The Magnetomechanics () interface combines Solid Mechanics and Magnetic Fields interfaces together with a moving mesh functionality. The interface can be used for modeling deformation of magnetically actuated structures, which includes interaction of magnetic fields with magnetic materials and current carrying elements such as coils and wires.

The Magnetomechanics interface is available for 3D, planar 2D, and axisymmetric 2D geometries. It is found under the Electromagnetics-Structure Interaction () branch within the Structural Mechanics () branch. When this multiphysics interface is added using the Model Wizard, a Solid Mechanics interface and a Magnetic Fields interface are added to the Model Builder.

In addition, the Multiphysics Couplings node is added, which automatically includes the multiphysics coupling feature Magnetomechanical Forces.

The full functionality of the Solid Mechanics and Magnetic Fields interfaces is accessible under the respective interface at the domain, boundary, edge, or point level in the geometry. The participating Magnetic Fields interface by default adds the 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 also be added manually to the interface and configured to represent either solid or nonsolid (for example, air or free space) materials.

When a Magnetomechanics multiphysics interface is added using the Model Wizard, a Deforming Domain node and a Symmetry node are added automatically in Model Builder under the Definitions node. These nodes serve to represent domains and boundaries where the mesh can deform. By default, both nodes have empty selections. Under the Deforming Domain, you can select domain that represent nonsolid magnetic materials such as air, fluid, and 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 just introduce unnecessary overhead and nonlinearity in the model (see Deformed Mesh Fundamentals). Domains selected in the Solid Mechanics 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 of 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 Symmetry 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.