Error message
Mahmood Moosavizadeh
James Kennedy
Dear Mahmood,
I suggest looking at the dump file feature to possibly reduce your output and provide an
option to continue running (restarting) a simulation without restarting from time-0.0.
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Two types of dump files (d3dumpxx or runrsf) using either of the following data entries
*database_binary d3dump or
*database_binary_runrsf
can be written (saved).
The dump files write all the state variables values from your simulation at a particular integration cycle which will allow you to continue your simulation from that cycle, if your simulation has for some reason been unexpectedly terminated (power outage, program error, stability, etc.). Continuation of the simulation (changes allowed), called restarts, allow for changes in the input data.
I often suggest using the running restart dump, runrsf. This approach will write only one restart file (saves space) instead of multiple restart files when you use the d3dump option..
*database_binary_runrsf
$ dt/cycl
5000
The example entry of 5000 represents the output interval, in number of cycles (a cycle is a time step), that LS-DYNA will write out the restart file.
I probably would write a restart every six hours or so. Estimate the number of time steps it would take to achieve six hours of CPU and enter that as your output interval. You can increase or decrease the cycle interval as you see fit.
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Another short note.
The D3DUMP and the RUNRSF options create complete databases which are necessary for restarts. See *RESTART. When RUNRSF is specified, the same file is overwritten after each interval, unless the field NR is set which causes a series of restart files to be overwritten in a cyclic order. When D3DUMP is specified, a new d3dump file is created after each interval. After the first interval LS-DYNA will write d3dump01, after the second d3dump02 and so on. The default file names are runrsf and d3dump unless other names are specified on the execution line, see the GETTING STARTED, EXECUTION SYNTAX. Since all data held in memory is written into the restart files, these files can be quite large and care should be taken with the d3dump files not to create too many. If *DATABASE_BINARY_D3PLOT is not specified in the keyword deck, then the output interval for d3plot is automatically set to one twentieth of the termination time.
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Two comment comments regarding small restarts:
1. If you stopped your calculation prior to your original termination time, you can simply restart using the last saved d3dumpxx file with no input file needed.
2. If you stopped your calculation due to reaching your original termination time,
you can simply restart using the last saved d3dumpxx file and a new restart input deck; example given here:
*KEYWORD
*CONTROL_TERMINATION
[new termination time]
*END
Please see pages 2-21 and 2-22 in the latest LS-DYNA User’s Manual for execution syntax for Restart Analysis:
http://ftp.lstc.com/anonymous/outgoing/jday/manuals/DRAFT_Vol_I.pdf
Some older notes that might be helpful:
Day, J., “Restarting LS-DYNA”.
http://ftp.lstc.com/anonymous/outgoing/jday/restart.pdf
Sincerely,
James M. Kennedy
KBS2 Inc.
February 25, 2023
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