANSYS. According to the relationship between micro-hardness and strength, cyclic material constants of different zones in the periphery of spot welds were determined in accordance with hardness distribution, as well as base material fatigue parameters. Using the local stress and strain obtained from finite element analysis, fatigue lives of spot welds were predicted with Morrow’s modified Manson–Coffin equation and Smith–Watson–Topper damage equation. Life prediction results showed that both equations gave good agreement with experimental data within low-cycle fatigue life regime.