An investigation of high-speed forming of circular plates in a liquid shock tube

High-speed metal forming with liquid shock waves, generated non-explosively in a liquid shock tube, is a new field of study. The advantage of forming with liquid shock waves in a shock tube in comparison to explosive forming is better control and increased safety. This paper describes the experimental set-up of the liquid shock tube and presents the results of experiments performed with fully clamped circular copper disks subjected to the impulsive load of the liquid shock wave. The strain conditions of the deformed disks are determined and the deformation energy is calculated. A theoretical approach is also given to predict the midpoint deflection of the specimen. The experiments show a good repeatability and the calculated deformation energy and the predicted midpoint deflections reveal a good agreement with the experiments. The deformation process of the metal disks during the impact of the liquid shock wave is investigated with a high-speed video camera. From the experiments the local and the average deformation velocities and the strain rates are determined. The pictures of the deforming plate also reveal a plastic hinge, which was theoretically predicted in literature. (C) 1998 Elsevier Science Ltd. All rights reserved.