CFD numerical simulation of melt flow and weld pool formation in semiconductor laser direct welding of 6061 aluminium alloy with PET based on surface microtextured

Microtexture pretreatment significantly enhances the strength of laser-directly weld joints between metals and thermoplastic polymers. The mechanism and quantitative characterization of the role of melt flow, melt pool formation, and heat transfer within microstructures in directly welded joints have not been addressed, this study establishes a three-dimensional transient heat-fluid-solid coupling numerical analysis model for the laser direct weld of 6061 aluminum alloy with a PET. This research elucidates the gas-liquid phase flow and heat transfer in the molten pool during the welding process and examines the influence of various process parameters on the filling effect of the molten pool. The results show that when the depth-to-width ratio of the groove is about 1.3 (depth 160 mu m, width 120 mu m), the spacing is 0.2 mm, the laser connection current intensity is 9A, the laser moving speed is 3 mm/s, and the pressing force is 1000 Pa, the strength of the welded joint reaches the maximum 20.12 MPa. Through the analysis of the volume fraction cloud diagram and velocity vector diagram, it is found that the molten polymer can effectively fill the Microtexture grooves on the surface of the aluminium alloy under the combined action of compression force and buoyancy force, and form a dense molten pool structure. This study provides theoretical support for the high-strength connection between metals and polymers