Characterizing unpoled piezoelectric ceramic film by lamb-waves

Determination of the physical properties of unpoled ceramic Alms on metalli c substrates is considered; the problem is important because these properti es may be quite different than those in the bulk, which are caused by the e ffects of porosity. It is shown that the density and elastic constant C-33 can be determined by a modification of the previously used modal frequency spacing (MFS) method, involving cut-off frequencies for longitudinal and sh ear sagittal plane modes. This method has the advantage of great simplicity compared with the standard inversion approach. Numerical calculations show that good accuracy of the order of 2% can be obtained for density and for C-33 for simulations of PZT Alms on stainless steel, platinum, and aluminum plates.