装备保障综合演练风险分析

采用工作结构分解(Work Breakdown Structure,WBS)和风险结构分解法(Risk Breakdown Structure,RBS)对装备保障综合演练全过程的风险及其风险因素进行了系统分析,得出了装备保障综合演练过程中存在的7类风险、24种风险因素;运用网络层次分析法(Analytic Network Process,ANP)对各种风险及其风险因素进行了评估,得出了其对装备保障综合演练风险影响的权重及排序。研究结果可为装备保障综合演练顺利开展,确保人员、装备安全提供参考。     

医院供配电系统谐波测量和分析

为治理日趋严重的医院供配电系统谐波污染,需要深入了解医院谐波分布。利用FLUKE 43B对某医院进行现场谐波测试,基于所得数据重点分析了医院供配电系统谐波污染和谐波源分布情况,根据医院谐波污染特点总结了治理方法。结果表明:医院供配电系统存在严重的谐波污染。被测量医院设备先进,种类齐全,测试所得数据具有较强的代表性,可为医院供配电系统谐波研究、谐波治理和滤波设备选择提供基础数据参考。     

基于ANSYS的油罐拱顶稳定性分析

针对加肋拱顶稳定性十分复杂的问题,基于ANSYS建立了加肋拱顶油罐的三维有限元模型,对加肋拱顶的结构稳定性进行了数值模拟。对加肋拱顶在外压作用下的线性与非线性临界屈曲载荷进行了对比分析,利用弧长法获得了拱顶在加肋情况下径向、环向、轴向的载荷-位移曲线。结果表明:数值模拟的加肋拱顶屈曲方向和屈曲区域与实际失稳结果相一致,可以为加肋拱顶设计和稳定性分析提供一定参考。     

基于FEM/SPH算法的弹丸侵彻土体数值模拟

基于有限元法(FEM)和光滑粒子流体动力学(SPH)结合的算法,用数值模拟了钢质弹丸对钢筒约束土体的侵彻过程。基于ANSYS/LS-DYNA显式动力分析和LS-PrePost后处理软件,形象再现了钢质弹丸冲击作用下土体飞溅形成漏斗坑和直线通道的物理过程。侵彻深度计算结果与实验数据吻合较好,钢质弹丸的速度和加速度时程曲线图与理论分析一致,体现了FEM/SPH算法的精确性。研究结果表明FEM/SPH算法在模拟侵彻土体方面具有可行性和有效性。     

钢丝增强复合条带抗弹性能数值分析

为研究钢丝增强聚合物基复合条带的抗弹性能,基于冲击动力学理论分析其抗弹机理,再借助ANSYS/LS-DYNA软件和LS-PrePost前后处理器模拟有无增强钢丝2种工况下,条带对7.62 mm弹体的冲击响应。分析表明：条带的弹性模量、剪切模量和面密度会影响其能量吸收性能,能量吸收量随三者的增大而增大;由于聚合物基体的正交各向异性,应力云图显示出扁平椭圆状是合理的;在聚合物基复合条带中嵌入增强钢丝对条带整体的抗弹性能有积极的影响,但嵌入过量的钢丝会导致重量和成本的增加,因此需要对合理的钢丝配比率作进一步研究。研究结果可为钢丝增强聚合物基复合条带在野战防护结构中的应用提供参考。     

基于FLAC^3D的岩土边坡施工效应研究

采用FLAC3D对预应力锚索框架梁支护的岩土边坡施工过程进行数值模拟,围绕施工中坡体位移场与应力场的变化以及下级边坡施工对上部已完成的支挡结构受力影响进行研究.结果表明坡体开挖引起的松弛区呈圆弧状,且位移由临空面向坡体内逐渐减小,坡体弹性模量与其变形呈非线性递减关系;预应力锚索框架梁能有效抑制坡体变形,从坡顶到坡脚锚索轴力依次增大,故工程设计中宜对其分别设计,做到“强腰固脚”;下级边坡与上级边坡的支挡结构相互约束,共同承担滑坡推力,形成一种“联合支挡结构”.     

基于备件需求预测的两步法理论

在对备件需求时间序列研究的基础上,结合指数平滑法和Croston法的特点,分析了指数平滑法与两步法的原理,通过对指数平滑法和两步法方差的研究,得到两步法是指数平滑法的一般形式的结论,为两步法的进一步研究提供一定的理论支撑。     

基于排队论的协同防空作战效能分析

舰艇编队协同防空作战是未来海战的重要形式,运用排队论对舰艇编队协同防空的作战效能进行了研究。以排队理论为基础建立了舰艇编队协同防空的排队模型,运用理论分析得到了以整个编队毁伤目标概率为指标的防空效能。通过对防空效能的计算与仿真,分析了几个重要参数对防空效能的影响,为多层舰艇防空系统的设计与运用提供了理论支持。     

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.     

On the continued acceleration of bomb casing fragments following casing fracture

It has been said that, once a bomb casing has fractured, “detonation gases will then stream around the fragments or bypass them, and the acceleration process stops there.” However, while apparently copious gas flow through casing fractures indicates some pressure release, it is also an indication of significant gas drive pressure, post casing fracture. This paper shows two approaches to the problem of calculating the actual loss of drive. One presents first-order analytical calculations, in cylindrical geometry, of pressure loss to the inside surface of a fractured casing. The second shows the modelling of a selected example in the CTH code. Both approaches reveal that gas escape, while occurring at its own sound-speed relative to the adjacent casing fragments, has to compete with rapid radial expansion of the casing. Together with some historic experiments now publicly available, our calculations indicate that post-fracture casing fragment acceleration is, for most systems, unlikely to be reduced significantly.