Estimating of Work Hardening in Bent Sheet Metal Products at an Early Stage of Virtual Product Development

Sammanfattning: The thesis has two aims: firstly, to investigate the influence of work hardening due to forming simulation on test simulation. The investigated question was also: Is it worth the effort to include work hardening effect into test simulation? The second aim was, to propose a quicker method to estimate work hardening without forming simulation. The first aim was investigated by two methods. In Method A, forming simulation was carried out on the steel blank sheet and followed by test simulation. In Method B, test was simulated by using just the CAD geometry of the same component with virgin properties. The 2D and 3D test simulation were performed and it was found that result of method A is about 30% higher than method B, which suggests that it is essential to include work hardening. The problem is that at an early stage of product development the data of the forming process is not available. To solve this problem in the thesis an approach is proposed based on estimation of the hardening effect using analytical approach to calculate the strain just by geometrical parameters. This calculated so called postulated strain was then transferred to test simulation (Method C). The validation of results of test simulation with method C against ones obtained from Method A showed that they were almost identical. The results of the study showed that the proposed quick method to include forming history in test simulation can be used instead of very complex and time consuming FEM simulations of forming process.