AXISYMMETRICAL WAVE-PROPAGATION IN FLUID-LOADED CYLINDRICAL-SHELLS .2. THEORY VERSUS EXPERIMENT

The axisymmetric wave propagation along fluid-loaded cylindrical shells (excluding torsional modes) has been investigated both theoretically and experimentally. For a steel cylindrical shell with a fixed ratio of inner to outer radius, four different fluid configurations are considered: water inside and outside the steel shell, air inside and outside; water inside and air outside; and air inside and water outside. Calculations of the transient pressure response for the case of an axisymmetric ring source and a point receiver are made as a function of source-receiver separation. Experimentally, a PZT ring source and ring receiver are placed around a steel cylindrical shell with an outer radius of 9.53 mm and an inner radius of 7.94 mm. Waveforms are recorded for multiple source-receiver hydrophone spacings in the frequency band 50-240 kHz. Using a Prony's method, the complex wave number for each of the modes in the system are derived from both the theoretical and experimental waveforms. These axisymmetric modes are grouped into three categories: steel modes, noncutoff fluid modes, and cutoff fluid modes. Excellent agreement is obtained between theory and experiment.