On cavity development in superplastic bulging

In the process of forming aerospace components with superplastic bulging technology, cavitation frequently occurs, causing deterioration of mechanical properties. A model is established to prevent such cavitation by combining adroitly Hill's quadratic yield criterion with the modified Gurson's viscoplastic potential for porous ductile materials. The experiments were taken with Chinese aluminum alloy LY12CZ (corresponding to US 2024) and Chinese brass H62. The specimens were cut from the same 2 mm thick sheets. The variation of volume fraction of cavity with respect to the average strain were shown. Results calculated according to the model agree well with the test data.