Enhancing the forming quality of Al2024-T351 sheets in laser peen forming through a novel energy sequence arrangement strategy

Laser peen forming (LPF) employs laser-induced shock waves for shaping and modifying bent structures, exhibiting high flexibility and non-contact advantages. This study investigated the impact of different laser energies, laser peening sequences, and energy sequences on the bending deformation, surface quality, and stress distribution of 4 mm thick sheets, using both experiments and simulations. Increasing laser energy and peening sequences were found to enhance the degree of sheet deformation, while adjusting the energy sequence had an insignificant effect on deformation. Higher laser energy resulted in increased surface roughness in the peened area, whereas increasing the peening sequence reduced surface roughness. The optimal approach for reducing surface roughness in forming sheets was found to be utilizing low-energy peening after high-energy peening (high-then-low). Moreover, compared to single low-energy peening, employing the high-then-low-energy peening strategy decreased the attenuation rate of the compressive stress wave, which led to a 23.5 % increase in the magnitude and 25 % increase in the depth of the final compressive stress. The compressive residual stress (CRS) in the length and width direction of the sheet's surface layer was higher with the high-then-low energy peening strategy compared to other treatment strategies.