Shear-lag modeling of surface-bonded omnidirectional shear horizontal wave transducer based on two thickness-poled piezoelectric half-rings

The shear horizontal (SH) wave in thin-walled structures has great potential in structural health monitoring since only a single SH0 mode exists when the excitation frequency is lower than the cut-off frequency of SH1 and SH0 is non-dispersive. Thickness-poled d15 lead zirconate titanate (PZT) ring-based omnidirectional SH wave piezoelectric transducers (OSH-PTs) have been proven to excite SH waves in the structure through the bonding layer. However, the analysis of interfacial shear stress in OSH-PT-bonding layer-structure (OBS) remains a critical and challenging issue. To this end, this paper first conducts static analysis on OSH-PT and the structure in a cylindrical coordinate system, then combines the stress–strain relationship in the bonding layer to obtain the differential equation for interfacial shear stress. Since the equation does not have a closed-form solution, a three-dimensional model of OBS was further established, and finite element analysis was conducted to obtain the variation law of shear stress distribution under different parameters of the bonding layer and OSH-PT. The results indicate that to generate greater maximum interfacial shear stress thus bettering SH wave excitation, the OSH-PT selected should have a smaller inner diameter and a larger ratio of outer diameter to inner diameter. Besides, the thickness and shear modulus of the actuator should also be greater. The bonding layer should be as thin as possible while having a larger shear modulus. The result of the paper can provide guidance for the OSH-PT design and optimization.