Damage visualization and deformation measurement in glass laminates during projectile penetration

Transparent armor consists of glass-polymer laminates in most cases. The formation and propagation of damage in the different glass layers has a strong influence on the ballistic resistance of such laminates. In order to clarify the course of events during projectile penetration, an experimental technique was developed, which allows visualizing the onset and propagation of damage in each single layer of the laminate. A telecentric objective lens was used together with a microsecond video camera that allows recording 100 frames at a maximum rate of I MHz in a backlit photography set-up. With this technique, the damage evolution could be visualized in glass laminates consisting of four glass layers with lateral dimensions 500 mm x 500 mm. Damage evolution was recorded during penetration of 7.62 mm AP projectiles with tungsten carbide core and a total mass of 11.1 g in the impact velocity range from 800 to 880 rn/s. In order to measure the deformation of single glass plates within the laminates, a piece of reflecting tape was attached to the corresponding glass plate, and photonic Doppler velocimetry （PDV） was applied. With the photonic Doppler velocimeter, an infrared laser is used to illuminate an object to be measured and the Doppler-shifted light is superimposed to a reference light beam at the detector. The simultaneous visualization and PDV measurement of the glass deformation allow determining the deformation at the time of the onset of fracture. The analysis of the experimental data was supported by numerical simulations, using the AUTODYN commercial hydro-code.     

Experimental investigation of a cook-off temperature in a hot barrel

The experimental investigations of the effect of contact time/temperature on initiating the cook-off using 7.62 mm calibre cartridge cases （CC） were conducted previously. These cartridges were filled with commercial off-the-shelf （COTS） double based （DB） propellant （Bulls Eye） and were loaded in a hot chamber. The thermal explosion temperature is of great significance to both weapon designers and safety inspectors as it provides the operational limit and safe operating temperature. For CC under test, it was found that the cook-off temperatures of this propellant were encountered with the heat transfer profile of the simulated gun barrel between 151.4 ℃ and 153.4 ℃, with a reaction occurring in less than 300 s after the round was chambered. Usefully, each experiment was found to be consistent and repeatable.     

Research on Microcrack Extension Mechanism of SiCp/Al in the Machining Process

The generation and development of microcracks of SiCp/Al materials in the machining process were researched, and the forming causes and mechanism of the cut surface morphology for ap=0.2 mm or ap=0.4 mm and at 2 m/min～10 m/min were systematically analyzed. The supporting and "floor"roles of aluminum are wake at a shallower cutting depth and a lower speed, the SiC particles are shed under the role of cutting force, and the microcrack size of cut surface is larger. With the increase in the cutting depth and the cutting speed, the cutting temperature increases, the supporting and "floor" roles of aluminum are enhanced, the shedding and fracture of the reinforcement particles are flexible under the action of the cutting force, the fracture of cutting transforms from brittle to ductile, and the expansion of microcrack on the entire surface tends to balance with a smaller size. A curve between the cutting force and the cutting speed was plotted, a microcrack form of the cut surface was given, and some theoretical basis is provided for the mechanical processing and the surface quality.     

Formulation development and characterization of cellulose acetate nitrate based propellants for improved insensitive munitions properties

Cellulose acetate nitrate （CAN） was used as an insensitive energetic binder to improve the insensitive munitions （IM） properties of gun propellants to replace the M1 propellant used in 105 mm artillery charges. CAN contains the energetic nitro groups found in nitrocellulose （NC）, but also acetyl functionalities, which lowered the polymer＇s sensitivity to heat and shock, and therefore improved its IM properties relative to NC. The formulation, development and small-scale characterization testing of several CAN-based propellants were done. The formulations, using insensitive energetic solid fillers and high-nitrogen modifiers in place of nitramine were completed. The small scale characterization testing, such as closed bomb testing, small scale sensitivity, thermal stability, and chemical compatibility were done. The mechanical response of the pro- pellants under high-rate uni-axial compression at, hot, cold, and ambient temperatures were also completed. Critical diameter testing, hot fragment conductive ignition （HFCI） tests were done to evaluate the propellants＇ responses to thermal and shock stimuli. Utilizing the propellant chemical composition, theoretical predictions of erosivity were completed. All the small scale test results were utilized to down-select the promising CAN based formulations for large scale demonstration testing such as the ballistic performance and fragment impact testing in the 105 mm M67 artillery charge configurations. The test results completed in the small and large scale testing are discussed.     

Research on Top-layer Planning and Overall Design Project Decision of Weapon System Based on Analytic Hierarchy Process

Based on analytic hierarchy process(AHP) theory,a vital important problem for top-layer planning and overall design of modern self-propelled gun-howitzer system,namely overall project decision-making,was analyzed.A hierarchy model was built to solve the complex and uncertain problem,and a decision-making index system was established.Then,the weights in all layers of the model were determined by simulating experts.Finally,according to the calculated results of the elements in each layer,the weights of the alternatives to the overall goal were calculated to conduct the hierarchy total decision.A decision example shows that the overall project of a self-propelled gun-howitzer A is much better than that of another self-propelled gun-howitzer B,digitalized in comprehensive efficiency,operability,system accuracy and economy,but inferior to it in the information capability,and there exists relatively larger gap between them in the information sharing index.     

Long-rod penetration： the transition zone between rigid and hydrodynamic penetration modes

Long-rod penetration in a wide range of velocity means that the initial impact velocity varies in a range from tens of meters per second to several kilometers per second. The long rods maintain rigid state when the impact velocity is low, the nose of rod deforms and even is blunted when the velocity gets higher, and the nose erodes and fails to lead to the consumption of long projectile when the velocity is very high due to instantaneous high pressure. That is, from low velocity to high velocity, the projectile undergoes rigid rods, deforming non-erosive rods, and erosive rods. Because of the complicated changes of the projectile, no well-established theoretical model and numerical simulation have been used to study the transition zone. Based on the analysis of penetration behavior in the transition zone, a phenomenological model to describe target resistance and a formula to calculate penetration depth in transition zone are proposed, and a method to obtain the boundary velocity of transition zone is determined. A combined theoretical analysis model for three response regions is built by analyzing the characteristics in these regions. The penetration depth predicted by this combined model is in good agreement with experimental result.     

Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

Quenched and Tempered （Q＆T） steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking （HIC） in the heat affected zone （HAZ） after welding. The use of austenitic stainless steel （ASS） consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in anstenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q＆T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic steel （LHF） consumables can be used to weld Q＆T steels, which can give very low hydrogen levels in the weld deposits. The use of ASS and LHF consumables will lead to distinct microstructures in their respective welds. This microstructural heterogeneity will have a drastic influence in the fatigue crack growth resistance of armour grade Q＆T steel welds. Hence, in this investigation an attempt has been made to study the influence of welding con- sumables and welding processes on fatigue crack growth behaviour of armour grade Q＆T Steel joints. Shielded metal arc welding （SMAW） and Flux cored arc welding （FCAW） were used for fabrication of joints using ASS and LHF consumables. The joints fabricated by SMAW process usin~ LHF consumable exhibited superior fatigue crack growth resistance than all other joints.     

Flame Retardant and Pyrolytic Behaviors of Polyamide 6/Montmorillonite Nanocomposite

Na -montmorillonite(Na -MMT) was converted to organic montmorillonite(OMMT) using modifier which was synthesized at authors‘ laboratory. PA6/OMMT nanocomposite was prepared via in situ intercalative polymerization. The limiting oxygen index (LOI), UL 94V flame retardancy and thermal stability of PA6/OMMT using thermal gravity analysis (TGA) were measured. The Fourier transform infrared (FTIR) technique was used to analyze the pyrolytic residuum and the cone calorimeter (CONE) was applied to determine a number of combustion parameters which were closely related to fire safety, including heat release rate, mass loss rate, effective combustion heat, total heat release, specific extinction area and the time of ignition. In addition, the elemental composition of the surface pyrolytic residuum and the corresponding X-ray photoelectron spectroscopy (XPS) data were obtained, and the morphology of the residuum from CONE measurement was examined by scanning electron microscope (SEM).     

Particle Velocity Measurement for Spherical Wave in Solid

An experimental technique for research on spherical divergent wave propagation in a solid has been developed, in which the source of generating spherical wave is a center initiating explosive charge designed in a mini-spherical shape with yield equivalent to 0. 125 g and 0. 486 g TNT and a set of circular electromagnetic particle velocity gages is used to record the particle velocity histories. By using the circular electromagnetic particle velocity gages, the signal outputs not only are unattenuated due to the geometrical divergence, hut also represent the average of the measured dynamic states of the medium over a circle on the wavefront. The distinctive features of this technique are very useful for the study of spherical divergent wave propagation in a solid, especially in an inhomogeneous solid, and the corresponding material dynamics. Many experimental measurements were conducted in polymethylmethacrylate （PMMA） and granite by means of the technique, and the reproducibility of tests was shown to be good. The measurement technique of the circular electromagnetic particle velocity gages is also suitable to the case of cylindrical wave.     

Microstructure and corrosion behaviour of gas tungsten arc welds of maraging steel

Superior properties of maraging steels make them suitable for the fabrication of components used for military applications like missile covering, rocket motor casing and ship hulls. Welding is the main process for fabrication of these components, while the maraging steels can be fusion welded using gas tungsten arc welding(GTAW) process. All these fabricated components require longer storage life and a major problem in welds is susceptible to stress corrosion cracking(SCC). The present study is aimed at studying the SCC behaviour of MDN 250(18% Ni) steel and its welds with respect to microstructural changes. In the present study, 5.2 mm thick sheets made of MDN 250 steel in the solution annealed condition was welded using GTAW process. Post-weld heat treatments of direct ageing(480 C for 3 h), solutionizing(815 C for 1 h) followed by ageing and homogenizing(1150 C for 1 h) followed by ageing were carried out. A mixture of martensite and austenite was observed in the microstructure of the fusion zone of solutionized and direct aged welds and only martensite in as-welded condition. Homogenization and ageing treatment have eliminated reverted austenite and elemental segregation. Homogenized welds also exhibited a marginal improvement in the corrosion resistance compared to those in the as-welded, solutionized and aged condition. Constant load SCC test data clearly revealed that the failure time of homogenized weld is much longer compared to other post weld treatments, and the homogenization treatment is recommended to improve the SCC life of GTA welds of MDN 250 Maraging steel.     

小尺寸装药爆轰在有机玻璃隔板中的衰减规律

利用锰铜压阻传感器法测量了某聚奥传爆药在不同直径下的小尺寸装药爆轰输出冲击波经不同厚度有机玻璃隔板衰减后的冲击波压力,通过对实验数据进行拟合,得到了有机玻璃介质中冲击波衰减系数与装药直径的指数型关系.实验中传爆药装药密度为90%的理论密度,约束条件分45#钢和有机玻璃两种,装药直径为1.5 mm、3 mm、5 mm和8 mm.结果表明: 衰减系数随装药直径增大而减小,装药的约束条件越弱,这种变化越明显.     

贮氢玻璃微球敏化乳化炸药的爆炸特性

为了提高传统乳化炸药的爆炸威力,研制了一种贮氢玻璃微球敏化的乳化炸药。利用水下爆炸试验和猛度测试试验,研究了添加不同含量的贮氢玻璃微球的乳化炸药的爆轰性能。理论计算得到了炸药猛度的比冲量。结果表明,与普通玻璃微球乳化炸药相比,贮氢玻璃微球含量为4%的乳化炸药的冲击波超压峰值、比冲击波能、比气泡能、总能量分别提升了14.25%、14.22%、11.11%、12.67%,猛度(铅铸压缩量)提高了3.03 mm,且随着贮氢玻璃微球的含量的增加,炸药的冲击波参数逐渐降低。贮氢玻璃微球在乳化炸药中起到敏化剂与含能材料的双重作用,因此贮氢玻璃微球敏化乳化炸药的作功能力与猛度得到显著提高。     

陶瓷/玻纤复合防护结构层间位置对抗破片侵彻性能的影响规律研究

为研究陶瓷/玻纤复合防护结构的层间位置对抗破片侵彻性能的影响规律,文中采用145 mm弹道枪加载方法进行了30 g破片对18 mm厚陶瓷(含有3 mm厚玻纤包裹层)/20 mm厚玻纤复合板的侵彻试验,并获得了破片的最小贯穿速度.同时,通过数值仿真进一步研究了复合板层间位置对抗破片侵彻性能的影响.结果表明,当靶板总厚度为38 mm左右,30 g破片以1 300 m/s的初始速度侵彻陶瓷/玻纤复合结构时,陶瓷板与玻纤板的厚度比在0.9.~1.7之间时其抗破片侵彻能力较好.     

壳体厚度对TNT炸药快速烤燃响应的影响

采用自行设计的快速烤燃试验方法,测试厚度为2,4,6 mm梯恩梯(TNT)装药壳体的响应状态,结合TNT的高压差示扫描量热(PDSC)分解特性,研究了厚度对炸药装药响应的影响.结果表明:在快速烤燃试验条件下,壳体厚度由2-6 mm变化时,TNT炸药均为爆炸反应等级;壳体厚度变化对TNT炸药响应等级没有显著影响,但炸药装...     

不同机械约束下压装PBX炸药反应演化行为

为研究机械约束下炸药反应演化行为,加深对武器装药意外点火后反应烈度演化影响因素及机制的认识,对压装PBX炸药反应演化过程进行实验研究。设计一种机械约束装药点火实验装置,采用激光干涉仪和压力传感器分别测量壳体膨胀速度和内部压力,分析不同约束下两种HMX基压装PBX炸药装药的反应演化行为;结合空气冲击波超压测试结果和装置、炸药残骸回收分析,表征装药的反应烈度。研究结果表明：2 MPa机械约束下,PBX-1和PBX-2装药反应最高压力不超过200 MPa,壳体膨胀速度在70 m/s左右,装药反应烈度为爆燃;50 MPa机械约束下,PBX-1和PBX-2装药在百微秒甚至几十微秒内压力超过1 GPa,壳体膨胀速度达到500 m/s,装药发生爆炸反应;不同炸药的力学性能会造成装药反应演化过程存在一定差异,但机械约束影响更明显,新装置2 MPa和50 MPa机械约束装药反应压力和约束壳体速度相差接近1个数量级。     

小尺寸传爆药爆轰反应区厚度研究

利用双灵敏度VISAR测试了小尺寸传爆药装药的爆轰反应区厚度.试验采用JO-9C和HNS传爆药,装药直径为6mm和4mm,约束条件为45~#钢和有机玻璃,利用4μm厚的铝箔作为粒子速度载体,得到了装药与LiF窗口界面粒子速度的全过程.结果表明:JO-9C小尺寸装药的反应时间约为40ns,相应的反应区厚度约为0.22mm和0.23mm;HNS小尺寸装药的反应时间约为120ns,相应的反应区厚度约为0.60mm.     

“原位”合成铜叠氮化物的爆速测试

为了测试铜叠氮化物的爆速,采用多层叠片装药方式制成长药柱,将镀在约束壳体表面的细金属线用作特殊的探针,测试了两种装药直径(0.8mm、1.0mm)下的爆速。测试结果表明:采用该特殊探针测试铜叠氮化物装药爆速的结果一致性好;当装药厚度达到0.9mm时,铜叠氮化物已经达到稳定爆轰状态;装药直径为1.0mm时的平均爆轰速度为5 317 m·s~(-1),大于装药直径为0.8mm时的平均爆轰速度5 229 m·s~(-1)。     

多元共渗及其在高炉风口上的应用

介绍了多元共渗的特点,重点阐述了国内高炉紫铜风口的使用寿命及该工艺在风口上的应用,并从经济效益上进行了初步分析。为提高风口寿命应采取的对策,指出多元共渗是当前提高风口寿命的有效途径之一。作者还对多元共渗风口今后研究开发的方向提出了建议。     

短波红外纳米PbSe薄膜制备及光电性能研究

采用化学沉淀的方法在石英衬底上制备了短波红外纳米PbSe薄膜.XRD,SEM,TEM以及红外透射光谱测试分析结果表明,所制备的PbSe薄膜为纳米多晶薄膜,表面平整致密,薄膜的晶粒尺寸为10 nm左右,由于量子效应,薄膜吸收截止边相对PbSe体材料蓝移至1.6 μm；经过敏化、光刻及金属化制备了PbSe单元光导探测器,在...     

载荷加载速率对碳纤维镁合金层合板层间断裂韧性的影响

分别采用镁合金和碳纤维代替工程中常用的玻璃纤维增强铝合金层合板中的铝合金和玻璃纤维,通过将单向碳纤维/环氧树脂预浸料交替层压,得到复合材料板,并用环氧树脂将复合材料板与镁合金薄板加压黏结在一起,得到碳纤维增强镁合金层合板。采用单悬臂梁测量载荷速率对碳纤维增强镁合金层合板层间断裂韧性的影响。结果表明:层间裂纹在低载荷速率时以稳定的方式扩展,而在高速率时裂纹的扩展变得不再稳定;在低速率(1~1 000 mm/min)载荷下,载荷速率对层间断裂韧性有轻微的影响;层合板在高速率载荷下的层间断裂韧性大于低速率下的层间断裂韧性。