Fatigue crack diagnostics: A comparison of the use of the complex bicoherence and its magnitude

This paper considers the performance of a novel extension of previous methods for use in the diagnosis of cracks in structures. It concentrates on the comparison of two ways of exploiting the bicoherence as tool to detect cracks: the first method just using the magnitude of the bicoherence and the second using its real and imaginary components. This comparison is conducted using measured data from cracked and un-cracked compressor blades from an aircraft engine.