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.