Initial strain erro...
 
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Initial strain error

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(@justintime98)
Student
Joined: 4 months ago

Hello everyone, 

I am trying to use an altered stress state of the material as initial condition for the analysis, I used the function INCLUDE with the dynain file, however i received warning 30183 shell strains inactive and 30136 solid strains inactive.

Does anybody know how to actually include these data in the initial condition of the simuation? 

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Negative Volume
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(@negativevolume)
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Joined: 4 years ago

Hi @justintime98, this is my personal experience, but I believe you need to import the dynain file into a preprocessor like Primer which converts the altered state stresses into *Initial_stress cards, which you then save out to include in your 2nd simulation. I'm not sure if this is possible with LS-Prepost if that's what you are using. I feel like it should be though...

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(@justintime98)
Joined: 4 months ago

Student
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@negativevolume Thank you for the help, I will try to look into Primer; however in the input keyword the initial values for strain seem to appear, still I receive the warning when I try to run the code.

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Negative Volume
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(@negativevolume)
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@justintime98 can you upload an image of your input keyword you are talking about?

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(@justintime98)
Joined: 4 months ago

Student
Posts: 8
(@justintime98)
Joined: 4 months ago

Student
Posts: 8

Moreover, it seems to be that at step zero of the d3 plot the effective strain are actually non-zero, hence it could be just a visual bug of the solver... 

 

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Negative Volume
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(@negativevolume)
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@justintime98 hmm, so if you remove the *Include with the dynain file, then all of those *Initial_ files are no longer in the model correct? Just trying to make sure those weren't already there. I've never known you can just *Include a dynain file which is why I'm asking. 

Seems like the issue you are getting is only due to the *Initial_strain. In my experience, I've only used *Initial_stress for things like pre-loading or settling simulations. So I'm not sure you need the strain anyways if you already have the stresses. Try just using the *Initial_stress and see how that works out for you. 

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(@justintime98)
Joined: 4 months ago

Student
Posts: 8

@negativevolume yes I created just a blank file and then use the option INCLUDE to load geometry, stress and strain data. Actually it's possible that I don't need the strain, my purpose is to evaluate a structure under subsequent impacts and testing.

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Negative Volume
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(@negativevolume)
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@justintime98 Oh very cool, that's good to know. Let me know how it works with just the stress.

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Negative Volume
Posts: 577
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(@negativevolume)
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Here's an alternative approach too. I'm looking into if Prepost can do what you need though. 

https://www.dynasupport.com/howtos/general/preload-general

Also look into *inital_foam_ref_geometry. It's more restrictive in terms of what materials you can use, but you just input the initial nodal coordinates of all the parts you want preloaded and it will preload those parts. 

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