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

4pPA7. Axisymmetric propagation modes in a liquid-filled elastic waveguide.

L. Dwynn Lafleur

F. Douglas Shields

Christopher C. Lawrenson

Natl. Ctr. for Phys. Acoust., Coliseum Dr., University, MS 38677

Using Del Grosso's theoretical treatment [V. A. Del Grosso, ``Errors in Ultrasonic Propagation Parameter Measurements. Part 4---Effect of Finite Thickness Solid Tubes Enclosing the Liquid Cylinder of Interest,'' NRL Report 6852, Naval Research Laboratory, Washington, DC (1968)] as a foundation, axisymmetric modes of progressive wave propagation in a liquid-filled elastic waveguide are studied. The waveguide system consists of a liquid cylinder surrounded by a hollow cylinder of elastic solid of arbitrary thickness. Dispersion curves and particle displacement profiles for propagating modes are calculated for several liquid/solid combinations. Modal characteristics are compared to those in the extreme cases of the rigidly bound cylinder and the empty hollow elastic cylinder. It is also shown that certain liquid/solid combinations can produce a near-plane-wave mode propagating at the intrinsic sound speed of the liquid over a range of frequencies. Experimental measurements demonstrating modal properties are presented. [Work supported by ONR.]