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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.

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1IntroductionReactive material is ac lass of solid energetic materials with an adequate amount of strength and sufficienti nsensitivity [1].G enerally,t hey are formed by meanso fu niformly mixing active metal powders, alloyp owders or intermetallic compounds with ap olymer matrix (typically polytetrafluoroethylene) and consolidated via ap ressing process. These materials areformulatedtoself-initiate and release aconsiderable amount of energy under highly dynamic loads, thus efficient damage is achieved by incorporating the defeat mechanisms of kinetic energya nd chemicale nergy.A s af ocus researchd irection at present in the field of efficient damage,r eactive materials and theira pplications in military technology haver eceived extensivea ttentiona nd have been researched vigorously around the world[ 2-5],e specially for the formulations design, preparation technologies, mechanical properties, impact-induced initiation, energy release characteristics, and weaponization applications technology.H owever,i ti sc lear that much additional workw ill be requiredb efore ac ompleteu nderstanding about the jet formationb ehavioro ft he shapedc harge with ar eactive material liner is achieved [6,7].I nf act, reactivem aterials are significantly different from traditional metal materials in material composition, damage mechanism, damage model, damage effect,e specially the applicationi nashaped charge liner wheret he reactivem aterial will react during the jet formation process. The delayt ime of reaction and reaction rate have direct impact on the damage effect of target. The key questionsa re:w hat additional effects in at arget could be caused by ar eactivej et, what self-initiation conditions are required, and what mechanisms are involved during the jet formation process.In this paper, the jet formation behavior of the shaped charge with reactivem aterial liner is investigated by flash X-rays. In addition, the numerical simulations are performed to understand the jet formationp rocess of shaped charge with reactive material liner and that with copperl iner. 2Preparation of Reactive Material LinersThe main ingredients of liner material are 74 wt-% polytetrafluoroethylene (PTFE) and 26 wt-% aluminum powders in experiments. The averagei nitial particle sizes of the PTFE and Al are approximately 28 mma nd 9 mm, respectively. The preparation of reactive liner consists of pretreatment, cold pressinga nd hardening treatment. At ypical preparation process is shown in Figure 1. The main advantages of this process are high material utilization rate, simple production process and low requirement of large-scale precision instruments and equipment. However,t his process also has some disadvantages. Firstly,b ecause of the differences in the physical properties such as density,h ardness and particle size of the powder material, the compound made up of variousk inds of powder materials is non-uniform. As ar esult, the delamination phenomenon of mixed materials would be observed in the process of molding,r e-Abstract:R eactive mater...