Computer simulation and experimental verification of a metal forming process

A description is given of a physical model designed to simulate pressure-forming operations, and the results from computational models and actual samples are used to validate the use of this physical model. Results from both the computational and physical models, coupled with experimental evidence from actual specimens, indicate that the free deforming profiles of a thin superplastic sheet is spherical. A state of biaxial stress exists at the pole in both physical and actual specimens. The clamping pressure due to the clamps creates a plane strain state in the rubber model. However, the clamps are unable to prevent displacement of the material laterally in actual specimens; this may be due to the bending and shearing action caused when the sheet is bent over the die radius. The drawing action is also responsible for a thickening of the sheet near the die edges. The present physical setup is unable to account for such bending and shearing stresses.