A numerical investigation on the effect of transfer medium in explosive forming

This research numerically investigates the effect of the energy transfer medium on the deformation behavior of the 2024-T351 Al alloy tube during the explosive forming process. Simulations were carried out in air, water, and plasticine mediums by using the finite element method to study the effect of the medium on the formability of the tube. Explosive forming experiments were performed in air with C-4 as a high explosive and the results were used to verify the developed finite element model (FEM). In computational modeling, to simulate hydrodynamic interaction Coupled-Eulerian–Lagrangian (CEL) method was selected. To simulate the expansion of the explosive Jones-Wilkins-Lee (JWL) model was chosen. Also, Johnson–Cook (J-C) strength and damage models were employed to define the mechanical response of the 2024-T351 Al alloy tube. Hillerborg’s fracture energy was calculated with the Charpy impact tests and given as input to the FEM to delete the elements that lost their stress-carrying capacity. The results of the constructed finite element model were then analyzed for verification purposes. The simulations conceded that the energy transfer medium has an influence on both the strain rate and the final shape of the Al tube The highest strain rate was obtained in air explosions and thus the highest flow stress. Also, higher stress triaxiality in the air medium led to an earlier fracture. A linear dependence was obtained with the normalized maximum principal stress and normalized dilatation stress for all mediums. By carrying out manufacture in water, the mass of explosives used in the air can be diminished.