转管机枪膛口振动位移的测试

转管武器发射时身管处于高速旋转状态,通过炮口安装加速度传感器测量炮口的振动很困难．本文利用非接触式的电涡流传感器,针对武器发射时的特殊环境,进行了传感器选择、传感器标定以及温漂的影响分析,设计了测量转管机枪膛口垂直振动位移和水平振动位移的测试系统,并在某车载转管武器上进行了静态和动态的现场测试,得到了膛口振动位移和身管组旋转中心的轨迹曲线．     

Influence of autofrettage on metal matrix composite reinforced gun barrels

Advanced materials are considered as candidates for the replacement of traditional gun barrel steel with the hope that weapons as durable as steel but at a fraction of the weight will be developed. Through an analytical model that simulates the effects of autofrettage on a cylindrical gun barrel, the resultant compressive residual stresses are quantified, and different materials examined as to their possible resistance to fracture under repeated internal pressure loads. This study investigates a traditional low-alloy gun steel, a high temperature SiC/titanium-alloy metal matrix composite, as well as various hybrid combinations of these materials, for their ability to develop the necessary residual stress and inelastic strain states necessary for durability. It is discovered that a hybrid composite comprised of low-alloy gun steel on the inner region of the gun barrel and circumferentially wound SiC/Ti–24Al–11Nb on the outer region can still exhibit the same compressive residual stress (and corresponding inelastic strains) seen in homogeneous steel barrels, but with a weight savings of up to 37%, while maintaining the original barrel dimensions.     

炮管材料的发展现状与趋势

简述了炮管材料的发展历程,并根据炮管的工作条件总结出其基本性能要求。对传统炮管材料——炮钢的化学成分、力学性能进行了论述,重点归纳了现阶段炮钢发展思路和研究重点。对国外新型炮管材料技术——复合材料炮管技术及新型绿色炮管抗烧蚀涂层技术动态进行了跟踪介绍。     

Hypervelocity macroparticle accelerator experiments at CEM-UT

Several railgun experiments designed to accelerate projectile masses of 2 to 5 g to velocities greater than 6 km/s were performed. Two parallel rail-type accelerators with 12.7 mm square bores were used for the experiments. One gun is 2 m long, has molybdenum rails and alumina ceramic insulators. The other is 1 m long, has molybdenum rails and granite insulators. The greatest velocity achieved to date during the experiments was 5.1 km/s. During the test program, the following ideas to enhance launcher performance were tested: stiff-gun structures to reduce plasma leakage and rail movement, refactory bore materials to reduce ablation and frictional losses, and prefilling the gun bore with gases which will eliminate precursor arcs. After three experiments utilizing the 2 m long launcher, with peak currents ranging from 660 to 780 kA, a gun barrel comprised of 96% pure alumina ceramic insulators and 99.9% pure molybdenum rails has survived with minimal damage and no degradation of seals     

Where did Greenhill's twist rule come from?

Greenhill's Rule for estimating rifling twist in artillery and small arms is interesting both because of its simplicity and longevity. This article describes (a) Greenhill's Simplified Rule for estimating the twist of rifling; (b) describes his original, more complete, but much less known Rule; (c) summarizes how he got the Rule; and (d) relates it to the modern stability factor. Some comments about twist, bullet stability, and black powder velocities are presented.     

Press-Fit Sheathing for Ceramic Gun Liners

Ceramic materials are being investigated by the Army for use in gun tubes. Compared to gun steels, ceramics possess superior wear resistance at ballistic temperatures, thus enabling improved lifetime for gun tubes. In order to survive the ballistic event, however, it is necessary to prestress the ceramic components with external sheathing to offset the tensile stresses in the tube wall that occur during the ballistic event. Previous sheathing designs for ceramic liners have included thermal shrink fits of tubular metallic components, steel wire overwrapped under high tension, and advanced fibrous composites overwrapped under high tension. In the present investigation, press-fitted composite sheaths are fabricated and tested with the purpose of validating a computer model applicable to the design of ceramic gun barrel liners.     

Reliability analysis of hybrid ceramic/steel gun barrels

ABSTRACT Failure of the ceramic gun‐barrel lining during single‐shot and burst firing events has been studied by combining a finite‐element method based thermo‐mechanical analysis with a structural reliability analysis. An initial distribution of residual stresses in the lined barrel, as introduced during shrink‐fitting of the steel jacket over the ceramic lining, is taken into account. Forced‐convection boundary conditions at the inner surface of the barrel are determined by carrying out an internal‐ballistic analysis, followed by compressible boundary‐layer modeling of the heat transfer coefficient. The results obtained reveal that due to thermal expansion of the steel jacket during single‐shot and burst ballistic events, tensile axial stresses develop in the ceramic lining near the barrel ends. These stresses are sufficiently high, particularly in the case of burst firing, that they can induce formation of circumferential cracks and, in turn, failure of the lining. Using the Weibull structural reliability analysis, the failure probability for the lining has been computed as 0.0025 and 0.0121 for the single‐round and the 10‐round firing modes, respectively. Optimization of the main design, materials and processing parameters in order to minimize the failure probability for the lining is also discussed.     

Material Selection for Ceramic Gun Tube Liner

The U.S. Army Research Laboratory is investigating the application of ceramics as bore materials in advanced gun systems. The lower mass and improved high temperature performance of ceramics over traditional gun steels could produce new barrels with improved service life and lower weight while enabling the use of new propellants. Several different ceramics have been researched into which material would best survive the interior ballistic conditions for a variety of different caliber systems. The candidate materials are commercially available monolithic ceramics. Alumina, zirconia, three silicon carbide compositions, two silicon nitride compositions, and a SiAlON material were initially selected. A coupled approach of modeling and experimental verification led to the downselection of the silicon nitride and SiAlON materials as the most capable of surviving the interior ballistic conditions and functioning as a barrel liner. This paper describes the tests, presents the results, and discusses the reasons for these selections.     

不同材料管壳对螺旋线慢波系统性能的影响

利用实验测评和模拟分析的方法研究了螺旋线慢波系统中采用不同材料的管壳对其性能的影响。主要分析了蒙乃尔管壳、铜管壳和蒙乃尔内嵌铜管壳的应用,对螺旋线慢波系统的散热性能和高频特性的影响。研究表明,在蒙乃尔管壳内部嵌铜,即可以保证管壳的机械强度,又可以改善慢波系统的散热性能,并在低频段降低高频损耗。     

锻造比对身管膛线成形影响分析

目的膛线是身管的关键部位,其主要作用是使弹头旋转运动,以保持弹头飞离膛口后稳定飞行。膛线成形性的状况对枪管的初速、精度都有重要的影响,故需要分析径向锻造过程中不同锻造比对身管膛线成形性的影响。方法使用有限元商业软件Abaqus建立三维有限元模型,对身管膛线的成形过程进行数值模拟,得出不同锻造比对身管膛线成形影响的规律。结果锻造比大于35%时,阴线的边界处的Mises应力大于材料的强度极限,膛线因应力过大而扭曲;锻造比小于15%时,阳线上的菱角处成形不充分,膛线的阴、阳线边界不分明;当锻造比为25%时,膛线应力分布在合理范围内且成形良好。结论通过仿真得出新材料的合理锻造比范围在25%左右,在15%~35%之间。     

身管内膛镀铬层-钢基体界面损伤退化行为研究进展

现代战争对身管武器技战术指标的要求不断提高,身管内膛镀铬层-钢基体界面在服役过程中的损伤退化制约着高性能武器的发展。为揭示身管内膛镀铬层-钢基体界面损伤退化的行为与机制,简述了身管内膛镀铬层的制备过程,并对身管内膛镀铬层-钢基体界面损伤退化行为的过程、影响因素以及研究方法等近年来的研究工作进行了综述,最后对该领域未来研究的发展以及延缓身管失效的途径进行了展望。     

内喷涂钢桶性能特点及生产工艺实践

目的提出钢桶以内壁形式进行分类的方法,论述目前常用的内喷涂材料的性能特点,在生产实践的基础上对内喷涂钢桶生产工艺进行提炼总结。方法在钢桶按开口形式及材料厚度的基础上,以是否有内壁材料及内壁材料的种类对钢桶进行分类。然后以比较的方式列出内喷涂材料的性能特点,按工艺流程提炼总结内喷涂钢桶生产工艺,并提出工艺要点。结果以有内壁材料、无内壁材料的内套软包装或直接接触定义为钢桶第3种分类方法,国内最常用的内壁材料主要有环氧树脂涂料、聚氟乙烯涂料、酚醛树脂涂料。结论批量生产内喷涂钢桶其成熟的内喷涂工艺流程为:表面去油—表面磷化—烘干—喷涂—烘烤塑化—涂层表面质量检测。     

The electromagnetic θ gun and tubular projectiles

Unlike the better known rail gun, the θ gun applies the propelling force along the length of its projectile. This is shown to allow much greater acceleration of high fineness ratio projectiles for a given barrel pressure, allowing much shorter barrels for military applications. A computer code which simulates performance of the θ gun is described and experimental results from a few simple, low energy experiments show close agreement with code predictions. Trajectories and aerodynamic heating for three candidate military projectiles are calculated for vertical and horizontal atmospheric launches where initial velocity is as high as 3 km/s. The calculations indicate that in some cases a thin layer of heatshield (ablator) will be required to control projectile heating.     

Carbon Fiber/Thermoplastic Overwrapped Gun Tube

The emphasis on lightweight large caliber weapons systems has placed the focus on the use of advanced composite materials. Using traditional thermoset composites has been difficult, as the coefficient of thermal expansion mismatch between the steel substrate and the composite jacket causes a gap after manufacturing. Using a thermoplastic resin and a cure on the fly process has improved the manufacturability of the barrels and has eliminated the gap. For the first time a 120-mm barrel has been manufactured using this process and successfully test fired. This paper will present the design, manufacturing, and test firing of this barrel.     

光电窥膛光学系统参数优化选择

通过分析炮管内膛影响CCD成像质量的光强，光的均匀性，视场大小和空间分辨力等因素，提出了增大CCD成像镜头的景深对光电窥膛光学系统的光路结构及其参数优化设计的方法，并建立数学模型，提高了CCD摄像机在炮管内膛的成像质量，使图像在亮度，均匀性，色彩和清晰度方面达到很好效果。     

Melt temperature variations in the barrels of an injection moulder and a twin screw extruder

This article investigated temperature variations of a polypropylene melt in the barrels of an injection moulding and a twin screw extruder under an isothermal state. The melt temperature profiles in the barrel of an injection moulding machine were observed to be different from those a twin screw extruder, this being associated with differences in the flows occurring in the barrels of each processing equipment. The major parameters influencing the melt temperature profiles were shear heating and heating conduction effects, residence time, flow length and the flow patterns of the flowing PP melt in the barrel. Received: 4 January 2000 / Reviewed and accepted: 15 February 2000     

Hybrid Ceramic Matrix/Metal Matrix Composite Gun Barrels

Future Army gun systems will require lighter weight and significantly more erosion-resistant materials. One route to achieve this goal is via the development of ceramic matrix composite barrel liners with lightweight metal matrix composite jackets. Such materials systems are hybrids of a ceramic matrix composite/metal matrix composite (CMC/MMC), which can provide functionally graded properties. This paper will describe the materials system development, fabrication, and property validation testing of such a hybrid CMC/MMC for a 25-mm-bore, 915-mm-long, rifled barrel.     

Fabrication of low specific resistance ceramic carbon composites by colloidal processing using glucose as soluble carbon source

Ceramic carbon composites were fabricated by colloidal processing using glucose as soluble carbon source. Glucose is converted into conducting carbon at high temperature treatment. Ceramic carbon composites were sintered in flowing argon at \(1400{^{\circ }}\hbox {C}\) showing resistor behaviour even at low carbon content (1 wt%). In this work, ceramic carbon composites were fabricated using alumina–clay slurries with addition of glucose as a soluble carbon source. Morphology of the sintered samples was characterized by field emission gun (FEG) electron microscopy. Phase analysis was done by X-ray diffraction (XRD). Electrical properties of ceramic carbon composites were measured by broad band dielectric spectrometer. Carbon produced from glucose at high temperature was characterized independently by BET surface area, dynamic light scattering, field emission gun scanning electron microscopy, field emission gun transmission electron microscopy, XRD and Raman spectroscopy.     

一种新型的陶瓷电弧管——整体结构的半透明氧化铝管

研究了一种具有新的末端结构的半透明氧化铝陶瓷管。在烧结前,将瓷塞装入管内末端,通过仔细控制管和塞在烧结过程中收缩的不同,达到烧结成为显微结构均一的整体陶瓷管。讨论了影响烧结整体电弧管的各种因素。