### 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.]