2D Static Magnetic Analysis of this document describes the quick way to solve a 2D static magnetic analysis using the MAGSOLV command or its equivalent menu path. This section explains how to step manually through the two-step solution sequence.
You can specify general or nonlinear load step options for a 2D static magnetic analysis
You use general options mostly in nonlinear static analyses. The options are:
The number of substeps or the time step size.
A nonlinear analysis requires multiple substeps within each load step, so that the specified loads can be applied gradually to obtain an accurate solution. By default, the program uses one substep per load step.
To specify substeps or time step size, use either of the following:
Command(s): NSUBSTGUI:Stepped or ramped loads.
If you step-apply loads, the program applies the entire load value at the first substep and holds it constant for the remainder of the load step.
If you ramp loads (the default), the program increments the load values at each substep. To step or ramp loads, issue the KBC command or use one of the GUI paths shown above for TIME.
The only nonlinear load step option for the approximate initial solution is the number of equilibrium iterations.
This option obtains a converged solution at each substep. The default is up to 25 equilibrium iterations per substep. However, a converged solution is not needed at each substep in the approximate solution, so just one equilibrium iteration per substep is recommended.
To specify the number of equilibrium iterations, use one of the following:
You can either write load data for the initial approximate solution to a load step file or solve the load step immediately. To write the data to a load step file, use one of the following:
To solve the load step immediately, use one of the following:
You can specify general options, nonlinear options, or output controls for the final solution.
The only general option to specify is the number of substeps. (Use the NSUBST command or its menu path equivalent, as described in Step 2). For the final solution step, issue just one substep.
Specify the equilibrium iterations option (described in Step 2). However, for the final solution, specify five to 10 equilibrium iterations over one substep. Other nonlinear load step options you should specify include:
Convergence tolerances.
Mechanical APDL considers a nonlinear solution to be converged whenever specified convergence criteria are met. Convergence checking may be based on magnetic potentials, current segments, or both. You specify a typical value for the desired item (
VALUEfield) and a tolerance about the typical value (TOLERfield). The convergence criterion is then given byVALUE*TOLER. For instance, if you specify 5000 as the typical value of current segment and 0.001 as the tolerance, the convergence criterion for current segment would be 5.0.For potentials, the program compares the change in nodal potentials between successive equilibrium iterations (ΔA = Ai - Ai-1) to the convergence criterion. For current segments, the program compares the out-of-balance load vector to the convergence criterion. The out-of-balance vector is the difference between the applied current (segments) and the internal (calculated) current (segments).
Mechanical APDL enables you to graphically track convergence norms via its Graphical Solution Tracking (GST) feature, available for both interactive and batch runs of the program. For a detailed description of this feature, see Tracking Convergence Graphically and the /GST command description in the Command Reference.
To specify convergence tolerances, use either of the following:
Command(s): CNVTOLGUI:Terminate an unconverged solution.
If the solution doesn't converge within the specified number of equilibrium iterations, the program either stops the solution or moves on to the next load step, depending on what you specify as the stopping criteria. For a 2D magnetostatic analysis, Ansys, Inc. recommends convergence based on current segments.
To specify convergence tolerances, use either of the following:
Command(s): NCNVGUI:
The third class of load step options enables you to control output. The options are as follows:
Control printed output.
This option enables you to include any results data in the printed output file (Jobname.out). To use this option, choose either of the following:
To control printed output, use either of the following:
Command(s): OUTPRGUI:Control database and results file output
This option controls what data goes to the results file (Jobname.rmg). To send output to the database and results file, use either of the following:
Command(s): OUTRESGUI:Extrapolate results.
Use this option to review element integration point results by copying them to the nodes instead of extrapolating them. (Extrapolation is the default.)
To specify convergence tolerances, use either of the following:
Command(s): ERESXGUI:
To write load data for the final solution to a load step file or to solve the load step immediately, use the procedures described in Step 2.
You need to perform this step only if you do not solve loads steps immediately via the SOLVE command or its menu path equivalent. To initiate the solution for all load steps, use either of the following:
An example command sequence for nonlinear 2D static magnetic analysis follows:
/solu nsubst,3 ! Three substeps neqit,1 ! One equilibrium iteration outres,all,none ! Do not save results solve ! Solve the analysis nsubst,1 ! One substep neqit,20 ! Up to 20 equilibrium iterations cnvtol,csg,,le-3 ! Convergence criteria outres,all,last ! Save converged solution solve ! Solve finish