航空金属构件损伤复合材料单面贴补修复力学性能

Repair performance of damaged aircraft metal structure with one-sided composite patch

  • 摘要: 针对航空金属构件损伤碳纤维增强树脂基复合材料(CFRP)单面修补结构,研究了3种贴补修复工艺(湿铺法、预浸料法、预固化法)、复合材料补片厚度、补片长度与修复界面形貌、胶接特性、失效形式和极限载荷之间的对应关系;建立了三维有限元模型,基于三维Hashin失效准则模拟复合材料补片的层内损伤和演化过程,基于内聚力模型模拟胶层和复合材料补片的层间破坏,通过与试验和理论分析对比,验证了该有限元模型的有效性。研究结果表明:3种修补工艺具有不同的界面形貌和失效形式,湿铺法工艺的修复效果最好,是预固化法的3.3倍、预浸料法的1.3倍;随着复合材料补片厚度的增加,修补结构的极限失效载荷先增大后减小,最后趋于稳定,失效形式逐渐从复合材料补片分层崩裂、纤维断裂与胶层损伤的混合失效逐渐演化到胶层的剪切失效,得到修复效果最好的补片厚度为7层约1.05 mm;随着补片长度的增加,修补结构的极限失效载荷先增大后线性减小,胶层的损伤从接头中央和两端起始并往中间区域演化,得到修复效果最好的补片长度为80 mm。该结论为航空维修工程应用提供了良好依据和建议。

     

    Abstract: For the repair structures of aircraft metal components with one-sided carbon fiber-reinforced polymer (CFRP) patches, the tensile tests on repair specimens with different repair processes (wet lay-up, prepreg and pre-curing methods) and CFRP patch parameters were carried out. The ultimate load, failure mode and interface of the specimens were observed. The three-dimensional (3D) finite element (FE) model had been established. Based on 3D Hashin failure criteria, the damage initiation and evolution in CFRP were simulated. The damages of the adhesive layer and delamination of CFRP were simulated with cohesive zone model. The FE model was validated by experimental and theoretical analysis. The results show that the three repair processes have different interface morphology and failure modes. The wet lay-up method has the best repair effect, 3.3 times of the pre-curing method and 1.3 times of the prepreg method. With the increase of patch thickness, the ultimate load first increases, then decreases, and finally tends to be stable. The failure mode gradually evolves from patch delamination, mixed failure of fiber breakage and adhesive layer damage to adhesive layer shear failure. The best patch thickness is 7 layers, about 1.05 mm in thickness. With the increase of patch length, the ultimate load first increases and then decreases linearly. The damage of the adhesive layer starts from the center and both ends of the joint and evolves to the middle region. The best patch length is 80 mm. The results reported herein could provide useful guidance for the application of aviation maintenance engineering.

     

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