A 3D study of the superplastic forming of lids by the method of the critical sections

While developing the technological processes for isothermal gas forming of the complicated shape shells, it is very important to have the information about the progression of the shape changes, and to be able to predict thinning of a shell and filling of die cavities. These problems are solved using computer simulation. Creating a complex 3-dimensional mathematical model for this simulation is not always justified as it leads to a significant labor cost resulting from both data preparation and subsequent calculations. In order to obtain the essential estimates for the above-mentioned technological processes and for the optimization of pressure and temperature parameters, it is more practical to use simplified 2.5D models. This allows analyzing significantly larger number of feasible parameter sets in search for the optimal solution. It turns out that in many cases these estimates are practically acceptable except for extremely complex die patterns. For the most critical parts, after getting an initial estimate solution, one can carry out additional calculations utilizing a full 3D model. This approach reduces to a minimum the number of prototypes of forming trials. In this paper, we introduce a new technique estimating progressive shape changes for 3-dimensional shells based on the generalized cross-sections method.