A finite-element model for the superplastic bulging deformation of Ti-alloy pipe

The superplastic bulging deformation process of Ti-alloy pipe under constant strain rate at the apex has been analyzed using a finite-element model (FEM). For the simulation of the process and the prediction of the final thickness distribution of the deformed part, MARC-MENTAT was used as a computational tool. An incremental approach based on a rigid-plastic flow formulation was employed. Special sub-routines were developed and linked to the main program for the superplastic material properties and the results of pressure calculations of constant apex-strain-rate deformation for each step. By FE modelling it is confirmed that the constant apex-strain-rate deformation process is superior to the constant pressure deformation process with respect to wall-thickness bulging. The results of calculation are compared to experimental results. (C) 1997 Elsevier Science S.A.