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*Restart |
 
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*Restart
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*Restart |
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To nominate a preceding simulation as the starting point for the present analysis, and/or to specify the contents of the restart file generated by the present analysis.
Refer to Restart Analyses for further information on this feature.
A single line defining the preceding (restart) file name, restart type, database appendage type, and storage options for the restart file to be generated by the present analysis.
[LAST=Restart File Name] [, TYPE=Restart Type] [, OPTION=APPEND] [, NEXT=Supported Next Simulation Type]
Restart File Name is not required or valid for initial static analyses. Restart Type can be DYNAMIC/STATIC or CONTINUATION. OPTION=APPEND is appropriate only for a CONTINUATION analysis. Restart Type is set to DYNAMIC/STATIC by default. Supported Next Simulation Type can be AUTOMATIC (the default), FLEXCOM, FLEXCOM/MODES or NONE.
Input: |
Description |
Restart File Name: |
The name of the analysis from which the present run is to be restarted. This may be input in terms of the analysis name (e.g. Example1-Static) or the full path of the analysis (e.g. C:\Flexcom\Example 1\Example1-Static). |
Restart Type: |
The restart type, which may be either New Loads or BCs (the default) or Continuation. |
Database Appendage: |
For continuation restarts, you may create a New Database, or Append the new results to the previous ones in a single database. |
Next Simulation Type: |
This option gives you control over the contents of the restart file generated by the present analysis. If you are planning to restart a Modes or Freecom simulation from the present analysis, you should select Flexcom/Modes here. Otherwise you may use the default Automatic setting, or simply omit the keyword altogether. |
(a)Most restarts involve the addition of new loads such as current or waves, or changes to boundary conditions, and for this you use the New Loads or BCs restart type. Occasionally, a restart is performed which is simply a continuation of the previous run, and for this you use the Continuation option. An example here might be where a regular wave analysis is found not to have reached steady state, and must be continued for further wave periods. Continuation - New Database means that a new database is created, while Continuation - Append means that the previous analysis results and the present analysis results are both contained within the present analysis database.
(b)In order to restart an analysis, Flexcom requires a bank of knowledge regarding the solution status at the end of the preceding simulation, including nodal positions/velocities/accelerations, element restoring forces, contact and frictional forces, and final amounts of all user specified loads etc. Freecom and Modes also require specialised versions of the stiffness and mass matrices assembled without the flexibility coefficients, and the solution profile without the penalty terms included, which adds significantly to the time taken to write the restart file. The majority of Flexcom static analyses are only used as restart points for subsequent Flexcom simulations, and the majority of Flexcom dynamic analyses are never used as restart points. Restart file writing can be surprisingly time consuming, particularly in the context of static analysis. Starting from Flexcom 2027.1, restart file creation has been optimised in Flexcom. Consider Example C3 - Turret Disconnect for example, a model which contains 12 separate lines and 1428 elements.
1.Static Analysis: Running on a standard laptop, the static analysis takes 7 seconds to execute, but over 80% of this time is due to restart file writing. With the default settings for restart file writing (a restart file is created which supports subsequent Flexcom restarts), the run time reduces to just 3 seconds. Experienced users will notice that static analysis feels noticeably quicker as a result.
2.Dynamic Analysis: Running a regular wave simulation for 5 wave periods, the dynamic analysis takes 120 seconds to execute. With the default settings for restart file writing (no restart file is created by default), the run time reduces by 6%. However for random sea analyses, any run time savings should not be noticeable.
(c)Restart file writing operates as follows:
•Flexcom: A restart file is written which enables execution of a subsequent Flexcom simulation.
•Flexcom/Modes: A restart file is written which enables execution of a subsequent Flexcom or Modes (or Freecom) simulation.
•Automatic:
▪Static or quasi-static analysis: A restart file is written which enables successful execution of a subsequent Flexcom simulation.
▪Dynamic analysis: No restart file is written.
•None: No restart file is written.
(d)When migrating from Flexcom 2026 to Flexcom 2027 or a later version, you should bear the following in mind.
1.If you are performing a modal or frequency domain dynamic simulation (where restarting is mandatory), you must explicitly specify *RESTART -> NEXT=FLEXCOM/MODES in the preceding Flexcom static file.
2.If you are restarting a Flexcom analysis from a dynamic simulation, you must explicitly specify *RESTART -> NEXT=FLEXCOM in the preceding Flexcom dynamic file. A good example of this scenario would be Example H05 - Steel Pipe Installation in which a series of dynamic restart analyses are used to simulate the payout of the pipe over the vessel stinger down to the seabed.
(e)Filenames containing spaces must be enclosed in inverted commas, e.g., "sample 1.keyxm".
(f)The only input which is relevant for frequency domain dynamic analysis is Restart File Name.