Fatigue strength of a fibre-reinforced material

Abstract The constant and variable amplitude fatigue strengths, and the tensile and compressive strengths of cfrp have been determined. Unnotched specimens of carbon/HT fibre in an epoxy matrix were used in the form of multi-ply 0 ± 45° and 90° laminates. Results of constant amplitude tests for the stress ratios +0.1, −0.5, −1.0, −1.66 and −5.0 are presented. Variable amplitude tests have been carried out using a flight-by-flight loading sequence typical for the wing root area of fighter aircraft. Calculated life and test results are compared and the influence of loading modifications examined with regard to the high and low load cycle ranges of the load spectrum. The fatigue behaviour of the composite material is compared with that of metals.