Design and analysis of 3-D superplastic forming processes

SuperPlastic Forming (SPF) is widely accepted as an advanced technique for forming complex aerospace components. With the observation of superplasticity in ceramics, intermetallics and composites including high strain rate superplasticity there is an increasing need to model the forming process. The deformation process needs to be precisely controlled to maintain the optimum conditions to achieve the maximum ductility. A brief review of simplified numerical and non-linear finite element methods available for the purpose are briefly outlined. A three dimensional thin shell formulation is detailed in the paper. The formulation uses a constant stress constant moment triangular thin shell element using a convective coordinate system. The contact algorithm is incorporated through a pseudo equilibrium concept whereas the time integration is performed using an explicit scheme. Results of the numerical 3-D model are compared with experimental measurements.