Method and Device for Measuring Underwater Vehicle Hull Vibration.
Patent, filed 25 Jul 91, patented 4 May 93,
DEPARTMENT OF THE NAVY WASHINGTON DC
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A method and device for measuring higher mode vibrational energy is provided. The device includes a plurality of sensors placed with uniform spacing around the circumference of a structure and a processing unit. The sensor placement may be either on the inside or the outside of a structure depending on the structure and on the experiment. In operation, signals from individual sensors, preamplified if required, are fed to processing equipment. The processing equipment performs a double Fast Fourier Transform. The first transform is done on temporal data thereby providing an output representing a frequency spectrum. The second transform is performed on simultaneous data readings from all sensor locations thereby providing an output representing a spectrum of mode numbers. The combining of these outputs provides a three-dimensional plot of amplitude versus frequency and mode number.
- Marine Engineering