ASA 127th Meeting M.I.T. 1994 June 6-10

2aSA11. The effects of fuzzy attachments on compressional and shear waves in a plate.

Judith L. Rochat

Victor W. Sparrow

Graduate Program in Acoust., Penn State Univ., 157 Hammond Bldg., University Park, PA 16802

Using the theory established by A. D. Pierce et al. [ASME Paper 93-WA/NCA-17 (1993)], regarding fundamental structural-acoustic idealizations for structures with fuzzy internals, the effects of fuzzy structures on different wave types are examined. In this problem, the structure that undergoes vibrations is a rectangular elastic plate mounted in an infinite baffle. On one side of the plate is a fuzzy structure, represented as a random array of point-attached spring-mass systems. The known theory explains the effect of these attachments on bending waves in the plate. In this presentation, the theory is extended to isolated compressional and shear waves and predicts that, in either case, the fuzzy structure can be modeled in the system solely by (1) an added frequency-dependent mass and (2) an added frequency-dependent damping. These results are similar to those for bending waves. [Work supported by ONR.]