Modeling and management of process-induced shape distortion of sheet metal products

The present research involves a process system approach utilizing both experimental and numerical techniques toward the modeling and management of process-induced shape distortion caused by the springback phenomenon in the sheet forming process. Investigations in the first stage were focused on the development of understandings of the sheet forming process and the effects of various process/material parameters on process-induced damage and shape distortion. This was achieved through a series of parametric studies. The second stage emphasized the optimal process design for minimal post-forming shape distortion by integrating the numerical model with the optimization technique, Genetic Algorithms (GAs), the results of which were verified experimentally. The materials used in the study were Al-Zn alloy 7075-T6 (hard) and 7075-O (soft). A square pan model was used as the case study for this research. Numerical studies were carried out by modeling the forming and springback process with the finite element code, ABAQUS. The results of this research showed that different punching velocity history could affect the amount of the post-forming shape distortion when coupled with other process/material parameters, especially for materials with high elastic modulus/yield strength ratios. Also, the integrated system showed the effectiveness and potential of utilizing GAs with FEM for optimal process design of nonlinear forming processes. The modeling results showed good agreement with the experimental findings.