基于阈值超越概率的结构耐久性与损伤容限综合分析方法

COMBINED ANALYSIS METHOD FOR STRUCTURAL DURABILITY AND DAMAGE TOLERANCE BASED ON THRESHOLD BEYOND PROBABILITY

飞机结构耐久性分析和损伤容限分析都是以裂纹扩展分析为基础的,该文根据二者之间的内在联系,将耐久性分析与损伤容限分析进行综合考虑。该方法以损伤容限设计手册中规定的非概率初始裂纹尺寸作为阈值裂纹尺寸,根据裂纹尺寸超过阈值的概率以及耐久性分析结果确定概率损伤容限分析时的初始裂纹尺寸分布。裂纹尺寸超过阈值的概率可以通过检测数据给出,评估结果较为可靠。在概率损伤容限分析时,为了避免多重积分的计算,给出了结构安全余量的显式表达式以及一次二阶矩方法的计算公式,提高了可靠度计算效率。该文结合工程实例并与现有方法进行了对比分析,结果表明该方法是合理的、有效的。

The durability assessment and damage tolerance assessment of aircraft structure are both based on the crack propagation analysis. The combined analysis method of the durability and damage tolerance in this study is proposed on the basis of the intrinsic relationship between them. The non-probability initial crack size in the damage tolerance design handbook is adopted as the threshold value of crack size. The probability distribution of initial crack size at probability damage tolerance analysis is derived by the probability of the crack size beyond the threshold value and the results of durability analysis. The probability of crack size beyond the threshold value is given by test data. The evaluation system is proved reliable by our examples. The explicit expression of structural safe margin and formulas of the first order second moment method （FOSM） are derived at the damage tolerance analysis in order to avoid the calculation of multiple integrals, which improves the efficiency of computation. Through a comparison of our results with those yield by other method, it is concluded that the proposed method is of reasonable and efficient.