飞机结构可靠性分析的若干问题

 本文提出了计算飞机结构在使用中破坏率的一组基本公式,估计了各种因素对结构可靠性的影响。本文指出,英国皇家航空研究院工程科学数据活页所建议的破坏率为10~(-7)/h量级,置信水平为95％的匹配是不合适的。对几个重要影响因素的数据处理,本文发展了新的方法,得到了若干新的结果。

SOME ASPECTS OF THE RELIABILITY ANALYSIS OF AIRCRAFT STRUCTURES

This paper briefly introduces some researches about the reliability analysis of aircraft structures plroceeding in Northwestern Polytechnical University (NPU). A set of fundamental equations with some numerical examples to compute the failure rate of aircraft structures in service is presented. It takes the factors into consideration as complete as possible.From the numerical results the influences of various factors on reliability of aircraft structures are estimated and the current criteria of aircraft fatigue design are evaluated. It is also pointed out that the 10-7 level of failure probability (per hour) with 95% confidence recommended in Engineering Sciences Data of RAE is unreasonable.For the data treatment of some important f actors, i. e. the probability of detection, the distribution of initial length of flaw and the distribution of klc, some new methods are developed with some new results obtained. Among them are an estimation method of the parent distribution parameters of initial life from the laboratory test as well as the detection at airports with the results of incomplete life and "ultracom-plete" life, and an modified method using the F-distribution to be able to estimate simply the flaw detection probability curve. Some large samples have been tested by the authors in order to obtain more confident distribution patterns of initial crack length and of fractuer toughness, being used to evaluate the existing results in literature.