Hygrothermal effects on translaminar fracture toughness of quasi-isotropic laminates with different stacking sequences

Hygrothermal effects on the translaminar fracture toughness of the carbon/epoxy composite with two different stacking sequences at 120 °C were studied and the failure mechanisms are explained. The eccentrically loaded single-edge-notch tension (ESET) experiments showed that two different quasi-isotropic stacking sequences ([90/45/0/-45]_4s and [45/90/-45/0]_4s) have negligible difference in translaminar fracture toughness. It was found that the fracture toughness of conditioned specimens at hot temperature wet (HTW) condition increased by 75 % compared to that at room temperature dry (RTD). The average saturated damage height at HTW increased by 48 % compared with that at RTD according to ex situ X-ray computed tomography (CT) observation. The larger saturated damage height observed in the 0° plies of the HTW specimens results in the higher translaminar fracture toughness.