Excitation of fundamental shear horizontal wave by using face-shear (d36) piezoelectric ceramics

摘要

The fundamental shear horizontal (SH0) wave in plate-like structures isextremely useful for non-destructive testing (NDT) and structural healthmonitoring (SHM) as it is non-dispersive. However, currently the SH0 wave isusually excited by electromagnetic acoustic transducers (EMAT) whose energyconversion efficiency is fairly low. The face-shear (d36) mode piezoelectricsis more promising for SH0 wave excitation but this mode cannot appear inconventional piezoelectric ceramics. Recently, by modifying the symmetry ofpoled PbZr1-xTixO3 (PZT) ceramics via ferroelastic domain engineering, werealized the face-shear d36 mode in both soft and hard PZT ceramics. In thiswork, we further improved the face-shear properties of PZT-4 and PZT-5Hceramics via lateral compression under elevated temperature. It was found thatwhen bonded on a 1 mm-thick aluminum plate, the d36 type PZT-4 exhibited betterface-shear performance than PZT-5H. We then successfully excite SH0 wave in thealuminum plate using a face-shear PZT-4 square patch and receive the wave usinga face-shear PMN-PT patch. The frequency response and directionality of theexcited SH0 wave were also investigated. The SH0 wave can be dominate over theLamb waves (S0 and A0 waves) from 160 kHz to 280 kHz. The wave amplitudereaches its maxima along the two main directions (0{\deg} and 90{\deg}). Theamplitude can keep over 80% of the maxima when the deviate angle is less than30{\deg}, while it vanishes quickly at the 45{\deg} direction. The excited SH0wave using piezoelectric ceramics could be very promising in the fields of NDTand SHM.