高速弹体对钢筋混凝土靶的侵彻/贯穿效应实验研究

为了研究高速弹体对钢筋混凝土靶的侵彻/贯穿效应,以100 mm口径滑膛炮作为发射平台,驱动10 kg级卵形弹体以820～1195 m/s速度撞击强度为31.0～43.6 MPa的钢筋混凝土靶,获得了弹体侵彻/贯穿钢筋混凝土靶的终点弹道实验数据,并对弹体的侵彻/贯穿深度、靶板侧面自由面效应、弹体的变形进行了详细分析。结果表明:弹体的侵彻/贯穿深度为2.2～2.8 m,部分经验公式预估的侵彻/贯穿深度与实验结果吻合较好;当靶面相对尺寸较小且弹速较高时,靶板侧面自由面效应比较明显;当弹速达到1195 m/s时,弹体开始由刚体向半流体转变。     

弹体高速侵彻钢筋混凝土靶的结构变形及质量损失的实验研究

设计了高速钻地结构弹,采用35mm口径的弹道炮和100mm口径的滑膛炮,进行了0.15和1.5kg弹体在1 030~1 630m/s速度范围内侵彻钢筋混凝土靶的实验研究,对高速侵彻条件下弹体的结构响应、质量损失及生存极限速度等问题进行了探讨。结果表明:在高速侵彻混凝土过程中,弹体结构的变形破坏包括头部侵蚀/墩粗+侧壁磨蚀、弯曲/尾部破裂、破碎等形式,弹体头部侵蚀和弹体质量损失程度随撞靶初速度的增加而增加。     

高速弹体非正侵彻混凝土靶的弹道偏转实验研究

利用二级轻气炮,进行了980~1870m/s速度范围内小尺寸弹体非正侵彻半无限混凝土靶实验,详细测绘了弹道轨迹及特征参数,重点研究了高速非正侵彻的弹道特性,并根据侵彻机理进行了侵彻过程分区。研究结果表明:与中、低速条件下的弹道不同,高速弹体非正侵彻半无限混凝土靶的侵彻弹道偏转更为明显,表现为典型的“J”形弹道,弹体终点姿态变化很大,弹道末端的偏转角可达130°。     

不同材料弹体超声速侵彻钢筋混凝土靶的结构破坏对比实验

设计了超声速钻地结构弹,采用203 mm口径的火炮,开展了25 kg量级弹体在1100~1300 m/s速度范围内侵彻钢筋混凝土靶的实验研究,应用数值仿真对弹体侵彻钢筋混凝土靶的过程进行了模拟计算。基于实验和仿真结果,对超声速侵彻条件下两种金属材料弹体的结构响应、质量损失等问题进行了分析。结果表明:在超声速侵彻钢筋混凝土靶的过程中,两种金属材料的弹体结构变形破坏形式主要为头部侵蚀和侧壁磨蚀,头部侵蚀量的大小与弹体壳体材料有关,高强度G50钢材料更适合用于1200 m/s速度量级的超声速侵彻环境。对出现的“径缩”现象作了初步分析,并对今后工程应用的结构弹体设计提出了指导意见。     

双层A3钢靶对平头杆弹的抗侵彻性能研究

 钢板被广泛用于构建防护结构,大量文献报道了单层金属靶的防护性能,而对双层金属靶,特别是大间隙双层金属靶,报道的却很少。在轻气炮上进行了平头杆弹体正撞击由两层5 mm厚A3钢板组成的接触式和具有200 mm间隙的间隙式双层靶的实验研究,得到了两种结构的初始-剩余速度曲线。实验表明：（1）两种形式双层靶均发生了充塞剪切;（2）接触式双层靶的弹道极限是5 mm单层A3靶的1.92倍;（3） 间隙式双层靶的抗侵彻性能具有较大的分散性,通过高速摄像和对回收靶板的分析表明,该分散性产生的原因是,弹体贯穿第一层靶后存在两种典型弹道状态;（4）间隙式双层靶存在两个弹道极限;（5）接触式双层靶的弹道极限接近或者大于间隙式双层靶的弹道极限。使用ABAQUS/EXPLICIT有限元软件进行了相应的数值模拟,得到了与实验一致的现象和结果。     

GFRP复合三明治板在高速弹体冲击下的弹道极限预测（英文）

研究了玻璃纤维复合三明治板在圆柱形平头弹体打击下的预测弹道极限的理论预测方法。建立了玻璃纤维复合三明治板的三阶段侵彻模型,包括侵彻面板阶段、侵彻复合材料夹芯层阶段和侵彻内板阶段。基于高速弹体侵彻下靶板的局部变形假设建立了理论关系,将弹体侵彻复合材料夹心层时视为刚体处理,面板和背板的侵彻阶段考虑了弹体的墩粗效应和靶板的绝热剪切效应。基于能量平衡原理,推导了复合材料三明治板的弹道极限,并将理论计算结果与实验结果进行对比和分析,研究了不同侵彻速度、弹体质量和夹心层厚度对弹道极限的影响。结果表明,理论计算结果与实验结果具有较好的一致性。     

分段PELE弹体冲击多层靶板数值分析

为了实现侵彻体对多层靶板的高效毁伤,采用数值模拟方法研究了分段式横向效应增强体(PELE)对4层金属靶的侵彻效应,获得了弹体侵彻速度和靶板厚度对弹体终点效应的影响。结果表明,分段PELE弹侵彻4层靶的靶后效果优于普通PELE弹。与金属杆相比,分段PELE弹侵彻多层靶后的弹孔直径更大。弹丸贯穿各层靶板后壳体的径向速度峰值随着靶板厚度的增加而增大,而壳体破碎长度并不随之线性变化。提高弹丸侵彻速度时,弹丸穿过第1层靶板后壳体破碎长度的变化趋势与径向速度峰值的变化相似,穿过第2层和第3层靶板后壳体破碎长度和径向速度峰值在侵彻速度为1.4km/s时达到极大值,随后下降,而穿过第4层靶板后壳体破碎长度和径向速度峰值随着初速度的增加而增大。     

岩石、混凝土和土抗侵彻能力数值计算与分析

利用LS-DYNA3D软件数值计算了弹体侵彻岩石、混凝土和土问题,分析在不同碰撞速度条件下的弹体响应和靶体抗侵彻能力。碰撞速度小于900 m/s时,弹体侵彻岩石的减加速度峰值约是侵彻混凝土的2倍,而侵彻混凝土的减加速度峰值约是侵彻土的6倍。减加速度峰值高则稳态侵彻过程短,弹体能量消耗很快。碰撞速度超过1.5 km/s时,随靶体材料的强度、密度逐渐减小,侵彻深度和孔径逐渐缓慢增加,岩石、混凝土和土3种靶体材料相比,最大侵彻深度增加41%~62%,最大扩孔口径增加16%~25%。     

刚体与SPH耦合的三维数值方法研究

 研究了刚性体与SPH（Smoothed Particle Hydrodynamics）方法相耦合的计算方法和技术,以此技术为核心,在原有三维综合拉氏程序CL3D的基础上,研制了适用于斜侵彻问题数值研究的刚性弹体与SPH靶体耦合计算的拉氏三维数值模拟程序CRSPH3D。针对金属材料编入了Johnson-Cook本构模型计算模块,针对混凝土材料编入了Johnson-Holmquist本构模型及与之配套的损伤模型和状态方程等的计算模块。用研制的计算程序对弹体分别正碰和斜碰穿透中厚铝靶和侵彻厚混凝土靶的过程进行了数值模拟计算和分析。结果表明,对于铝靶穿透问题,模拟计算得到的弹体剩余速度、弹体动能损失和贯穿图像与实验结果符合得较好。对于混凝土靶的侵彻问题也得到了与实验现象一致的、定性合理的图像。     

基于速度势侵彻模型的应用研究

 研究了Rubin等人提出的基于Rankine卵形体速度势函数分析的侵彻模型。根据该侵彻模型的基本方法编制了计算程序,计算头部形状为锥形、卵形和球形的长杆弹体垂直碰撞靶板时的侵彻深度和穿透靶板后的剩余速度,分析侵彻模型对不同头部形状的长杆弹体的适用性。另外,利用该分析方法计算并分析了卵形头部长杆弹体对铝靶侵彻和穿透的缩比模型问题,用分析方法验证了无量纲侵彻深度和剩余速度相等的侵彻几何相似规律,同时得到了弹体减加速度与几何尺寸成反比的重要结论。最后对混凝土靶板的侵彻与穿透问题进行了尝试计算,得到了同实验基本一致的计算结果并对其进行了深入分析。     

爆炸磁通量压缩发生器金属管爆炸试验研究

 描述了对爆炸磁通量压缩发生器（MFCG）的爆炸金属管进行的爆轰测试试验。利用电探针方法,测试得到了金属管中的粉状RDX炸药的爆轰速度。采用高速分幅相机测试技术,得到了金属管膨胀运动过程的分幅照片,掌握了金属管的膨胀及破裂情况,并由此测得了膨胀角。本试验结果为MFCG的设计和改进提供了依据。     

Interphase sizing temperature effect of LaRC PETI-5 on the dynamic mechanical thermal properties of carbon fiber/BMI composites

The dynamic mechanical thermal properties of carbon fiber-reinforced bismaleimide (BMI) composites processed using polyacrylonitrile(PAN)-based carbon fibers unsized and sized with LaRC PETI-5 amic acid oligomer as interphase material at 150°C, 250°C, and 350°C were investigated by means of dynamic mechanical thermal analysis. It was found that the storage modulus, loss modulus, tan δ and the peak temperature significantly depend on the sizing temperature as well as on the presence and absence of LaRC PETI-5 sizing interphase. The result showed that the carbon fiber/BMI composite sized at 150°C had the highest storage modulus at a measuring temperature of 250°C. The storage modulus decreased with increasing sizing temperature from 150°C to 350°C, being influenced by interdiffusion and co-reaction between the LaRC PETI-5 interphase and the BMI matrix resin. The present result is quite consistent with the interfacial result reported earlier in term of interfacial shear strength and interlaminar shear strength of carbon fiber/BMI composites. It is addressed that in the present composite system the sizing temperature of LaRC PETI-5 interphase critically influences not only the interfacial properties but also the dynamic mechanical thermal properties and its control is also important.     

Pulsed laser deposition of metals at target temperatures close to the melting point

Tin and bismuth metals are irradiated by KrF excimer laser pulses of fluences around 5 J/cm². Supressing the formation of surface inhomogeneities on the target is achieved by increasing the target temperature to close to its melting point. The characteristics of surface structures developed on targets ablated at room temperature and heated to approximately 40 °C below the melting point of the respective metal, are presented. Optical microscopy is used to follow the changes in the surface morphology of the deposited films, and especially in the surface number density of particulates. Approaching the melting point of the tin target resulted in a threefold decrease in surface number density of particulates, while for bismuth only a slight decrease was obtained. In the latter case, the anisotropic growth properties of bismuth precluded the effective smoothing of certain domains on the target surface, even at temperatures close to its melting point.     

A Numerical Investigation on the Influence of Steel Fiber Shape and Interface Strength in Reinforced Concrete

Not all steel fiber reinforced concrete composites are equally effective in enhancing structural performance. Their mechanical behaviour strongly depends upon the reinforcement morphology as well as the properties of the interface lying between steel reinforcement and concrete matrix. Using bone-shaped short (BSS) steel fibers, instead of conventional straight short (CSS) steel fibers, to reinforce concrete has demonstrated their potential in improving toughness, ductility and energy absorbing capacity under impact significantly and simultaneously. Accomplishing a strong steel–concrete interface leads to a slight increase in composite strength but simultaneously to a significant decrease in its toughness. Due to the sensitivity of steel reinforced concrete performance on these complex geometric and material parameters, the development of a numerical tool capable of simulating accurately the composite mechanical behaviour and thus leading to optimized design solutions is desirable. The physical problem of the present work involves a typical concrete composite uniformly reinforced with steel fibers subjected to tensional loading. A micromechanical non-linear finite element formulation is utilized in order to predict the load transfer characteristics and the failure process. A linear material behaviour is assumed for the steel component; a non-linear multi-crack material response is used to describe concrete while a mix-mode bilinear behaviour is utilized for the interface providing separation of primary material phases. Numerical results are presented in terms of the global design parameters. The influence of the fiber end shape, the interface strength and the fiber volume fraction on the composite strength and toughness is addressed and consequently optimized design preferences arise.     

Mechanical properties of metal matrix composites

The concept of reinforcing a material by the use of a fiber is not a new one. The Egyptian brick layer employed the same principle more than three thousand years ago when straw was incorporated into the bricks. More recent examples of fiber reinforced composites are steel-reinforced concrete, nylon and rayon cord reinforced tires, and fiberglass reinforced plastics. In the last several years considerable progress has been made on new composite structures particularly utilizing boron (on tungsten substrate) fibers in various matrices. Many of these advances have been reviewed recently by P. M. Sinclair¹ and by Alexander, Shaver, and Withers.² An excellent earlier survey is available by Rauch Sutton, and McCreight.³ Boron-reinforced epoxy composites are being fabricated and tested as jet engine components, fuselage components, and even as a complete aircraft wing because of the tremendous gain in experimentally demonstrated properties such as modulus, strength, and fatigue resistance, particularly on a weight normalized (e.g., strength/density) basis. Other than glass/epoxy and boron/ epoxy composites and perhaps boron/aluminum, the systems now under study are in the early stages of research and development. These include other boron/metal composites, graphite/polymer, graphite/metal, graphite/graphite, alumina/metal, and aligned eutectic (directionally, solidified) combinations. As Sinclair points out, designers are wary about filamentary composites because “there is little background information and scant experience.”     

一种新的氮化碳相的冲击波合成

 为了合成理论预测存在的高密度氮化碳相，以富氮的C-N-O非晶材料和晶态的双氰胺为前体，在低于50 GPa的冲击压力范围内进行了一系列冲击回收实验。回收产物的XRD衍射表明，形成了由β-C₃N₄和一种新的氮化碳相组成的复合相。该新相的衍射峰可以完全指标化为一个单斜晶胞，晶胞常数为a=0.981 nm，b=0.723 nm，c=0.561 nm，β=95.2°，晶胞体积V_cell=0.396 6 nm³。根据实验结果可以认为，氮化碳复合相的形成是前体有机分子在瞬态的冲击波化学反应后，经历了极高速的冲击淬火过程（约10⁹ K/s），作为一种高压亚稳相而被保存下来。冲击压缩富氮的有机物前体，是合成氮化碳相的一种新方法。     

Production of Helium Projectile Fragments in 16O-Emulsion Collisions at 60 A GeV

Production of helium projectile fragments in ¹⁶O-emulsion interactions at 60 A GeV is investigated. The total charge changing and partial production cross-sections are measured experimentally on the basis of helium multiplicity. The multiplicity distribution of helium projectile fragments obeys a KNO scaling. In the peripheral collision of ¹⁶O at 60 A GeV in nuclear emulsion, the production of target fragments depends on the multiplicity of helium projectile fragments linearly. The averge multiplicity of target fragments decreases with the increasing of the number of helium projectile fragments which can be well expliained by the model of participant-spectator (the nuclear geometric model) of nucleus-nucleus interactions.     

超高速碰撞闪光强度与碰撞角度关系

为了测量超高速碰撞过程中产生的闪光现象,进而研究相近碰撞速度、不同入射角度(弹道与靶板平面的夹角)条件下超高速碰撞产生闪光在整个物理过程的闪光强度随时间的变化规律,设计了适用于瞬态闪光测量的光学高温计测量系统。通过二级轻气炮加载LY12球形铝弹丸,运用设计的瞬态高温计测量系统分别进行了入射角度为30°,45°,60°和90°相近碰撞速度条件下碰撞LY12铝靶产生闪光现象的测量。获得了平均碰撞闪光强度峰值与碰撞角度的关系,平均碰撞闪光强度峰值随碰撞角度的减小而增大,碰撞角度为30°时表现更为明显。     

Formation of adhesive phase onto high strength and modulus PE fiber by PE solution treatment for making PE fiber-reinforced PE composite

The method for the formation of adhesive phase onto polyethylene (PE) fiber surface by passage of the PE fiber through hot PE solutions has been investigated for making composite materials reinforced by the PE fibers. When the PE fiber is treated by the low density PE (LDPE) solution in o-xylene in the range of 120 to 135^°C, the tensile strength of the PE fiber is maintained at that of the original PE fiber. Adhesive strength between the PE fiber surface and LDPE phase formed on the PE fiber through the hot PE solution is found to be so high that the PE fiber itself is torn off. The application of the present method to PE fiber-reinforced PE composites will be expected.