某型飞机外翼5—8肋损伤原因分析及修复探讨

目的 分析某型飞机外翼5—8肋油箱区结构不同程度损伤的原因，制定修复方案。方法采用受载分析、有限元仿真计算、静力试验数据分析等强度计算方法分析损伤产生的原因，采用扫描电子显微镜和光学显微镜对磨痕形貌进行观测等失效分析，对损伤结构件开展失效模式分析，根据损伤原因及失效模式制定科学简便的修复方案，同时对损伤长桁采取的修补措施进行强度校核。结果 通过对外翼油箱充压破坏理论分析、有限元仿真计算、静力试验数据反推，并结合飞机实际损伤情况，得出油箱破坏理论分析危险薄弱部位与真实破坏情况一致的结论。有限元仿真计算最危险结构部位与实际结构首先发生破坏部位吻合，可作为深入制定修复方案及推测实际加载压力的依据。通过静力试验数据反推、结构实际损伤及有限元仿真计算结论得出，外翼5—8肋结构出现损伤时油箱施加压力约0.5 MPa，针对损伤制定了更换外翼油箱内部第5—8肋损伤结构和贴补加强损伤长桁的修理方案，经结构强度校核，满足设计要求。结论 分析认为外翼5—8肋油箱区结构损伤原因为油箱压力超过设计值导致结构过载断裂，采用贴补加强修理损伤长桁和更换第5—8肋损伤结构的修复方案能够满足强度设计要求，可指导同类飞机类似结构损伤故障的原因分析和修理，提醒同类飞机维修人员在飞机维护时应关注外翼油箱压力超压问题。

Cause Analysis and Repair Discussion on Structure Damage of the Fifth to Eighth Rib Structure of an Aircraft Wing

Objective To analyze the cause of structure damage of fifth to eighth rib structure of an aircraft wing and to make a repair plan. Methods The causes of the damage were analyzed by means of load analysis, finite element simulation, static test data analysis, etc. The failure morphology of grinding crack was analyzed with SEM and optical microscope. The failure mode of the damaged structure was analyzed. Scientific and simple repair procedures were formulated based on damage cause and failure mode. The repair measures used for the damaged long truss were verified by strength. Results According to theoretical analysis, finite element simulation calculation, backstepping results of static test data and actual damage situation of aircraft, the conclusion was that the dangerous parts of the tank failure theory were in accordance with the actual damage situation. And the most dangerous structural parts of the finite element simulation were the first to be in line with the actual structure. It can be taken as the basis for formulating in-depth repair procedures and predicting the actual loading pressure. According to the backstepping results of the static test data, the conclusion of the damage check and the finite element simulation, the pressure of the tank was about 0.5 MPa when the fifth to eighth rib structure was damaged. The repair plan for replacing the damage fifth to eighth rib structure inside the fuel tank of wing was formulated. It was verified by the structure strength and the design requirement was met. Conclusion The cause of the damage of fifth to eighth ribs of an outer wing is that the fuel tank pressure is more than the design value. The repair of the damaged truss and the replacement of the damaged fifth to eighth rib structure meet the design requirement on strength. It could guide cause analysis and repair of structure damage of similar aircrafts. It reminds us that serviceman of aircraft should pay attention to the overload issue on fuel tank of the outer ring.