ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

4pSAa1. Estimating acoustic radiation from a Bernoulli--Euler beam using shaped polyvinylidene fluoride film.

Brian L. Scott

Scott D. Sommerfeldt

Grad. Prog. in Acoust. and Appl. Res. Lab., Penn State Univ., P.O. Box 30, State College, PA 16804

A number of methods exist for determining far-field sound radiation from structures. Among such prediction techniques are purely analytical models and use of discrete sensors placed directly on the structure or in the surrounding fluid media. Analytical methods suffer from a lack of ability to model the structure completely and adapt to unforeseen system changes. Discrete sensors on the beam may require a large number of transducers to obtain an accurate estimate of the radiation and may also suffer from aliasing problems. Far-field sensors are often not suitable due to environmental constraints. An alternative method is the use of shaped distributed sensors on the structure, which act as low-pass filters in the wave-number domain. The use of this type of sensor helps to isolate the radiating portion of the wave-number spectrum and is also beneficial in reducing the number of sensors required to avoid aliasing. This work presents numerical results of using shaped polyvinylidene fluoride (PVDF) film to predict the far-field radiated sound. These results are compared to the theoretical results and to the results obtained when discrete sensors mounted to the structure are used.