In superplastic forming, it is often necessary to control the strain rate. Consider the forming of a hemispherical dome by clamping a sheet over a circular hole and bulging it with gas pressure.
A. Compare the gas pressure needed to form a 2.0-in. dome with that needed to form a 20-in. dome if both are formed from sheets of the same thickness and at the same strain rate.
B. Describe (qualitatively) how the gas pressure should be varied during the form- ing to maintain a constant strain rate.