The error of LS-DYN...
 

The error of LS-DYNA cutting simulation  

 

Takaishi
(@takaishi)
New Member
Joined: 6 months ago
Posts: 4
November 28, 2019 3:32 pm  

I set a cutting simulation as ls-prepost and the unit is kg-ms-ms, but when I input the .k to ls-dyna, it print this kind of error. I try to find the reason but failed. Who could help me solving this problem?

1574955161-2019-11-28-112624.png

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Takaishi
(@takaishi)
New Member
Joined: 6 months ago
Posts: 4
November 28, 2019 3:35 pm  

Correct: kg-mm-ms, not kg-ms-ms.


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Negative Volume
(@negativevolume)
Estimable Member Admin
Joined: 1 year ago
Posts: 217
November 28, 2019 4:26 pm  

@takaishi

This seems to be an issue with a couple people here. There was a topic a while back by @erick and I’m not sure if he ever got it figured out:

https://feassistant.com/forums/ls-dyna/what-may-be-the-cause-for-forrtl-severe-157-program-exception-access-violation-error-how-can-it-be-addressed/#post-100

A few thoughts that may cause it would be if there is a contact between two rigid parts or if there are initial intersections between parts in a contact. Are you experienced or beginner in LS-Dyna?


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Takaishi
(@takaishi)
New Member
Joined: 6 months ago
Posts: 4
November 29, 2019 12:49 am  

@negativevolume

Sorry, I just join this forum yesterday and I regard the "report" as "reply". Just now I edit my message and report to you.


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Negative Volume
(@negativevolume)
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Joined: 1 year ago
Posts: 217
November 29, 2019 1:00 am  

@takaishi

It’s okay. Report is for reporting somebody’s post for violating the rules.


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Takaishi
(@takaishi)
New Member
Joined: 6 months ago
Posts: 4
November 29, 2019 1:22 am  

@negativevolume

Sorry again, I though that report is writing message to somebody. I didn't notice the icon of it.

Thanks for your reply. I'm a beginner in LS-DYNA for cutting simulation. I set the .k according to a video at a website before. I used my 3D model and his parameters such as Density, Elasticity Module and so on. It is successful.

His simulation is about common cutting but mine is micro cutting. And his unit is g-cm-us, mine is kg-mm-ms. My 3D model's length is 0.x mm approximately. It's also to say that when I use his parameters, my model is 0.x cm.

After success, I adjusted the order of magnitudes of parameters to change the unit to kg-mm-ms. But this time the error appeared. I don't know why it is. I just changed the order of magnitudes and didn't change values.


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Negative Volume
(@negativevolume)
Estimable Member Admin
Joined: 1 year ago
Posts: 217
December 17, 2019 9:31 pm  

@takaishi

Sorry this is so late, I finally got a look at the files that you sent me. I ran both files but I feel like you named them backwards or maybe you converted the opposite way?

The *Control_Termination time of the g_cm_us one should be 0.4 us, not 4 us. The length conversion seems correct but your sph mass conversion is off because it went from 0.006 kg to 6.0e-6 g, it should be 6 g. 

Both of these issues are probably causing weird issues with your simulation timestep. 

I hope this helps. 


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