典型机身框地板梁缘条裂纹修理损伤容限分析

采用简单有效的方法对复杂的飞机结构进行损伤容限评定具有重要的意义,提出一种简单有效的应力强度因子获取方法,并结合损伤容限分析的一般流程,分析某机身框地板梁缘条含裂纹修补结构的疲劳寿命及使用寿命期内结构的剩余强度。根据机身框地板梁结构受载特点建立简化的分析模型,计算单位载荷时不同长度下裂纹尖端应力强度因子,再由结构边界载荷与应力强度因子的关系确定无量纲应力强度因子;根据损伤容限分析方法编制程序,计算结构在飞行载荷谱下从初始裂纹扩展到临界长度的寿命及各裂纹长度下结构的剩余强度,给出结构检查间隔。结果表明:结构修补后的疲劳寿命及剩余强度均满足损伤容限设计要求。本文给出的损伤容限分析过程及方法可应用于工程中类似结构的损伤容限评定。

Damage tolerance analysis for crack repair of fuselage floor beam

The purpose of this paper is to find a simple and effective method to evaluate the damage tolerance of complex structure. Aiming at the problem of evaluating fatigue life of complex structure repaired in aviation engineering, a simple and effective method was put forward to obtain the stress intensity factor. Combined with damage tolerance analysis method, the fatigue life and the residual strength of the repaired structure with cracks in the flange of a frame floor of a frame are analyzed. A simplified analysis model is built according to the loading characteristics of fuselage floor beam structure, the stress intensity factor of crack tip under different crack length was calculated, and then the dimensionless stress intensity factor is determined by the relationship between structural boundary load and stress intensity factor. According to the damage tolerance analysis method program, the lifetime of the structure from the initial crack to the critical length and the residual strength of the structure under the length of each crack are calculated. The analysis shows that the fatigue life and residual strength of repaired structures meet the design requirements of damage tolerance. The damage tolerance analysis procedure and method presented in this paper can be applied to evaluate the damage tolerance of similar structures in engineering.