Quantification of fiber strength degradation in SFC under water environment

Long-term durability of FRP under hostile environment is strongly influenced by fiber strength degradation. In this paper, the fiber strength degradation in the FRP in water under constant loading has been investigated using a single fiber composite (SFC). In order to estimate the fiber degradation due to aging in water, distributions of remaining fiber strength were obtained by fragmentation test. The remaining strength distributions have been quantified on the basis of microscopic stress corrosion cracking of initial defects on the fiber surface. Because the initial defect growth depends on the fiber stress history, increase of SFC strain in water has been also formulated. The remaining strength distribution obtained by the proposed model shows a good agreement with the experimental results. Additionally, it has been exhibited that the proposed model is available to predict increase of fiber failure caused by the fiber degradation in the SFC under constant loading in water.