1996 Volume 45 Issue 5 Pages 502-506
A damage criterion on CFRP under fatigue loading defined in terms viscoelasticity is proposed. In order to elucidate the change in viscoelastic property of CFRP composites under cyclic loading, due to matrix hardening, matrix crack, interface debonding and delamination, a series of creep tests was incorporated during monotonic tensile fatigue test. A generalized Voigt model was applied to describe the creep behavior of the damaged composites. By use of the increment of creep strain induced by internal damage growth, a damage variable was proposed in the framework of Kachanov-Ravotnov's classical damage theory. The evolution of the damage variable in relation to the maximum stress is discussed. Lemaitre-Chaboche's damage evolution equation was employed to estimate the fatigue life of composites successfully.
