Cohesive zone model-based experimental–numerical study of the influence of external magnetic field on FSW lap joints

The objective of this study is to evaluate the influence of an external magnetic field on the interfacial fracture behavior of friction stir welded aluminum alloy joints using combined experimental testing and numerical simulation. T-peel and U-peel tests were performed under different magnetic field intensities to determine the variations in maximum cohesive traction and fracture energy at the weld interface. A cohesive zone model was calibrated based on the experimental load–displacement responses, and the magnetic-field-dependent parameters were implemented through a UMAT subroutine. The results showed that applying a moderate magnetic field led to a measurable increase in interfacial performance, with approximately 13% enhancement in maximum cohesive traction and about 10% improvement in fracture energy. Numerical simulations using the calibrated model accurately reproduced the experimental trends and confirmed the magnetic-field-induced strengthening effects. These findings demonstrate that incorporating a controlled magnetic field during friction stir welding can effectively improve the resistance of the interface to fracture.