Electromechanics, Boundary Elements
Use an Electromechanics, Boundary Elements () boundary multiphysics coupling to model electromechanical interaction between deformable solid domains and nonsolid voids, where the electric field is computed using the boundary element method. The backward coupling to Electrostatics is due to the deformations of the boundaries.
The presence of such multiphysics node in the model will enforce the Include geometric nonlinearity option on all applicable study nodes.
Settings
The Label is the default multiphysics coupling feature name.
The Name is used primarily as a scope prefix for variables defined by the coupling node. Refer to such variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different coupling nodes or physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.
The default Name (for the first multiphysics coupling feature in the model) is emeb1.
BOUNDARY Selection
Applicable boundaries are those that are both external boundaries to the domains selected under the Solid Mechanics interface and boundaries to the domains selected under the Electrostatics, Boundary Elements interface. In particular, all boundaries external to Solid Mechanics selection are applicable if the selection of the Electrostatics, Boundary Elements contains Infinite void.
For nonsolid dielectric domains, remove them from the Solid Mechanics interface selection but keep them selected in the Electrostatics, Boundary Elements interface selection.
The coupling is a boundary load on a structure caused by the Maxwell stress at the selected boundaries. The backward coupling to Electrostatics is due to the change of the spatial position of the boundaries caused by the deformation of the structure.
Only electrically linear and isotropic materials can be modeled using Electrostatics, Boundary Elements. For more details, see The Electrostatics, Boundary Elements Interface chapter in the AC/DC Module User’s Guide.
Coupled interfaces
This section defines the physics interfaces involved in this multiphysics coupling. The Solid mechanics and Electrostatics, Boundary Elements lists include all applicable physics interfaces.
The default values depend on how the coupling node is created.
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If it is added from the Physics ribbon (Windows users), Physics contextual toolbar (Mac and Linux users), or context menu (all users), then the first physics interface of each type in the component is selected as the default.
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If it is added automatically when the physics interface is chosen in the Model Wizard or Add Physics window, then the two participating physics interfaces are selected.
You can also select None from either list to uncouple the coupling from a physics interface. If the physics interface is removed from the Model Builder, for example Solid Mechanics is deleted, then the Solid mechanics list defaults to None as there is nothing to couple to.
If a physics interface is deleted and then added to the model again, then in order to reestablish the coupling, you need to choose the physics interface again from the lists. This is applicable to all multiphysics coupling nodes that would normally default to the once present physics interface. See Multiphysics Modeling Workflow in the COMSOL Multiphysics Reference Manual.