结晶特性与制造工艺对炸药件力学性能的影响

通过对塑料粘结炸药(PBX)在压制、热老化及贮存中炸药HMX、TATB和粘结剂F的性能变化规律的研究,揭示了加工和贮存条件对炸药件的力学性能的影响。得出如下结论:1)随着老化温度的提高,粘结剂F结晶度增加。TATB基PBX炸药经老化后力学性能没有明显变化,说明粘结剂结晶度和炸药颗粒度的变化对炸药总体性能影响不大。2)钢模压制的TATB基PBX药柱在经历多次温度循环后,TATB与粘结剂F界面的作用有所减弱,药柱内部产生由脱粘引起的缺陷,其力学强度下降。TATB基PBX药柱的力学强度与模量均随着环境温度的升高而呈下降趋势,而等静压成型能明显改善TATB基PBX的力学性能。     

模拟月壤微观结构形态的定量化研究新方法

针对土体的微观结构测试设备价格较高、操作相对复杂以及传统的微观结构测试主要针对单一粒组进行的缺陷,以同济一号(简称TJ-1)模拟月壤为例,介绍了一种可测定由不同粒组组成的砂样微观结构参数(如长短轴比例、粗糙度)的新方法.通过电镜扫描获取TJ-1模拟月壤不同粒组颗粒的高倍清晰照片,利用AutoCAD和MATLAB软件获取各粒组的微观结构参数.采用离散元数值试验,近似确定TJ-1模拟月壤中各粒组颗粒所受接触力占所有颗粒接触力的权重,并与各粒组形态参数的平均值相结合,采用加权平均,最终获取TJ-1模拟月壤形态参数的代表值.     

奥克托今基战斗部装药与壳体匹配关系的数值模拟

自然破片战斗部装药与壳体之间的匹配关系对破片的形成起着至关重要的作用,破片的数量直接影响战斗部的毁伤威力。本文以某HMX基浇注PBX炸药作为杀爆战斗部主装药,为研究主装药与壳体材料及厚度之间的匹配关系,建立简化缩比战斗部有限元模型,选取30CrMnSi、4340钢、45钢三种材质作为壳体材料,并设置每种壳体的厚度分别为5 mm、5.5 mm、6 mm、6.5 mm、7 mm,采用AUTODYN软件中的Stochastic随机破坏模型对自然破片战斗部的爆炸过程进行模拟。结果表明,当主装药浇注PBX炸药爆炸时,壳体厚度为6.5 mm的4340钢作产生的有效破片数量最多,为325 个,并且有效破片占破片总数的比例较优,达到43.10%;其动能大于98 J的破片数量最多,为276 个。研究结果可以为杀爆战斗部的设计提供一定理论支撑。     

Bioactive Electrospun Fibers of Poly(ε-Caprolactone) Incorporating α-Tocopherol for Food Packaging Applications

Antioxidant activity is an important feature for food contact materials such as packaging, aiming to preserve freshness and retard food spoilage. Common bioactive agents are highly susceptible to various forms of degradation; therefore, protection is required to maintain functionality and bioavailability. Poly(ε-caprolactone) (PCL), a biodegradable GRAS labeled polymer, was used in this study for encapsulation of α-tocopherol antioxidant, a major component of vitamin E, in the form of electrospun fibers. Rheological properties of the fiber forming solutions, which determine the electrospinning behavior, were correlated with the properties of electrospun fibers, e.g., morphology and surface properties. Interactions through hydrogen bonds were evidenced between the two components. These have strong effect on structuration of macromolecular chains, especially at low α-tocopherol amounts, decreasing viscosity and elastic modulus. Intra-molecular interactions in PCL strengthen at high α-tocopherol amounts due to decreased solvation, allowing good structural recovery after cease of mechanical stress. Morphologically homogeneous electrospun fibers were obtained, with ~6 μm average diameter. The obtained fibers were highly hydrophobic, with fast release in 95% ethanol as alternative simulant for fatty foods. This induced good in vitro antioxidant activity and significant in vivo reduction of microbial growth on cheese, as determined by respirometry. Therefore, the electrospun fibers from PCL entrapping α-tocopherol as bioactive agent showed potential use in food packaging materials.     

PBX-9404炸药高压反应速率方程的研究

研究了ＰＢＸ ９４０４ 炸药在高幅值冲击波加载下的化学反应速率方程。将所得高压反应速率方程与Ｊｏｈｎｓｏｎ 等的经验热点模型的低压项结合,得到ＰＢＸ ９４０４ 炸药的冲击波起爆反应速率模型。利用一维特征线程序模拟该炸药的冲击波起爆过程和爆轰波传播过程。     

基于曲率模态和神经网络的结构损伤识别与仿真

探讨用曲率模态和神经网络对混凝土结构裂缝进行损伤识别和定位的方法.以一矩形截面悬臂梁为研究对象,通过完好结构和损伤结构的有限元分析,获得损伤标识量,输入Elman神经网络进行训练,以损伤位置和损伤程度作为网络的输出参数,进行单处损伤和多处损伤的定位研究.数值仿真结果表明,曲率模态振型对结构的损伤敏感,采用曲率模态和神经网络结合的方法可以同时确定结构损伤的存在、程度和位置,并且可以用于结构多处损伤的检测.该方法对于实际工程结构的损伤识别具有一定的指导意义.     

高聚物粘接炸药失效机理与寿命评估研究综述

了解高聚物粘接炸药(polymer bonded explosive, PBX)失效机理对改善PBX老化性能、准确评估PBX寿命具有重要意义。讨论了PBX中炸药晶体、黏接剂和黏接剂-晶体界面等对PBX性能的影响,以及常见的PBX寿命预测方法。结论表明,PBX炸药晶体粒径分布影响炸药的性能释放和感度,晶体越小,分布越均匀,性能释放越好,感度越小。老化过程中由于多种作用的综合影响,感度变化不大,但炸药晶体分解深度仍是评价炸药性能的重要因素。黏接剂作为炸药的基体对PBX性能有着重要影响。黏接剂在老化过程中会发生氧化交联和降解断链,黏接剂的交联和断链是PBX力学性能变化的根本原因,氧化交联占主导时PBX变硬,变脆,降解断链占主导时,PBX变软、变黏。界面脱粘是PBX损伤的重要形式,是PBX力学性能变化的直接原因,可以通过在炸药基体中添加功能助剂可改变界面的力学性能从而提升PBX的强度。     

月壤工程地质特性综述

根据国内外的最新研究成果,综述了近年来月壤工程地质力学特性研究的新进展.首先简述了月壤的矿物特征与化学成分,分析了月壤的级配、颗粒形态与孔隙率等物理性质;然后总结了月壤的变形特性与强度特征,阐述了目前模拟月壤的主要类别,及其内摩擦角、弹性参数等力学参数的研究成果;最后指出月壤研究中存在的问题,即模拟月壤试验必须注意环境变量(如弱重力)及化学成分对于工程地质性质的影响,同时应加强对月壤动力性质方面的研究.     

Analytical procedure for the determination of Ethyl Lauroyl Arginate (LAE) to assess the kinetics and specific migration from a new antimicrobial active food packaging

Ethyl Lauroyl Arginate (LAE) is a cationic tensoactive compound, soluble in water, with a wide activity spectrum against moulds and bacteria. LAE has been incorporated as antimicrobial agent into packaging materials for food contact and these materials require to comply with the specific migration criteria. In this paper, one analytical procedure has been developed and optimized for the analysis of LAE in food simulants after the migrations tests. It consists of the formation of an ionic pair between LAE and the inorganic complex Co(SCN)₄²⁻ in aqueous solution, followed by a liquid–liquid extraction in a suitable organic solvent and further UV–Vis absorbance measurement. In order to evaluate possible interferences, the ionic pair has been also analyzed by high performance liquid chromatography with UV–Vis detection. Both procedures provided similar analytical characteristics, with linear ranges from 1.10 to 25.00 mg kg⁻¹, linearity higher than 0.9886, limits of detection and quantification of 0.33 and 1.10 mg kg⁻¹, respectively, accuracy better than 1% as relative error and precision better than 3.6% expressed as RSD. Optimization of analytical techniques, thermal and chemical stability of LAE, as well as migration kinetics of LAE from experimental active packaging are reported and discussed.     

Experimental study on the micromechanical behavior of a PBX simulant using SEM and digital image correlation method

The micro-scale mechanical behavior of a polymer-bonded explosive (PBX) simulant was experimentally studied using a scanning electron microscope (SEM) imaging system and digital image correlation (DIC) method. The semi-circular bend (SCB) test was chosen for the study. During the testing, a series of SEM images of the specimen was acquired in situ. The natural micro-structural features of the specimen were used as random speckle pattern for DIC analysis. The displacement and strain fields at the area of interest were obtained by DIC. The deformation and damage of PBX were analyzed. Heterogeneous strain fields demonstrated the damage evolution underneath the specimen surface and predicted possible micro-crack growth. Based on the contour plots of the correlation coefficient, the formation and extension of microscopic cracks were quantitatively analyzed.