Experimental demonstration of spiral frequency-steerable acoustic sensors

Abstract

Fabrication and testing of frequency-steerable acoustic transducers (FSATs) enabling directional guided wave (GW) inspection of plate-like structures is demonstrated. A spiral FSAT is a two-electrode device which acts as a spatial filter on the propagating wavefield thanks to its shape. In sensing operation, FSAT differential output exhibits a dominant spectral component uniquely associated with the incoming wave direction. A single signal thus provides 2D imaging capabilities, as experimentally demonstrated in various pitch-catch configurations. Low hardware/software complexity and easy fabrication make FSATs ideal candidates for low-cost, in-situ and wireless structural health monitoring (SHM) applications.