Numerical Investigation of the Effect of Residual Stresses on the Behavior of Semi-Elliptical Surface Cracks in Aluminum Plates

This study numerically investigates the fracture behavior of semi-elliptical surface cracks in 5000-series aluminum sheets, with emphasis on the role of residual stresses. Since the coexistence of cracks and residual stresses can seriously compromise the integrity and safety of engineering structures, their combined effect must be evaluated for reliable fracture prediction. A three-dimensional finite element model was developed in ABAQUS and the responses of specimens with and without residual stresses were compared. The mechanical properties of the alloy were obtained from tensile tests conducted in accordance with ASTM B557-02a and implemented in the simulations. To improve accuracy near the crack front, a refined, spider-web (focused) mesh was employed to capture the stress–strain fields with higher resolution. Elastoplastic fracture behavior was assessed using the J-integral as the primary fracture mechanics parameter. Residual tensile stresses were generated through a simulated four-point bending procedure; after unloading, the specimens were subjected to tensile loading. The results indicate that tensile residual stresses increase the crack-driving force and reduce the load-carrying capacity in the elastic–plastic regime. At low applied loads, a significant difference in J-integral values was observed between the two conditions, whereas with increasing load and plastic zone development, the influence of residual stresses diminished and the responses converged.