斜侵彻薄靶板过程中弹体偏转的姿态修正方法

弹体斜侵彻靶板后姿态发生偏转,是常规武器侵彻类战斗部研制过程中必须面临和解决的问题,而弹体发生偏转的影响因素很多.在准定常条件下,通过分析弹体侵彻薄靶板时受到的作用力及其偏转角加速度,明确偏转力和偏转力矩的来源和方向.针对不同靶体材质,比较金属靶和混凝土靶侵彻过程中弹体偏转角加速度的异同,结果表明通过调整质心位置和改变弹尾形状能修正弹体过靶姿态.采用数值模拟方法验证了上述结论,该结论可为侵彻弹体的设计和外形优化及提高侵彻弹道的稳定性提供参考.     

刚性弹正侵彻随机骨料混凝土靶的弹道偏转规律分析

针对弹体可能受到非对称力作用从而发生弹道偏转的问题,对刚性弹正侵彻随机骨料混凝土靶的弹道偏转规律进行分析。采用混泥土细观模型,运用 LS-DYNA 显式动力计算软件,对刚性弹正侵彻随机骨料混凝土靶进行数值模拟。以弹体偏转角度为指标,重点考虑混凝土靶的骨料/砂浆强度、弹体侵彻速度等因素,讨论其对弹体正侵彻条件下弹道偏转的影响规律。结果表明：根据混凝土的材料特性,可认为砂浆和骨料共同对正侵彻弹体提供轴向阻力,而随机非均匀的骨料作用力与砂浆阻力之差则提供导致其偏转的侧向力;弹道偏转角度随混凝土砂浆强度减小而增大,相反地,随骨料强度增加而增大;当名义抗压强度较小时,弹体偏转对砂浆强度变化的敏感度显著大于骨料强度变化的影响;在刚性弹假设下,弹道随着弹体侵彻速度增加而更加稳定,即偏转角随着靶速度增加而减小;但若弹体非刚性假设,越高速度侵彻,越容易变形破坏,则越容易偏转且容易出现“J”弹道。     

降低终点弹道偏转效应弹体结构设计

针对弹体侵彻过程中弹道偏转现象,开展了降低弹体弹道偏转效应研究.设计了一种锥形结构实验弹体,对其侵彻混凝土靶板过程中受力情况进行了分析,锥形结构弹体侧壁力矩有助于降低弹体侵彻过程的弹道偏转程度;采用130 mm轻气炮开展了锥形实验弹体侵彻混凝土靶板实验,并与普通直杆形弹体侵彻结果进行了对比.实验结果表明,锥形弹体侵彻弹道的偏转程度小于普通直杆形弹体,锥形弹体在斜侵彻以及高速侵彻厚目标情况下,将有更好的侵彻性能.     

混凝土侵彻过程中弹道偏转的影响因素和规律研究

为了研究弹体斜侵彻半无限厚混凝土过程中不同因素对弹道偏转的影响规律,采用半经验公式法,确定了靶体响应力函数,然后利用ABAQUS,将靶体响应力函数加载到弹体表面作为有限元计算的边界条件,计算得到了弹体侵彻混凝土时弹体质心运动轨迹。分析发现,倾角越大,倾角对侵彻深度和偏转角的影响越明显;入射速度对弹道偏转的影响随着入射速度的增大呈现减小的趋势;质心位置越靠近弹体尾部,弹道偏转越大,越不利于侵彻。     

斜截头弹体入水的弹道特性

斜截头弹体的入水会发生姿态偏转和弹道弯曲。从理论上分析弹丸在水中的偏转过程,得出斜截头弹体姿态偏转方程。利用AUTODYN软件对斜截头弹体入水过程进行数值模拟,基于模拟结果提出描述弹体质心轨迹的经验公式,并通过试验验证其准确性。设计炮射垂直入水试验,利用高速摄像机记录弹丸的撞击速度和运动过程。试验结果表明：理论分析得出的姿态偏转方程可靠,数值模拟和基于数值模拟得出的质心弹道经验公式的预测精度可信。     

椭圆变截面弹体斜贯穿薄靶姿态偏转机理

随着新型武器平台的发展,具有良好平台适应性、高升阻比及隐身性能等特点的异形截面（椭圆形及变截面椭圆形）战斗部开始受到广泛关注。为探究椭圆变截面弹体斜贯穿薄靶机理与姿态偏转规律,对3种不同截面（圆形、椭圆形、变截面椭圆形）弹体斜贯穿双层945舰船薄钢板实验过程及结果进行整理与分析,根据椭圆变截面弹体贯穿过程、靶板破坏失效模式与弹体受力特征,将贯穿过程分为弹体头部压入阶段、弹体头部贯穿阶段、过渡阶段与弹身贯穿阶段。基于能量守恒、虚功原理分阶段分析弹体受力特征,建立弹体姿态偏转理论模型。通过对已有实验和数值模拟结果与理论模型所得结果进行对比,验证理论模型的可靠性。采用该理论模型着重讨论弹体撞击速度、初始倾角、质心位置、弹体翻滚角及椭圆截面长短轴之比等参数对椭圆变截面弹体姿态偏转的影响。结果表明：随着椭圆变截面弹体初始撞击速度的增加,弹体姿态偏转角度呈现指数型减小趋势;随着椭圆变截面弹体初始倾角的增大,弹体姿态偏转量增大;随着椭圆变截面弹体质心位置的后置,弹体姿态偏转角度增大;椭圆变截面弹体以不同的翻滚角撞击靶板时,弹体姿态偏转角度不同,γ_pt=0°较γ_pt=90°时弹体姿态偏转角度更大;当γ_pt=0°时,椭圆变截面弹体椭圆截面长短轴之比增大,弹体姿态偏转角度随之增大;当γ_pt=90°时,规律则相反。     

复合式侵彻体斜侵彻多层钢靶弹道研究

为优化弹体头部外形,减小侵彻过程头部侵蚀对弹道偏转的影响,进而提升弹体斜侵彻多层靶弹道稳定性,设计了一种复合式侵彻体,利用ANSYS/LS-DYNA,计算了复合式侵彻体以500～800 m/s速度侵彻3层间隔钢靶的弹道偏转情况,对比了复合式与整体式侵彻体弹道偏移量,探讨了帽罩材质对复合式侵彻体弹道的影响机制,并进行了实...     

弹体高速入水弯曲弹道实验研究

通过模型高速入水实验,利用高速摄像机拍摄了弹体入水过程和空泡形态演变过程,得到了4种头部外形模型的弹道曲线,并分析了头型、入水角、入水速度对水下弹道的影响。研究结果表明：椭圆斜截头弹体由于其特殊的头部更容易产生偏向水面的弯曲弹道,而其他3种弹体在一定速度内弹道比较稳定,基本趋于直线,虽然在有些工况下弹道发生了偏转,这是由于弹体加工过程中结构误差等造成的弹道不稳定性;入水角对弹道影响比较显著,小的入水角条件下弹体迅速向水面偏转,而入水角增大到一定程度时弹道向缸体底部偏转。所得结论可为高速入水武器的研究提供参考。     

采用合成射流激励器的小口径枪榴弹弹道修正仿真

针对小口径枪榴弹尺寸小，舵面和舵机执行机构进行弹道修正存在困难这一问题，采用基于合成射流激励器的小口径枪榴弹弹道修正。首先采用计算流体力学软件对单个合成射流激励器模型进行数值模拟，获取合成射流激励不同时刻振动膜的外形变化及对应的喷口流速分布；在此基础上，将合成射流激励器布置在枪榴弹弹体内，指定振动膜的振动方式，通过网格重构算法计算合成射流-弹体绕流-体化流场，获取合成射流激励器作用下弹体表面射流喷口速度与弹体法向力；最后通过6D弹道模型计算小口径枪榴弹的弹道，评估修正弹的修正能力。仿真结果表明，合成射流激励器作用时能够影响小口径枪榴弹尾部局部流场，改变弹体表面压力分布并产生法向力，该力能够满足小口径枪榴弹在射程和横偏方向修正能力需求。     

弹体形状对侵彻弹道的影响分析

为了避免弹体非正侵彻时侵彻弹道失稳,提高弹体侵彻深度,通过理论计算和数值仿真分析了柱形弹体和不同半锥角的锥形弹体的侵彻弹道,由于锥形弹体相比于柱形弹体,增大了与弹道洞壁的接触面积,产生的稳定力矩削弱了偏转力矩的不利影响,因而锥形弹体提高了侵彻弹道稳定性,弹道偏移量随着弹体半锥角的增大而减小,且存在一个最优半锥角使得垂直侵深最大。     

Nitrosation and Nitration of Tetraacetyldibenzylhexaazaisowurtzitane

Tetraacetyldibenzylhitane (TADBIW) was subjected to debenzylation by nitrosating with inorganic materials available commercially to synthesize tetraacetyldinitrosohexaazaisowurtzitane (TADNSIW). TADNSIW was purified, and its structure was determined by FTIR, 1H NMR, MS and element analysis. The debenzylation reaction of TADBIW gave quantitative benzaldehyde as a by-product. This indicates that the reaction produces an imine cation as an intermediate. Hexanitrohexaazaisowurtzitane (HNIW) was prepared from unpurified TADNSIW with the yield over 96.0 % and the purity more than 98.0 %. And the mechanism of the reaction from TADNSIW to HNIW is proposed to be oxidation of nitroso and nitration of acetyl on the molecule of TADNSIW, This reaction system involved is simple, and the reaction can complete within a short time and under mild conditions. The product can be easily to separate and the waste disposed readily.     

A Robust Algorithm for Watermarking 2D Vector Maps with Low Shape-Distortions

The technique of watermarking has been introduced into 2D vector maps for many potential applications such as protecting the copyright of important GIS （geographical information system） data and tracing the data source of military maps. In most previous works, although the validity of the map data could be preserved during the embedding procedure, the shape-distortions of the map elements are usually neglected which would tend to degrade the invisibility of the watermarking schemes. A shape-preserving algorithm for watermarking 2D vector maps is presented in this paper. A 1D distance sequence extracted from the original map is adopted as the cover data instead of 2D coordinates. A watermark bit is represented by changing the distributions of the cover data. The embedding procedure induces lower shape-distortions than in former works. Experimental results indicate better invisibility of the proposed scheme, as well as its robustness to certain attacks such as map simplification, interpolation, additive noise and most geometric transforms.     

Open Rule-setting System Applied to Conceptual Design of Engines

Open rule-setting method advanced in this paper concentrates on providing designers of engines with a convenient way to express their design innovations and develop the expected prototypes in the early CAD stage, and constitute effective models for the following analysis process of CAE and CAPP. The problems arisen in the process of conceptual design with the traditional experience-based development method are analyzed. Based on those analyses, open rule-setting method is presented and some associated technical problems are discussed. The functional framework of open rule-setting system was built as software engineering methods. The speciality of the engine product as a kind of complex product and the requirement of the engine product based on its structural particularity to rule-setting system are considered carefully. A demonstration is supplied to illustrate how the open rule-setting method enhances the efficiency and quality of the engine conceptual design.     

Research on Linux Network Device Driver

By analyzing the working principle of Linux network device driver, discussing the Linux network driver structure and its key technologies, the general network driver structure and its design methodologies in Linux system are summarized. Through modifying the network device driver of Linux device driver 3rd version snull, c and improving the COW technology, the Zero-Copy technology in Linux （kernel version 2.6.11 ） is implemented. In the end, the success test tells us that the thorough analysis of network device driver is the foundation of many applications, and it also provides a certain improvement to a lot of real applications, even to military application development.     

Improvement and Experiment of the Reamer in Vibra Cutter Against Wave Edge of Titanium Sheet Alloy Parts

By analyzing the influencing factors of part quality making of sheet alloy of titanium by vibra cutter, the shape of upper reamer is set as cylinder and wedge-shaped form, and the lower reamer as plain and hemicycle form, and its main structural parameters are defined as well. Then it is validated further that such improved vibra cutter reamer can be used to process curve-edged parts of titanium alloy sheet. The experimental result shows that the titanium alloy sheet parts processed by above equipment have no sharpen angles for convex parts and evident crevasse of concave-edged part. In summary, such improvement can eliminate the free-waved edge and improve the manufacture quality of titanium alloy sheet parts greatly.     

Experimental Study on the Small Flyer Initiating Behavior of Fine-grained Explosives

The initiating behavior of fine-grained explosives by small flyer is studied. The diameter of small flyer in this device is 1 ram. The test results indicate that the granularity of explosives has great effect on its flyer initiating sensitivity.The flyer initiating sensitivity of the fine-grained explosives is higher and the critical initiating energy is lower than that of common explosives. For common explosive, the flyer initiating sensitivity increases as the density is reduced. But for the fine-grained explosive, the test results are exactly opposite.     

Stability of the Third Generation Intensifier under Illumination

The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.     

Algorithm for Multi-laser-target Tracking Based on Clustering Fusion

Multi-laser-target tracking is an important subject in the field of signal processing of laser warners. A clustering method is applied to the measurement of laser warner, and the space-time fusion for measurements in the same cluster is accomplished. Real-time tracking of multi-laser-target and real-time picking of multi-laser-signal are introduced using data fusion of the measurements. A prototype device of the algorithm is built up. The results of experiments show that the algorithm is very effective.     

Robust Graded Sliding Mode Tracking Control for Low Speed Spinning Ballistic Missiles

The nonlinear dynamic model of spinning ballistic missiles is established during the first boosting phase of the missile. Based on the conventional backstepping sliding mode control and the assumption of a two time-scale separation of missile dynamics, a graded sliding mode controller is designed with two sub-sliding surfaces which have invariability to external disturbances and parameter perturbations, and a matrix which comprises three first order low pass filters is introduced to prevent ＂explosion of terms＂. Owing to the upper bounds of the uncertainties are difficult to obtain in advance, adaptive laws are introduced to estimate the values of the uncertainties in real-time. Eventually, the numerical simulation results given to show the proposed controller can ensure the steady flight of missiles.     

A Study on the Estimation of Aeroheating upon the Warhead Nose at Supersonic Speed

An expression for estimating the aeroheating on a warhead nose at different supersonic speeds is proposed by incorporating CFD （computational fluid dynamics） and the least-square method. Compared with the traditional estimation formula, the expression is more accurate, convenient and can be used in the optimized design of warheads. The error from the result obtained in the test of a ball cartridge flight is less than 3 %. It satisfies the engineering requirements.