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Guided wave (GW) based structural health monitoring (SHM) can greatly benefit from directional scanning. In frequency-steerable acoustic transducers (FSATs) this is achieved through the particular geometry of the actuator/sensor. These devices behave as spatial filters, thus providing a one-to-one correspondence between the direction of propagation and the spectral content of the actuated/recorded signal. In transmission mode, GWs can be steered in specific radiation directions by properly choosing the frequency content of the excitation signal, thus allowing for selective inspection of the waveguide. In sensing mode, the direction of an incoming wave can be retrieved from the spectrum of the recorded signal: imaging of large two-dimensional areas is thus accomplished through the output of a single device. In contrast with typical phased array operation, which requires a large number of individually controlled channels, directional capabilities are incorporated in one- or two-channel devices thanks to the FSAT concept. Current FSAT implementations include a single-channel periodic array and a wavenumber-spiral differential-channel transducer.
Georgia Institute of Technology – School of Aerospace Engineering Atlanta, Georgia 30332-0150 Contact Us:
Massimo Ruzzane Emanuele Baravelli Matteo Senesi	ruzzene@gatech.edu ebaravelli@arces.unibo.it msenesi3@gatech.edu
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