Structural health monitoring based on omni-directional SH wave piezoelectric transducers

Abstract

The fundamental shear horizontal (SH 0 ) wave has been regarded to be specially useful in guided wave-based detection techniques since it is the only non-dispersive wave mode in plate-like structures. In structural health monitoring (SHM) applications, it is required that the transducers can generate and receive guided wave omni-directionally to detect defects in all directions. However, developing omnidirectional SH wave piezoelectric transducer (OSH-PT) has always been a challenge. In this work, we firstly proposed an OSH-PT based on a thickness-poled piezoelectric ring. By dividing the ring into twelve sectors and applying the electric field circumferentially, a new thickness shear (d 15 ) mode was formed. Both finite element simulations and experiments indicated that the proposed OSH-PT can excite and receive single-mode SH 0 wave in a wide frequency range with uniform sensitivities. Then the performance of the proposed OSH-PT is demonstrated by defects localization in a 1000 mm×1000 mm×2 mm aluminum plate. Both single defect and multiple defects were detected and the defects localization algorithm was also presented. Results indicated that the proposed SH 0 wave-based SHM scheme can locate defects in high resolution with the position error less than 10 mm. Considering its excellent performances, low cost and easy fabrication, the proposed OSH-PT is expected to be widely used in SHM of plate-like structures in near future.