Piezoelectric shear rings for omnidirectional shear horizontal guided wave excitation and sensing

An ultrasonic guided wave system for defect detection in a plate-like structure, includes at least one first circumferentially-polarized piezoelectric d15 shear ring element configured to be coupled to a structure. The controller includes a machine readable storage medium and a processor in signal communication with the machine readable storage medium. The processor is configured to cause a pulse generator to pulse the at least first circumferentially-polarized piezoelectric d15 shear ring element such that shear horizontal-type guided wave energy is transmitted in all directions in the plate-like structure, process at least one guided wave signal to identify the presence and location of at least one possible defect in the plate-like structure, and store the guided wave signal and defect detection data in the machine readable storage medium.