不确定性信息条件下系统可靠性分析

在系统可靠性分析中,参数不确定性的正确表达是评价系统稳定与否的先决条件。然而,在实际情况中,影响系统可靠性的参数分布往往缺乏严格的规律性,即便参数大体符合某种分布,也存在漂移现象,采用传统方法处理这类不确定性,存在信息丢失问题。为此引入概率盒理论,提出一种新的不确定性信息条件下系统可靠性分析方法。首先对各个不确定参数进行概率盒建模;其次,将各参数概率盒等信度离散,结合系统可靠性方程计算笛卡尔积,进而得到系统可靠性概率盒模型;最后,以零点为边界划分出风险区和稳定区,并通过积分计算面积定量地分析系统的可靠性。实验以悬臂梁系统为分析对象,与传统方法进行对比分析,实验结果表明,该方法不仅有效而且提高了准确性。

System reliability analysis under uncertain information

In system stability analysis, a correct expression of the uncertain parameters is a prerequisite for stability evaluation. However, the parameter distribution that affects system reliability often lacks strict regularity in engineering. Even the parameters generally obey a certain distribution, they always drift. Information loss is another concern when traditional methods are used to deal with such uncertainties. Therefore, a new method to conduct system reliability analysis under uncertain information is proposed by introducing probability box theory. Firstly, the probability box is used to model uncertain parameters. Secondly, the probability box model of system reliability is obtained by discretizing each parameter into equally confidence levels and calculating Cartesian product with the system reliability equation. Finally, the risk zone and the stable zone are divided with zero as boundary, and the system reliability is quantitatively analyzed by integral calculating the area of probability box. The cantilever beam system is analyzed in the experiments. Experimental results demonstrate that the proposed method is effective, and can also improve the accuracy compared with other related approaches.