7.2. Performing a Harmonic Edge-Based Analysis

To perform a harmonic edge-based magnetic analysis, do the following tasks:

  1. Specify the electromagnetics edge formulation by choosing Main Menu> Preferences> Electromagnetics: Magnetic-Edge from the GUI. Doing so lets you filter out other Mechanical APDL commands not involved in an edge-based magnetic analysis.

  2. Define a jobname and title for your analysis. To do so, use the commands or GUI paths shown below:

    Command(s): /FILNAME and /TITLE
    GUI: Utility Menu> File> Change Jobname
    Utility Menu> File> Change Title

  3. Enter the preprocessor to begin defining your model:

    Command(s): /PREP7
    GUI: Main Menu> Preprocessor

  4. Choose element type SOLID236 or SOLID237 via either of the following:

    Command(s): ET
    GUI: Main Menu> Preprocessor> Element Type> Add/Edit/Delete

  5. Select the formulation option suitable for the specified element type and physics region. (For information on formulation options, see the earlier discussion.)

    Command(s): KEYOPT
    GUI: Main Menu> Preprocessor> Element Type> Add/Edit/Delete

  6. Define material properties. 2D Static Magnetic Analysis describes the material properties you can use and tells you how to specify them. For an eddy current region, you must specify the electric resistivity, RSVX.

  7. Build the model. For instructions on building and meshing models, see the Modeling and Meshing Guide.

  8. Assign attributes to the volumes (that is, associate the element types, the conducting and nonconducting regions, the material properties, etc. with the appropriate volumes).

    Command(s): VATT
    GUI: Main Menu> Preprocessor> Meshing> Mesh Attributes

  9. Mesh the model, specifying brick or tetrahedral element shape.

    Command(s): VMESH
    GUI: Main Menu> Preprocessor> Meshing> Mesh> Volumes> Mapped

  10. Enter the SOLUTION processor, using either of the following:

    Command(s): SOLU
    GUI: Main Menu> Solution

  11. Apply flux-parallel and flux-normal solid model boundary conditions to the boundaries.

    Command(s): DA
    GUI: Main Menu> Solution> Define Loads> Apply> Magnetic> Boundary

    For edge-based analyses, the label AZ (when set to zero) applies the flux-parallel boundary condition. No prescription is required to set flux-normal, because it is the natural boundary condition. In the rare case where the AZ = 0 condition is not general enough for flux-parallel conditions, you can prescribe constraints using individual D commands (or the equivalent GUI path).

  12. Apply source loading. See Characteristics and Settings for Physical Regions of a Model for information on source loading.

  13. Choose the harmonic analysis type and select the frequency of the time change. To specify the analysis type, use either of the following:

    Command(s): ANTYPE,HARMIC,NEW
    GUI: Main Menu> Solution> Analysis Type> New Analysis> Harmonic

    To specify the frequency, use the command or GUI path shown below:

    Command(s): HARFRQ
    GUI: Main Menu> Solution> Load Step Opts> Time/Frequenc> Freq and Substps

  14. Choose the solver you wish to use. Edge formulation analyses can use the sparse direct (SPARSE) solver (default), the Jacobi Conjugate Gradient (JCG) solver, or the Incomplete Cholesky Conjugate Gradient (ICCG) solver. Select an equation solver using either of the following:

    Command(s): EQSLV
    GUI: Main Menu> Solution> Analysis Type> Analysis Options

    The sparse and ICCG solvers are recommended for harmonic edge analysis.

  15. Choose load step options. (Alternative Analysis Options and Solution Methods of this manual describes these options.)

  16. Solve the model by using either of the following:

    Command(s): SOLVE (with OPT field set to zero)
    GUI: Main Menu> Solution> Solve> Current LS

    When you use the edge-element formulation, by default the program gauges the problem domain over all selected elements and nodes. Gauging removes unneeded degrees of freedom by setting them to zero; this in turn reduces solution time. You can control gauging using either of the following:

    Command(s): GAUGE
    GUI: Main Menu> Solution> Load Step Opts> Magnetics> Options Only> Gauging

    Gauging is required for electromagnetic analyses with elements using an edge formulation. Therefore, in most cases you should not turn automatic gauging off unless you are an expert user and want to do your own gauging. The program removes the extra constraints set by gauging after solution; therefore, gauging is transparent to users.

  17. To leave the SOLUTION processor, use one of the following:

    Command(s): FINISH
    GUI: Main Menu> Finish

  18. Do postprocessing and review the analysis results, as described below.