The Magnetic–Rigid Body Interaction in Rotating Machinery Interface
The Magnetic–Rigid Body Interaction in Rotating Machinery () interface combines Multibody Dynamics and Rotating Machinery, Magnetic interfaces together with moving mesh features. The parts modeled using the Multibody Dynamics interface can be either rigid or flexible. In flexible domains, you can compute deformations caused by mechanical and electromagnetic forces in, for example, stator and rotor of an electric motor. It is also possible to compute stress, in which case it is recommended to change the discretization for the displacement degrees of freedom in the Multibody Dynamics interface to second order.
The Magnetic–Rigid Body Interaction in Rotating Machinery interface is available for 3D and for planar 2D geometries. It is found under the Rotating Machinery, Magnetic–Structure Interaction () branch under Electromagnetics–Structure Interaction () branch within the Structural Mechanics () branch. When this multiphysics interface is added using the Model Wizard, a Multibody Dynamics interface and a Rotating Machinery, Magnetic interface are added to the Model Builder.
In addition, the Multiphysics Couplings node is added, which automatically includes the multiphysics coupling Magnetic Forces, Rotating Machinery.
On the Constituent Physics Interfaces
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The Rotating Machinery, Magnetic interface is described in The Rotating Machinery, Magnetic Interface.
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The Multibody Dynamics interface is described in The Multibody Dynamics Interface.
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The Deforming Domain feature is described in the Moving Mesh Features.
Settings for Physics Interfaces and Coupling Features
When physics interfaces are added using the predefined couplings, all specific settings are included with the physics interfaces. However, if physics interfaces are added one at a time followed by the coupling features, these modified settings are not automatically included.
The full functionality of the Multibody Dynamics and Rotating Machinery, Magnetic interfaces is accessible under the respective interface at the domain, boundary, edge, or point level in the geometry.
The participating Rotating Machinery, Magnetic interface by default adds an Ampère’s Law node with its selection set to all domains, and the Material type set to Solid. This node serves to represent solid magnetic material domains. Any number of Ampère’s Law nodes can be added manually to the interface and configured to represent either solid or nonsolid (for example, air or free space) materials.
The Multibody Dynamics interface by default adds a Rotating Frame node to model the effect of rotation. To add the rotation to the definition of the spatial frame, the Define spatial frame rotation check box is selected by default.
Moving Mesh
When a Magnetic–Rigid Body Interaction in Rotating Machinery multiphysics interface is added using the Model Wizard, a Deforming Domain node and a Rotating Boundary node are added automatically to the Model Builder. These nodes represent domains and boundaries where the mesh can deform. By default, both nodes have empty selections. Under the Deforming Domain, you can select domains that represent nonsolid magnetic materials such as air, a fluid, or free space. However, this is only needed if the boundaries of such domains experience significant changes due to the deformation or rotation of the adjacent solid domains. Otherwise, the moving mesh computations could introduce unnecessary overhead and nonlinearity in the model (see Deformed Mesh Fundamentals). Domains selected in the Multibody Dynamics interface are not applicable.
Under the Deforming Domain, you can also choose the Mesh smoothing type, which is by default set to Hyperelastic. More information about the smoothing type can be found in the Deforming Domain chapter in the COMSOL Multiphysics Reference Manual.
By default, the mesh is fixed at all external boundaries of the geometry. Use the Rotating Boundary node to select the external boundaries, where the mesh can slide along the boundary. You can also add other types of boundary conditions for the mesh motion, for details see Moving Mesh Features in the COMSOL Multiphysics Reference Manual.
Coupling features are available from the context menu (right-click the Multiphysics node) or from the Physics toolbar, Multiphysics Couplings menu.
Coupling Features
The Magnetic Forces, Rotating Machinery multiphysics coupling is used to couple the interfaces.