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...
The behind‐plate overpressure effect by a reactive material projectile with a density of 7.7 g cm−3 was investigated by ballistic impact and sealed chamber tests. The reactive projectile was launched onto the initially sealed test chamber with a 2024‐T3 aluminum cover plate with a thickness of 3 mm, 6 mm, and 10 mm, respectively. Moreover, the overpressure signals in the test chamber were recorded by a pressure sensor and a data acquisition system. The experimental results show that the behind‐plate overpressure effect is significantly influenced by plate thickness and impact velocity. For a given plate thickness, the peak overpressure in the test chamber shows an increasing trend with increase of impact velocity. However, for a given impact velocity, when impacting the 6 mm thick aluminum plate, the peak overpressure measured and the impulse delivered to chamber are higher than the values recorded for the 3 mm and 10 mm thick aluminum plates. As such, it is inferred that there is an optimum plate thickness to maximize the behind‐plate overpressure effect by reactive projectile.
Two-dimensional simulation models are established to investigate the impact-induced mechanical behavior of the PTFE/Al/W reactive materials. Random distribution of the metal particles and mesh generation of the specimen are obtained by using ANSYS parametric design language. Moreover, based on the experimental results of the Hopkinson bar, the loading curve in the simulation is simplified. Influences of the tungsten particle size, the particle distribution, and the loading strain rate on the mechanical behavior are analyzed by ANSYS/LS-DYNA. The results show that local severe deformation of the polytetrafluoroethylene (PTFE) matrix is generally caused by extrusion and slippage of the metal particles. The generation, growth, and interaction of the cracks are then induced gradually. Finally, many macrocracks form and the specimen dramatically fractures. Results also show that the local deformation of the PTFE matrix, deformation outline, and crack distribution are significantly influenced by the tungsten particle sizes and the particle distribution. In addition, with a decrease in the loading strain rate, the time for initial crack generation gradually delays and the deformation severity of the PTFE matrix shows a decrement.
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