Fatigue load ratio and load amplitude effect on crack propagation under mode I loading

Load ratio effect on fatigue crack propagation is explored on a carbon/epoxy composite material. The fatigue load could be better represented by their amplitude instead of their maximum value. Cumulative damage is then investigated by achieving consecutive fatigue tests on the same specimen. Consequences on the crack growth rate are highlighted. It is shown that the fatigue pre-crack length, as well as the building method of the fatigue pre-crack plays an important role in the fatigue crack propagation rate.