Analysis of superplastic bulge forming by the finite element method

This article is a finite element method (FEM) study of hemispherical shell superplastic forming. The scope of this numerical simulation is to obtain the more detailed information about the deformation process that cannot be obtained by means of analytical and experimental studies. Two original calculation techniques proposed by the authors were used to investigate several industrially interesting parameters: using a subroutine presented in [1] it was possible to calculate the thickness distribution in a deformed sheet; an original technique presented herein provides the optimum pressure-time load curve needed to maintain a constant strain rate. Furthermore, on the basis of results obtained through a numerical simulation, the authors propose an accurate and alternative method to the tension test to characterise superplastic materials. Unlike the known methods present in the literature, this method does not require any hypothesis regarding deformation geometry. The experimental activity, carried out to support the numerical activity, showed good agreement between the numerical predictions and the experimental data.