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The penetration enhancement behaviors of a reactive material double-layered liner (RM-DLL) shaped charge against thick steel targets are investigated. The RM-DLL comprises an inner copper liner, coupled with an outer PTFE (polytetrafluoroethylene)/Al reactive material liner, fabricated via a cold pressing/sintering process. This RM-DLL shaped charge presents a novel defeat mechanism that incorporates the penetration capability of a precursor copper jet and the chemical energy release of a follow-thru reactive material penetrator. Experimental results showed that, compared with the single reactive liner shaped charge jet, a deeper penetration depth was produced by the reactive material-copper jet, whereas the penetration performance and reactive material mass entering the penetrated target strongly depended on the reactive liner thickness and standoff. To further illustrate the penetration enhancement mechanism, numerical simulations based on AUTODYN-2D code were conducted. Numerical results indicated that, with increasing reactive liner thickness, the initiation delay time of the reactive materials increased significantly, which caused the penetration depth and the follow-thru reactive material mass to increase for a given standoff. This new RM-DLL shaped charge configuration provides an extremely efficient method to enhance the penetration damage to various potential targets, such as armored fighting vehicles, naval vessels, and concrete targets.

1IntroductionReactive materials areaclass ofs olid energetic materials that are formulatedt orelease energy under highly dynamic loads. In general, they are formed by introducing active metal powders into ap olymer binder, typically such as PTFE, and then consolidatedb yapress/sinterp rocess. Remarkably different from traditional energeticm aterials,t hey have features of high mechanical strength and sufficient insensitivity so as not to sustain ad eflagration reaction using traditional initiationt echniques, such as exploding bridge wires or flame initiation [ 1,2].A ss uch, the mechanical work of ah igh-strain-rate plastic deformationp rocess is required to providet he necessarye nergy to drivet he reaction.Due to their unique performance,r eactive materials have ag reat variety of applications, and haveb een intensively investigated in the past decade [3][4][5][6][7][8][9].O ne of the most important applications is demolition. Several researches show that much greater efficiency could be achieved by reactive materials baseds haped charge liner (reactive liner), which could release chemicale nergyi nt he target. The lethality of reactive liner against concrete targets was demonstrated by E. L. Baker [ 10,11]. Reactive jets were identifieda nd they were foundt oc reate much more collaterald amage than inert ones, as ar esult of the chemicale nergyr eleased inside the targets during or after the penetration process. Althought he excellent damage effects were confirmed, the demolition mechanism and behavior of this reactive material liner have not been understood well.Althoughn umericals imulationi sauseful way to reappear the penetration and blast process of reactive jets, it is difficult to find an adequate constitutivem odeling for reactive materials. For unreacted equation of state (EOS), Instron compression tests andh igh-rate split Hopkinson bar experiments were carried out to determine parameters of the Johnson-Cook model [12].Onthe other hand, atheoretical model was developed to describet he blast characteristics, and af itting method was employed to determine the corresponding parameters of reacted EOS [13].The demolition behavior depending on penetration and blast effects of ar eactivej et, is significantly influencedb y the self-delay initiationt ime and chemical energy release of reactive materials. The totalt ime of activation and selfdelay that occurs in impact-initiatedr eactivem aterials is stronglyd ependent on the dynamic loads [1].O ne step further,ah igher stress value likely leads to ar elatively shorter self-delay time. However,s ignificantlyd ifferent from an impact,w hen explosively activated, the stress imposed upon the reactivem aterials is much higher,a nd whether the highers tress will reduce the self-delay time remainsu nknown.Abstract:T he application of reactive materials on shaped charge liners has received much attention. Herein, the demolition mechanism and behavior of reactive materials based shaped chargeliner are investigated by experiment, numerical simulation, and theoretical...

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Physical experiments were performed to investigate the enhanced lethality of reactive materials (RMs) shaped charge liner against concrete target. The results show that the shaped charge with RMs liner left a funnel shaped hole on the pure concrete target front surfaces, whereas the Cu liner just left a slender penetration hole and produced less damage in comparison. The damage events were recorded by high‐speed photography with the frame rate up to 10,000 frames/s, and the results indicate that deflagration reaction of RMs has occurred inside the target after the detonation of main charge. By comparison of damage effects between RMs and inert Cu liners, we conclude that the gaseous products of the deflagration are the main inducement of catastrophic damage. For multi‐layered concrete targets, a cavity inside the target and several cracks on the targets front surfaces were formed, and the formation mechanisms are deeply discussed in this paper. Based on the isentropic expansion and crack growth theories, the computational formula for crack length was developed, and the influences of the mass of RMs and initiation depth on crack effects are achieved.

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