RIGID VISCOPLASTIC FINITE-ELEMENT ANALYSIS OF THE GAS-PRESSURE CONSTRAINED BULGING OF SUPERPLASTIC CIRCULAR SHEETS INTO CONE DISK SHAPE DIES

This paper describes the development of a rigid viscoplastic finite el ement formulation for analysing the gas-pressure constrained bulging p rocesses of superplastic circular sheets in cone disk shape dies. In t his formulation, the effects of strain hardening and strain-rate sensi tivity of materials are included, and the boundary friction condition is introduced into the formulation in the form of friction functional. The finite-element model based on the membrane theory is developed, a nd then applied to simulate superplastic constrained bulging processes . The solutions by the rigid viscoplastic finite element method are co mpared with existing experimental data. The influences of the geometri cal parameters of the dies, the friction factor in the friction functi onal, the strain hardening and the strain-rate sensitivity on the inho mogeneity of thickness distribution are studied in detail. Copyright ( C) 1996 Elsevier Science Ltd.