What is really measured on a d33-meter?

Mechanical boundary conditions of PZT sample are not well defined in the measurement process on a d33-meter due to the misfit in size or shape of the jaws and of the sample. Result of such d33 measurement is usually an effective value d 33eff. Mechanical stress/strain conditions are simulated for PZT discs/cylinders in a d33-meter by the finite element method (ANSYS® software) and an effective d 33eff is calculated and compared to the original input d33 value as well as to the values measured on a d33-meter (type ZJ-3C). Relative d 33effd33 value seems to be more sensitive to the disc aspect ratio than to the PZT material type tested. Although such strong dependence on the aspect ratio has been found in simulations, it is not correlated with experiments. Coefficient d 33eff is not significantly sensitive to the position of a d33-meter metallic jaws with respect to the disc center.