Metal Forming by Underwater Wire Explosion : 1. An Analysis of Plastic Deformation of Circular Membranes Under Impulsive Loading

Abstract

The plastic deformation of circular membranes of a strain-rate dependent, work-hardening metal is analyzed based on the strain increment theory. Numerical solutions for aluminum membranes are obtained under various types of loading as well as impulsive pressure pulses caused by underwater wire explosions. When the duration of a loading pulse is less than one-third of the time required to finish the deformation of the membrane, the deflection of a deformed membrane depends almost only on the impulse of the loading pulse and the instantaneous profile of the membrane is found to be trapezoidal during deformation. The relation between impulse of loading and deflection is calculated and illustrated. The forming limit due to peripheral necking is discussed. The neglect of strain-rate dependency of material leads to a notable underestimation of the forming limit.