Create the Piezoelectric Effect Interface and Define Domains
A piezoelectric problem can be set up in different ways:
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By selecting Piezoelectric Devices from the Model Wizard,
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By choosing Piezoelectric Devices from the Add Physics menu when working in an existing model, or
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By adding the corresponding features to create the coupling manually.
In the first two cases, by default all the domains in the model are assumed to be piezoelectric materials.
When setting up the problem manually (that is, by adding single physics interfaces one at a time) both Solid Mechanics and Electrostatics interfaces should be added. Then, you have to specify which domains are in each physics, and which domains are to be modeled as piezoelectric materials.
1
On the Solid Mechanics interface Settings window, locate the Domain Selection section. Select the domains which undergo structural deformation, including the piezoelectric material domains.
2
Go to the Solid Mechanics>Piezoelectric Material node (if it is not yet available, add it). Select the domains where the piezoelectric effect applies. Non-piezoelectric domains can be modeled using the other available material models.
3
Go to the Electrostatics node and under Domain Selection select the domains the electrostatics equations must be solved. These domains include all the piezoelectric domains, and any other insulating domains.
Since metals usually have a conductivity several orders of magnitude higher than other materials, it is normal not to solve the electrostatics equations in their corresponding domains, but instead the surfaces of the material are represented as isopotentials with an appropriate boundary condition (usually a terminal or floating potential).
4
Go to the Electrostatics>Charge Conservation, Piezoelectric node (if it is not yet available, add it). Select the domains where the piezoelectric effect has to be modeled.
5
A Multiphysics>Piezoelectric Effect node is already present if the coupling was added using either the Model Wizard or Add Physics window. If the model is set up manually (that is, single physics interfaces are added), right-click the Multiphysics Couplings node to add a Piezoelectric Effect coupling.
6
Confirm that all the domains where the piezoelectric material is present are selected.
Only domains that have both Charge Conservation, Piezoelectric selected in the Electrostatics interface and Piezoelectric Material selected in the Solid Mechanics interface are selected. The selection of this feature cannot be edited. If several Solid Mechanics or Electrostatics interfaces are present, select the correct ones.
7
Confirm that remaining domains are well assigned:
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Solid and electrostatic domains: In these domains, the electrostatics and structural problems are solved independently without any piezoelectric coupling. This is the case for insulators.
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Solid-only domains: In these domains, only mechanical phenomena are modeled, and the electrostatics phenomena are neglected. Metals are typically modeled in this way, because their conductivity is so high that their surfaces can be treated as isopotential surfaces within the electrostatics problem. In some cases, insulators are modeled using these settings, for example, when there is no potential applied across the domain, and correspondingly solving the electrostatics equations would produce a constant potential and waste computing resources.
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Electrostatics-only domains: Those domains are nonsolid. This is typically the case of air, in which the electrostatics is solved but not mechanics.
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Nonsolid and nonelectrostatic domains: In those domains, another physics is solved. A typical example is an acoustic domain in the case of piezoacoustic modeling.