Stamping process design using FEA in conjunction with orthogonal regression

A process design technique is presented for the formability assessment of sheet metal stamping parts and feasibility analysis of process conditions. The proposed approach is based on numerical simulation of stamping processes by using explicit – incremental and implicit – iterative finite element techniques. The influence of the numeric model parameters are investigated with factor analysis and described with response surfaces obtained by multi-linear regression. A forming process leading to springback-critic channel geometry is selected for the application of the proposed methodology. The effects of modeling parameters are determined by evaluating influences of the punch velocity and the element size, in order to obtain a numerically calibrated simulation model. Then the sensitivity of the springback deformations to the contact interface friction and the blankholder force is predicted, and a set of response surfaces is generated. Comparisons with the experimental data indicated the suitability of the proposed approach in springback predictions. The proposed technique is employed in the stamping analysis of an engine suspension bracket made of high-strength steel. The process conditions are investigated in terms of drawbead penetration and blankholder force setting, and the predicted part shapes are compared with CMM measurements of the manufactured parts. An evaluation of computed springback distortions shows a good correlation with experiment results and confirms the use of process parameters estimated with the proposed design.