Finite element simulation and heat source modeling of J-shape and spiral laser welding paths in aluminum 1050 using custom DFLUX implementation

Laser welding simulation plays a critical role in predicting thermal behavior and optimizing joining strategies for modern manufacturing applications. This study presents a finite element modeling approach to compare two nonlinear laser welding trajectories, J-shape and spiral welding, applied to aluminum 1050. A custom FORTRAN-based DFLUX subroutine is implemented in ABAQUS to simulate the thermal response during 2D welding using a moving Gaussian heat source. Both welding trajectories are modeled under identical boundary and material conditions to enable a fair comparison. The study analyzes the thermal distribution (NT11 output) across the weld zone to assess the impact of path geometry on temperature gradients and heat-affected zones. Results show that the spiral path yields a more uniform thermal field, whereas the J-shape trajectory generates higher peak temperatures with localized heat input. The model provides valuable insights into welding heat flow behavior and contributes to the understanding of trajectory-based optimization strategies for heat-sensitive applications. This simulation-only study demonstrates how finite element method tools combined with custom subroutines can inform weld process design even in the absence of experimental validation.