雷管爆炸产物与破片飞散过程研究

运用高速摄像技术探究钢壳平底、凹底雷管爆炸产物与破片的飞散规律,同时对不同管壳材质的凹底雷管反转弹丸的速度变化规律进行探究。研究表明:钢壳凹底雷管爆炸产物径向运动速度大于平底雷管;钢壳凹底雷管爆炸后,其聚能穴翻转变形产生反转弹丸,反转弹丸的头部速度在尾部拉应力的作用下逐渐下降;雷管爆炸95μs后,反转弹丸头部和尾部断裂,拉应力作用消失,头部速度骤然升高达到最大值;在距离雷管底部270mm内,钢壳凹底雷管反转弹丸的头部速度为1 440m/s,铜壳为3 204m/s,铝壳为6 350m/s。     

无起爆药雷管爆炸过程研究

文中论述了无起爆药灼热桥丝式雷管的ＤＤＴ传播过程，采用黑索今为雷管装药，以装药连续爆速测试获取雷管ＤＤＴ过程信息，８＃无起爆药雷管的引爆能低于＃６有起爆药工业雷管的引爆能。     

定向战斗部破片飞散的数值模拟与试验研究

利用数值模拟方法对展开型定向战斗部的破片飞散过程进行研究,获得了破片数目和速度的分布规律,对比分析了不同展开姿态对破片飞散区域的影响特性,总结得到了最优展开姿态的取值范围,并通过静爆试验验证了数值模拟结果的准确性。研究结果验证了展开型定向战斗部具有较高的定向毁伤效能,为战斗部展开过程及二次起爆设计提供了重要的参考依据。     

钢板局部接触爆炸破片形成过程分析

对钢板进行局部接触爆炸试验,分析了钢板破坏的主要特征.在此基础上基于AutoDyn进行数值计算,剖析了破片的形成过程,计算出破片初速度并与基于金属材料临界破坏功理论估算出的破片速度进行比较.接触爆炸破坏试验和数值模拟结果验证了用绝热剪切破坏理论解释钢板接触爆炸破片的生成现象是合适的.     

金属雷管聚能射流和金属飞片防护的试验研究

为了防止地表传爆雷管对导爆管网路的破坏,提出了采用防护帽对金属雷管聚能射流和金属飞片进行防护的方法,并设计了靶痕试验法,分别对单发雷管和安装防护帽、绑扎导爆管、安装防护帽并绑扎导爆管的单发雷管进行了起爆试验。雷管爆炸后产生的聚能射流、金属飞片在靶纸上留下了大量的穿孔,通过对比分析4种工况下靶纸上穿孔的数量、大小、形状、分布范围等情况,认为防护帽能够在一定范围内破坏金属雷管的聚能射流作用,极大降低雷管轴向金属飞片破坏导爆管网路的概率,改变径向金属飞片的分布,同时发现绑扎导爆管对金属飞片也是一种防护。     

水下爆炸法销毁废雷管研究

分析了空气冲击波的危害性,利用水对爆炸能的吸收特性,设计了可行的销毁水坑和谨慎操作规程,有效地解决了爆炸噪音和飞石等危害,提供了一条安全销毁废雷管的新途径.     

轴向预制破片战斗部的设计研究

为了研究壳体厚度、炸药爆速、起爆点距离3种因素对轴向预制破片战斗部平均飞散角的综合影响,利用LS-DYNA动力有限元程序,采用Lagrange算法对轴向预制破片战斗部的加速过程进行了数值模拟.以破片平均飞散角为指标,应用正交优化方法针对3种因素对破片平均飞散角影响规律和主次关系进行了分析.结果表明,壳体厚度是主要影响因素,炸药爆速次之,起爆点距离影响最小;并得到了影响破片平均飞散角的3种因素各水平的最优组合,优化之后对应的破片平均飞散角为4.520°.     

雷管爆炸威力自动化动态测试系统研究

为自动、动态、可靠、定量地测试雷管爆炸威力,该文提出一种新测试方法,并建立了一个由测试装置、计算机、自动测试软件组成的测试系统.该系统利用雷管爆炸输出威力冲击测试装置上的旋转机构,通过测速装置对旋转机构的角速度进行实时监测,再通过自动测试软件处理实验数据,最终以冲量、冲击波峰值、冲击波作用时间等物理参数定量表征雷管输出威力,以角速度-时间曲线、冲量-时间曲线、压力-时间曲线等来描述雷管威力时间特性.实验结果表明:这种测试方法能够灵敏准确地反映雷管威力对应于装药量及装药结构的变化,系统具有良好的稳定性.     

雷管爆炸对邻近导爆管影响的试验研究

在导爆管雷管起爆网路中,传爆雷管爆炸产生的破片及金属射流易对邻近导爆管产生影响,致使网路传爆中断。对8#铝壳工业导爆管雷管爆炸对侧向及轴向不同距离导爆管的影响进行了试验研究,得到侧向导爆管可被起爆的最大间距为10 cm左右,被切断的最大间距为12 cm左右,被损伤的最大间距为15 cm以上的结论。导爆管被聚能射流击中后可能出现两种情况:被击断且被起爆,被击断未被起爆。可被起爆的最大间距在17.5 cm左右,被击断的最大间距在70 cm以内。     

爆炸冲击波与破片对RC桥的耦合毁伤研究

对地导弹成为现代桥梁的重要威胁,其战斗部对桥梁的毁伤作用包括爆炸冲击波和破片群两个方面。研究了导弹战斗部爆炸特性,采用SPH-FEM方法实现了导弹战斗部爆炸、爆炸冲击波与破片耦合毁伤RC桥的全过程仿真,分析了耦合毁伤机理,对比了不同配筋率、爆炸高度等因素对桥梁耦合毁伤效果的影响。得到了以下结论:爆炸冲击波与破片耦合作用明显,耦合作用大于单独作用之和;配筋率影响吸能模式,随着配筋率的提高,桥梁吸能模式发生改变;爆炸高度影响毁伤分布明显,对"破片场"分布也有影响。     

Auto-ignition and upper explosion limit of rich propane-air mixtures at elevated pressures

The auto-ignition limits of propane-air mixtures at elevated pressures up to 15 bar and for concentrations from 10 mol% up to 70 mol% are investigated. The experiments are performed in a closed spherical vessel with a volume of 8 dm3. The auto-ignition temperatures decrease from 300 degrees C to 250 degrees C when increasing the pressure from 1 bar to 14.5 bar. It is shown that the fuel concentration most sensitive to auto-ignition depends on initial pressure. A second series of experiments investigates the upper flammability limit of propane-air mixtures at initial temperatures up to 250 degrees C and pressures up to 30 bar near the auto-ignition area. Finally the propane auto-oxidation is modelled using several detailed kinetic reaction mechanisms and these numerical calculations are compared with the experimental results.     

Re-explosion hazard potential of solid residues and gaseous products of coal dust explosion

In the present work, solid residues and gaseous products after the initial explosion of coal dust were collected by self-made devices, respectively, and their explosiveness was further studied to assess the re-explosion hazard. The results show that the solid residue can explode again, and its explosion pressure (P_ex) and pressure rise rate ((dP/dt)_ex) both increase gradually as dust concentration and ignition energy increase, but decrease with the larger particle size. Solid residue is characterized by a lower deflagration index (K_st) than raw lignite dust, but it can produce greater severity than some raw high-rank coal dust in some cases. The gaseous products of coal dust explosion are mainly composed of CO, H₂ and CH₄, and some trace gases. The volume fraction of CO and H₂ in the gaseous products rises in proportion to the concentration of coal dust. For coal dust explosion with a concentration >200 g/m³, the gaseous products collected are flammable and have a wider explosion limit and a lower limited oxygen content. This research provides valuable information and reference for future prevention and control of secondary explosion disasters in coal mines.     

复杂环境下建(构)筑物控制爆破拆除的设计与应用

结合湖南岳阳某水泥厂厂房控制爆破拆除情况,通过爆破方案及参数的设计,介绍了炸高的选取,以及利用控制爆破多段延时起爆技术的利弊,经过科学的理论计算采取了有效的防护措施降低了爆破危害,并通过爆破测振仪TC-4850测振数据详细分析了爆破拆除过程中的振动情况,为以后相关类似实例提供了宝贵工程经验。     

Fabrication and characterisation of Al–7Si–0.35Mg/fly ash metal matrix composites processed by different stir casting routes

In the present investigation, the effect of three different stir casting routes on the structure and properties of fine fly ash particles (13 μm average particle size) reinforced Al–7Si–0.35Mg alloy composite is evaluated. Among liquid metal stir casting, compocasting (semi solid processing), modified compocasting and modified compocasting followed by squeeze casting routes evaluated, the latter has resulted in a well-dispersed and relatively agglomerate and porosity free fly ash particle dispersed composites. Interfacial reactions between the fly ash particle and the matrix leading to the formation of MgAl₂O₄ spinel and iron intermetallics are more in liquid metal stir cast composites than in compocast composites.     

Breakup of brittle deposits by supersonic air jet: The effects of varying jet and deposit characteristics

The breakup by supersonic air jet of cylindrical brittle gypsum deposits formed on tube surfaces was studied using high-speed imaging. The breakup of symmetric deposits was visualized from the front and back simultaneously, and the effects of deposit asymmetry, jet/deposit attack angle, and jet duration and frequency, were investigated. Three jet types were considered: short and long duration single pulses, and a pulsating jet. For each experiment, the time to breakup, the breakup duration, and the breakup length were measured. Results indicate that the breakup of asymmetric deposits depends on orientation, and that attack angle affects the probability of breakup and breakup length. Results also indicate that soft deposits can be broken by any jet type, while harder deposits, especially those farther from the nozzle exit, require a longer exposure time to be broken. Pulsating jets do not improve breakup effectiveness. This work has relevance to cleaning of fireside deposits formed on heat exchanger tubes in boilers.     

Evolution of corrosion products and metal release from Galvalume coatings on steel during short and long-term atmospheric exposures

Non-treated Galvalume (55% Al, 43.4% Zn and 1.6% Si by weight) coatings have been studied through a combination of surface, near surface and bulk analysis after exposure at marine conditions, and for comparison also in an urban test site and in successively more complex short-term laboratory exposures. Slightly polished Galvalume surfaces exhibit dendritic aluminum-rich areas with higher Volta potential compared with interdendritic zinc-rich areas. These effects were not observed on bare as-received surfaces due to the overall presence of aluminum oxide. As a result, preferential corrosion occurred initially in interdendritic areas. The zinc release rate followed the same time-dependence as the surface coverage of zinc-containing phases at the marine exposure condition with zinc predominantly released compared to aluminum. Short term laboratory exposures generated the same main phases as formed at marine conditions. This confirms that the evolution of corrosion products and time dependence of zinc release rates can be explained by the uniform formation of less soluble Al₂O₃, AlOOH and Al(OH)₃ compared to observed zinc-containing phases, e.g. ZnO, zinc hydroxycarbonate and zinc hydroxychloride. The same underlying mechanism is believed to operate also during exposure of Galvalume in the urban site studied.     

Quantitative hazard and risk analysis for fragments of high-explosive shells in air

A hazard and risk analysis is given for personnel from primary fragments of fast moving and variably oriented high-explosive sources with spatially distributed event probability of a single event, e.g. for conventional threat. The approach assumes scenarios with static person densities on earth's surface. The spatial initiation distribution is described with a probability density function along a curve. The density can be constructed using expert estimates, technical safety analysis of an existing fuzing system or minimal technical safety requirements for fuzing systems. Arena test data are used for dynamic point source launching conditions of representative fragments to compute the physical consequences. Hazard criteria visualize the fragment density. Vulnerability models determine the individual local risk. In addition using the person density collective risks are computed. The individual and collective risks can be compared with various risk criteria, in particular for F-N curves. In a case study the approach is applied to a fuzing system of an artillery shell. Thus the post launch safety and the overhead safety or post safe separation safety taking third party into account are assessed. In this case the hazards and risks of fragments dominate when compared to blast effects. Assessing multiple scenarios the initiation density can be assessed.     

Hysteresis and process stability in reactive high power impulse magnetron sputtering of metal oxides

In the further development of reactive sputter deposition, strategies which allow for stabilization of the transition zone between the metallic and compound modes, elimination of the process hysteresis, and increase of the deposition rate, are of particular interest. In this study, the hysteresis behavior and the characteristics of the transition zone during reactive high power impulse magnetron sputtering (HiPIMS) of Al and Ce targets in an Ar-O₂ atmosphere as a function of the pulsing frequency and the pumping speed are investigated. Comparison with reactive direct current magnetron sputtering (DCMS) reveals that HiPIMS allows for elimination/suppression of the hysteresis and a smoother transition from the metallic to the compound sputtering mode. For the experimental conditions employed in the present study, optimum behavior with respect to the hysteresis width is obtained at frequency values between 2 and 4 kHz, while HiPIMS processes with values below or above this range resemble the DCMS behavior. Al-O films are deposited using both HiPIMS and DCMS. Analysis of the film properties shows that elimination/suppression of the hysteresis in HiPIMS facilitates the growth of stoichiometric and transparent Al₂O₃ at relatively high deposition rates over a wider range of experimental conditions as compared to DCMS.     

Adsorptive separation and photocatalytic degradation of methylene blue dye on titanate nanotube powders prepared by hydrothermal process using metal Ti particles as a precursor

Titanate nanotube powders (TNTPs) with the twofold removal ability, i.e. adsorptive separation and photocatalytic degradation, are synthesized under hydrothermal conditions using metal Ti particles as a precursor in the concentrated alkaline solution, and their morphology, structure, adsorptive and photocatalytic properties are investigated. Under hydrothermal conditions, the titanate nanotubes (TNTs) with pore diameter of 3-4 nm are produced on the surface of metal Ti particles, and stacked together to form three-dimensional (3D) network with porous structure. The TNTPs synthesized in the autoclave at 130 °C for 24 h exhibits a maximum adsorption capability of about 197 mg g⁻¹ in the neutral methylene blue (MB) solution (40 mg L⁻¹) within 90 min, the adsorption process can be described by pseudo second-order kinetics model. Especially, in comparison with the adsorptive and the photocatalytic processes are performed in turn, about 50 min can be saved through synchronously utilizing the double removal ability of TNTPs when the removal ratio of MB approaches 95% in MB solution (40 mg L⁻¹) at a solid-liquid (S/L) ratio of 1:8 under ultraviolet (UV) light irradiation. These 3D TNTPs with the twofold removal properties and easier separation ability for recycling use show promising prospect for the treatment of dye pollutants from wastewaters in future industrial application.