Solution dialog box (Nastran), Restart Management page

The options on the Restart Management page in the Solution dialog box apply to Simcenter Nastran SOL 401 Multi-Step Nonlinear and SOL 402 Multi-Step Nonlinear Kinematics. They correspond to the NLCNTLG bulk entry.

Use this page as your primary method for managing restart options. If you need to access advanced settings, such as changing the unit number of the initial run file (Simcenter Nastran ASSIGN statement), or if you temporarily need to override a setting, you can use the Nonlinear Control Parameters - Global (NLCNTLG) modeling object. However, the restart options in the Nonlinear Control Parameters - Global modeling object require that you know the subcases numbers in advance of setting the options. The Restart Management page provides the subcase numbers for you.

When you set options in the Nonlinear Control Parameters - Global modeling object and on the Restart Management page, the settings on the Nonlinear Control Parameters - Global take precedence.

Option	Description	Corresponding Nastran syntax
Generate Restart Data	Specifies whether to save results and restart points to use in a restart solution. This data is saved at the end of the subcase or at the last converged timestep for each static, dynamic, and preload subcase.Select Yes if this is the initial run solution or if this is the restart run of a solution that you also want to use as an initial run. For SOL 401, the data is saved in the .op2 file.For SOL 402, the data is saved in the .op2, .sdb, .adb, and .u18 files.Select No if this is the restart run. The solver does not save restart data.	RSTGEN
Restart Parameters
Restart Option	Specifies whether you want to use the results of the initial run for this solution.
Restart File	Available when Restart Option is set to Yes.Sets the name of the .op2 file of the initial run. The restart subcases in this file populate the Restart Subcase list.
Restart Subcase	Available when you select a restart file.Specifies the subcase whose results you want to use in the restart run. The restart solution starts from the end computation state and final time step of the subcase you select. The restart solution uses the restart subcases that precede or equal the specified subcase. If you cloned the initial run solution to be your restart solution, the restart solution has the same subcase ID numbers of the initial run solution. Thus, the restart subcases in the initial run .op2 file replace the same numbered subcases in the restart solution starting with the subcase you select here. If three restart subcases are available and you select subcase 2, the solution starts with the end state of subcase 2 and recomputes subcase 3.If you created a new restart solution, the restart solution starts from the end subcase you specify here. All restart subcases prior to the one you select are included in the solution. For example, if the initial run .op2 file contains five subcases and you specify subcase 3 as the subcase from which to restart the solution, subcases 1 and 2 are included in the restart solution, but subcases 4 and 5 are not.To verify the subcase IDs and the time steps that you want to use, view the initial run results in the Post Processing Navigator. The Post Processing Navigator organizes the results according to subcase ID and time step.	RSTFROM
Execute Subcase	Available when you select a restart file.Specifies the subcase from which you want the restart run to start. The option you select depends on whether you are using a cloned solution or a new solution, and whether your initial run results are for preload/pre-stress or troubleshooting convergence. Note: The subcase you select must be sequentially dependent.Restart Subcase ID + 1Start the solution with the first subcase that follows the restart subcase. For example, if the restart subcase ID is 3, the solution starts with subcase ID 4, and subcase 4 uses the results of subcase 3. Select this option when your initial run results contain preload or pre-stress results that you want to use with the solution.Restart Subcase IDStart the solution with the restart subcase. Select this option to continue a subcase that did not converge in the initial run. The end time of the restart subcase must be greater than the time step that is saved in the restart results for this subcase.First SubcaseStart the solution with the first subcase in the solution. Select this option when you create a new restart solution instead of cloning the initial run solution. This is useful when your initial run results contain preload or pre-stress results that you want to apply to a different analysis.When you select this option, the restart subcase precedes the first subcase in your new solution. Because the restart subcase precedes the first subcase, you must ensure that the end time of the first subcase in the new solution is greater than the end time of the restart subcase.Note: The subcases are renumbered in the .op2 file. For example, even though your restart solution starts with subcase 1, the results in the .op2 file start with the restart subcases. Thus, if two restart subcases are in your initial run results, the subcase 1 in your solution becomes subcase 3.If these options are not suitable for your particular restart solution, you can specify a specific subcase number in the Nonlinear Control Parameters - Global modeling object. If you do not specify a starting subcase, the solver starts with the subcase you specified for Restart Subcase.	EXEFROM
Model Validation for Restart Run	Available when you select a restart file.Specifies whether to compare the model data in the initial run .op2 file to the current model data. In general, the models should match. Sometimes, however, you may need to modify the model to ensure convergence. For example, you may need to add a spring connection. If you do that, select No. Otherwise, the solution will not run.For information on the changes you can make in the restart run solution, see External restarts.	MDLVAL

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Solution dialog box (Nastran), Restart Management page, Simcenter 3D 2021.1 Series

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