FATIGUE CRACK PROPAGATION BEHAVIOR OF ADHESIVELY BONDED CFRP/CFRP AND CFRP/ALUMINUM JOINTS

摘要

Fatigue tests were conducted on adhesively bonded CFRP/CFRP and CFRP/aluminum double cantilever beam (DCB) joints to investigate the effect of adherend thickness on the fatigue crack growth rate. Components of joints were unidirectional composite, aluminum plate and a filmy-type epoxy adhesive. The experimental results indicate that the increase of the CFRP or aluminum plate thickness lower the fatigue threshold value and steepens the slope in the Paris region. To elucidate the effect of adherend thickness on the fatigue crack propagation behavior, a finite element analysis conducted to investigate the mode ratio, and stress distributions near the crack tip, where the coefficient of thermal expansion mismatch between the aluminum and the CFRP plates was taken into account. The effect of adherend thickness on the crack propagation rate has been tentatively explained in terms of stress distributions near the crack tip.