复杂产品可靠性评定中的矩拟合法

Moment Conversion Method for Reliability Evaluation of Very Expensive System

利用数理统计原理针对复杂产品，提出了一种适用于其可靠性评定的矩拟合法。该方法是将部件和分系统试验数据折合成系统的试验数据，作为系统试验的验前信息，从而由二项式分布求任意置信度下的系统可靠度下限。计算方法简单，适用于复杂产品的可靠性评定。

In marine engineering projects in China, we encounter rellability proolem of systemsthat are too expensive to be tested more than once or twice. We have to evaluate the reliability through evaluating its subsystems and the components of subsystems'We find that moment conversion method is an effective tool for our purpose. Using thismethod, we derive three key equations:eqs. (10), (11), and (20). We use eqs. (10) and(11) to convert test data of components and subsystems into equivalent test data for the totalsyStem. Then we use eq. (20) to compute the reliability of the total system for any givenconfidence level.We present an illustrative example. A total system composed of 16 suosystems is givenin Table 1, where m and fi represent respectively the number of tests and number of failures.Then we use eqs. (10), (11) and (20) to compute reliability and list the reliabilities in Table2. It can be seen that as a (confidence level) varies from 0. 2 to 0.9, R.(lower limit of reliability) varies slowly and smoothly from 0. 858 8 to 0. 800 0. The slow and smooth variationof RL with a indicate that our proposed method is promising for evaluating very expensivesystems