Experimental Investigation of the Effects of Fluid Loading on Flexural Waves in Plates.
NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF
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An experimental investigation was conducted of the effects of fluid loading on axially symmetric flexural waves in a circular aluminum plate 25 in. in diameter and 516 in. thick. Measurements were made of the flexural wavelength and natural frequencies with the plate in air, and with water loading on one side, over a frequency range from 20 kHz to 80 kHz. The critical coincidence frequency, that frequency at which the speed of the flexural wave equals the speed of sound in water, occurs at approximately 45 kHz. The measured flexural-wave speeds with air loading are in good agreement with theory. With water loading, the wave speed decreases, the amount of decrease increasing to approximately 14 percent below the in-air value just below the critical frequency. At the critical frequency, the wave speed appears to jump to values nearly equal to the unloaded values. Radiation patterns were obtained and when edge effects are eliminated, are in qualitative agreement with theoretical predictions for an infinite fluid-loaded plate. Author
- Electrical and Electronic Equipment