Theoretical prediction and FEM analysis of superplastic forming of AA7475 aluminum alloy in a hemispherical die

An aluminum alloy AA7475 holds a position of foremost importance among the high strength materials of interest to the aerospace industry. Superplastic forming is a manufacturing process whereby sheet metal is blow formed into a die to produce very light and strong aerospace components. The crucial importance is the prediction of the final thickness distribution and the strain-rate necessary to maintain superplasticity. This paper attempts to explore the superplastic deformation behaviour of the AA7475 aluminum alloy during blow forming into a circular die by a simple theoretical model and by a numerical simulation using standard finite element code ABAQUS. The numerical results obtained by a finite element code (ABAQUS) and the values obtained by the theoretical model are compared with the existing experimental values to verify the validity of both the models. The theoretical prediction of the thickness distribution, strain-rate and time to form the required bulge has been analyzed with the existing experimental values.