Dynamic Disintegration of Explosively-Driven Metal Cylinder with Internal V-Grooves

Abstract

Machining V-shaped grooves to the internal surface of cylindrical shells is one of the most common technologies of controlled fragmentation for improving warhead lethality against targets. The fracture strain of grooved shells is a significant concern in warhead design. However, there is as yet no reasonable theory for predicting the fracture strain of a specific grooved shell; existing approaches are only able to predict this physical regularity of non-grooved shells. In this paper, through theoretical analysis and numerical simulations, a new model was established to study the fracture strain of explosively driven cylindrical shells with internal longitudinal V-grooves. The model was built based on an energy conservation equation in which the energy consumed to create a new fracture surface in non-grooved shells was provided by the elastic deformation energy stored in shells. We modified the energy approach so that it can be applicable to grooved shells by adding the elastic energy liberated for crack penetration and reducing the required fracture energy. Cylinders with different groove geometric parameters were explosively expanded to the point of disintegration to verify the proposed model. Theoretical predictions of fracture strain showed good agreement with experimental results, indicating that the model is suitable for predicting the fracture strain of explosively driven metal cylinders with internal V-grooves. In addition, this study provides an insight into the mechanism whereby geometric defects promote fracturing.

Numerical analysis on dynamic behaviour of novel grooved cylindrical casing with different explosive loads

“…Helte et al [6]assessed the influence of groove depth on the fracture mode of casings. Zhou et al [7]established a new model to study the fracture strain of explosively driven cylindrical casing with internal V-grooves through theoretical analysis and numerical simulations. They proved that the dynamic behavior and fragmentation of the grooved casing were mainly affected by the casing geometric parameters and the explosive load strength.…”