Test research on fatigue crack propagation law in aluminum alloy 7B04-T6 under flight-by-flight spectrum

In order to educe the fatigue crack propagation law under flight-by-flight spectrum, several experiments on CCT specimen made from aluminum alloy 7B04-T6 were tested under constant amplitude spectrum of two kinds of stress ratio and three kinds of flight-by-flight spectrum. The study educes parameters in Paris equation of stable crack growth range under constant amplitude spectrum. According to Paris equation the study educes fitting parameters of stable crack growth range under flight-by-flight spectrum in which the unit is block. The results indicate that the constant n in Paris equation under flight-by-flight spectrum is related to spectral intensity obviously which can reflects the spectral intensity of flight-by-flight spectrum.