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1.
通过在粉状乳化炸药中添加不同比例的密度调节剂,配制了爆速范围为1 450~2 550 m/s的低爆速炸药;采用该爆速炸药进行了铝/不锈钢复合管爆炸焊接实验,结合最小碰撞速度理论,对实验结果及其界面微观结构和结合强度进行了测试和分析,确定该复合管爆炸焊接的合适爆速约为1 950~2 150 m/s,其结合质量能够满足后续加工要求;同时发现界面由介于直线与波形之间的波状形态组成,且呈现不太规则的扁平波状结合,经分析,炸药爆速、复合管的爆炸焊接环境和爆炸产物飞散条件对界面结合波形及熔化层厚度有很大影响。  相似文献   

2.
基于J-C本构模型的Comp.B炸药落锤冲击数值模拟   总被引:2,自引:0,他引:2  
为研究Comp.B炸药在惯性冲击下的力学响应特性, 基于Johnson-Cook本构模型, 对 点火前的Comp.B炸药大落锤(400kg)冲击实验进行了数值模拟. 在不同应力加载条件下模 拟计算得到了用状态方程和不用状态方程的$\sigma$-$t$曲线, 对比应力峰值、应 力上升时间等主要力学参数, 结果表明考虑了状态方程的数值模 拟结果与实验吻合最好, 可以很好地模拟炸药惯性冲击下的力学响应.  相似文献   

3.
为了提高捷联惯导(SINS)/天文导航(CNS)/合成孔径雷达(SAR)组合导航系统的定位精度,在吸收模型预测滤波和抗差自适应滤波算法优点的基础上,提出了一种新的抗差自适应模型预测滤波算法。该算法首先利用模型预测滤波估计出系统模型误差,并对其进行实时修正,以抑制系统模型误差对导航解算精度的影响;然后利用抗差自适应因子控制观测异常,抑制观测噪声对导航解算精度的影响。将提出的算法应用于SINS/CNS/SAR组合导航系统进行仿真验证,并与抗差自适应滤波进行比较,结果表明,提出的算法得到的姿态误差、速度误差和位置误差分别在[0.2,0.2]、[0.3m/s,0.3m/s]和[6 m,6 m]以内,滤波性能明显优于抗差自适应滤波算法,说明该算法能有效抑制系统模型误差及观测异常对导航解的影响,提高组合导航的解算精度。  相似文献   

4.
高云亮  赵伟  姜宗林 《力学学报》2008,40(4):473-478
介绍了中国科学院高温气体动力学实验室JF-16爆轰驱动高焓激波膨胀 管的研制进展及其性能测试结果. 性能研究主要测量了入射激波速度和压力曲线. 根据入 射激波速度,应用Mirels的黏性激波管理论计算了超高速试验气流的运动速度,然后应用 Gaseq软件计算了试验气流的热力学参数. 研究结果表明:在16.35\,m长的JF-16激波膨胀 管中获得了流速7\,000\,m/s以上的稳定试验气流,试验时间 为50$\sim$100$\mu$s, 试验气流总焓30\,MJ/kg左右.  相似文献   

5.
针对系统误差的不确定性可能会引起滤波精度降低或发散的问题,提出一种新的基于模型预测滤波的前向神经网络算法。首先,采用模型预测滤波估计网络在正向传递过程中的模型误差,并对其进行修正,以弥补模型误差对隐含层权值更新的影响;然后,利用模型预测滤波为神经网络提供精确的训练样本,学习待估计系统的非线性关系。将提出的算法应用于SINS/CNS/BDS组合导航系统,并与扩展卡尔曼滤波进行比较,仿真结果表明,提出的算法得到的姿态误差、速度误差和位置误差分别在[-0.25′,+0.25′]、[-0.05 m/s,+0.05 m/s]和[-5 m,+5 m]以内,滤波性能明显优于扩展卡尔曼滤波算法,表明该算法能提高组合导航定位的解算精度。  相似文献   

6.
冲击波对含水炸药减敏作用的实验研究   总被引:7,自引:1,他引:6  
对水胶炸药和乳化炸药在冲击波作用后的爆炸性能作了对比实验研究,结果表明水胶炸药的抗压性能明显优于乳化炸药,分析认为造成这种差别的原因是两种炸药不同的结构组分和敏化方式。用示波器捕捉两种炸药受冲击波作用前后的水中爆炸冲击波,利用冲击波参数计算炸药的减敏程度,将炸药的压力减敏作用数量化,克服了以往的研究方法只能用半爆率、拒爆率等概念计数表述的不足。  相似文献   

7.
乳化炸药配方设计的数学模型研究   总被引:5,自引:0,他引:5  
陆明  吕春绪 《爆炸与冲击》2002,22(4):338-342
根据炸药爆炸反应的热化学 ,建立了乳化炸药配方设计的数学模型 ,利用数学模型讨论了不同含量的硝酸铵、硝酸钠、水、乳化剂Span 80和油相材料对乳化炸药的热化学参数 (爆热和比容 )的影响。结果表明 :(1)硝酸铵的含量增加 ,乳化炸药的爆热和比容提高 ;硝酸钠的最佳含量为 7%~ 9% ;水的最佳含量为 9%~ 10 % ;乳化剂的最佳用量为 1.5 %~ 2 %。 (2 )油相材料的用量满足整体乳化炸药为零氧平衡即可。  相似文献   

8.
为了获得JB-9014未反应炸药的Hugoniot关系,在火炮加载平台上利用反向撞击技术对JB-9014炸药进行一维平面冲击实验。将JB-9014炸药样品作为飞片安装于弹托前表面,将镀膜氟化锂窗口作为装置靶。利用火炮加速弹托,使炸药样品以一定速度撞击镀膜氟化锂窗口,通过光子多普勒测速仪(photonic Doppler velocimetry,PDV)测量炸药样品击靶速度以及炸药/镀膜氟化锂窗口界面粒子速度。最终根据冲击波阵面守恒关系计算获得了JB-9014炸药冲击Hugoniot数据,采用正交回归直线拟合得到了炸药样品在3.1~8.2 GPa压力范围内的冲击Hugoniot关系:Ds=2.417+2.140us (Ds和us的单位均为km/s)。结果表明:该方法测试精度较高,响应时间快(小于5 ns),同时该方法可以对炸药的反应情况进行检测,便于判断实验是否测得真实的未反应炸药冲击Hugoniot数据。  相似文献   

9.
将简支梁简化为 Euler 梁,基于振动理论推导建立了用于桥梁动力响应分析的任意移动质量弹簧列模型,并通过适当的参数选取将其退化成任意移动荷载列模型,使得两类经典模型合二为一。通过计算表明:在共振车速下,质量弹簧列模型条件下的桥梁响应较荷载列模型小;而在非共振车速下,两类模型条件下的桥梁响应差别不大。此外,对高铁简支梁应用分析可知:一定条件下在32m梁上行驶的车辆长度控制在19~23m范围内较合适;且该梁的共振车速约为156m/s、52m/s、39m/s,消振车速约为134m/s、78m/s、57m/s。这在实际应用时应予以注意。  相似文献   

10.
吴平  徐世烺  李庆华  周飞  陈柏锟  蒋霄  AL MANSOUR Ahmed 《爆炸与冲击》2021,41(7):075101-1-075101-14
为研究超高韧性水泥基复合材料(ultra-high toughness cementitious composites, UHTCC)在内埋炸药爆炸下的抗爆性能和损伤破坏规律,对不同炸药埋深下的UHTCC和高强混凝土(high-strength concrete, HSC)进行了内埋炸药抗爆实验。得到了两种材料靶体的破坏状态,并利用接触爆炸的实验结果计算出了两种材料的抗爆性能参数。结果表明,在相同条件下,UHTCC抗爆性能优于高强混凝土。为了进一步探究UHTCC的抗压强度、抗拉强度以及拉伸韧性对靶体在内埋炸药下抗爆性能的影响,首先,采用改进的K&C模型对炸药埋深为40 mm的超高韧性水泥基复合材料靶体进行数值模拟,模拟结果与实验结果基本吻合,并根据数值模拟的结果得到了爆炸冲击波沿靶体径向衰减速度大于轴向衰减速度这一规律,验证了数值模型的有效性;然后,通过调整改进K&C模型中与抗压强度、抗拉强度以及拉伸韧性相关的参数,数值预测了不同抗压强度、抗拉强度以及拉伸韧性下UHTCC靶体的破坏状态,发现增强UHTCC的韧性可以有效防止靶体发生整体性破坏,增大UHTCC的抗拉强度可以减小靶体迎爆面的开坑直径,增大UHTCC的抗压强度对减小开坑直径效果不明显。  相似文献   

11.
In this study, we aimed at optimizing the parameters which govern the separation efficiency in the magnetic filtration of magnetizable dispersed particles from a water medium. Response surface methodology (RSM) was used to determine the influence of the process parameters. Also, the optimal processing conditions were determined in order to reduce the external magnetic field strength, diameter of the filter matrix elements, and filter length to a safe level. A three-level central composite design (CCRD) involving the variables, such as external magnetic field strength (148–282 kA/m), diameter of the filter elements (0.005–0.011 m), and the filter length (0.01–0.10 m) was developed for this purpose. Data obtained from the RSM was subjected to the analysis of variance (ANOVA) using a second-order polynomial equation, which provided the optimized process conditions as 298 kA/m for external magnetic field strength, 0.0015 m for diameter of the filter elements, and 0.095 m for the filter length. The separation efficiency was optimized for magnetic filtration of micron sized particles that can be magnetized in an external magnetic field and the value was found to be 97%.  相似文献   

12.
Reactive infiltration is a fast and cost-effective technique for manufacturing ceramic-matrix composites (CMCs). CMCs are used in elevated temperature applications like rocket engine casings, jet nozzles, gas turbine blades and nuclear cladding. There is an urgent need for minimizing experimental costs as well as optimizing process parameters during manufacture, so that we have minimized manufacturing costs and reduced infiltration times. Towards this end, the objective of this research was to develop an integrated micro-macro model of reactive flow of molten silicon in a porous preform consisting of carbon-coated silicon carbide fibers and then optimize process parameters computationally. The overall objective of the research was to arrive at a modified equation of Darcy's law for flow through a porous medium with the help of numerical/computational modeling. This paper deals with the flow of silicon through porous carbon at the macro level. The macro flow of silicon was integrated with an available micro model by determining the transient porosity from the micro model and using it in Darcy's law written for the macro flow of silicon. From the results of this study, we recommend suitable process parameters such as initial temperature of the solid reactant and the specific kind of reactants to be used for achieving complete infiltration. These conclusions are drawn after observation of the rate of decrease of permeability with more reaction.  相似文献   

13.
在对最优加权组合理论和高斯-牛顿法优化非线性模型参数的方法研究的基础上,依托于洒勒山滑坡的实际变形监测资料,建立了该滑坡变形预测的3个非线性预测模型:指数模型、Verhulst模型和灰色GM(1,1)模型;利用最优加权组合理论建立了洒勒山滑坡的最优加权组合预测模型,并运用高斯-牛顿法对各单一模型和组合模型的参数进行了优化。通过对比分析得出:组合模型的预测精度高于任何单一模型的预测精度;参数优化后各单一模型的预测精度都有不同程度的提高;参数优化后的组合模型预测精度是最高的。因此,综合运用最优组合理论和高斯-牛顿法处理滑坡预测预报模型,是提高滑坡预测预报精度的行之有效的方法。  相似文献   

14.
An experimental study on pulsating turbulent flow of sand-water suspension was carried out. The objective was to investigate the effect of pulsating flow parameters, such as, frequency and amplitude on the critical velocity, the pressure drop per unit length of pipeline and hence the energy requirements for hydraulic transportation of a unit mass of solids. The apparatus was constructed as a closed loop of 11.4 m length and 3.3 cm inner diameter of steel tubing. Solid volumetric concentrations of up to 20% were used in turbulent flow at a mean Reynolds number of 33,000–82,000. Pulsation was generated using compressed air in a controlled pulsation unit. Frequencies of 0.1–1.0 Hz and amplitude ratios of up to 30% were used. Instantaneous pressure drop and flow rate curves were digitized to calculate the energy dissipation associated with pulsation. The critical velocity in pulsating flow was found to be less than that for the corresponding steady flow at the same volumetric concentration. Energy dissipation for pulsating flow was found to be a function of both frequency and amplitude of pulsation. A possible energy saving was indicated at frequencies of 0.4–0.8 Hz and moderate amplitudes ratios of less than 25%.List of symbols A cross-section area of the tube (m2) - C D drag coefficient of sand particles - C v volumetric concentration (%) - D inner diameter of test-section pipe (m) - F frequency (Hz) - f friction factor - g gravitational constant (m/s2) - J energy dissipation of suspension (W/m)/(kg/s) - J p energy dissipation of pulsating suspension (W/m)/(kg/s) - J s energy dissipation of steady component of suspension (W/m)/(kg/s) - J w energy dissipation of pure water (W/m)/(kg/s) - L length of test-section (m) - m mass flow rate (kg/s) - P pressure drop in test-section (N/m2) - S specific gravity of sand - V instantaneous flow velocity (m/s) - V c steady flow critical velocity (m/s) - V cp pulsating flow critical velocity (m/s) - V F settling velocity of particles (m/s) - V s steady component of mean flow velocity (m/s) - dynamic viscosity (g/cm sec) - m mean density of suspension (kg/m3) - angular velocity (rad/sec) - amplitude ratio (V — V s)/V - nondimentional factor equal to - nondimentional factor equal to (VV s/V - NI nondimentional factor equal to (V 2C d/g D(S – 1)) - Re Reynolds number (V 2C d/C v g D(S – 1))  相似文献   

15.
薛创  宁成  彭先觉 《爆炸与冲击》2023,43(5):150-157
金属丝电爆炸包含丰富的物理内容,近年来国内的实验和理论研究取得了重要进展,理解该过程有助于完善Z箍缩及磁加载等离子体动力学过程的物理建模,校验物性参数。在自相似运动假设条件下,发展了冷启动计算的水中电爆炸丝零维动力学模型。从一维磁流体模型出发,推导了描述丝等离子体膨胀的零维动能方程和内能方程,采用实际气体状态方程和修正的李-莫尔电导率参数作为封闭条件,根据质量守恒及水中激波雨贡纽关系式获得了丝等离子体的边界条件。应用于水中铜丝电爆炸动力学过程和能量转化分析,结果表明:该零维模型的物理假设合理,在一定范围内改变丝直径等参数可产生不同的放电模式,与一维模型及实验结果符合较好,能够为同类实验的优化设计和数据分析提供参考。  相似文献   

16.
Topologically optimized granular-solid structures from additive manufacturing processes have impending applications as lightweight load bearing structures. To facilitate application, a procedure for characterizing optimal structural performance is devised for the design optimization of ‘end-use’ functional structures. An approach capable of realizing this objective is presented and demonstrated for horizontal prismatic beams produced from Nylon-12 granular-solid polymer, by Selective Laser Sintering (SLS). It combines topology (or layout) optimization, calibration of material parameters, and finite element (FE) modelling. The metamorphic development (MD) method forms the basis of an adaptive growth and degeneration optimization by material distribution approach. Experimental measurements are used to calibrate a bimodulus constitutive Drucker–Prager (D–P) model. Simply-supported three-point bending (3PB) tests are used to assess the fidelity of optimized beams on the basis of numerically predicted performance.  相似文献   

17.
强爆炸冲击波作用下天线结构的离散变量优化设计   总被引:1,自引:0,他引:1  
王晨曦 《爆炸与冲击》2003,23(4):313-317
首先建立了强爆炸冲击波作用下天线结构受精度和应力约束的连续变量优化设计数学模型 ;其次 ,根据材料特点 ,将设计变量取为离散变量 ,提出了天线结构在强爆炸冲击波作用下受精度和应力约束的离散变量优化设计数学模型。采用离散变量优化算法离散复合形法 ,对强爆炸冲击波作用下的 8m天线进行了优化计算。结果表明 ,经优化设计后 ,天线重量仅为初始重量的 4 0 %。  相似文献   

18.
提出了一种采用菱形连杆组件作为负刚度机构的准零刚度隔振器(下文简称菱形准零刚度隔振器)。通过静力学分析方法,建立了菱形准零刚度隔振器数学模型,并与其他调节变量较少的隔振器模型进行了对比;以被测量曲线在隔振器平衡位置处的曲率作为评价参数,研究了负刚度机构几何参数对系统刚度、阻尼非线性的影响,推导了利用几何参数进行隔振优化的条件;采用谐波平衡法求解系统动力学方程,对隔振器在不同几何参数下的隔振性能进行了分析。结果表明:菱形准零刚度隔振器具有体积相对较小且非线性调节能力较好的特点,可通过调节杆长,或满足相关临界值条件时调节杆长偏差量(下文简称杆长差)对刚度及阻尼非线性特征进行优化;刚度与阻尼的非线性优化方向不同,但通常情况下,刚度非线性因素对隔振优化起主导作用;归一化振动相对位移小于0.1时,由刚度曲线曲率得到的临界值可以较好地作为杆长差参数的隔振优化调节依据。本文提出的非线性评价方法与几何非线性优化临界值计算方法,对于类似隔振器研究和设计具有一定的指导意义。  相似文献   

19.
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