SIMULATION WITH MINIMUM EQUIPMENT OF RANDOM VIBRATION INDUCED BY COMPLEX EXCITATION.
HOUSTON UNIV TEX DEPT OF MECHANICAL ENGINEERING
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Complete simulation of random response induced in service by complex, ergodic, Gaussian excitation requires the exact reproduction of the response spectral densities at all points of the system and the cross-spectral densities between each pair of points. This in turn requires exact reproduction of the service loading. If a less-than-complete exact simulation of the response spectra at and between n system locations is acceptable, this can be accomplished using n discrete random forces. For certain types of systems previous theorization has shown that one discrete random force can be used to produce simulation which is accurate in the neighborhood of the resonance frequencies and approximate in the vicinity between resonance peaks. These systems must have light damping and widely spaced resonances so that modal coupling does not exist. The discrete random simulation force must have the appropriately shaped spectrum and must be properly located so that all modes will be excited. For systems of this type the theory shows that reproduction of the response spectral density at any one point assures reproduction of the spectral and cross-spectral densities at and between all other points. Author
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