Experimental and numerical investigations on the dynamic fracture of a cylindrical shell with grooves subjected to internal explosive loading

Abstract

A detailed experimental investigation on the dynamic fracture of a cylindrical shell with internal and external grooves subjected to internal explosive loading was carried out. Distributions of fragment velocities and fragment masses were measured and analyzed for specimens with different depths of the external grooves and different explosive materials, with the internal grooves of a fixed rectangular shape. Based on the experimental results, corresponding numerical simulations using the commercial software LS-DYNA were undertaken. By inspecting the fragments recovered from the experiments and the numerical results, the dynamic fracture of the casing led to fragments of approximately three shapes: a large cuboid fragment, a small cuboid fragment, and two irregular fragments formed by three classical fracture trajectories. The formation mechanism of fragment shapes was analyzed using the fracture trajectories. A good agreement has been obtained between the numerical and experimental results. Finally, a parametric study for the casing thickness, grid patterns of the grooves and explosive materials was carried out in order to investigate the effects of fracture. The results showed that grid patterns of grooves and explosive materials had significant effects on the fracture mechanism of the casing. The numerical technique was used to predict the dynamic fracture of casing with internal and external grooves under internal explosive loading and for structural design in order to achieve desirable fragments with controlled shapes.