Random excitation for modal testing of rotating machinery: Use of modulation technique

One of the most popular excitation methods for modal testing of rotating ma chinery is known to be the uncorrelated isotropic excitation, which require s two independent random sources with equal power for generation of a pair of uncorrelated excitation signals. In this work, a new excitation method, the modulated random excitation, is proposed such that a pair of random sig nals with equal power for modal testing of anisotropic rotors can be effect ively generated by modulating the random signal from a single random source with two harmonic carriers of a frequency with 90 degrees phase difference . The real as well as complex approaches are taken to illustrate the effect iveness of the modulation technique. Finally, digital data processing techn ique is discussed in relation to the implementation of the modulation techn ique in the discrete time domain, (C) 2000 Academic Press.