GF/PCBT复合材料熔融连接接头失效分析的实验研究与数值模拟

为了解决高黏度热塑性树脂难以制备高强度、大尺寸纤维增强热塑性复合材料构件的问题,采用真空辅助树脂传递模塑(VARTM)工艺与热压工艺相结合的方法,以环状对苯二甲酸丁二醇酯(CBT)在催化剂作用下聚合成的聚环状对苯二甲酸丁二醇酯(PCBT)为基体,制备了纤维体积分数达70%的连续玻璃纤维(GF)/PCBT复合材料层合板及熔融连接件,并测得其力学参数。采用数值模拟方法对连接界面层数分别为1、2、3层的A、B、C型3种不同方案的GF/PCBT复合材料熔融连接接头的承载能力和失效模式进行了预测。结果表明:不同的结构设计方案对GF/PCBT复合材料接头性能的影响较大,当连接长度在一定范围内时,接头区域主要发生界面分层失效,接头处复合材料的翘曲为界面裂纹加速扩展的主要因素,C型连接方式的接头结构承载能力相比于A型连接方式有明显提高;增加C型接头连接长度,试件承载能力提高,直至接头处界面分层失效和纤维、基体失效同时发生;继续增加连接长度,纤维与基体失效将成为接头区域的主要失效模式,此时承载能力无明显提升。

Experiment research and numerical simulation on failure analysis of GF/PCBT composite fusion joints

Aiming to solve the difficult manufacture of high strength and large size fiber reinforced thermoplastic composite components using high viscosity thermoplastic resins, combined vacuum assisted resin transfer molding(VARTM) technology with hot-pressing technology, continuous glass fiber (GF) reinforced poly (cyclic butylene terephthalate)(PCBT) composite laminates and fusion joints with 70% fiber volume fraction were prepared with PCBT as matrix via polymerization of cyclic butylene terephthalate (CBT) under the action of catalyst. And the mechanical parameters were measured. The carrying capacity and failure mode of three different schemes of GF/PCBT composite fusion joints with 1, 2, 3 layers of connection interfaces (A, B, C type) were predicted by numerical simulation method. The results show that different structure design schemes have a great impact on properties of GF/PCBT composite joints. When connection length is within a certain range, the interface delamination failure is the main failure mode of bonding region and the warping of composites in joint area is the main factor accelerating the expansion of interface crack. Compared with joint A, the structure carrying capacity of joint C is obviously improved and it has been increased with the increase of the connection length of joint C until the interface delamination at joint, fiber and matrix failure occur at the same time. Continue to increase the connection length, the fiber and matrix failure will become the main failure mode of bonding region and the carrying capacity has no obvious improvement.