Published online by Cambridge University Press: 04 July 2016
In the “Peak Amplitude” method of resonance testing the total amplitude of vibration is plotted against frequency or (frequency). The method is unreliable for systems which are heavily damped and for systems with close natural frequencies (for both of which a vector plot such as that suggested by Kennedy and Pancu should be used) but for many systems it provides a rough guide to the resonance properties. One of the principal difficulties attending the analysis of the amplitude plots is to find which part of a given peak is due to the resonant mode and which to the off-resonant vibration. In the note a method is described for analysing a peak assuming that:—
(i) only a single resonant mode is involved
(ii) the contribution to the amplitude from the off-resonant vibration is constant in the neighbourhood of the peak.