COMPARATIVE ANALYSIS OF ARBITRARY LAGRANGE IN EULERIAN (ALE) AND ADAPTIVE SMOOTH PARTICLES HYDRODYNAMIC (SPH) SIMULATION OF ROCKET PROPELLED GRENADE (RPG) ON ARMORS

摘要

Military ground vehicles and helicopters are vulnerable to buried landmines, Improvised Explosive Devices (IED) and unguided ground launched threats particularly, the RPG-7 Rocket Propelled Grenade. Detonating IED's and landmines creates a blast pressure and propagating blast waves near the ground vehicles causing both structural damage and crew injuries. On the other hand, projectiles and RPG's cause the structural damage and crew injuries by their impacting velocities. RPG-7 with a top speed of 294 meters per second (660 mph), strikes the target with a velocity in excess of 1100 meters per second (2460 miles per hour) with its jet tip speed and pierces up to 400 mm of Rolled Homogenous Armor (RHA) steel. High penetration of RPG's with a shaped charge is a big problem to protect against and to simulate. Arbitrary Lagrange in Eulerian (ALE) method of simulation is well suited for large deformation blast problems. In this study, two simulation methods of RPG are compared, namely ALE and ALE coupled with adaptive Smooth Particle Hydrodynamics (SPH). In order to capture the jet tip formation and slug formation with high degree of accuracy, it is necessary to model the RPG threat with fine details. It is also necessary to model the vehicle platform and the RPG in detail to understand better and quantify its impacting on engagement. There are many probabilistic models available to predict the chances, but they don't capture the accuracy. The simulation method addressed in this study aims at capturing the armor response with high accuracy on RPG impact and engagement. To perform these analysis, LS-DYNA based ALE and ALE-SPH (3D) methods were used. This will enable us to understand the RPG threat better and the effectiveness of the impact on the target, and helps to develop a suitable defeating mechanism and mitigating solutions