Chain damage effects of multi-spaced plates by reactive jet impact

Chain damage is a new phenomenon that occurs when a reactive jet impacts and penetrates multispaced plates.The reactive jet produces mechanical perforations on the spaced plates by its kinetic energy(KE),and then results in unusual chain rupturing effects and excessive structural damage on the spaced plates by its deflagration reaction.In the present study,the chain damage behavior is initially demonstrated by experiments.The reactive liners,composed of 26 wt%Al and 74 wt%PTFE,are fabricated through a pressing and sintering process.Three reactive liner thicknesses of 0.08 CD,0.10 CD and 0.12 CD(charge diameter)are chosen to carry out the chain damage experiments.The results show a chain rupturing phenomenon caused by reactive jet.The constant reaction delay time and the different penetration velocities of reactive jets from liners with different thicknesses result in the variation of the deflagration position,which consequently determines the number of ruptured plates behind the armor.Then,the finite-element code AUTODYN-3D has been used to simulate the kinetic energy only-induced rupturing effects on plates,based on the mechanism of behind armor debris(BAD).The significant discrepancies between simulations and experiments indicate that one enhanced damage mechanism,the behind armor blast(BAB),has acted on the ruptured plates.Finally,a theoretical model is used to consider the BAB-induced enhancement,and the analysis shows that the rupturing area on aluminum plates depends strongly upon the KE only-induced pre-perforations,the mass of reactive materials,and the thickness of plates.

Reactive jet density distribution effect on its penetration behavior

In this paper,the penetration mechanism of reactive jet with non-uniform density distribution is studied.The simulations show that the density deficit occurs in the whole reactive jet,and the density increases from the jet tip to tail.The density of jet tip is approximately 1.5 g/cm3,which is lower than that of the reactive liner materials.The X-ray experiments show similar results with the simulations.The density decreasing effect of jet tip has a significant influence on the penetration behavior when the reactive jet impacts steel plate.According to the simulation results,this paper assumes that the density gradient in the jet section has linear distribution.Then,the deflagration pressure generated by each jet element at the bottom of crater is introduced into the Bernoulli equation.Based on the virtual origin model and Szendrei-Held equation,the analytical models for penetration depth and radial cratering of reactive jet with the density reduction are obtained.Moreover,to further prove the validity of analytical models,the penetration experiments of the reactive liner shaped charge against steel plate under different standoffs are carried out.There is a convergence between the analytical crater profiles and experimental results when reactive jets penetrate steel plates under different standoffs,especially at standoff of 1.5 and 2.0charge diameters.