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

An ultrasonic guided wave system, comprising:

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