Piezoelectric Material
The Piezoelectric Material node defines the piezoelectric material properties either in stress-charge form using the elasticity matrix and the coupling matrix, or in strain-charge form using the compliance matrix and the coupling matrix. It is normally used together with a Piezoelectric Effect multiphysics coupling node and a corresponding Charge Conservation, Piezoelectric node in the Electrostatics interface. This node is added by default to the Solid Mechanics interface when adding a Piezoelectric Devices interface.
This material model requires the Structural Mechanics Module, MEMS Module, or Acoustics Module.
By adding the following subnodes to the Piezoelectric Material node you can incorporate many other effects:
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Initial Stress and Strain
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Thermal Expansion (for materials)
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Mechanical Damping
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Coupling Loss
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Dielectric Loss
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Conduction Loss (Time-Harmonic)
When the Piezoelectric Material node is added to the structural mechanics interface in the absence of an active Piezoelectric Effect multiphysics coupling node the material behaves similarly to a Linear Elastic Material node, with elastic properties as corresponding to the elasticity or compliance matrix entered (see below). The piezoelectric effect is then not included in the corresponding equation system.
See also Piezoelectric Material in the Structural Mechanics Theory chapter.
Piezoelectric Material Properties
Select a Constitutive relation — Stress-charge form or Strain-charge form. For each of the following, the default uses values From material. For User defined enter other values in the matrix or field as needed.
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For Stress-charge form, select an Elasticity matrix (ordering: xx, yy, zz, yz, xz, xy) (cE).
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For a Strain-charge form, select a Compliance matrix (ordering: xx, yy, zz, yz, xz, xy) (sE).
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Select a Coupling matrix (ordering: xx, yy, zz, yz, xz, xy) (d).
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Select a Relative permittivity (erS or erT).
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Enter values for the Remanent electric displacement Dr.
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Select a Density (p).
For entering these matrices, use the following order (Voigt notation), which is the common convention for piezoelectric materials: xx, yy, zz, yz, xz, zy.
The density is needed for dynamic analysis or when the elastic data is given in terms of wave speed. It is also used when computing mass forces for gravitational or rotating frame loads, and when computing mass properties (Computing Mass Properties).
Geometric Nonlinearity
If a study step is geometrically nonlinear, the default behavior is to use a large strain formulation in all domains. There are, however, some cases when the use of a small strain formulation for a certain domain is needed. In those cases, select the Force linear strains check box. When selected, a small strain formulation is always used, independently of the setting in the study step. The check box is not selected by default to conserve the properties of the model.
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Modeling Piezoelectric Problems
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Modeling Geometric Nonlinearity
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The Electromagnetics Interfaces in the COMSOL Multiphysics Reference Manual
Location in User Interface
Context Menus
 Solid Mechanics>Material Models>Piezoelectric Material
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Physics tab with Solid Mechanics selected:
Domains>Material Models>Piezoelectric Material