Running Multiple Explicit Analyses

[jae.kang]

I am trying to run multiple explicit (quasi-static) analyses in batch using Nastran Editor. 

For non-explicit analyses, I learned that I can run a batch by loading .nas files into queue and running the queue (https://equitusengineering.com/running-multiple-analysis-in-a-queue-using-batch-mode-with-autodesk/).

I tried the same procedure with .nas files that I want to run in explicit. However, when I start the queue, the solver runs non-explicit analysis instead. Is there a way to run the queue in explicit mode?

[Roelof.Feijen · Accepted solution]

Hello @jae.kang ,

You can create a batch file and run it from the Windows Command Prompt. There is a description for the implicit solver here

https://knowledge.autodesk.com/support/inventor-nastran/learn-explore/caas/sfdcarticles/sfdcarticles...

If you want to run the explicit solver you can find the command you need to use in this post

https://forums.autodesk.com/t5/inventor-nastran-forum/how-to-run-an-explicit-dynamics-analysis-from-...

[jae.kang]

Thank you! Following the links you've provided works perfectly!

[jae.kang]

Hello @Roelof.Feijen 

Since your help, I have been avidly using Command Prompt to run multiple explicit analyses. Thank you!

I've noticed a minor problem though, and I was wondering if you’ve encountered this problem too.

Often, I find that explicit analysis stalls while running in Windows Command Prompt.

When I check Task Manager , the CPU usage of Autodesk Explicit Solver drops to 0%.

However, when I click on the Command Prompt window and press Enter multiple times, CPU usage goes up again and the analysis continues. Half of the time the analysis continues until the end, and the other half the analysis stalls again.

I'm not sure what's happening behind the scene, but I feel like this issue has more to do with Command Prompt itself, where it minimizes it's CPU usage when not activated. I have also tried to set the priority of Command Prompt and Autodesk Explicit Solver as high, but that didn’t solve the problem.

Any idea or suggestion would be appreciated, thank you!

[Roelof.Feijen]

Hello @jae.kang ,

I haven't seen that behavior with the Command Prompt or an Explicit Analysis before, but I have seen it with Inventor.

I thought it was specific to Inventor, but I am now wondering if it is not caused by the operating system. You may have to look for it in the Power Options. For example, when does the Hard Disk go to sleep or the Processor Power Management settings. But to be honest, I also wouldn't know what's causing this.

[jae.kang]

@Roelof.Feijen 

Thank you for replying and the suggestion!

I was presuming that this problem is specific to Windows Command Prompt because I no analyses stalled on me when I ran them on Inventor Nastran or Nastran Editor. But I haven't ran that many analyses in those two, so who knows.

I tried playing around with the Power Option but that didn't do much. I also forgot to mention that the first stalling can happen from seconds to few minutes into analyses.

I tried this one thing and it seem to stop stalling most of the time:

- while running an analysis in Command Prompt, set Autodesk Explicit Solver priority to High in Task Manger

- activate Command Prompt window and press Enter multiple times

- immediately after hitting Enter, right click title bar of Command Prompt and open Properties

- while the Properties is open, analysis does not stall. Leave the Properties window open until the analysis is complete.

I'm guessing that having Properties window open keeps the Command Prompt active and running. I find that this method does not always work, but it works most of the time.