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increasing LS-DYNA run time abnormally

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Posts: 15
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(@kamrani)
Paid Intern
Joined: 3 years ago

Dear All

I have made a car chassis crash model with 50 mSec termination time. At the beginning of LS_DYNA running, estimation of run time is 15 hr that is normal I guess. After a while (approximately after one hour and at 1.6 mSec of solving time) the run speed decreases abnormally. after Ctrl-c and SW2. I see 277777 hr for run time estimation, that means continuing the run is really impossible although the software is still running. Of course this problem is Simultaneous with a huge buckling of a angle section part in the model and breaking some of it's elements due to it's impact to rigid wall. However I'm not sure to be relation between these two phenomenon because even before of time 1.6 mSec such sophisticated impact and breaking was happen for another portions of the model. 

please help me to solve the problem.

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Negative Volume
Posts: 665
Admin
(@negativevolume)
CEO
Joined: 6 years ago

Hi @kamrani,

How many cpus are you running this on? Or a better question is are you running this on a local computer or a cluster/HPC? 

Also, you can check your energy plots and I’m sure you will see some weird behavior. Look at your total energy, internal, kinetic etc and see how it looks.

Additionally, try running the same simulation without contact between the wall and vehicle and see if you get the same problem. If you do, then it’s something wrong with the vehicle model or the wall if it’s deformable.

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Posts: 61
(@icebreakersours)
Lab Tech
Joined: 4 years ago

Weird!

Are you running out of memory by any chance?

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