建立一类挠性航天器的动力学模型及面向控制的仿真环境

对于一类具有一个中心刚体和两块对称安装的太阳帆板的挠性航天器,针对其帆板较长、弹性位移较大,导致根据文献[2]直接建立的模型不准的问题,提出将弹性帆板分段处理的方法,分别引入浮动坐标系,建立系统的动力学仿真模型。并将针对整体模型设计的控制规律作用于该模型,进行了数值仿真。仿真结果表明,对于大变形情况,分段处理的方法十分有效。     

伞盘结构对大长径比发动机药柱结构完整性的影响

为了提高大长径比发动机药柱结构完整性水平,基于三维黏弹性有限元法,计算某大长径比固体发动机在温度和内压荷载联合作用下的结构响应;研究伞盘结构及其位置对药柱最大Von Mises应变的影响规律;讨论当伞盘位于药柱中部时,伞盘最大Von Mises应变随伞盘宽度、深度以及顶部圆弧半径比的变化规律。结果表明,伞盘位于药柱中部时可以有效地降低大长径比药柱的最大Von Mises应变,增加伞盘宽度、深度或选取合适的半径比均可降低伞盘结构的最大Von Mises应变。所得结论可为固体发动机设计提供参考。     

基于SPRT的组合导航故障检测与隔离互辅算法

针对SPRT(序贯概率比检验)算法无法准确判断缓变故障结束时间的问题,提出了一种故障检测与隔离互辅算法。采用SPRT算法对滤波残差进行故障检测,确认故障后隔离故障观测量,重新建立卡尔曼滤波观测方程并完成量测更新,将隔离后的滤波结果作为下一时刻的滤波初值辅助故障检测。仿真结果表明,该方法能准确定位故障观测量并判断出故障的结束时间,提高了系统可靠性。     

一种齿轮箱振动控制方法

从机械结构的振动控制理论出发 ,提出了一种齿轮箱振动控制方法 ,研究并讨论几种齿轮箱箱体以及齿轮本体的结构参数对动态特性的影响 ,其结论可以为齿轮箱的振动设计提供参考依据     

一种基于程序域边界分析的测试方法

边界附近的点对程序故障更加敏感.针对这一特征,提出了一种基于程序域边界分析的测试方法.从被测程序本身出发,进行定义域确定及子域划分,分析定义域边界和子域边界,并跟据其边界测试点产生测试用例,以检测域边界附近的处理.实验表明对定义域边界及其子域边界进行测试,可有效地提高故障覆盖率.     

The “signature” of a coherent system and its application to comparisons among systems

Various methods and criteria for comparing coherent systems are discussed. Theoretical results are derived for comparing systems of a given order when components are assumed to have independent and identically distributed lifetimes. All comparisons rely on the representation of a system's lifetime distribution as a function of the system's “signature,” that is, as a function of the vector p= (p₁, … , p_n), where p_i is the probability that the system fails upon the occurrence of the ith component failure. Sufficient conditions are provided for the lifetime of one system to be larger than that of another system in three different senses: stochastic ordering, hazard rate ordering, and likelihood ratio ordering. Further, a new preservation theorem for hazard rate ordering is established. In the final section, the notion of system signature is used to examine a recently published conjecture regarding componentwise and systemwise redundancy. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 507–523, 1999     

无人机电磁弹射器的综合制动方法

利用直线电机实现无人机在短距离内可控地加速起飞已是固定翼无人机弹射起飞一种新的发展方向。为了使飞机分离后弹射台能在较短距离里完成制动,提出了直线电机弹射轨道末段定子实铁心涡流制动、运用Halbach永磁体阵列的涡流制动和橡胶阻尼制动等三种方式的综合方案,并分别对它们进行了分析计算。当弹射台的速度大于10m/s时,定子实铁心产生的涡流制动效果明显,当弹射台的速度低于3m/s时,定子实铁心涡流制动产生的制动力将迅速下降。Halbach永磁体阵列的涡流制动方式在飞机分离点开始实施,可以增加30%以上的制动效果。通过模型分析和碰撞试验,橡胶阻尼制动作为最后一级制动方式,能够有效吸收能量,实现在较短距离里的制动。     

防空导弹发动机的模态分析

对某型号防空导弹发动机结构的固有特性进行了较为系统的研究,分别从理论计算和试验测试２ 个方面进行了分析,并在这２ 种分析的基础上对它们进行了比较。初步确定了发动机的固有模态,为今后防空导弹发动机乃至导弹结构动力响应分析提供参考依据,为今后开展进一步的结构动力学研究提供模型基础。     

Effect of particle gradation of aluminum on the explosion field pressure and temperature of RDX-based explosives in vacuum and air atmosphere

To optimize the energy output and improve the energy utilization efficiency of an aluminized explosive, an explosion device was developed and used to investigate the detonation pressure and temperature of R1 (Al6) aluminum powder and the aluminum powder particle gradation of R2 (Al6+Al13), R3 (Al6+Al24) and R4 (Al6+Al flake) in a confined space. By using gas chromatography, quantitative analysis and calculations were carried out to analyze the gaseous detonation products. Finally, the reaction ratios of the aluminum powder and the explosion reaction equations were calculated. The results show that in a confined space, the quasi-static pressures and equilibrium temperature of the aluminum powder in air are higher than in vacuum. In vacuum, the quasi-static pressures and equilibrium temperatures of the samples in descending order are R1>R3>R4>R2 and R3>R4>R1>R2, respectively. In air, the quasi-static pressures and equilibrium temperatures of the samples in descending order are R1>R2>R4>R3 and R1>R4>R2>R3, respectively. R4 (Al6+Al flake) and R3 (Al6+Al24) have relatively higher temperatures after detonation, which shows that the particle gradation method can enhance the reaction energy output of aluminum during the initial reaction stage of the explosion and increase the reaction ratio by 10.6% and 8.0%, respectively. In air, the reaction ratio of Al6 aluminum powder can reach as high as 78.16%, and the reaction ratio is slightly reduced after particle gradation. Finally, the reaction equations of the explosives in vacuum and in air were calculated by quantitative analysis of the explosion products, which provides a powerful basis for the study of RDX-based explosive reactions.     

高超声速变形飞行器翼面变形模式分析

为提高高超声速翼身组合式飞行器的射程,研究了采用不同翼面变形模式时,飞行器在马赫数3~8内的气动特性和翼面效率。针对典型的轴对称翼身组合式外形,采用Navier-Stokes方程进行数值模拟,对伸缩、变后掠和二维折叠三种变形模式下的外形在超声速及高超声速来流条件下进行模拟,并对升阻比、翼面单位面积升阻比和操稳特性进行分析。结果表明:在超声速及高超声速范围内,变后掠变形模式在宽速域内升阻比提高明显,同时具备优良的翼面效率及操稳特性,其在马赫数3~8范围内具有最优的综合性能。研究成果能对高超声速翼身组合式变形飞行器布局设计提供参考,具有一定的指导意义。