Effect of Confinement on the Velocity of Detonation (VOD) of Explosives by Employing Fibre Optic Technique

Abstract

The velocity of detonation termed as VOD of an explosives is a vital characteristic in the arena of energetic materials. It is measurement of the velocity at which the detonation reaction proceeds within an explosive when initiated by a desired activation energy. The detonation reaction is the combine effect of shock wave generated by detonation further induces the swift combustion of the energetic material and that of a reaction zone which enhances/stabilizes the propagation of shock-front. The VOD of an explosive is directly proportional to the power index of the explosive; hence its applications are best suited for that particular explosive. So far various methods have been established & being applied for measurement of VOD of an explosive experimentally or theoretically, nonetheless the one of precise method for this research topic is the use of optical fibre technique to measure the VOD with the help of “eplomet-fo-2000” instrument which uses optic fibre and records the delay time between two probs. The VOD of an explosive is influenced by its confinement with different materials and its influence is function of the density of confinement & weight ratio of explosives vis-a-viz material of confinement. Usually explosives are processed at lower densities that of TMD (Theoretical maximum density) of that particular explosives reducing the detonation performance characteristics mainly the VOD. The confinement with higher density & hardness materials tend to increase the VOD near to its TMD values. In the present work Tetryl pellets with density of 1.5~1.51 g/cm3 have been used and detonated in different confinements. The VOD recorded with the help of explomet-fo-2000. This instrument records the time interval/delay-time and analyses the VOD accordingly. The achieved results are in fair agreement with theoretical values having variation less than 3%. The upshot of this study is that the confinement of explosive charge considerably enhances the VOD which in turn helps to enhance the performance of the explosive. Keywords: Explosives; Velocity of Detonation; Shock Velocity/wave. Theoretical maximum density