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摘要:
为了分析在不确定性元器件失效率影响条件下动态系统的失效问题,提出了满足工作时间要求的系统失效概率和满足失效概率限制的系统正常工作时间的分析方法。同时,为了研究元器件失效率对动态系统失效的影响程度,提出了元器件失效率对系统失效概率以及系统正常工作时间不确定性影响的重要性分析方法,建立了元器件失效率对系统失效概率和系统正常工作时间方差贡献的重要性测度指标。首先给出了指标求解的直接蒙特卡罗方法,然后采用基于分数矩的极大熵方法来高效估计系统失效的概率密度函数,采用乘法降维积分建立了2种重要性测度指标的高效解法。阀门控制系统和民用飞机电液舵机系统的算例结果表明所提方法的合理性和算法的高效性。
Abstract:In order to study the failure of dynamic system when the failure rates of components are uncertain, a new method is proposed to analyze the system failure probability when function time is given and function time when the threshold of failure probability is shown in system. Meanwhile, a new importance measure technique is developed to estimate the impact of components' failure rates on system failure probability and function time in dynamic system. In this paper, the Monte Carlo procedure is given to solve the proposed indices. The fractional moments-based maximum entropy method is used to obtain failure probability density function in system efficiently. An efficient technique with multiplication dimensionality reduction is developed to estimate two importance measure indices. Valve control system and civil aircraft electro-hydraulic actuator system are presented to illustrate the rationality and efficiency of the proposed method.
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表 1 阀门控制系统元器件失效率分布参数
Table 1. Distribution parameters of components' failure rates in valve control system
λi 均值/10-2 方差/10-5 λ1 4 2 λ2 2 1 λ3 1 0.5 表 2 阀门控制系统失效概率的概率密度函数特征
Table 2. Characteristics of probability density function about failure probability of valve control system
方法 μPf σPf 置信区间(95%) 计算量 MCS-KDE 0.489 3 0.045 1 [0.401 2, 0.578 0] 1×103 MaxEnt-FMD 0.489 4 0.045 6 [0.400 0, 0.578 8] 16 表 3 基于系统失效概率的元器件失效率重要性测度指标
Table 3. Importance measure indices of components' failure rates based on failure probability of system
方法 λ1 λ2 λ3 计算量 MCS 0.090 2 0.353 1 0.569 0 4×106 本文方法 0.089 8 0.354 0 0.567 1 181 表 4 阀门控制系统正常工作时间概率密度函数特征
Table 4. Characteristics of probability density function about function time of valve control system
方法 μt σt 置信区间(95%) 计算量 MCS-KDE 13.058 6 1.424 8 [10.266 0, 15.851 2] 142 172 MaxEnt-FMD 13.010 3 1.511 5 [10.047 8, 15.972 8] 2 279 表 5 基于系统正常工作时间的元器件失效率重要性测度指标
Table 5. Importance measure indices of components' failure rates based on function time of system
方法 λ1 λ2 λ3 计算量 MCS 0.060 2 0.201 2 0.786 5 2.36×108 本文方法 0.067 9 0.189 9 0.780 3 26 656 表 6 民用飞机电液舵机系统底事件失效率分布参数
Table 6. Distribution parameters of basic events' failure rates in civil aircraft electro-hydraulic actuator system
λi 均值/10-7 方差/10-14 λ1 3.5 2 λ2 2 1 λ3 3 1.5 λ4 10 5 λ5 6 5 λ6 2.5 1 表 7 民用飞机电液舵机系统失效概率的概率密度函数特征
Table 7. Characteristics of probability density function about failure probabilityof civil aircraft electro-hydraulic actuator system
方法 μPf σPf 置信区间(95%) 计算量 MCS-KDE 0.068 1 0.004 0 [0.060 3, 0.075 9] 1×105 MaxEnt-FMD 0.068 1 0.003 9 [0.060 5, 0.075 7] 31 表 8 底事件失效率重要性测度指标(t0=5 000 h)
Table 8. Importance measure indices of failure rates of basic events (t0=5 000 h)
方法 λ1 λ2 λ3 λ4 λ5 λ6 计算量 MCS 0.068 2 0.032 3 0.050 2 0.165 2 0.655 1 0.031 5 7×107 本文方法 0.065 2 0.032 6 0.048 9 0.162 9 0.651 7 0.032 0 811 表 9 民用飞机电液舵机系统正常工作时间的概率密度函数特征
Table 9. Characteristics of probability density function about function time of civil aircraft electro-hydraulic actuator system
方法 μt σt 置信区间(95%) 计算次数 MCS-KDE 3 111.78 207.21 [2 705.65, 3 517.91] 132 178 MaxEnt-FMD 3 115.26 203.46 [2 716.48, 3 514.04] 5 894 表 10 底事件失效率重要性测度指标(Pf0=0.01)
Table 10. Importance measure indices of failure rates of basic events (Pf0=0.01)
方法 λ1 λ2 λ3 λ4 λ5 λ6 计算量 MCS 0.040 8 0.031 2 0.059 2 0.145 2 0.621 1 0.031 5 5.97×109 本文方法 0.043 8 0.029 6 0.058 6 0.147 1 0.614 4 0.029 7 42 851 -
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