Analysis of Variable Amplitude Spectra

In Sect. 8.2 it has been shown how to separate and count cycles of equal amplitude in a complex variable amplitude (VA) spectrum. In Sect. 8.3 rules have been given to analyze these individual or blocks of cycles of equal amplitude and combine their effects. There is another method to analyze the effect of a VA spectrum that consists in calculating how many times the block of cycles can be repeated before producing fatigue failure. In other words, the VA spectrum is not decomposed in its stress amplitude content, but it is rather applied as a whole to the specimen or work piece or component. This spectrum can be representative, as it has been shown in Sect. 8.1, of an entire commercial airplane mission. Fig. 8.1, or be the 

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Analysis of the ESEEM signal can be performed either directly in the time domain, by measuring the amplitude of echo modulation, or in the frequency domain, after numerical Fourier transformation of V T). Because theoretical descriptions of ESEEM " predict that the stimulated echo is modulated according to a cosine function, with t=x + T sls time variable, the real Fourier transform must be used to get the frequency spectra ... 

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