Mixed Mode I/II interlaminar fracture toughness of carbon Fiber/RTM‐6 laminates manufactured by VARTM

This work investigates and compares the interlaminar fracture behavior of composites manufactured by vacuum‐assisted resin transfer molding subjected to three different temperatures (–54, 25, and 80°C) and mode ratios (25, 50, and 75%). The results indicate ductility enhancement with increasing temperature, which were confirmed by fractographic analyses. In tested specimens with 25% mode ratio, the G_I and G_II values were not greatly affected by the temperature. As the temperature and the mode ratio increases, the specimens exhibited higher G_I and G_II values compared with those measured at −54°C. In the tested specimens with 75% mode ratio, an unstable crack propagation was observed at −54°C due to brittle behavior of matrix, which is promoted by the decrease of the adhesion represented by cusps and broken fibers in SEM images. The cusps formation is less pronounced for specimens tested at 80°C and the fracture surface is flatter compared with those tested at −54 and 25°C. POLYM. COMPOS., 40:E1029–E1040, 2019. © 2018 Society of Plastics Engineers