EXPERIMENTAL PREDICTION OF BAND-SELECTIVE ABSORPTION AND DISPERSION OF NOISE IN AXIALLY UNCOUPLED VISCOELASTIC CYLINDRICAL-SHELLS FILLED WITH FLUID

This work deals with experimentally aided prediction of band-selective absorption and dispersion properties for noise propagation in cylindr ical fluid-filled pipes in which wall-axial vibration transmission may be neglected. While pipes with yielding walls are known to posses dis persive and attenuation characteristics for acoustic waves propagating within the fluid medium, considerable practical difficulties may be e xperienced in the determination of these characteristics. This is part icularly the case for pipes with a complex wall structure. Here, we re port an experimental technique which overcomes this difficulty and giv e an example of a helical-rib-reinforced polymer pipe filled with wate r to demonstrate the correspondence between the predicted and observed dispersive and attenuative behaviour. The dispersive properties of th e pipe were characterised with an unconventional technique, based on t ransient excitation and group velocity measurements.