碳纤维层合板胶接接头在湿热环境下的性能演变

Property Evolution of CFRP Laminate Adhesive Joints under Hygrothermal Environments

为了研究碳纤维复合材料(CFRP)胶接接头对汽车涂装过程中的高温高湿环境的适应性,对单搭接CFRP胶接接头进行了烘烤和加速吸湿实验,对经历不同湿热环境的胶接接头进行了剪切拉伸和正向拉伸试验,对连接强度改变及接头的失效模式演变进行了讨论,对环氧树脂与聚氨酯两种胶粘剂连接的接头对烘烤的适应性进行了比较,并研究了在搭接区域边缘增加胶瘤对提高连接强度的效果。研究结果表明:单搭接CFRP胶接接头的剪切拉伸强度远高于正向拉伸强度。烘烤处理后CFRP层合板及CFRP胶接接头的强度不但没有下降,反而有所提高。DP420环氧树脂胶比DP6330聚氨酯胶具有更好的耐烘烤性。吸湿后,CFRP胶接接头的强度、刚度以及最大断裂位移出现了减小。接头的失效模式从胶层内聚失效逐渐演变为与CFRP层合板的层间失效。在搭接区域边缘增加胶瘤能有效提高CFRP胶接接头的剪切拉伸强度。

In order to study the adaptability of CFRP adhesive joints to the high temperature and high humidity environments in the automobile painting processes,the experiments of baking and accelerated moisture absorption of single lap CFRP adhesive joints were carried out.The shear tensile and normal tensile tests of bonded joints undergoing different environmental tests were performed.The strength changes and failure mode evolution of CFRP adhesive joints were discussed under different environments.The adaptability of the joints bonded by epoxy resin and polyurethane adhesives to baking was compared,and the effects of adding spew fillet at the edge of the lap area on improving the joint strength were studied.The results show that the shear tensile strength of single lap CFRP adhesive joints is much higher than the normal tensile strength.After baking treatment,the strength of CFRP laminates and CFRP adhesive joints are increased instead of decreasing.DP420 epoxy resin adhesive has better baking resistance than that of DP6330 polyurethane adhesive.After moisture absorption,the strength,stiffness and maximum fracture displacement of CFRP adhesive joints are decreased.The failure modes of the joints are gradually evolved from the cohesive failure of the adhesive layers to the inter-laminar failure of the CFRP laminate.For single lap CFRP adhesive joints,adding a spew fillet at the edge of the lap area may effectively enhance the tensile shear strength.