Acoustic Source Localisation Using Distributed Sensing

The actuation of Lamb waves in thin plate-like structures and subsequent interpretation of the scattered wave field offers a capability for broad area damage detection and location. In practice, interpretation of a scattered field can be difficult when there are several overlapping wave modes propagating which is a realistic scenario for many applications. This paper reports on the use of spatially distributed in situ measurements to decompose a wave-field into its constituent modes. A pass-band filter is applied to the complex spectrum of the wave-field and an inverse transform then applied to affect a complete time-domain separation of the constituent modes. Knowledge of the group velocity and time-of-flight for each mode allows the distance of the sensor from the source to be accurately determined while the pass-band filtered spectrum enables a determination of the relative orientation between the source and the sensor via the application of a corrective angle. The method is validated numerically and experimentally.