ANALYSIS OF LIQUID-CORE CYLINDRICAL ACOUSTIC WAVE-GUIDES EMBEDDED IN SOLID MEDIA

The propagation of elastic waves in liquid-core cylindrical acoustic w aveguides is studied. The model analyzed represents a liquid-filled tu be embedded inside a solid medium. The frequency equations are derived , and expressions for the displacement components and stress component s are presented. Phase velocities of wave motions at low-frequency and high-frequency limits and cutoff conditions for all propagation modes are provided. Wave motions of three example waveguides constructed of different materials are calculated. The results show that the materia l properties of the waveguide and its surrounding medium determine the existence and the asymptotic limits of the guided wave motions. Displ acement distributions and geometry effects are also studied, and the r esults reveal that, by selecting proper material combination for the l iquid core and the solid tube, the waveguide can help to transmit sign als in materials with high acoustic attenuation. Results also show tha t there are two propagation branches (the first branch of the longitud inal mode L(01) and of the first flexural mode F-11) with a zero cutof f frequency that can achieve a stable propagation mode along the liqui d-solid interface at all frequency ranges; and that will be useful for efficient signal transmission.