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The delamination crack growth behavior under iso-thermal and thermo-mechanical fatigue were investigated with unidirectional CF/epoxy laminates. Tests were conducted either in air or in water with double cantilever beam specimens. The crack growth tests were conducted under constant ΔK conditions at the load ratio of 0.5 with a loading frequency of 1/180 Hz. The test temperature was between 20℃ and 70℃. In air, the effect of test temperature on the crack growth behavior was not observed in the iso-thermal fatigue tests, and the crack growth rates for the thermomechanical fatigue tests were almost identical to those for the iso-thermal fatigue tests. In water, however, the crack growth rates for the iso-thermal fatigue tests were higher for lower temperature, and the rates for the thermomechanical fatigue test were almost the same value as those for the isothermal fatigue test whose test temperature was equal to that at the maximum load for the thermomechanical fatigue test. The effect of environment was not observed for the iso-thermal fatigue test at 20℃. For the iso-thermal fatigue test at 70℃ and in-phase thermo-mechanical fatigue test, however, the crack growth rates in water were lower than those in air.
