## 1aAO14. Radiation impedance of a circular vibrating plate on the surface of viscoelastic media.

### Session: Monday Morning, May 13

### Time: 11:35

**Author: Masao Kimura**

**Location: Dept. of Ocean Eng., Tokai Univ., 3-20-1 Orido, Shimizu, Shizuoka, 424 Japan**

**Abstract:**

Radiation impedance of a vibrating plate on the surface of a visco-elastic
medium such as marine sediment varies with the viscoelastic properties of the
medium. Therefore, it is possible to predict the viscoelastic properties using
the characteristics of the radiation impedance. In this paper, the
characteristics of radiation impedance of a circular vibrating plate on the
surface of viscoelastic media were obtained by numerical analysis. The results
showed that the values of ka (k is the wave number, a is the radius of a
circular vibrating plate) at which the imaginary part of the radiation impedance
becomes zero can be related to the ratio of the shear wave velocity to the
longitudinal wave velocity, that is, the Poisson's ratio. Next, measurements of
radiation impedance for three kinds of urethane rubbers and two kinds of dry
beach sands were done, and the measured values were compared to the calculated
values.

from ASA 131st Meeting, Indianapolis, May 1996