LS-DYNA Restart Tutorial

In this tutorial you will learn how a LS-DYNA simulation can be restarted on the Rescale platform. You can use this tutorial in distributing your analysis into multiple steps to review the results and continue as needed. Please contact us if you're having trouble.

As part of this tutorial, we have split the analysis into two parts:

  1. Step 1: Performing the initial job run.

     A. Run the desired LS-DYNA as you would normally.
     B. SSH into running cluster and input sw1 switch command.
    
  2. Step 2: Using results from Step 1 to establish a restart job.

     A. Clone new job with results obtained from Step 1.
     B. Modify command line with `-r d3dump##` to instruct restart.
     C. Submit job to continue from saved point in step 1.
    
  • Click on the import Job Setup below to clone the example job. Click Submit to run the job. The job is a modified version of the LS-DYNA Neon Example with Distributed Memory Parallel (DMP), with a run duration of 0.05s to allow for ease of establishing a restart point. It is a frontal crash model with initial speed at 31.5 miles/hour created by National Crash Analysis Center (NCAC) at George Washington University. This is One of the few publicly available models for vehicle crash analysis, based on 1996 Plymouth Neon.

Import Job Setup Get Job Results


Simulation Code LS-DYNA R11.0.0
Analysis Type FEA
Suggested Hardware Onyx / 4 cores
Command
ls-dyna -i neon.refined.rev01.k -p single
Estimated Run Time 24 minutes


Ensure that you utilize the Live Tailing feature to moniter the ls-dyna.log file and the simulation run time under termination time.

Once the simulation run time reaches 15000, you'll need to SSH into your running cluster. For this tutorial, it is recommended that you utilize In-browser SSH for simplicity.

ssh.png

Once you are on the bash interface of the virtual machine, please navigate into the correct folder using cd work/shared. Next please enter the following command echo <switch> > d3kil, replacing <switch> with the switch command you wish to execute. For example: echo sw2 > d3kil

terminal.png

Here is the list of sense switches and its response for LS-DYNA:

  • sw1 - A restart file is written and LS-DYNA terminates (cluster will shutdown)
  • sw2 - LS-DYNA responds with time and cycle numbers (output in ls-dyna.log)
  • sw3 - A restart file is written and LS-DYNA continues
  • sw4 - A plot state is written and LS-DYNA continues
  • swa - LS-DYNA flushes all output i/o buffers
  • stop/quit - halt execution (cluster will shutdown)

For this instance use you are to set the switch command to be sw1, with the full input as echo sw1 > d3kil

Please note that the d3kil file will be consumed and removed once it is executed.

Clone with the Results from Step 1

  • Go to the Results section of the job. Select all the files, by clicking on the check box.

  • From the drop down menu under Actions select Clone this job with selected files as input files (see below).

step2_clone_with_results.png

Restart Simulation using Cloned Job

  • Once cloned, please ensure that you have the d3dump01 files from Step 1 as inputs, as these files are important for the restart procedure.

Set Fields

  • Edit the job name to your choice - again in this example we will use LS-DYNA Restart Tutorial [Step 2].

  • Replace the original job command from part 1 with the following ls-dyna -r d3dump01. The inclusion of the -r d3dump01 flag allows the LS-DYNA to initiate a simple restart and will begin the simulation from the point at which the job was stopped in part 1.

On completion, the Inputs page should look like as shown below.

Step2_inputfile2_review.png

Software Settings

  • Review the input files and the Command field.

Step2_commandline_changes.png

  • Once the necessary steps have been completed review and Submit the job. The job will begin from the point at which the sw1 command was input into the initial job setup in part 1.