Simulation of Impact and Penetration with Hydrocodes
Akhilesh Sharma, Bhupinder Sewak and Dr Manjit Singh
Military Modelling and Simulation Symposium (MMS 2008) (MMS 2008)
Ottawa, Ontario, Canada, April 14-17, 2007
Summary
Recent simulations of impact, ductile failure, and fragmentation have tended to use Lagrangian approaches with special techniques for simulating fracture and failure. However mesh-based methods are limited by issues involving mesh entanglement under large deformation and considerable complexity in handling contact. In such cases Eulerian approaches can be utilized more effectively. Smooth Particle Hydrodynamics (SPH) techniques offer another powerful method for simulation of hypervelocity impact. This paper presents a simulation methodology developed to study the impact and penetration mechanism of projectiles into different targets. The purpose was to investigate the penetration processes, crater formation and residual velocities after penetration of the projectiles. Two cases with different impact velocities were considered. In the first case, simulation was carried out for hypervelocity impact of 7 to 15mm dia steel balls against 32mm thick mild steel plate targets. The balls were launched at impact velocities ranging from 1.8 to 5.2 km/sec with the help of two stage light gas gun at TBRL. Impact phenomenon was simulated using Autodyn 2D non-linear hydrocode using Eulerian solver. The crater and penetration depth were predicted accurately through simulation. Hypervelocity impact at 5.2km/s was simulated using Euler, Lagrange and SPH solvers for comparison. In the second case simulation of impact of 10mm dia steel ball projectiles against 6mm thick mild steel target plate was carried out using explicit finite-element analysis code LS DYNA 3D. Several simulation runs were carried out for impact velocities ranging from 590m/s to 785m/s. In all runs, residual velocities were predicted and compared with the experiments carried out at TBRL with fragment launching smooth bore propellant guns. In both the cases simulated results agreed within 5 to 7% of the experimental results. Simulation results have guided the future experiments on projectile target interaction resulting in considerable decrease in the number of experiments
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