The Dielectric Loss subnode allows you to model electrical losses in the Piezoelectric Material, The losses can be prescribed either by using a loss factor for the electrical permittivity, or in the form of dielectric dispersion.

From the Dielectric loss list, select Loss factor for εS (the default) or Dispersion.

For Loss factor for εS select a Loss factor for electrical permittivity εS. Select From material (the default) to use the value from the material or select User defined to enter values or expressions for the loss factor in the associated fields. Select Symmetric to enter the components of ηeS in the upper-triangular part of a symmetric 3-by-3 matrix, select Isotropic to enter a single scalar loss factor, or select Diagonal. The default values are 0.

For Dispersion enter the Relaxation time τd, and the Relative permittivity increment in the associated fields. For the latter, you can select Isotropic, Diagonal, or Symmetric matrix input options.

Physics tab with Piezoelectric Material node selected in the model tree:
Attributes>Dielectric Loss