Defining Material Properties and Interface Conditions

To define the magnetic behavior of the motor, you specify the magnetic permeability of its components and the residual magnetic flux density of the permanent magnet. As you model a single magnet (1/8 of the geometry), rather than a pair of magnets with opposite polarity (1/4 of the geometry), you use antiperiodic interface conditions that account for the different polarity at the two sides of the interface.

To define the materials for the motor components:
  1. Expand the Continua > Motor Components > Models > Multi-Part Solid node.
  2. Right-click the Solids node and select Select Mixture Components...
  3. In the Select Mixture Components dialog:
    1. Select UNSS30200 (Stainless Steel) from the standard material database.
      Although all motor components are made of steel, they have different magnetic properties. To set the material properties of the magnet and the plates independently, you require two material definitions.
    2. To add two material definitions, click Apply twice, then Close.
  4. Rename the Multi-Part Solid > Solids > UNSS30200 node to Magnet and UNSS30200 2 to Plates.


Specify the magnetic permeability and the remanence magnetic flux density of the permanent magnet, and the magnetic permeability of the plates.

The remanence magnetic flux density is the magnetic field remaining in a permanent magnet after any external magnetic field is removed. For simplicity, this simulation models the plates and the magnet using the same physics continuum, Motor Components. To deactivate the Permanent Magnet model for the plates, you set the plates remanence magnetic flux density to zero.

  1. Expand the Solids > Magnet and Plates nodes.
  2. For each material, edit the Material Properties node and specify the following values:
    Material Magnetic Permeability > Constant Remanence Magnetic Flux Density > Constant
    Magnet 1.319493E-6 H/m 1.2 T
    Plates 6.2833E-4 H/m 0 T
To specify the direction of the magnet remanence magnetic flux density:
  1. Select the Motor Components > Models > Permanent Magnet > Magnetization Direction node and set Value to [0.0,0.0,1.0].
Associate each solid region to the relevant material:
  1. Expand the Regions node.
  2. Select the Magnet > Physics Values > Material Part Groups > Magnet node and set Parts to Magnet.
  3. Select the Magnet Plate > Physics Values > Material Part Groups > Plates node and set Parts to Magnet Plate.
  4. Using the same procedure, assign Stator Plate to the Plates material group.
To replicate the magnetic behavior of the full motor, you apply antiperiodic magnetic potential conditions at all periodic interfaces:
  1. Right-click the Interfaces > Topology: Periodic node and select Edit.
  2. In the Multiple Objects edit dialog, expand the Physics Conditions > Magnetic Vector Potential Periodicity node and set Method to Anti-Periodic.
  3. Save the simulation.