The Piezoelectricity Interface, Solid
The Piezoelectricity interface () combines Solid Mechanics and Electrostatics together with the constitutive relationships required to model piezoelectric phenomena. Both the direct and inverse piezoelectric effects can be modeled, and the piezoelectric coupling can be formulated using either the strain-charge or stress-charge forms.
When a predefined Piezoelectricity interface is added from the Structural Mechanics branch () of the Model Wizard or from Add Physics windows, Solid Mechanics and Electrostatics interfaces are added to the Model Builder.
In addition, the Multiphysics node is added, which automatically includes the multiphysics coupling feature Piezoelectric Effect.
The participating Solid Mechanics interface includes the default Piezoelectric Material feature with its selection set to all domains. The Electrostatics interface has a default Charge Conservation, Piezoelectric feature with similar settings.
Such features can be also added manually to their corresponding interfaces similar to any other material model therein.
The Piezoelectric Effect multiphysics coupling node can be active only on the selection, where both features Piezoelectric Material and Charge Conservation, Piezoelectric are active.
You input both the mechanical and electrical material data under the Piezoelectric Material node. The data can be presented in either stress-charge or strain-charge form.
When it is used without an active Piezoelectric Effect coupling feature, the Piezoelectric Material node works similarly to a Linear Elastic Material feature with the material data input limited to anisotropic form using Voigt notations. All the electric material data has no effect.
You use the Charge Conservation, Piezoelectric feature under Electrostatics to select those domains, where the material is supposed to experience piezoelectric coupling. When used without a counterpart under the Solid Mechanics interface (or without the coupling feature), the Charge Conservation, Piezoelectric node acts as an ordinary Charge Conservation feature with its material data input limited to the electric permittivity only.
All solid mechanics and electrostatics functionality for modeling is also accessible to include surrounding elastic solids or air domains. For example, add any solid mechanics material for other solid domain, a dielectric model for air (via Charge Conservation feature), or a combination. Note that in order to model a nonsolid dielectric domain, you need to remove such domain from the domain selection for the entire Solid Mechanics interface. This is because all material models under that interface represent solid materials (with the Linear Elastic Material node being always present and active in all those domains, where it is not explicitly overridden by any other material model).
In 2D and 2D axial symmetry, adding a Piezoelectricity interface also adds predefined base-vector coordinate systems for the material’s (in the plane 2D case) XY-, YZ-, ZX-, YX-, XZ-, and XY-planes. These additional coordinate systems are useful for simplifying the material orientation for the piezoelectric material.
On the Constituent Physics Interfaces
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The Solid Mechanics interface is described in The Solid Mechanics Interface.
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The Electrostatics interface is described in The Electrostatics Interface in the AC/DC Module User’s Guide.
In previous versions of COMSOL Multiphysics, a specific physics interface called Piezoelectric Devices was added to the Model Builder. Now, a predefined multiphysics coupling approach is used, improving the flexibility and design options for your modeling. For specific details, see The Multiphysics Branch and Multiphysics Modeling Workflow in the COMSOL Multiphysics Reference Manual.
Settings for Physics Interfaces and Coupling Features
When physics interfaces are added using the predefined couplings, for example Piezoelectricity, specific settings are included with the physics interfaces and the coupling features.
However, if physics interfaces are added one at a time, followed by the coupling features, these modified settings are not automatically included.
For example, if both Solid Mechanics and Electrostatics interfaces are added, COMSOL Multiphysics adds an empty Multiphysics node. You can choose the available coupling feature Piezoelectric Effect but the modified settings are not included.
Coupling features are available from the context menu (right-click the Multiphysics node) or from the Physics toolbar, Multiphysics Couplings menu.
Physics Interfaces and Coupling Features
Use the online help in COMSOL Multiphysics to locate and search all the documentation. All these links also work directly in COMSOL Multiphysics when using the Help system.
Coupling Feature
The Piezoelectric Effect coupling node is used to couple the interfaces.
Additional Features
Additional nodes and subnodes available with this multiphysics interface are described with the interfaces where they are available. Coupling Loss, Dielectric Loss, Mechanical Damping, and Conduction Loss (Time-Harmonic) subnodes are available for Piezoelectric Material under the Solid Mechanics interface. The Charge Conservation, Piezoelectric feature is described for the Electrostatics interface.
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Piezoelectricity
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Modeling Piezoelectric Problems
Piezoelectric Shear-Actuated Beam: Application Library path Structural_Mechanics_Module/Piezoelectric_Effects/shear_bender
Surface Acoustic Wave Gas Sensor: Application Library path MEMS_Module/Sensors/saw_gas_sensor