This study investigates the characteristics o f shaped charge je t form ed with a high-polymer (PTFE) liner, as well as its penetration capabilities, by theoretical, experimental, and numerical methods. This work presents a viscoplastic model and equation o f compressible flu id to describe the je t cohesive condition. It also shows that the high-polymer je t is inevitably distended. Two types o f liner materials were studied: a high-polymer PTFE liner and a pure copper one. The corresponding numerical simulations o f the two je t formations are presented. The pulse X-ray photographic technology was employed to observe the distended je t o f the PTFE liner and the particulate je t o f the copper one. The simulation and je t radiography results show that the two types o f je t behavior with particulate and radial dispersion are ductile and related to the liner material. The distended je t formation result from the liner material was crushed at the high-pressure region because a sudden pressure jum p induces the radial velocity rise, which results in lateral expansion. As compared with a typical copper penetration performance, the polymer distended je t had a larger aperture and lower penetration depth. Due to polymer liner lower density, this je t will have limited penetration as compared to that o f a copper liner. The simulated results strongly agree with the experimental ones. The polymer material can be modified to obtain much better performance, which will greatly enhance the penetration capacity o f polymer jets. K e yw o rd s: explosive m echanics, shaped charge, high-polym er, jet. In tro d u c tio n . To produce longer and m ore stable jets, designers have used m etal liner m aterials because m etals have h igh density, high sound speed, good therm al conductivity, high dynam ic fracture elongation properties, low viscosity, and low com pression properties. These are necessary conditions for the form ation of cohesive and stable jets. M o st research about m etal je ts describe hom ogeneous dense m etal m aterials th at form the jet, and the penetration process through the constant ideal incom pressible fluid th eo ry and quasi ideal incom pressible theory; this research is relatively m ature. H ow ever, w ith the developm ent o f n ew m aterials, techniques, designs, and protective devices (com posite, reactive, electro m agnetic, and intelligent arm ors), there is a need for additional research. M oreover, the superior protection ability o f the new protective devices challenges the traditional anti arm or w eapons. C onsidering these factors, the im provem ent o f dam age perform ance o f arm or-piercing w eapons has becom e a research focus in recent years. C urrently, research on liner m aterial is divided into three categories: pure metal, m ultiphase com posite m aterial, and non-m etal m aterial. Pure m etal liners are m ainly produced from Cu, N i, M o, W, and Ta [1], w hile m ultiphase com posite ones involve W -C u , R e -C u , and T a-C u [2]. C ow an and B ourne [3] studied oxide glasses as s...

The tensile properties of a polymer‐bonded explosive (PBX) were systematically studied by using quasi‐static and dynamic experiments. A non‐linear constitutive relation was developed to describe the tensile behaviour of the PBX. The tensile properties of the PBX under different strain rates and temperatures were measured in quasi‐static tests. The tensile behaviour of the PBX was found to exhibit high strain rate and strong temperature dependence, attributable to the large fraction of the polymer binder. To obtain the rational dynamic tensile results, a modified split Hopkinson tensile bar (SHTB) setup was designed such that the specimens were in dynamic stress equilibrium and deformed homogeneously at nearly constant strain rates. To characterise the viscoelastic behaviour, the master modulus curve was derived from the tensile stress relaxation tests at different temperatures. The non‐linear constitutive model was implemented in ABAQUS to predict the tensile behaviour of the PBX. The computational results were found to be in good agreement with the experimental results.

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For the design o f the novel anti-explosive reactive armor tandem warhead, a prerequisite is to improve the reaming capacity and the damage performance o f the preceding kill element so that the channel is ready fo r the subsequent penetration by the kill element. Meanwhile, the selection o f appropriate shaped charge liner material in the warhead could help enhance the integrated penetration performance o f the kill element. Traditional shaped-charge liners made o f metals or metal alloys with high density, high sound speed and good ductility are capable o f form ing a good-shape and stable je t kill element, which also demonstrate the advantages o f large impact and high-performance penetration depth against the target. When the traditional liners are used to impact reactive armor, however, the weak reaming capacity and easily-induced charge explosions prevent the subsequent penetration o f kill element into the main armor. In addition, the je t kill element form ed by shaped-charge liners with low-density materials generally displays a low penetration depth against the reactive armor. In the present study, filled modifiedpolytetrafluoroethylene (PTFE) was selected as the material ofthe shaped charge liner. The damage performances on the armor from the kill elements form ed with metallic or nonmetallic liners were evaluated and compared based on the numerical simulations and experimental studies. The results showed that the head diameter o f the PTFE-Cu je t kill element was increased by 11.1% as compared to the PTFE je t kill element, and the form er was twice as large as that o f the copper je t kill element. The stronger reaming capacity against the target was essential fo r the opening o f a channel fo r the tandem warhead's subsequent element. In addition, when compared to the PTFE je t kill element, the penetration depth and the je t hole diameter o f the PTFE-Cu one were increased by 45.8 and 12.6%, respectively, demonstrating the high damage potential o f the PTFE-Cu je t kill element. Therefore, the present comparative analysis o f the kill element damage performance with different materials under high-speed impact loading has provided a reference fo r the research and the design o f the anti-armor tandem warhead with large penetration apertures and high damage performance.

The PTFE/Cu composite powder was selected as the experimental raw material, and the modified material PTFE/Cu with dense structure was prepared by hot pressing sintering process. The morphology of the product before and after the test was compared and observed by SEM. The effect of different material ratios on the densification results of the powder was studied, and the difference between molding and hot pressing sintering was analyzed. The results show that hot-pressed sintering can produce modified PTFE/Cu with a density of up to 99.9%, which is higher than that obtained by molding under the same pressure. The SEM image shows that, unlike the molding, hot-pressing sintering makes the crystal grains of the two materials exist independently in the modified polymer, and makes the powder crystal grains gradually perpendicular to the hot pressing direction.