FE simulation of rectangular box forming using material characteristics from the multi-dome forming test

The finite element (FE) simulation of superplastic rectangular box forming process was conducted to examine the validity of the material characteristics, stress–strain rate relationship, strain rate sensitivity, m, and strength coefficient, K, which have been obtained by utilising a multi-dome test. The simulation results were then compared with those obtained with material characteristics from the tensile jump test. The material characteristics m and K were included as variable parameters and a function of the strain rate in a special subroutine. The subroutine was linked to the FE simulation in order to investigate the correctness of the superplastic material characteristics. The influence of die shape factor (length-to-width-to-depth ratio) and die friction on the deformation behaviour and on the final thickness distribution was also demonstrated. The results of rectangular box forming simulation revealed that the multi-dome test can be used not only in simple processes (such as free bulge-forming) but also in more complex situations such as rectangular box forming process and with consideration of the friction between the sheet metal and the die surface.