New acoustic plate modes with Quasi-Linear polarizations

New acoustic plate modes (APMs) with quasi-shear-vertical (QSV) and quasi-shear-horizontal (QSH) polarizations are found numerically in piezoelectric, nonpiezoelectric, and isotropic plates with free faces. Experimental verification of the modes is accomplished for ST,X-quartz plate, as an example. Similar to the modes with quasi-longitudinal displacement reported recently, the new counterparts exist when their velocities v_APM are close to the velocities v_BAW of the relevant bulk waves, the value of the dispersion slope d_vAPM/d(h/λ) is low enough (d_vAPM/d(h/λ) ~100 m/s, where h is thickness and λ is wavelength), and allowable plate thickness h/λ form a regular succession. All modes with quasi-linear polarization originate from generalized Lamb modes transformed at the aforementioned conditions.