Influence Factors in Measuring Mode I Delamination Resistance of High Strength Type CFRP

High strength type CFRP has low delamination resistance, although it has high mechanical properties. In this low delamination resistance, an opening mode (mode I) delamination crack growth resistance is the most important because this mode shows relatively lower resistance and usually occurs in actual structures. Recently, the energy release rate concept has been applied to estimate this mode I delamination resistance. Various test methods have been proposed to measure it using double cantilever beam test specimens. The test method, however, has not been established yet and the micromechanism of delamination is still unknown. In this study, therefore, various factors affecting the testing, such as large deformation of beam, jig and loading rate, are discussed based on a beam theory and the experiments of mode I delamination resistance using high strength type CFRP (T-400/epoxy). The results obtained are as follows. (1) It was reconfirmed that the effects of large deflection and jig are negligible under the condition of low deflection value (0.1