From the knowledge of piezoelectric material tensorial components one can, by the finite element method, calculate the electrical impedance versus frequency and simulate the mechanical deformation of piezoelectric bars. Here, the simulation results obtained with lead zirconate‐titanate and leadtitanateceramics are reported. In order to check the validity of the simulation, interferometric measurements of the mechanical deformation amplitude were performed. It is shown that these measurements are able to reveal the inhomogeneity of the materials under study and that a small error in the tensorial parameter absolute values leads to an inconsistent picture of simulated mechanical deformation.