The Piezomagnetism Interface

The interface (

) combines Solid Mechanics and Magnetic Fields together with the constitutive relationships required to model linear magnetostrictive materials and devices. Both the direct and inverse piezomagnetic effects can be modeled.

When a predefined interface is added from the branch (

) of the or from windows, and interfaces are added to the Model Builder.

In addition, the node is added, which automatically includes the multiphysics coupling feature .

The participating interface includes the default feature with its selection set to all domains. The interface gets a default feature with similar settings.

Such features can be also added manually to their corresponding interfaces similar to any other material models therein.

The Piezomagnetism multiphysics coupling node can be active only on the selection where the features Piezomagnetic Material and Ampère’s Law, Piezomagnetic are both active.

Input the mechanical and magnetic material data under the Piezomagnetic Material, and the electrical properties under Ampère’s Law, Piezomagnetic.

When used without an active Piezomagnetism coupling feature, the Piezomagnetic Material node works similarly to a Linear Elastic Material feature with some limitations on the format for the elastic material data input. The magnetic material data and coupling data will have no effect.

Use the Ampère’s Law, Piezomagnetic feature under Magnetic Fields to select the domains where the material is supposed to experience linear magnetostrictive coupling. When used without a counterpart under the Solid Mechanics interface (and/or without the coupling feature) Ampère’s Law, Piezomagnetic node acts as an ordinary Ampère’s Law feature with its material data input limited to the electric properties only. The magnetic permittivity of free space will be assumed.

All solid mechanics and magnetics functionalities for modeling are also accessible to include surrounding elastic solids or air domains. For example, add any solid mechanics material for other solid domain, a nonsolid model for air (via Ampère’s Law feature), or a combination. Note that in order to model a nonsolid magnetic material, 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 Piezomagnetism 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 nonisotropic materials.

When physics interfaces are added using the predefined multiphysics interface, for example , 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 and interfaces are added, COMSOL Multiphysics adds an empty node. You can choose the available coupling feature 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.

	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.

The Piezomagnetism coupling node is used to couple the interfaces.

Additional nodes and subnodes available with this multiphysics interface are described with the interfaces where they are available. and subnodes are available for under the Solid Mechanics interface. The feature is described for the Magnetic Fields interface.