Insensitive Munitions Fragment Impact Gun Testing Technology Challenges

The STANAG 4496 Ed. 1 Fragment Impact, Munitions Test Procedure, specifies a standard test of 2530±90 m s⁻¹, an alternate test of 1830±60 m s⁻¹ and a standard fragment (projectile) geometry. The standard can be challenging to achieve and has several loosely defined and undefined characteristics that can affect the test item response. In particular fragment velocity variation, projectile tilt upon impact and aimpoint variation are commonly observed challenges. Achieving 2530 m s⁻¹ consistently and cost effectively can be challenging. Additionally, there are some efforts where over testing to higher velocities are viewed as desirable. The aimpoint of impact of the fragment is chosen with the objective of obtaining the most violent reaction: one test is conducted with impact in the center of the largest presented area of energetic material and a second in the most shock sensitive region. No tolerance for aimpoint is specified, although it is shown through high rate continuum modelling that aimpoint variation can be a dominant source for IM response variation. Continuum modelling also shows fragment tilt on impact is to be a possible source for response variation and it is common to observe fragment tilts of 30° or even higher. The standard fragment is specified to be fabricated from mild, carbon steel with a Brinell Hardness (HB) less than 270. In the U.S., the fragment is often fabricated using ASTM1018 steel, which has a significant margin for mechanical properties that lay within the specification. These, as well as other gun testing issues, have significant implications to resulting IM response.     

MSIAC – Supporting the Insensitive Munitions Community

The NATO Munitions Safety Information Analysis Center (MSIAC) is a multinational collaboration that collects, stores, and analyses technical information related to Munitions Safety (MS) and Insensitive Munitions (IM). MSIAC supports its member nations through a variety of products and services. In addition to a core responsibility of addressing technical questions related to Munitions Safety posed by members, MSIAC has a diverse programme of work aimed at developing and sharing the related underpinning scientific knowledge. This is applied to support munition safety policy development and implementation. This article provides an overview of some of the current and future areas of work which MSIAC is involved in, with a focus on IM and energetic materials.     

LLM-105/CL-20基高能钝感PBX的制备与性能表征

为满足含能材料高能钝感的要求,以CL-20为主体炸药,LLM-105为钝感剂,采用溶液水悬浮法制备了LLM-105质量分数分别为10%、20%、30%的3种LLM-105/CL-20基PBX。通过扫描电子显微镜(SEM)、粉末X射线衍射仪(PXRD)和差示扫描量热仪(DSC)对样品的形貌、晶体结构和热性能进行表征,并测试其机械感度;采用EXPLO5软件计算了其爆轰参数。结果表明,LLM-105/CL-20基PBX样品呈类球形,颗粒密实,粒径约为500μm;PBX中各组分的晶体结构未发生改变;3种配方的热安定性都较好,且随着钝感剂LLM-105含量的增加,LLM-105/CL-20基PBX的热爆炸临界温度呈递增趋势;与原料CL-20相比,3种LLM-105/CL-20基PBX的特性落高分别提高了25.88、33.68、37.18 cm,摩擦爆炸概率分别下降29%、38%、45%;LLM-105质量分数为10%的LLM-105/CL-20基PBX的特性落高与PBX-9501相当,而LLM-105质量分数为20%和30%的LLM-105/CL-20基PBX分别比PBX-9501高16.6%和25.12%;理论爆速分别高381.76、279.2、82.03 m/s。3种配方LLM-105/CL-20基PBX炸药的爆轰性能明显优于PBX-9501。     

Development of a Design Methodology Against Fast Cook‐Off Threat for Insensitive Munitions

This work provides a design methodology for a typical energetic system to get Type V insensitive munition (IM) response against fast cook‐off threat. Experimental and numerical results for a generic test item filled with PBXN‐109 explosive are presented. Two key aspects of IM design against fast cook‐off threat are investigated, which are “time‐to‐reaction” and “critical ventilation area”. By dividing the problem to pre‐ignition and post‐ignition, the complexity of the problem is reduced. The first part of the study covers two‐dimensional and three‐dimensional simulations of the problem, where the generic test item is modelled using commercial CFD software (ANSYS – Fluent). The second part of the study reveals low pressure (2–10 MPa) burning characteristics of a PBXN‐109 by strand burner tests. After obtaining the pressure dependent burning rate, a conservation of mass equation is used to determine the chamber pressure using MATLAB Simulink software. Calculations are in reasonable agreement with the experimental results. Calculations are compared with the tests performed. The results are in reasonable agreement with some discrepancies of 8.9 % for time to reaction prediction and of 10.9 % for ventilation characteristics analyses. Possible reasons of these differences are discussed.     

A Flow Time Model for Melt‐Cast Insensitive Explosive Process

Diphasic flows of concentrated suspensions of melt‐cast insensitive explosives exhibit specific rheological properties. In order to limit the handling of pyrotechnical products presenting a risk with respect to the mechanical and thermal shocks, a lot of work has been undertaken for many years in the civil engineering sector. The objective of this study is to propose a predictive model of the flow time of a concentrated suspension through a nozzle located at the bottom of a tank. Similar to our industrial process, the suspension is made out of insensitive energetic materials and flows under gravity. Experimental results are compared to three models (Quemada, Krieger‐Dougherty, and Mooney) predicting the viscosity μ of a suspension as a function of the solid volume fraction ϕ, the maximum packing density ϕ_m and the viscosity μ₀ of the interstitial liquid. De Larrard's model is used to calculate ϕ_m. The value of viscosity measured for the pure liquid is close to the one predicted by the Bernoulli theorem, where liquids are considered as incompressible and inviscid. Finally, it was found that the Quemada's model gives a fair agreement between predictions and experiments.     

高性能浇注型聚氨酯弹性体的动态性能研究

通过高性能浇注型聚氨酯弹性体的合成，研究了二异氰酸酯结构、多元醇结构对浇注型聚氨酯弹性体动态性能的影响，结果表明，异氰酸酯基团含量增加，聚氨酯弹性体的硬度、撕裂强度和耐热性提高。     

PBX炸药剪切流动点火性能的实验研究

为了研究PBX炸药在完全约束加载和剪切流动加载下的点火性能,采用一级轻气炮对完全约束、剪切流动(不同开孔直径)的实验样弹进行加载,采用高速摄影记录了PBX炸药装药在冲击加载过程中的反应情况,并通过压力传感器测得了加载过程中的应力曲线。使用LS-DYNA软件对完全约束加载和剪切流动加载进行四分之一模型仿真计算,用完全约束下应力参数进行模型参数校核,使用校核的模型参数对剪切流动实验进行计算,获得了炸药在不同条件下的流动速率等参数。结果表明,炸药在剪切流动加载过程中相比于完全约束的装药更容易发生反应;剪切流动加载过程中,PBX炸药是否发生反应,不仅与剪切流动速率有关,而且还与单位时间流量有关,3 mm开孔直径单位时间流量比2 mm开孔直径增加62%。     

Energy Output of Insensitive High Explosives by measuring the detonation products

The detonation products of high explosives are dependent on pressure and also on the confinement under which the detonation reaction proceeds. To determine the detonation products of less-sensitive high explosives, such as TNT/nitroguanidine (NQ) and PBX charges with polybutadiene (PB) binder containing RDX together with or without aluminium (Al), experiments have been performed in a stainless steel chamber with a volume of 1.5 m³. These experiments were done under different ambient argon pressures up to 0.3 MPa. Gaseous reaction products were analysed by mass spectrometry and chemiluminescence analysis. Solid reaction products were analyzed measuring the carbon residue or the unreacted aluminium. It was found that the detonation products were highly dependent on the ambient pressure of argon. The most important changes of the reaction products and therefore also of the energy output were found between vacuum and atmospheric pressure of argon. With increasing pressure, H₂ and CO decrease and CO₂, H₂O, C_s, NH₃, HCN and CH₄ increase together with the reaction enthalpy. By analysing the physical structure of the carbon residue, diamonds have been observed between 4 nm and 7 nm in diameter.     

Estimations of Vapor Pressures by Thermogravimetric Analysis of the Insensitive Munitions IMX‐101, IMX‐104, and Individual Components

We have calculated the vapor pressures of the new explosives ordnances IMX‐101 and IMX‐104 and their respective components, 2,4‐dinitroanisole (DNAN), nitroguanidine (NQ), nitrotriazolone (NTO), and hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) by the method of rising temperature thermogravimetric analysis. Clausius‐Clapeyron relationships were assumed for each case and the vapor pressures were estimated from the Langmuir equation over an appropriate temperature range just below substance melting/decomposition points. For vapor pressures extrapolated to room temperature, the rank with respect to decreasing volatility was found to be: DNAN>IMX‐104>IMX‐101>NQ>RDX>NTO. Interestingly, vapor pressure depression is observed in IMX formulations, where the formulation has a lower vapor pressure than its most volatile component, DNAN. The enthalpy of sublimation was determined for each substance and formulation from Clausius‐Clapeyron equations generated by analysis of the thermogravimetric data. The general trends in vapor pressures and sublimation enthalpies associated with the component materials were in good agreement with previous experimental and computational results. The results obtained by this study have importance for future investigations of IMX, specifically for chemical detection and assessment of environmental fate.     

Calibration and uncertainty quantification for Davis Equation of State models for the High Explosive PBX 9501 products

This paper investigates the uncertainty in the parameters used in the calibration of an Davis Equation Of State (EOS) for the detonation products of the High Explosive PBX 9501. The procedure sought to make use of all available information about this HE to inform the best set of calibration parameters as well as the uncertainty in these parameters. The procedure made use of historical experimental data, the results from thermo-chemical modeling as well as data on the best isentrope function fit to cylinder test experimental data. Combining all these heterogeneous data sources together in a Bayesian calibration, yielded a posterior mean and covariance. Sampling from the posterior distribution and evaluating an important Quantity Of Interest (QOI) in the EOS model, the detonation speed of a one-inch rate stick, produced a distribution which showed variations which were in agreement with experiments. The uncertainty in the EOS was reported as eleven sets of model calibrations which spanned the range of this QOI.     

轧辊用合金铸钢热疲劳性能的研究

文章主要研究贝氏体和铬系合金铸钢轧辊材料的热疲劳抗力及其裂纹的萌生和扩展,在相同条件下,对比不同成分及热处理工艺的热疲劳性能,确立最优成分及最佳热处理工艺,从而提高轧辊的使用性能。     

用于隧道高性能填充砂浆性能研究

为了向隧道盾构、城市管道和煤矿回填等实际工程提供性能优越、经济环保的高性能填充材料,本文通过正交试验,以凝结时间、泌水率、稠度、流动性和抗压强度为性能指标,探讨了胶凝材料、减水剂、膨胀材料和水胶比等因素对水泥填充砂浆的各项性能的影响,得出优化配比.     

高硅铸铝合金镀前浸锌液

针对高硅铸铝件在组成，组织与性能上的特点，研究了8种高硅铝合金镀前浸锌液。用扫描电镜（SEM）观察了8种不同的浸锌液配方浸锌的试片的表面浸锌膜的微观形貌，测定了浸锌后镀镍层与试片的结合力，优选了能获得良好结合力的最佳浸锌液配方。并研究了随浸锌时间的增加，锌晶核的析出与成长的过程，结果表明，当氢氧化钠140g/L，氧化锌14～20g/L、氯化镍1.5g/L时，试片镀镍后结合力良好。发现浸锌液能够溶解铝合金部分组织，并在铝表面造成孔洞，这种孔洞对镀层起着锚链作用，铝合金表面孔洞的均匀分散以及细小锌晶粒的高度弥散是得到良好结合力的前提。     

Polymer Binder for High Performance Explosives

An evaluation on coating HMX crystals with three different polymeric binders using the “solvent slurry process” was conducted. Three polymers employed were:

• – a thermoplastic copolymer [Kel-F 3700],
• – a thermoplastic elastomer [kraton-G 1650] and
• – a polyurethane [Impranil DLH].

Kel-F 3700 presented an electrostatic hazard and was too insoluble for application by the slurry process. Kraton-G 1650 presented a similar electrostatic hazard and its process yield was low. Impranil DLH produced a high yield using the batch slurry process.     

活性染料HE-7B红的液相色谱分离

采用65％甲醇/水为流动相,四丁基溴化铵为对离子,三乙胺为调节剂,确定了活性染料HE-7B红的液相色谱分离条件,并对流动相的选择以及不同色谱柱的分离效果进行了对比和分析。所确定的分离分析条件对于活性染料HE-7B红的定性鉴定和定量分析具有实际应用价值。     

汽车面漆用高性能颜料

对汽车面漆用颜料的性能要求、主要类型及当前汽车面涂中推荐和使用的颜料作了介绍.     

锂离子电池用高性能五氧化二钒

在180℃水热条件下制备了钒氧化物,再通过煅烧前驱物VO2制备了微纳结构的五氧化二钒正极材料.通过X射线衍射、扫描电子显微镜、红外光谱等对样品的形貌、组成等进行表征.以合成的长方柱状V2O5作为锂离子电池的正极材料,测试了其充放电性能.结果表明:合成的V2O5为均匀的长方柱状结构,尺寸介于微米、纳米尺寸之间,对材料的结...     

适用于重防腐体系的高性能水性涂料

介绍了适用于重防腐的水性丙烯酸系列、水性环氧系列及水性无机硅酸锌三种水性涂料的加速测试结果和现场实际应用的经验,用大量的数据表明高性能水性涂料可以用于重防腐.     

高效液相色谱法同时测定牙膏中的维生素B_2、维生素B_3和维生素B_6

建立了同时测定牙膏中维生素B_2、维生素B_3和维生素B_6的检测方法。样品经水分散溶解后,用丙酮沉淀杂质,采用Waters T3色谱柱分离,HPLC测定,实验优化了沉淀剂的选择及用量等条件。结果表明,待测维生素在各自浓度范围内线性良好,相关系数均大于0.999,方法检出限在0.60~1.20 mg/kg之间,在高中低三个添加水平的平均回收率为95.0%~103.7%,相对标准偏差为1.67%~6.96%。该方法具有前处理简单、定量准确、灵敏快速的特点,适用于牙膏中维生素B_2、维生素B_3和维生素B_6的定量分析检测。