If an Explicit Dynamics analysis has partially or totally completed, you can resume the analysis from a non-zero time step (cycle). You may want to do this in order to:
Extend an analysis that has successfully completed beyond its current end time or cycle.
Complete an analysis that has been interrupted. For example you may wish to interrupt an analysis in order to review results part way through a longer simulation.
Continue an analysis that has stopped part way through. For example, if an analysis has terminated prematurely due to the time-step size being too small, you can make adjustments to mass scaling, and restart the calculation.
Adjust the frequency of restart file, result file or other output information. For example, you may wish to re-solve part of an analysis that is of interest with more frequent results.
Adjust damping or erosion controls.
You may resume an analysis from any cycle that has a restart file by first selecting the cycle in the Resume From Cycle field located in the Step Controls section of the Analysis Settings, then making any other required analysis changes and selecting Solve. The frequency of restart file output is controlled in the Analysis Settings Output Controls. There is no limit to the number of times an analysis may be resumed.
The following restrictions apply:
Changes made to any feature of the model outside of the Analysis Settings will prevent a resume from taking place.
Changes made to any of the (Analysis Settings) Solver Controls, except for Minimum Velocity, Maximum Velocity and Radius Cutoff, will prevent a resume from taking place.
Changes made to the Retain Inertia of Eroded Material field will prevent a resume from taking place.
Changes to all other Erosion Controls, Damping Controls, and Output Controls are valid and will not prevent a resume from taking place.
Note: You cannot edit the Static Damping and Output Controls for load steps with End Time values smaller than the Restart Time corresponding to the Restart Cycle.
To use Automatic Mass Scaling under Analysis Settings, Step Controls), it must be enabled from the start of the calculation. You cannot change the Automatic Mass Scaling property for a restart calculation. If Automatic Mass Scaling is active, the other Mass Scaling properties may be changed part way through a calculation.
Analyses with non-zero Displacement constraints defined may not be resumed.
For a model with loads and constraint, when using the resume capability to extend the end time of an analysis, the following points should be considered.
Loads and constraints may not be modified after cycle zero.
If an analysis end time has been increased, then it is possible that the analysis time may fall outside the defined region of a time-dependent load or constraint. If this is the case, no load or constraint will be applied.
Time-dependent data for loads and supports can be defined for times greater than the end time of the analysis, and these will become valid if the end time is then extended for a resumed analysis.
The solver representation of loads and constraints may be verified by looking at admodel.prt in the Solver Files directory.