脉冲x射线测速基准系统研究——脉冲x射线仪输入端触发电路的设计

输入端触发电路是为脉冲x射线仪而设计的,自成体系。利用脉冲x射线照像系统,当弹丸穿过两靶时,由线圈靶产生的正弦波过零信号触发脉冲x射线系统进行正交照像。     

测速线圈靶信号放大与转换电路

针对兵器行业弹丸速度测试常用的线圈靶,设计了一种信号放大、过零点触发和驱动测时仪的电路,将仪表放大器引入前级,提高抗干扰能力,针对长线传输设计了相应的驱动电路,设计的线圈靶信号转换器可以配接各种测时仪组成测速系统,实弹测试验证了设计电路可靠实用,给出了该电路中元件的详细参数。     

光幕靶光能分布研究及改善

光幕靶靶面光能分布的均匀性是影响弹丸测速精度的一个重要因素.以单个发光二极管为基础,近似处理后,进行数学建模分析,用代数叠加法推导出整个靶面光能分布公式,从而可得出靶面内任意点的光能量大小.当弹丸穿过靶面内任意一点时,都会遮挡一定的光能量引起接收端光通量的变化.过靶位置的光能量大小和接收端光通量变化大小成正比关系,从而导出靶面内不同位置和接收灵敏度的对应关系.对光幕靶进行一些改进以获得更均匀的光幕,提高弹丸测速精度.实验结果验证了理论的正确性和光幕靶改进的有效性.     

高原环境下天幕靶探测电路设计

针对现有天幕靶在高原环境下天空背景主要为蓝光引起的探测灵敏度急剧下降的问题,提出了双光幕探测方案,设计了过幕信号增强电路和程控放大控制电路.采用两套独立的光电转换模块在空间形成重合的探测光幕.当弹丸穿过重合光幕时,两套模块各自独立输出弹丸过靶信号,经信号增强电路进行处理后,提高信噪比、输出有效的弹丸过幕信号.设计的电路经在双镜头天幕靶上使用验证,电路工作可靠,提高了天幕靶的探测灵敏度.     

地磁感应线圈法探测火箭弹的滚转运动

为了对火箭弹实施简易控制,需要实时探测火箭弹滚转角度。本文给出了完整的感应电动势与弹体运动关系,提出了基于记录感应电动势过零点来探测火箭弹滚转角的方法,讨论了探测盲区的形成条件。利用该方法组成的测试系统结构简单,容易实现低成本和高工作可靠性,适合实时测试的要求。     

双稳悬臂梁电磁式振动能量采集研究

以双磁铁结构建立的双稳悬臂梁电磁式振动能量采集系统为研究对象,采用形状修正函数法和磁化电流理论分析了双稳悬臂梁振动响应特性,并根据电磁感应原理探索了运动坐标系下电磁感应电动势的精确仿真方法。数值模拟和实验验证表明,所建立的非线性磁力和磁场的分析以及悬臂梁振动响应和感应电动势的计算是合理正确的,可用于双稳悬臂梁电磁式振动能量采集系统的感应电动势和输出功率进行有效评估。     

基于光幕靶的亚音速弹和预制破片速度测量算法

针对亚音速弹和预制破片的速度测量,本文基于光幕靶和数据采集卡组成的弹丸测速系统,研究了一种弹形信号识别算法和测量结果处理算法.对亚音速弹,算法依据分拣电平和信号时间宽度大小,能很好地识别出弹形信号和冲击波信号;对预制破片,算法依据过靶信号脉冲宽度与两靶输出信号的时间间隔,识别出预制破片的过靶信号.通过对弹形信号的相关分析处理,即得到弹丸穿过两个光幕的精确飞行时间,进而确定出弹丸速度.经实弹射击验证,算法准确有效,满足靶场测试要求.     

基于六天幕靶弹丸弹道末端飞行速度的测试

在弹道末端,由于弹道降与弹丸散布的存在,用雷达和天幕靶测速装置测试弹丸飞行速度误差很大.本文提出一种由六天幕组成的天幕阵列与信号处理装置配合的测试系统,测试弹道末端弹丸的速度.该方法采用两台特殊的三天幕靶和信号处理装置组成测速系统,信号处理装置记录弹丸飞过六天幕的时刻,依据六天幕的几何结构参数和弹丸穿过六天幕的时间值,计算出弹丸的飞行速度和速度飞行的方向角.测得的结果为弹丸飞行方向上的速度值.该方法与雷达和常规天幕靶测速系统相比,测量精度较高.     

结合CPLD测时的改进互相关算法在红外测速系统中的应用

为了解决直接采用传统互相关算法计算炮弹过靶时间差计算量大而不利于实时测量的问题,提出了一种结合CPLD的改进的互相关算法计算炮弹穿过两靶的时间差的方法.在分析炮弹穿过光幕时信号变化过程的基础上,设计CPLD测时模块测出弹丸过靶的时间差的估计值,根据CPLD测时结果筛选出参与互相关测时的相应时间段的信号,再进行互相关分析从而得出炮弹过靶时间差,计算出速度.最后通过MATLAB对仿真信号进行分析,表明采用改进的互相关算法不仅具有较少的计算量且有较高的精度.     

CCD立靶弹丸攻角测量

基于CCD立靶坐标交汇测量原理,提出了通过测量弹头和弹尾过靶坐标进而解算出弹丸攻角的方法,使CCD立靶测量系统在完成弹丸着靶坐标测量的同时,还可以完成弹丸攻角的测量.对CCD立靶坐标测量精度进行了分析,推导了攻角测量的相关公式;结合试验,对攻角测量精度作了分析,对方法的可行性进行了验证.结果表明,利用CCD立靶测量系统...     

水中弹药的电磁感应测速方法研究

为解决现有的水下速度测试装置存在测试精度低和受水介质特性影响大的问题,设计了一种基于电磁感应原理的测速装置感应式线圈靶水下测速系统.针对水介质特性对测试系统的影响,对线圈靶进行了密封设计,对测试电路进行了抗干扰设计,并进行了水中弹药的速度测试实验.实验结果表明:测速系统受水介质特性干扰小,所测信号基本不含干扰信号,且对弹丸外弹道无影响;线圈靶与高速摄影的测速结果相比,测速精度高,相对偏差在5%以内,且可测速度范围宽,可广泛应用于水中弹药速度的测试.     

Normal penetration of an eroding projectile into an elastic–plastic target

The main objective of the present work is to describe normal penetration of a deformable projectile into an elastic–plastic target. The force imposed on the projectile by the target is generally a complex function of the strength of the target material, the projectile velocity, its diameter and shape, as well as the instantaneous penetration depth. When this force exceeds a certain critical value the projectile begins to deform. At moderate-to-high values of the impact velocity, the projectile's tip material flows plastically with large deformations causing the formation of a mushroom-like configuration. This process is accompanied by erosion of the projectile material. In the rear (“elastic”) part of the projectile the deformations remain small and the region can be approximated as a rigid body being decelerated by the projectile's yield stress. The general model allows one to predict the penetration depth, the projectile's eroded length and the crater diameter. It has been shown that in the limit of very high impact velocities the present model reduces to the well-known form of the hydrodynamic theory of shaped-charge jets. Also, a simplified asymptotic formula for the crater radius has been derived which includes the effect of the target's yield stress and compares well with experimental data for very high impact velocities.     

Impact damage in layered glass

High-velocity impact onto a layered glass target produces a very extensive damage pattern exhibiting many distinct morphologies. Material around the penetration cavity is finely comminuted. Under the arrested projectile, the glass is largely intact with spoke-like fracture regions. Around the projectile cavity, needle fragments are formed; they are radial in outer layers and circumferential in inner layers. Extensive radial cracks occur in all layers, but the spacing and frequency of transverse fractures change in each layer. Damage from radial cracks also progresses from being hoop-stress-induced to flexural-induced through the depth of the target. Fan and dicing cracks occur near the periphery of the target. Mesoscale damage features include conventional mist and hackle markings indicating very fast cracks. The map of damage presented herein should be a valuable reference for attempts to model impact damage of glass.     

Arc-commutated launcher

Arc-commutated launchers are a new type of linear electric motor being investigated by the electromagnetic acceleration group at M.I.T. The most promising is a coaxial discrete coil accelerator that uses the motion of the projectile itself to break down a linear array of gap switches via vapor arcing. The switches connect individual coils to a distributed energy source producing a traveling magnetic wave that is literally mechanically synchronized to the projectile position. This manner of switching is potentially much faster and certainly lighter and cheaper than conventional SCR switching. Since an arc is the only required electrical connection to the projectile, no sliding contacts are necessary. The projectile being guided by the magnetic field can ultimately achieve very high velocities (greater than 10 km/s).     

Analytical modeling for the ballistic perforation of planar plain-woven fabric target by projectile

This paper presents an analytical model to calculate decrease of kinetic energy and residual velocity of projectile penetrating targets composed of multi-layered planar plain-woven fabrics. Based on the energy conservation law, the absorbed kinetic energy of projectile equals to kinetic energy and strain energy of planar fabric in impact-deformed region if deformation of projectile and heat generated by interaction between projectile and target are neglected. Then the decrease of kinetic energy and residual velocity of projectile after the projectile perforating multi-layered planar fabric targets could be calculated. Owing to fibers in fabric are under a high strain rate state when fabric targets being perforated by a high velocity projectile, the mechanical properties of the two kinds of fibers, Twaron^® and Kuralon^®, respectively, at strain rate from 1.0×10⁻² to 1.5×10³ s⁻¹, are used to calculate the residual velocity of projectile. It is shown that the mechanical properties of fibers at high strain rate should be adopted in modeling rate-sensitivity materials. Prediction of the residual velocities and energy absorbed by the multi-layered planar fabrics show good agreement with experimental data. Compared with other models on the same subject, the perforating time in this model can be estimated from the time during which certain strain at a given strain rate is generated. This method of time estimation is feasible in pure theoretical modeling when the perforation time cannot be obtained from experiments or related empirical equations.     

Interior ballistics of a hybrid electromagnetic gun

The dynamics for the projectile inside an electromagnetic gun has been developed. The gun consists of a series of stationary cylindrical coils that are pulsed and of one inner concentric coil driven at constant current. The inner coil is the projectile. Two important design parameters are identified: one is the desired exit velocity divided by the square root of the number of stationary coils, the other is a characteristic time related to the rapidity with which the projectile attains its maximum velocity in any stationary coil.     

侵彻单层靶时着靶姿态对装药损伤的影响规律研究

为研究着靶姿态对高速侵彻弹装药损伤的影响,依据实际战斗部的结构尺寸设计了小尺寸模型试验弹,在125 mm口径的滑膛炮发射平台上开展了试验弹以不同攻角斜侵彻单层钢靶试验。通过理论计算得到着靶姿态对侵彻过程能量损失的影响。利用CT扫描无损检测技术观测不同着靶姿态下试验弹内部的损伤情况。运用LS-DYNA对试验弹侵彻钢靶过程中装药的力学响应过程进行模拟计算。结果表明:在斜侵彻单层钢靶的过程中,着角一定时,能量损耗与攻角呈指数关系;试验弹的倾角越大,装药尾部受到的应力波拉伸压缩反复作用越明显,装药在侵彻过程中长度变化越大,更易出现深度裂纹、塌边等损伤;壳体外形变化会引起装药受到的压缩应力阻碍微裂纹的扩展和滑移,减少宏观损伤的出现。     

Hard projectile penetration and trajectory stability

We present a general framework to describe the dynamics of a hard projectile penetrating into a solid target. Rigid body dynamics, differential area force law and semi-empirical resistance function are used to formulate the motion of the hard projectile. The proposed model is capable of predicting the projectile trajectory under various oblique and yaw angles. Critical conditions for the occurrences of the instability and the reverse of the projectile trajectory are discussed. It was found that the relative location of mass centre of the projectile has strong influence on the control of the rotation of the projectile, and thus, the projectile stability and the change of trajectory direction. The validity of the proposed model is limited to deep penetration and when the wake separation and reattachment between projectile body and target have negligible influence on the target resistance to the projectile.     

磁阻型电磁铆接工艺研究

目的 为了掌握磁阻型电磁铆接新技术,研究工艺参数对铆接驱动力的影响规律.方法 通过改变放电电压、线圈导线截面尺寸和弹丸尺寸等参数进行磁阻型电磁铆接试验研究,分析各参数对直径为8 mm的2A10铆钉镦头变形的影响,与感应式电磁铆接的成形铆钉进行对比.结果 随着放电电压的升高,铆钉镦头变形量增加;相同放电能量下,导线截面尺寸为2 mm×3 mm的线圈铆钉变形量小于3 mm×4 mm的线圈,弹丸直径为33 mm的铆钉变形量要大于弹丸直径为28 mm铆钉的变形量.相同放电能量下,外径70 mm螺线管线圈铆钉的变形量大于外径为120 mm平板线圈铆钉的变形量.结论 线圈和弹丸的相关参数是影响磁阻型电磁铆接吸引力的重要参数.与感应式电磁铆接相比,磁阻型电磁铆接能量利用率更高,其线圈外径更小,为电磁铆枪小型化提供了一种新方式.     

Predicting the fragmentation onset velocity for different metallic projectiles using numerical simulations

For cubes and spheres under high velocity impact there exists for each system of projectile and target, a threshold velocity that is just sufficient to shatter the projectile. This velocity, usually above 2km/s for metallic projectiles, is known as the fragmentation onset velocity. To determine the fragmentation onset velocity experimentally, a number of experiments in which the impact velocity of the projectile is varied in a controlled manner needs to be conducted [1]. In the work described in this paper, the numerical analysis code AUTODYN was used to simulate the impact of stainless steel and tantalum projectiles onto transparent targets in an attempt to simulate the onset of fragmentation. Using the meshfree SPH method for discretizing the spatial domain of the projectile and a simple failure model that allows the critical spall stress of the material to vary with the local material and loading conditions, encouraging results were obtained, with the fragmentation onset velocity for both projectile/target configurations being reasonably well predicted. In addition, further experiments conducted at TNO-PML, to determine the fragmentation onset velocity for tungsten projectiles, will be reported.