Reduction in Spall Threshold due to Non-Contact Impact: A Molecular Dynamics Study
S Rawat and M Warrier and S Chaturvedi and VM Chavan, SOLID STATE PHYSICS, PTS 1 AND 2, 1447, 123-124 (2012).
Impact of single crystal copper plates at 1100 m/s impact velocity has been simulated using the molecular dynamics code LAMMPS 1. We validate the void nucleation threshold obtained under tri-axial strain conditions 2 by high velocity impact of copper plates. In this set up, the flyer remains in intimate contact with the target before the impact. We have also performed the impact of non-contact configuration of the flyer- target system, where the flyer starts a small distance away from the target before impact. Due to small misalignment of crystal planes in the flyer & target, the shock produced by impact creates defects in the target during its propagation. These defects become preferred void nucleation sites at the time of interaction of release waves and lead to spall at a lower value of tensile pressure.
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