Minimum deformation path sheet metal stretch-forming based on loading at discrete points

摘要

In the forming process of three-dimensional sheet metal panels of large curvature, the metal is prone for necking, fracture, wrinkling, or other defects during large plastic deformation. To achieve the specified product shapes without failure, optimum forming process was designed based on the minimum deformation path approach, and the process was implemented in a new stretch-forming process based on loading at discrete points (SF-LDP). In this paper, the minimum deformation path in a material element in SF-LDP process was summarized, and the loading trajectories for the optimum process of SF-LDP were derived and employed in the numerical simulations and experiments. The simulation results show that, compared with those of conventional-SF, the distributions of the deformations on the surface formed by SF-LDP are more uniform, the levels of strain and stress are effectively reduced, and the maximum strain is decreased by 24 % for a convex-shaped surface and 38 % for a saddle-shaped surface. Finally, experimental validation has been carried out and the results demonstrate the feasibility of the designed process.