抄録
Over the past several years or so a Stress Corrosion Cracking of the FRP plant applications has been a serious problem. Under such conditions an establishment of a life prediction has been one of the great interests for a long time. A threshold property of the crack propagation, K_<ISCC>, is regarded as one of the fracture criteria for estimating life span. In this study, fracture mechanism in the threshold properties was investigated. C-glass/Vinylester composites were tested under constant load in the hydrochloric acid, sulphuric acid and water. The crack propagation behavior was depicted on the K_I-da-dt diagram. It was found that diffusion behavior of the acid solution ion into the matrix plays an important role in the process of the threshold failure. Especially, judging from the diffusion coefficient, there is a possibility that molecular of water diffuses precedent to hydrogen ion at the crack tip. As the time passes, the resin absorbs the water and this leads to a swelling of the resin. In addition, molecular of water and belated hydrogen ion corrode the C-glass fiber. Therefore it is suggested that the fracture of the C/VE systems was occurred by absorption and swelling derived from the diffusion of the water into the matrix and a changing of the stress sharing on the corroded fibers at the crack tip.
