The fundamental shear horizontal (SH0) 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 (d15) mode was formed. Both finite element simulations and experiments indicated that the proposed OSH-PT can excite and receive single-mode SH0 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 SH0 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.
Qiang Huan and Faxin Li, "Structural health monitoring based on omni-directional SH wave piezoelectric transducers ," Proc. SPIE 10600, Health Monitoring of Structural and Biological Systems XII, 106002O (Presented at SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring: March 08, 2018; Published: 27 March 2018); https://doi.org/10.1117/12.2293442.
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