
Running FEA or MPM Calculations
Once the input file commands are written (as outlined in the Finite Element Method and the Material Point Method sections), you can run FEA or MPM calculations. The running options, which are all in the Analyze menu, are:
- Interpret Commands
- Interpret and Check Mesh
- Run FEA/MPM Analysis
- Background FEA/MPM Analysis
- Export XML Input File - to run on another computer
This actions can also be done by clicking tool bar icons. The first three actions can be done by control (or right) clicking on commands editing field ans selecting them from the pop-up menu.
Interpret
This option will interpret the current input commands and write XML
commands to the lower part of the input commands file window. It will only interpret the commands and not launch any calculations. This option is used to check the XML
output of your commands.
If the current input commands are already direct XML
commands (which is one way to write commands), they will just be copied to the lower part of the input commands file window. When copying, the proper DTD
file will be inserted into the commands.
Interpret and Check Mesh
Before running full calculations, it is often useful to check that the input commands create the proper mesh (for FEA), materials points (for MPM) and boundary conditions for the problem you want to solve:
- Choose Interpret and Check Mesh menu command.
- You will be asked where the save the output results. Select a save location..
- The calculations will run.
This option will interpret the current commands (if needed), launch the code engine (NairnFEA for FEA or NairnMPM for MPM), but then exit after setting up the problem. For FEA problems, the analysis will not be started; for MPM problems, the calculations will exit before the first time step. As soon as the problem set up is complete, the visualization tools of NairnFEAMPM will show the mesh for the problem. You can use other visualization tools and plotting preferences, if needed, to check other features of the problem.
The set up results will appear in a results window of a results document. If a results window for the current commands is open, its calculation will be stopped (if any were running) and its document closed. You will be asked to select a save location for a new file before the calculations begin. The results will be saved to that new file when done.
Run FEA/MPM Analysis
This option will interpret the current commands (if needed) and run NairnFEA for FEA calculations or NairnMPM for MPM calculations:
- Choose Run FEA/MPM Analysis menu command.
- You will be asked where the save the output results. Select a save location.
- The calculations will run.
The type of analysis is automatically determined from the input commands. When done, the calculations will appear in a results window and the results document will automatically be saved. If a results window for the current commands is open, its calculation will be stopped (if any were running) and its document closed.
The analysis will continue until completed, although you can do other tasks, such as editing and running other calculations, while the task is in progress, To abort the task at any time, click the stop sign icon in the results window tool bar.
While an analysis is running, you cannot use visualization tools of NairnFEAMPM on that calculation. For long MPM calculations, however, you can save a copy of the current results and visualize them as a separate results file. To visualize results in progress, use the File→Export→Copy of Results... menu command and save to a file in the same folder as the input commands file. Once saved, the file will be automatically opened and you can visualize the results up to that point in the calculation.
Background FEA/MPM Analysis
Calculations run using the Run FEA/MPM Analysis command are run in foreground. If you quit NairnFEAMPM, all foreground calculations will be stopped. If you start another calculation using the same input commands file, any calculations in progress from the same input commands will be stopped and replaced by the new calculation. To avoid these two limitations, you can alternatively run calculations as background processes.
The background option will interpret the current commands (if needed) and then ask you to select a file to receive the output of the calculations. After you provide a file, NairnFEA (for FEA) or NairnMPM (for MPM) will be submitted as a background process. If the process is successfully submitted, you will get a window with the process ID and then the results window will automatically close. You can submit any number of background processes from the same input file commands provided they are output to different folders.
A background process will run until completion even if you quit NairnFEAMPM. The process, however, is running separately from NairnFEAMPM and thus you will not get feedback about when the process is done. To monitor current background jobs, use the Window→Process Info menu command. The process info will list all currently running background processes (including those that may have been submitted in earlier NairnFEAMPM sessions) and give information about the status of the job as illustrated in the following window:

The process info window tells which code engine is running, when the calculation started, how much CPU time it has used, the current percent of the CPU being used, and the memory usage for each running task (foreground or background). If you click on a task, the arguments to the job will be listed at the bottom of the window. The last argument gives the input XML file and tells the folder where the results are being saved. To terminate any job, select the job and click the stop sign icon.
While a NairnMPM process is running, you can select it and click on the MPM document icon to open the current results for that task (or double click the process line). You can visualize the calculations in progress without interfering with the continuing task. It is not useful to open a NairnFEA calculation that has not yet finished. When a background process is completed, it will disappear from the process info window. You can open the final results using the File→Open menu command. After opening the results file, you can visualize the final results.
Note that foreground processes will appear in this window as well. If you double click a foreground process, it may fail to open (for new processes) or open old results (if they happen to have same name as the input file). To visualize results of a foreground task, you should instead select the task from the Window menu and then use the File→Export→Copy of Results... menu command.
Export XML Input File
For many calculations, or long calculations, it might be desirable to submit one or many jobs for execution on a separate computer such as a cluster of computers. To use this approach:
- Use the Interpret Commands option to create the
XML
input commands without starting a calculation. - Use the File->Export→XML Input File... menu command to save the
XML
commands to a file. - Copy the
XML
commands file to a different computer that has compiled versions of NairnFEA and/or NairnMPM. To install compiled versions on another computer, you can download the source code from the code engine web site. - Submit the jobs to run on the other computer.
- When the calculations are done, either mount the disk from the other computer or transfer all results files to the Mac with NairnFEAMPM. You can then open the results file and visualize the results.