Effect of water absorption on interaction between matrix cracking and fiber bridging for stress corrosion cracking of PMC

The effect of water on fiber bridging of polymer matrix composites (PMCs) has been studied for stress-corrosion cracking (SCC). The fiber bridging during crack propagation in the PMC was observed directly using a transparent polymer matrix. Specimens were immersed and weighed just before conducting the crack propagation test. The contribution of mechanical degradation caused by the water to the bridging was measured as a function of weight gain due to water absorption. The critical energy release rate of the matrix decreased with increase of the water absorption. The energy release rate of a bridged crack varied with the water absorption. To investigate the variation in the bridging mechanism under the water environment, we calculated the bridging stress the σ_t and the bridging contribution to crack propagation resistance ΔG based on a single-fiber bridging mechanism with the interfacial debonding length and the interfacial debonding energy. The debonding length was measured directly, and the debonding energy was obtained in a fragmentation test. The calculation showed that the increase in the interfacial debonding length influenced the fiber bridging mechanism.