  The fundamental shear horizontal (SH0) wave in plate-like structures is
extremely useful for non-destructive testing (NDT) and structural health
monitoring (SHM) as it is non-dispersive. However, currently the SH0 wave is
usually excited by electromagnetic acoustic transducers (EMAT) whose energy
conversion efficiency is fairly low. The face-shear (d36) mode piezoelectrics
is more promising for SH0 wave excitation but this mode cannot appear in
conventional piezoelectric ceramics. Recently, by modifying the symmetry of
poled PbZr1-xTixO3 (PZT) ceramics via ferroelastic domain engineering, we
realized the face-shear d36 mode in both soft and hard PZT ceramics. In this
work, we further improved the face-shear properties of PZT-4 and PZT-5H
ceramics via lateral compression under elevated temperature. It was found that
when bonded on a 1 mm-thick aluminum plate, the d36 type PZT-4 exhibited better
face-shear performance than PZT-5H. We then successfully excite SH0 wave in the
aluminum plate using a face-shear PZT-4 square patch and receive the wave using
a face-shear PMN-PT patch. The frequency response and directionality of the
excited SH0 wave were also investigated. The SH0 wave can be dominate over the
Lamb waves (S0 and A0 waves) from 160 kHz to 280 kHz. The wave amplitude
reaches its maxima along the two main directions (0{\deg} and 90{\deg}). The
amplitude can keep over 80% of the maxima when the deviate angle is less than
30{\deg}, while it vanishes quickly at the 45{\deg} direction. The excited SH0
wave using piezoelectric ceramics could be very promising in the fields of NDT
and SHM.
