滚珠式推力终止装置可靠性研究

对滚珠式推力终止装置可靠性进行了分析。指出起爆管装药量是影响推力终止装置工作可靠性的关键因素。用试验确定工作状态下的起爆管极限药量。并用其评估滚珠式推力终止装置的结构可靠性,在置信度0.9时,可靠性下限为0.9999。     

正态分布环境因子的置信估计

给由两个正态随机变量之商定义的环境因子的一种简单有效的置信估计方法。     

Fault-tolerance wide voltage conversion gain DC/DC converter for more electric aircraft

In this paper, a fault-tolerance wide voltage conversion gain DC/DC converter for More Electric Aircraft (MEA) is proposed. The proposed converter consists of a basic Cuk converter module and n expandable units. By adjusting the operation state of the expandable units, the voltage conversion gain of the proposed converter could be regulated, which makes it available for wide voltage conversion applications. Especially, since mutual redundancy can be realized between the basic Cuk converter module and the expandable units, the converter can continuously work when an unpredictable fault occurs to the fault-tolerant parts of the proposed converter, which reflects the fault tolerance of the converter and significantly improves the reliability of the system. Moreover, the advantages of small input current ripple, automatic current sharing and low voltage stress are also integrated in this converter. The working principle and features of the proposed converter are mainly introduced, and an experimental prototype with 800 W output power has been manufactured to verify the practicability and availability of the proposed converter.     

A novel imprecise stochastic process model for time-variant or dynamic uncertainty quantification

This paper proposes a novel model named as “imprecise stochastic process model” to handle the dynamic uncertainty with insufficient sample information in real-world problems. In the imprecise stochastic process model, the imprecise probabilistic model rather than a precise probability distribution function is employed to characterize the uncertainty at each time point for a time-variant parameter, which provides an effective tool for problems with limited experimental samples. The linear correlation between variables at different time points for imprecise stochastic processes is described by defining the auto-correlation coefficient function and the cross-correlation coefficient function. For the convenience of analysis, this paper gives the definition of the P-box-based imprecise stochastic process and categorizes it into two classes: parameterized and non-parameterized P-box-based imprecise stochastic processes. Besides, a time-variant reliability analysis approach is developed based on the P-box-based imprecise stochastic process model, through which the interval of dynamic reliability for a structure under uncertain dynamic excitations or time-variant factors can be obtained. Finally, the effectiveness of the proposed method is verified by investigating three numerical examples.     

深海载人平台舵翼结构疲劳可靠性分析

对深海载人平台舵翼结构疲劳可靠性问题进行了研究,分析了舵翼结构的主要疲劳载荷和结构热点,提出了舵翼结构疲劳可靠性定量指标。以升降舵结构为例,建立了舵结构疲劳可靠性分析模型,给出模型中各参数的建议取值,并进行疲劳可靠性系数与疲劳寿命计算,计算表明:深海载人平台升降舵结构疲劳破坏几乎全部由水面砰击载荷导致,且采用 1.5倍强度安全系数进行设计不能满足长期服役的疲劳可靠性要求。最后,研究给出满足疲劳可靠性要求的安全系数与寿命的关系曲线,可供设计人员参考。     

东方红三号系列卫星在轨故障统计分析

迄今为止，东方红三号系列卫星累计运行时间已近30年，积累了相当可观的故障数据。文章在统计5颗卫星在轨故障信息的基础上，分析了该型卫星在轨故障随工作时间的总体变化规律，不同后果的故障和不同分系统的故障随工作时间的变化规律，以及卫星的可靠性增长。结论认为，该型早期卫星故障符合典型的浴盆曲线模型，早期故障较多，后期故障频繁；该型后期卫星同样存在早期失效，但特征不明显，除去空间干扰因素，卫星运行期间故障趋势相对平缓，卫星可靠性明显提高。     

二项串联系统可靠性经典方法精确置信限的计算及讨论

本文进一步阐述了用现有的三种不同的排序法计算二项串联系统可靠性经典的精确置信限的方法,指出了M.Lipow和J.Riley在1960年所编制的置信限表所存在的一些问题,介绍了我们所编制的程序具有精确度高且便于推广到多个元件(各元件的试验次数可不相同)的特点,发现了用现有的三种不同的排序法计算精确置信限时所存在的不合理性。我们认为,求解二项串联系统可靠性经典方法的精确置信限问题至今仍然没有解决。     

文献“Environmental Testing for Launch and Space Vehicles”[1]点评

作者根据多年的实践经验,对该文献中重要部分进行了点评,指出:空间系统的结构设计要"严格"按照环境设计来进行考核,而环境试验的目的除了筛选工艺质量之外,更重要的是验证设计载荷是否合理.文章还分别对声、振动和冲击试验中的关键步骤和内容进行了解析和说明.     

地空导弹热分离故障树可靠性数字仿真

根据导弹试验、贮存、发射和飞行中的各种故障信息，运用演绎法建立了以热分离失效为顶事件的热分离故障树（ＴＳＦＴ），并采用ＭｏｎｔｅＣａｒｌｏ方法来获取系统工作可靠度等参量。当底事件为非指数分布和非Ｍａｒｋｏｖ型分布时，或当系统的故障树规模很大时，都将是十分有效的。最后，通过仿真试验结果对一些可靠性参数进行了讨论。     

最大熵方法在系统可靠性Bayes评估中的应用

针对各种典型的系统，由单元的验后矩推导出准确的系统可靠性的验前矩，在此基础上运用最大熵准则给出了系统可靠性的验前分布的估计，进而根据系统试验数据得出系统的验后分布，运用该分布对系统的可靠性进行评估。仿真结果表明了该算法的简易性和有效性。