粒状发射药动态破碎研究进展

综述了落锤冲击试验、空气炮试验、分离式霍普金森压杆试验和动态挤压物理仿真试验等在发射药动态破碎研究中的应用状况,介绍了破碎度法、动态活度比法和燃烧渐增因子法等发射药破碎程度的描述方法,并提出建议:在冲击载荷条件下发射药床不同位置药粒的受力特点以及药粒的本构模型和破碎模型还需进一步研究,为描述发射过程中发射药破碎规律提供理论基础。     

基于燃气生成速率比的发射药破碎程度 定量表征方法

为定量表征发射药的破碎程度，引入了燃气生成速率比的概念。通过理论推导,得出燃气生成速率比即为破碎发射装药与相应未破碎发射装药的燃烧表面积比。提出采用破碎发射药燃烧前期的燃气生成速率比的平均值来定量表征发射药的破碎程度。对标准发射药、大块发射药、小块发射药和粉末发射药进行了密闭爆发器试验，获得了不同发射药的p-t曲线，数据处理得到不同发射药破碎程度的量化值。结果表明，基于燃气生成速率比的发射药破碎程度定量表征方法是可行的。     

高能发射药动态力学强度的影响因素研究?

对19孔的高能发射药进行落锤撞击试验,观测药粒撞击损伤状态以及F-t曲线,研究药粒受力方向、撞击能以及温度等对高能发射药动态力学强度的影响。结果表明,改变受力方向,裂纹和破碎均在沿发射药的轴线方向上出现,表明发射药力学强度的各向异性;因为受径向撞击作用时,发射药粒易于破碎,故装药设计时,可使发射药的主要受力方向为轴向排布,可有效防止发射药的撞击破碎。随着撞击能提高,发射药的损伤百分数增加,F-t曲线上峰值逐渐增大,增大的幅度不断减小。随着温度升高,F-t曲线峰值由25.0 k N降为5.8 k N,脉宽由1.6 ms增加至5.1 ms,发射药的响应情况由脆性断裂逐渐转变为塑性形变。     

基于PVDF压电薄膜的大口径火炮弹底发射装药挤压应力测试方法

发射环境下弹底发射装药承受的挤压应力和挤压破碎过程是发射装药发射安全性的依据。基于发射装药膛内燃烧与力学环境试验装置和PVDF压电薄膜,本文建立了大口径火炮弹底发射装药挤压应力PVDF传感器测试方法,并首次用该方法试验获得了自然温度和低温条件下的某大口径火炮弹底发射装药挤压应力时间历程,试验结果表明,本文方法满足大口径火炮大面积弹底压力测试要求,为发射装药发射安全性研究提供了新的测试手段。     

两级多锥内通道圆锥破碎机

两级锥体内通道破碎机是在破碎腔中设置多个破碎内锥体，它包括动力装置，传动装置，破碎体，破碎采用静压力破碎原理，使物料在破碎腔内以静压力，小能量多次挤压破碎，利用离心力排料，具有过载保护和粒度调节功能。     

无壳弹发射药燃烧特性研究

本文采用密闭爆发器测试无壳弹发射药药柱的P-T曲线,经过数据分析处理得到四点平均压力陡度,以此描述无壳弹发射药药柱的燃烧规律--破碎燃烧,并进一步证明不同点火压力下,无壳弹发射药药柱燃烧呈一致性的规律.     

三基发射药单螺杆压伸模具流场仿真及实验验证

为了实现三基发射药生产工艺中的连续化压伸,同时避免模具内部螺旋状流道造成的三基发射药成型的质量和安全问题,应用ANSYS软件模拟了发射药物料在模具内的挤压过程及模针的受力情况。分析了收缩角、出料方向和模具结构对物料在模具中的温度、模具壁面压力、模针表面受力和物料出料速度分布的影响规律,并通过实验进行了验证。结果表明:模具收缩角越大,模具内压力越大,物料温度也越高,且越容易形成热点,同时模针外表面受到的挤压力和摩擦力也越大,模针越容易出现变形和断裂;竖直挤出过程中,模具壁面压力及模针受力均远大于水平挤出中的相应参数,且容易造成挤出后物料的弯曲;增加多孔板有利于物料在挤出模具中的整流和取向,大幅减少物料的径向流动,降低模针在挤出过程中的受力,且成型质量更好。     

发射药落锤撞击试验及评价方法研究

提出了一种新的评价高能发射药动态力学强度的方法,即采用落锤撞击发射药粒,用药粒发生临界损伤时的撞击能和极限抗冲应力来表征发射药的动态力学性能。结果表明,该方法能够定量评价发射药的动态力学强度,并得到太根药、硝胺药、硝基胍药等3种发射药的临界撞击能分别为18.8 J/cm2、14.2 J/cm2、3.8 J/cm2,极限抗冲应力分别为247.2 MPa、214.2 MPa、118.5 MPa。     

七孔变燃速发射药内孔位置对燃烧性能的影响

为研究内孔位置对七孔变燃速发射药燃气生成规律的影响,推导了不同弧厚七孔变燃速发射药的形状函数和燃气生成猛度,利用maple软件对不同内孔位置的七孔变燃速发射药进行了数值计算。计算结果表明,内孔位置影响七孔变燃速发射药的燃烧性能。缓燃层燃烧结束后,外弧等于内弧时,发射药的燃烧渐增性最好;周围六孔的位置靠内或者靠外,导致外弧和内弧不相等,当两者相差较大时,都会使减面燃烧时间提前,影响发射药的渐增性。     

七孔变燃速发射药参数对燃烧性能影响的研究

为研究七孔变燃速发射药燃气生成规律,推导了七孔变燃速发射药的形状函数和燃气生成猛度,利用Maple软件七孔变燃速发射药进行了数值计算。分析了发射药大小、内外层燃速比与缓燃层厚度和内外层密度比对七孔变燃速发射药燃烧渐增性的影响。结果表明:内孔孔径d0=0.2~0.22mm、特殊七孔发射药的外径D1=5~5.5mm,同时燃速比大、缓燃层密度小的七孔变燃速发射药有较好的燃烧渐增性。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。