Explicit dynamic simulations on high explosive systems.

High Explosives are the substances which have rate of reactions in supersonic speed and releases high amount of energy associated with gaseous products. Explicit Dynamics are used for non-linear problems where the time scales of interactions are very less of the order of milliseconds which are transient phenomenon. Impact velocities are of the order of few km/sec where Hydrodynamic pressure exceeds many times than material strength, and behaves like fluids which are called as Hydrocodes. ANSYS AUTODYN is Explicit Dynamics simulation software which deals with high impact problems. In the present paper, Flexible Linear Shaped Charge (FLSC) is analysed. FLSC has High explosives like RDX or HMX encapsulated in a metallic liner like lead or copper in inverted V shape. On Detonation, it produces a high speed jet which cuts the target plate by jet formation and shock severance. FLSC behaviour is simulated in AUTODYN and model is generated in its inbuilt pre-processor. Lagrangian & Eulerian solvers are used. Material modelling data like Equation of State (EOS), Strength model and Failure model are taken from AUTODYN material library. Shock and JWL EOS are used for metallic lead and RDX. Steinberg Guinan strength model is used for metallic lead. Post processing is carried out in AUTODYN post processor. Simulation results show that FLSC on Detonation resulted in a high speed metallic jet, which is captured in various time steps up to 13.64 µs. The maximum jet velocity achieved is 1050 m/s and maximum pressure is 732 bar which happens at 3.03 micro seconds (µs). Energy conservation summary shows that internal energy of Composition B converted into kinetic energy of lead in 5 µs. Jet velocity along jet formation is measured with gauge points. FLSC jet formation studies play a vital role in understanding further the cutting mechanism of FLSC on various target plates used in Missiles and Satellite launch vehicles for Stage separation system and Command Destruct system. [ABSTRACT FROM AUTHOR]