Shaker Simulation of Random Vibration with a High Kurtosis Value

This paper presents a vibration test technique for extending the tails of amplitude probability distribution beyond the Gaussian values as is characteristic for vibration of ground vehicles on a rough road or terrain. The method proposed uses the commonly accepted approach of applying pseudorandom excitation in the form of a Fourier expansion. The procedure described in this paper can be implemented by updating currently available digital vibration controllers. The solution for amplitude domain fitting is based on an analytical expression derived for the kurtosis parameter of the polyharmonic process in terms of amplitudes and phase angles for any number of harmonic components. The results of theoretical analysis are embodied in software subjected to verification in computer and experimental tests. Even with additional kurtosis control, the closeness of the generated and desired spectra is the same as for the Gaussian simulation of power spectral density. Hence, this new technique for amplitude domain matching is not accompanied by the deterioration of ordinary test capabilities in the frequency domain.