Waveguide dispersion curves identification at low-frequency using two actuators and phase perturbations

Vered, Y., Gabai, R. and Bucher, I. (2019) Waveguide dispersion curves identification at low-frequency using two actuators and phase perturbations. Journal of the Acoustical Society of America, 146 (4), 2443-2451. (doi:10.1121/1.5128482).

Abstract

Dispersion curves of fluid-filled elastic-tubes are used for non-destructive measurement of material acoustic properties. The underlying physics leads to a singular numerical procedure when several modes or long-wavelength scenarios take part in the tube dynamics. The literature describes several methods to identify dispersion curves that require a large ratio of samples per length. Described is a method to enrich the amount of available information of an otherwise ill-posed problem, by multiple boundary phase perturbations at each excitation frequency. The method uses two actuators, one at either end of the waveguide to produce different relative phases, followed by a nonlinear model fitting procedure. Presented are a model-based derivation and experimental verification of the proposed approach on an air-filled elastic-tube. The latter shows the capability of the method to recover the dispersion curves even for very weak structural-acoustic coupling and at low frequencies. The portrayed scheme can be applied on various waveguides by using two actuators and only a single sensor, and hence makes dispersion curve estimation realistic in formerly inaccessible cases.

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Contributors

Author: Y. Vered

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