A Novel Quadrant Array for Material Characterization and SHM of Orthotropic Plate-like Structures

Abstract

A novel small footprint sensor patch (single-quadrant double-ring Single- Transmitter Multiple-Receiver (STMR) array) has been developed and demon- strated successfully for the simultaneous reconstruction of the elastic moduli, mate- rial symmetry, orientation of principal planes and defect imaging. The sensor array contains a single transmitter in the center of the array and two sets of receivers at two different radii on a single quadrant. A slowness based reconstruction algo- rithm is used to determine elastic moduli from measured fundamental Lamb wave mode velocities using the direct received signals at different angles in a quadrant. A method proposed by Cowin and Mehrabadi (1987) is used to determine material symmetry and orientation of principal planes. Imaging is carried out with a phased addition algorithm and the reconstructed elastic moduli using the signals from flaws and structural features. To show the applicability of the method, simulations were carried out to image defects with the single-quadrant double-ring STMR array con- figuration and are compared with the images obtained using simulation data of the full-ring STMR array configuration. The experimental validation has been carried out on a 3.15 mm thick quasi-isotropic graphite-epoxy composite plate.