Failure Prediction during uniaxial Superplastic Tension using Finite Element Method

Superplastic materials show a very high ductility. This is due to both peculiar process conditions and material intrinsic characteristics. However, a number of superplastic materials are subjected to cavitation during superplastic deformation. Evidently, extensive cavitation imposes significant limitations on their commercial application. The deformation and failure of superplastic sheet metals are a result of a combination and interaction process between tensile instability and internal cavity evolution. Thus, this study carried out modeling of the uniaxial superplastic tensile test using a code based on the finite element method, that used a microstructure based constitutive model and a deformation instability criterion. These models are the criterion account for both geometrical instabilities and cavitation. It is observed that the proposed approach captures the characteristics of deformation and failure during superplastic forming. In addition, the effects of the cavitation on the superplastic forming process were investigated. The results clearly indicated the importance of accounting for these features to prevent premature failure.