Bionic stab-resistant body armor based on triangular pyramid structure

A stab-resistant substrate was designed and realized with a triangular pyramidal structure, inspired by the biological armor model in nature. The stab-resistance behavior and dynamic response mechanisms were studied through numerical simulation and experimental testing of a knife impacting a substrate,and an optimal structural design was obtained accordingly, with a tilted angle of 22.5and optimal thickness of 1.2 mm. It was shown that the triangular pyramidal structure generated twice the internal energy of the knife than the flat substrate due to the dispersing effect of the structure. The force parallel to the inclination caused a significant scratch on the substrate surface, while the force perpendicular caused obvious substrate deformation. A new riveting method was used to form the total layer, which passed the GA 68-2008 standard. The stab-resistant clothing coupled with the reduced wearing burden could provide effective protection and avoid fatal injuries on security personnel working in dangerous environments. The method provided may enlighten the future design and manufacturing of stabresistant clothing.

Composite armor philosophy(CAP):Holistic design methodology of multi-layered composite protection systems for armored vehicles

A philosophy for the design of novel,lightweight,multi-layered armor,referred to as Composite Armor Philosophy(CAP),which can adapt to the passive protection of light-,medium-,and heavy-armored vehicles,is presented in this study.CAP can serve as a guiding principle to assist designers in comprehending the distinct roles fulfilled by each component.The CAP proposal comprises four functional layers,organized in a suggested hierarchy of materials.Particularly notable is the inclusion of a ceramic-composite principle,representing an advanced and innovative solution in the field of armor design.This paper showcases real-world defense industry applications,offering case studies that demonstrate the effectiveness of this advanced approach.CAP represents a significant milestone in the history of passive protection,marking an evolutionary leap in the field.This philosophical approach provides designers with a powerful toolset with which to enhance the protection capabilities of military vehicles,making them more resilient and better equipped to meet the challenges of modern warfare.

Study of the Ballistic Impact Behavior of Protective Multi-Layer Composite Armor

The abalone shell,a composite material whose cross-section is composed of inorganic and organic layers,has high strength and toughness.Inspired by the abalone shell,several multi-layer composite plates with different layer sequences and thicknesses are studied as bullet-proof material in this paper.To investigate the ballistic performance of this multi-layer structure,the complete characterization model and related material parameters of large deformation,failure and fracture ofAl_(2)O_(3)ceramics andCarbon Fiber Reinforced Polymer(CFRP)are studied.Then,3D finite element models of the proposed composite plates with different layer sequences and thicknesses impacted by a 12.7 mm armor-piercing incendiary(API)are built using Abaqus to predict failure.The simulation results show that the CFRP/Al2O3 ceramic/Ultrahigh Molecular Weight Polyethylene(UHMWPE)/CFRP(1 mm/4 mm/4 mm/1 mm)composite is the optimized stack of layers.The simulation results under specified layer sequence and thickness have a reasonable correlation with the experimental results and reflect the failure and fracture of the multi-layer composite protective armor.

Penetration resistance of Al_(2)O_(3) ceramic-ultra-high molecular weight polyethylene(UHMWPE)composite armor:Experimental and numerical investigations

To enhance the protective performance of ceramic composite armor,ballistic penetration experiments were conducted on Al_(2)O_(3) ceramic-ultra-high molecular weight polyethylene(UHMWPE)composite armor with different thickness configurations.The damage and failure modes of hard projectiles and ceramic-fiber composite targets were analyzed.The recovered projectiles and ceramic fragments were sieved and weighed at multiple stages,revealing a positive correlation between the degree of fragmentation of the projectiles and ceramics and the overall ballistic resistance of the composite targets.Numerical simulations were performed using the LS-DYNA finite element software,and the simulation results showed high consistency with the experimental results,confirming the validity of the material parameters.The results indicate that the projectile heads primarily exhibited crushing and abrasive fragmentation.Larger projectile fragments mainly resulted from tensile and shear stress-induced failure.The failure modes of the composite targets included the formation of ceramic cones and radial cracks under high-velocity impacts.The UHMWPE laminated plates exhibited interlayer separation caused by tensile waves,permanent plastic deformation of the rear surface bulging,and perforation failure primarily due to shear forces.Through extended numerical simulations,while maintaining the same areal density and configuration of9 mm Al_(2)O_(3) ceramic+12 mm UHMWPE laminated composite armor,the thickness configurations of the Al_(2)O_(3) ceramic and UHMWPE laminated backplates were varied,and various thicknesses of UHMWPE laminates were simulated as the cover layer for the ceramic panels.The simulation results indicated that the composite armor configuration of 10 mm Al_(2)O_(3) ceramic+8 mm UHMWPE composite armor increased energy absorption by13.48%.When altering the cover layer thickness,a 4 mm UHMWPE+9 mm Al_(2)O_(3)+8 mm UHMWPE composite armor demonstrated a 27.11%improvement in energy absorption,showing a relatively significant enhancement.

新型ARMOR热防护系统

热防护系统是保证航天运载器安全、快捷、经济飞行的关键技术之一。在经历了C/C与陶瓷基复合材料等热防护结构后,一种新型的热防护系统应运而生-ARMOR(Adaptable,Robust,Metallic,Operable,Reusable)热防护系统(TPS)。ARMORTPS是一种可适应的、坚固的、金属性的、可操作的、可重复使用的新型热防护系统。它具有易于安装、使用寿命(耐久能力)长、材料的兼容性好、维修时间短等许多特点,是RLV的重要的候选热防护系统之一。本文介绍了热防护系统的发展现状和要求。着重介绍了ARMORTPS的基本结构,连接方式和密封方法等特点。目前ARMORTPS外面板采用的材料为inconel617等材料,未来热防护系统外面板的候选材料为γ～TiAl和微叠层等材料。最后总结了ARMORTPS的优点。

New Method to Restrain Pumping Voltage of Braking Procedure for Brushless DC Motor of Electric Armored Vehicle

In order to restrain the high pumping voltage of braking procedure which is harmful to the system of electric armored vehicle. Based on the analysis of pumping voltage of the braking procedure, the relation between pumping voltage and PWM ratio is derived and a new digital control method to restrain the pumping voltage by changing PWM ratio is put forward. Because the capacitance is decreased effectively, the volume of controller is reduced and the performance to price ratio is improved. The results of computer simulation and experiment proved that this method is feasible and valid.

组合-填充药型罩成型及侵彻靶板数值模拟

针对聚能射流侵彻披挂爆炸反应装甲坦克顶部装甲的高效毁伤问题,提出了一种新型的组合-填充药型罩结构。采用非线性动力学分析软件AUTODYN-2D对射流形成和侵彻靶板过程进行了数值模拟,并分析了填充物材料和起爆方式对射流成型的影响以及炸高对侵彻性能的影响。研究结果表明:所提出的组合-填充药型罩可以形成首尾相连的两级串联射流,填充物采用铝和特氟龙时射流成型效果较好,但铝成型更加稳定;点环起爆形成的射流动能比单独点起爆形成的前级射流动能提高67.06%,后级射流动能提高29.51%;在炸高区间为2~6 CD(装药直径)时,成型射流均可以侵彻披挂爆炸反应装甲的坦克顶甲,并保持一定的剩余头部速度,且最佳炸高为5 CD。本研究对反披挂爆炸反应装甲坦克顶甲的新结构药型罩设计具有参考意义。

Re-visiting the mass-flux model for Explosive Reactive Armor and the effect of plate thickness

Explosive Reactive Armor was originally modeled under the assumption that the plates in the cassettes were very thin.Hence their thickness could be ignored,and the thicknesses of the plates were considered only based on their areal mass density.In particular,it was assumed that the jet-plate interaction was controlled by the plates to jet-mass-flux ratio criteria for a specific jet velocity and diameter.In the present study,we extended this analysis,examining the effect of the variation of the mass-flux along the jet on the disruption effect by the two plates.In addition,we examined the thickness effect of the plates on the plate's effectiveness,replacing the steel plates by low-density materials like aluminum and polycarbonate.The mass-flux model was adjusted to account for the plate-thickness effect.It was found that increasing the thickness of the plate,keeping the areal weight unchanged,slightly increases the overall effectiveness of the cassette,in particular by the forward moving plate interacting with the center and the slow parts of the jet.

Effect of fusion welding processes on tensile properties of armor grade, high thickness, non-heat treatable aluminium alloy joints

AA5059 is one of the high strength armor grade aluminium alloy that finds its applications in the military vehicles due to the higher resistance against the armor piercing (AP) threats. This study aimed at finding the best suitable process among the fusion welding processes such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) by evaluating the tensile properties of AA5059 aluminium alloy joints. The fracture path was identified by mapping the low hardness distribution profile (LHDP) across the weld cross section under tensile loading. Optical and scanning electron microscopies were used to characterize the microstructural features of the welded joints at various zones. It is evident from the results that GTAW joints showed superior tensile properties compared to GMAW joints and this is primarily owing to the presence of finer grains in the weld metal zone (WMZ) and narrow heat-affected zone (HAZ). The lower heat input associated with the GTAW process effectively reduced the size of the WMZ and HAZ compared to GMAW process. Lower heat input of GTAW process results in faster cooling rate which hinders the grain growth and reduces the evaporation of magnesium in weld metal compared to GMAW joints. The fracture surface of GTAW joint consists of more dimples than GMAW joints which is an indication that the GTAW joint possess improved ductility than GMAW joint.

Experimental study of transient pressure wave in the behind armor blunt trauma induced by different rifle bullets

Pressure wave plays an important role in the occurrence of behind armor blunt trauma(BABT),and ballistic gelatin is widely used as a surrogate of biological tissue in the research of BABT.Comparison of pressure wave in the gelatin behind armor for different rifle bullets is lacking.The aim of this study was to observe dynamic changes in pressure wave induced by ballistic blunt impact on the armored gelatin block and to compare the effects of bullet type on the parameters of the transient pressure wave.The gelatin blocks protected with National Institute of Justice(NIJ) class III bulletproof armor were shot by three types of rifle bullet with the same level of impact energy.The transient pressure signals at five locations were recorded with pressure sensors and three parameters(maximum pressure,maximum pressure impulse,and the duration of the first positive phase) were determined and discussed.The results indicated that the waveform and the twin peak of transient pressure wave were not related to the bullet type.However,the values of pressure wave's parameters were significantly affected by bullet type.Additionally,the attenuation of pressure amplitude followed the similar law for the three ammunitions.These findings may be helpful to get some insight in the BABT and improve the structure design of bullet.

Virtual Prototype Simulation and Reliability Analysis for Drive System of Armored Chassis

Drive system is the key device of armored chassis. Its working state and reliability influence the maneuver performance of armored chassis directly. In order to simulate the failure process and evaluate the service reliability of drive system in training or battle missions,a new kind of dynamic simulation model and driving simulation platform of the complete drive system were established based on virtual prototype and finite element technology in this paper. Using the platform, the kinematics and dynamic characteristics of drive system were studied and analyzed in detail,the dynamic load spectrum of key components was obtained,the service life was predicted, and the service reliability evaluation results were provided. A simulation example of transmission gear was shown to illustrate the simulation and evaluation process. The result proves that the simulation method not only can be used to compute and evaluate the service reliability of complex mechanical mechanism, but also has high precision and reasonable computational cost. Therefore,simulation and reliability analysis based on virtual prototype of the armored chassis drive system will provide scientific reference for the formulation of armored chassis reasonable repair cycle.

Bed Load Transport Rates during Scouring and Armoring Processes

Dambreak-induced bed scouring may undermine the foundation of bridge piers and other structures,and that destruction can pose a serious threat.Consequently,this paper aims at exploring the mechanisms of scouring and armoring.Firstly,the incipient velocity for nonuniform sediment particles was studied,and a formula was derived based on the angle of repose of nonuniform sediment.The results showed that the mechanism of incipient motion for sand and fine gravel differed from that for coarse gravel and cobbles.Also,comparison between experimental and field data shows that the results from the proposed formula agree well with those observed for all conditions.Secondly,a birth-death,immigration-emigration Markov process was developed to describe the bed load transport rate associated with scouring and armoring.The comparison between experimental data and computed results shows that our model can predict the bed load transport rate,although there may be some limitations,the chief of which is that there are many variables in the model to be determined through experiment.This makes its application in river engineering inconvenient.

Steering Control of Wheeled Armored Vehicle with Brushless DC Motor

Considering the steering characters of one type of wheeled armored vehicle, a brushless direct current （DC） motor is adapted as the actuator for steering control. After investigating the known algorithms, one kind of algorithm, which combines the fuzzy logic control with the self-adapting PID control and the startup and pre-hrake control, is put forward. Then a test-bed is constructed, and an experiment is conducted. The result of experiment confirms the validity of this algorithm in steering control of wheeled armored vehicle with brushless DC motor.

Shock tube design for high intensity blast waves for laboratory testing of armor and combat materiel

Shock tubes create simulated blast waves which can be directed and measured lo study blast wave effects under laboratory conditions.It is desirable to increase available peak pressure from ~1 MPa to ~5 MPa to simulate closer blast sources and facilitate development and testing of personal and vehicle armors.Three methods are experimentally investigated to increase peak simulated blast pressure produced by an oxyacetylene driven shock tube while maintaining suitability for laboratory studies.The first method is the addition of a Shchelkin spiral priming section which supports a deflagration to detonation transition.This approach increases the average peak pressure from 1.17 MPa to 5.33 MPa while maintaining a relevant pressure-time curve(near Friedlander waveform).The second method is a bottleneck between the driving and driven sections.Coupling a 79 mm diameter driving section to a 53 mm driven section increases the peak pressure from 1.17 MPa to 2.25 MPa.A 103 mm driving section is used to increase peak pressure to 2.64 MPa.The third method,adding solid fuel to the driving section with the oxyacetylene,results in a peak pressure increasing to 1.70 MPa.

Manufacturing techniques of armor strips excavated from Emperor Qin Shi Huang's mausoleum,China

The chemical compositions and microstructures of the armor strips excavated from the Emperor Qin Shi Huang's mausoleum were examined systematically by using optical microscopy and electron microscopy.It was found that the armor strips were made of pure copper.Based on the morphology of α-Cu recrystal grain and copper sulphide(Cu2S) inclusions in the armor strips,the manufacturing techniques were proposed as follows:smelting pure copper,casting a lamellar plate,forming the cast ingots into sheets through repeated cold forging combined with annealing heat treatment,and finally cutting the sheets into filaments.Furthermore,through the deformation of copper sulphide(Cu2S) inclusions in the strips,the work rate during forging was evaluated and calculated to be close to 75%.

A numerical study on the disturbance of explosive reactive armors to jet penetration

The disturbance of flat and V-shaped sandwich reactive armor configurations to shaped-charge jet is studied by a numerical approach. The disturbing and cutting effects of the two reactive armor configurations to the jet are successfully captured. The predicted disturbance characteristics and patterns are in fairly good agreement with the X-ray photographic observations. The residual depth of penetration into a semiinfinitive homogeneous steel target behind the reactive armor is computed for a series of jet/armor parameters. For the flat configuration, it is demonstrated that the residual penetration depth is not significantly reduced for a normal impact while it is reduced up to 75% for an oblique impact. In comparison, the V-shaped configuration reduces the penetration depth of the jet to 90%, and it is observed that the penetration depth is not sensitive to the V-shaped angle.

Dynamics analysis of planar armored cable motion in deep-sea ROV system

The armored cable used in a deep-sea remotely operated vehicle(ROV) may undergo large displacement motion when subjected to dynamic actions of ship heave motion and ocean current. A novel geometrically exact finite element model for two-dimensional dynamic analysis of armored cable is presented. This model accounts for the geometric nonlinearities of large displacement of the armored cable, and effects of axial load and bending stiffness. The governing equations are derived by consistent linearization and finite element discretization of the total weak form of the armored cable system, and solved by the Newmark time integration method. To make the solution procedure avoid falling into the local extreme points, a simple adaptive stepping strategy is proposed. The presented model is validated via actual measured data. Results for dynamic configurations, motion and tension of both ends of the armored cable, and resonance-zone are presented for two numerical cases, including the dynamic analysis under the case of only ship heave motion and the case of joint action of ship heave motion and ocean current. The dynamics analysis can provide important reference for the design or product selection of the armored cable in a deep-sea ROV system so as to improve the safety of its marine operation under the sea state of 4 or above.

Neural network modeling to evaluate the dynamic flow stress of high strength armor steels under high strain rate compression

An artificial neural network(ANN) constitutive model is developed for high strength armor steel tempered at 500 C, 600 C and 650 C based on high strain rate data generated from split Hopkinson pressure bar(SHPB) experiments. A new neural network configuration consisting of both training and validation is effectively employed to predict flow stress. Tempering temperature, strain rate and strain are considered as inputs, whereas flow stress is taken as output of the neural network. A comparative study on Johnsone Cook(Je C) model and neural network model is performed. It was observed that the developed neural network model could predict flow stress under various strain rates and tempering temperatures. The experimental stressestrain data obtained from high strain rate compression tests using SHPB, over a range of tempering temperatures(500e650 C), strains(0.05e0.2) and strain rates(1000e5500/s) are employed to formulate Je C model to predict the high strain rate deformation behavior of high strength armor steels. The J-C model and the back-propagation ANN model were developed to predict the high strain rate deformation behavior of high strength armor steel and their predictability is evaluated in terms of correlation coefficient(R) and average absolute relative error(AARE). R and AARE for the Je C model are found to be 0.7461 and 27.624%, respectively, while R and AARE for the ANN model are 0.9995 and 2.58%, respectively. It was observed that the predictions by ANN model are in consistence with the experimental data for all tempering temperatures.

Research on Protection Capability of Flying-Whip Multifunctional Explosive Reactive Armor

The experimental research on protection capability of the flying-whip multifunctional explosive reactive armor (ERA) was performed, in which the comparison experiment was made on the damage effect of the flying-whip's geometrical figuration, material property and driven velocity on the long-rod armor-piercing-projectile. The moving velocity of the flying-whip driven by different explosives and the pressure attenuation law of shock wave travelling in the back plate were measured respectively with the electric probe method and the manganin piezoresistive gauge technique. The following conclusions based on a great quantity of experimental data were drawn: compared with the sandwich ERA the flying-whip multifunctional ERA has very good protection function against the long-rod armor-piercing-projectile, the shaped charge warhead and the anti-armor tandem warhead. In addition, the composite plate made of the armor-steel and rubber plate can lessen the vibration and shock of the main armor caused by the explosion of the charge..

Design of Distorted Wave Protection Armor Units

In consideration of the global optimization for engineering projects, a group of calculation formulas have been derived by means of theoretical derivation and model tests. On this basis, a design procedure for the distorted units is proposed, by means of which the distorted units of an anology shape and an identical porosity ratio with the original units can be obtained after conducting a distorted enlargement and a normal contraction. The stability waveheight and stability factor of the distorted unit can be calculated with the enlargement factor, a, of the horizontal dimension of the distorted unit, or with the contraction scale, A , of the contracted distorted unit. As a result, the stability of the armor unit can be significantly improved without increasing the quantity of concrete. For the same wave met by the original units, the thickness of placement of the contracted distorted unit can be obviously reduced, thus, a large quantity of concrete can be saved, consequently, economic benefit can be achieved.