The Study Of The Mechanism And Its Influencing Factors On Laser Peen Forming Of Sheet Metal

The laser peen forming (LPF) is an emerging modern process of metal plate bending. It uses laser-induced shock wave pressure to induce unbalanced residual stress field in the sheet metal, then the moment of the residual stress causes the sheet metal to develop plastic bending deformation. In this paper, the primary process and mechanism of LPF are studied in detail, then the residual stress field induced by laser peeing and the bending deformation of sheet metal are researched by experiment and finite element method (FEM) simulation. The main contents in this paper were showed as following:The basic process and physics mechanism of laser shock wave are analyzed from the process of interaction between laser and materials. Then the dynamic response of sheet metal acted on the laser shock wave loading and the generation principle of residual stress were discussed. Afterwards some major factors which influence residual stress field were analyzed.The primary mechanism of the sheet's bending deformation caused by residual stress was researched in detail. In terms of mechanics theory, the analysis model that residual stress brought sheet's bending deformation in the LFP was established, then the relationship between the metal's curve and processing parameters was obtained. At last the influencing factors of LPF were discussed.The relationship between laser pulse parameters, peening numbers, peening coverage, peening space, thickness of the plate and the character of sheet forming were investigated by the experiments. Then the surface residual stress and surface qualities of sheet metal by LPF were observed and analyzed. The results of experiment indicated that both upper and lower layers of the deformed plate existed useful residual compressive stresses, and the laser peened surfaces were in good surface quality.Based on the above experiments, the processes of residual stress field and sheet's bending deformation induced by laser peening were simulated by using ABAQUS software.The simulation results were agreement with the analytic results and the experimental results. The gained conclusions have great significance for the purpose of optimizing the processing parameters and the controlling of LPF.