Restarting

Restarting solutions saves solving time by letting you reuse previously computed results. You can use the computed results to start subcases within the same solution (internal restarts), or you can use them to start new solutions (external restarts).

Internal restarts (SOL 402)

Internal restarts start a specified subcase with the computation state (displacements, velocities, stresses, state variables, and so on) of a preload, static, or dynamic subcase during the same solve. For example, you might want to start several non-sequentially dependent (NSD) subcases with the results of a bolt preload subcase. Similarly, you can start other NSD subcases with the results of a dynamics subcase.

Although these subcases restart with the computation state of the subcase you specify, they do not restart with the end time of the specified subcase. Time continues to increment for each subcase.

Note:

SOL 401 does not support internal restarts.

External restarts

External restarts start a nonlinear solve with results from a previous solve. For example, using existing computation files (restart results), you can do the following:

• Troubleshoot the convergence of unstable models by starting from the last converged state with new solver parameters, such as activating or deactivating contact, or adjusting time step increments. Each time you use the restart results to solve the solution, you can also save new restart results. Thus, as you adjust solver parameters and the solution progresses further before failing to converge, the .op2 file contains the cumulative results up to the newest time step that failed to converge.

• Solve static computations one time and then reuse the results.For example, if your analysis requires several pre-stress configurations, such as loading bolts, inflating a tire, and accelerating a vehicle to a required speed, you can compute these static analyses and then use the resulting .op2 files to run several transient configurations, such as different vehicle maneuvers.Or, after a static computation, you might perform a modal analysis. After you analyze the results, you might realize that you need more modes. To accomplish this, just update your modal solution and then request the restart with the static computation results.

How do I

Generate results to reuse with different analyses (external restart)

Troubleshoot convergence (external restart)

Restart a nonlinear solution (internal restart) (SOL 402)

Learn more

External restarts

Internal restarts (SOL 402)

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Restarting, Simcenter 3D 2021.1 Series

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