EXTREME TENSION WAVE: NECKING AND FRAGMENTATION

A typical cylindrical cased charge explosion has brought a great interest in the scientific community in terms of optimizing or prediction of fragmentation. The Mott’s theory has brought a scientific breakthrough in this area of study by providing an insight about the fragmentation behavior in rings or shells. This theory introduced a so-called ‘Mott’s wave’ during the sudden expansion of the cylinder, and thus, provides a clue to understand the size distribution of fragments during explosion. In this study, a series of hydrocode simulations with ANSYS Autodyn is used to identify the pressure profile in the high velocity necking area of metallic samples with the pull speed ranging 1~6km/s. The extreme tension pressure profile is evaluated by conservation equations based governing equations in the necking area. These equations provide a way to study the extreme sudden pull followed by necking and fragmentation. From a series of numerical observation, we were able to conclude that there is a high chance that cracks occur from the center of a sample during extreme tension, and the necking really is not the main driver of the crack formation during an extreme sudden pull.