Effect of Processing and Loading Conditions upon the Fatigue Behaviour of a Cf/Epoxy Laminate

Abstract

The current work reports on the tensile and fatigue behaviour of an autoclave-cured unidirectional carbon fibre reinforced epoxy-matrix laminate. The macromechanical properties of the composite are established under interrupted and uninterrupted, static and dynamic conditions at a maximum strain below the critical fatigue limit of the matrix material. The established S-N curve was used to calculate the endurance fatigue limit of the laminate as well as to record an increase in fatigue life of specimens tested at load levels lower than two standard deviations below the mean static strength of the material. The failure modes exhibited by the composite under all testing conditions were recorded and interpreted by means of the damage mechanisms that originate them. The results of interrupted testing showed that the combined effect of fatigue and residence at high stress levels for prolonged periods of time - conditions that simulate a realistic loading scheme- trigger premature fibre failure and thus specimen failure.