Dielectric Loss
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.
The Dielectric Loss subnode is only available with some COMSOL products (see https://www.comsol.com/products/specifications/).
Dielectric Loss Settings
From the Dielectric loss list, select one of the following options:
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Loss factor for εS. This choice is effective only in Eigenfrequency and Frequency Domain study. You can select the input type for Loss factor for electrical permittivity εS to be either From material to use the value from the material, or from User defined to enter values or expressions for the loss factor in the associated fields. Select Symmetric to enter the components of ηεS 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.
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Loss factor for εT. This choice is only available if the Constitutive relation in the parent node is Strain-charge form, and it is effective only in Eigenfrequency and Frequency Domain study. You can select the input type for Loss factor for electrical permittivity εT to be either From material to use the value from the material, or from User defined to enter values or expressions for the loss factor in the associated fields. Select Symmetric to enter the components of 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.
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Dispersion. This choice can be used in Eigenfrequency Frequency Domain, and Time Dependent study. Enter the Relaxation time τd, and the Relative permittivity contribution ΔεrS in the associated fields. For the latter, you can select Isotropic, Diagonal, or Symmetric matrix input options. You can also specify how the relative permittivity input εrS on the parent node should be interpreted by selecting the Static response (the default value is Low frequency limit).
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Complex permittivity. This choice can be used in Eigenfrequency, Frequency Domain, and Time Dependent study. You enter the Relative permittivity (real part) ε' and Relative permittivity (imaginary part) ε'', which can be either Isotropic or Diagonal matrices. You also enter the Reference frequency fref at which the permittivity values have been measured. You can also specify how the relative permittivity input εrS on the parent node should be interpreted by selecting the Static response (the default value is Low frequency limit). You can also specify how the relative permittivity input εrS on the parent node should be interpreted by selecting the Static response (the default value is Low frequency limit). In Time Dependent study, the software will use the dispersion model, for which the effective relaxation time and relative permittivity increment are computed automatically based on the node input parameters.
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Maximum loss tangent. This choice can be used in Eigenfrequency, Frequency Domain, and Time Dependent study. You enter the Maximum loss tangent ηmax together with the Reference frequency fref at which the maximum occurs. Both inputs can be either Isotropic or Diagonal matrices. In the latter case, different frequency can be used for the corresponding components of the loss tangent. You can also specify how the relative permittivity input εrS on the parent node should be interpreted by selecting the Static response (the default value is Low frequency limit). In Time Dependent study, the software will use the dispersion model, for which the effective relaxation time and relative permittivity increment are computed automatically based on the node input parameters.
See also Piezoelectric Losses.
If your license includes either the AC/DC Module or MEMS Module, more options for modeling dielectric dispersion can be found in Dispersion section in the AC/DC Module User’s Guide.
Location in User Interface
Context Menus
Solid Mechanics>Piezoelectric Material>Dielectric Loss
Layered Shell>Piezoelectric Material>Dielectric Loss
Ribbon
Physics tab with Piezoelectric Material node selected in the model tree:
Attributes>Dielectric Loss