A study on stress-corrosion cracking of GFRP (evaluation of fiber/interfacial strength considering the degradation of constituents)

摘要

The single fiber fragmentation tests were carried out to examine the degradation process of GFRP under an acid stress environment. The model composite consisting of single C-glass fiber and vinylester matrix resin was loaded and immersed in distilled water. From the in-situ observation of the fragmentation phenomenon, it was difficult to neglect the interfacial debonding generated with fiber fracture for the immersed specimens. Thus, in order to estimate the fiber strength and the interfacial shear strength properly, two points were considered in the data reduction process. First, the fragmentation stress analysis based on Cox's shear-lag model including partially debonded interface was adapted. Second, the effects of expansion strain due to the water absorption and the constant loading were corrected. As a result, it was found that the interfacial debonding due to water diffusion more significantly affect the interfacial shear stress value than the matrix modulus deterioration. Using the corrected model, more proper value of the fiber strength and the interfacial shear strength were obtained than that under the model which assumed perfect bond condition. Present results showed that the water absorption determined the absolute strengths and the constant loading accelerated the degradation.