民机结构涂层腐蚀维修间隔的确定方法

Determining the corrosion maintenance interval of the structural coatings for the civil aircraft

为量化民机结构防护涂层腐蚀失效对飞机结构维修间隔制定的影响,合理制定民机维修方案,针对环境损伤条件下的飞机连接结构(外露腐蚀关键件)防护涂层体系,综合考虑防护涂层体系损伤的特点,提出利用模糊综合方法评估腐蚀损伤等级以量化损伤程度,与地面停放时间进行关联,建立了民机结构涂层腐蚀维修间隔评估模型。在模型中提出了单项指标的等级区间划分方法,确定了评判因素集合,利用G1法求解各单项指标的权重,运用岭形分布隶属函数来确定评判矩阵,将权重与评判矩阵进行线性结合求解多因子包容方程,确定涂层腐蚀维修间隔。通过实例进行模型验证,确定的维修间隔与工程文件一致,符合腐蚀动力学规律,表明了模型的有效性。模型可为民机外露关键件的涂层有效性检验、涂层腐蚀维修间隔的确定提供参考,具有很好的工程应用价值。

The purpose of this paper is to propose a fuzzy comprehensive evaluation method to quantify the degree of the corrosion damage of the protective coating in the surface of the civil aircraft structures,so as to reasonably formulate the maintenance interval and the coating effectiveness inspection for the principal exposed parts of low utilization civil aircraft.And,to achieve the purpose,first of all,the paper has introduced the typical damage forms of the protective coatings for such civilian service aircraft structures.As combined with the GB/T 1766—2008 and ISO4628 standards,the corrosion damage evaluation index system and corresponding individual rating methods can be built up.And,secondly,the G1 method can be used to solve the weight coefficient of each individual index,with the ridge distribution membership function adopted to determine the fuzzy evaluation matrix.And,in so doing,the weight and evaluation matrix can be combined linearly to solve the multi-factor included equation,with setting up of the fuzzy comprehensive evaluation model of the coating corrosion damage level.Furthermore,it can also determine the maintenance interval of the civil aircraft structure protective coating according to the equivalent accelerated relationship between the environmental spectrum period of accelerated corrosion test and the actual service life.And,finally,the effectiveness of the evaluation model has been verified by comparing the experimental results of aluminum steel connector and the aluminum titanium connector coating commonly used on the lower surface of some certain aircraft wings,with the fuzzy comprehensive evaluation result.The result of the case analysis shows that the individual damage index level of the protective coating in each cycle is basically consistent with the final fuzzy comprehensive evaluation result,whereas the maintenance interval determined by the evaluation model turns out closely consistent with the maintenance engineering documents.And,moreover,the corrosion damage of the protective coating turns out in change with the service life in accordance with the corrosion dynamics regularity.And,then,in the future,more service corrosion data of the civil aircraft can be collected for comparison with the test reliability data under the environmental spectrum so as to correct the equivalent acceleration relationship between the environmental spectrum cycle and the service life of the corrosion test for further test and adjustment of the maintenance interval of the civilian aircraft structure.