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ANSYS Ogden HyperFoam and Lateral Strain

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Posts: 6
Topic starter
(@slaterim)
Active Member
Joined: 3 years ago

Hi, I have compression strain, lateral strain, and compression stress data.  I see that the Ogden HyperFoam model creates a beautiful fit to the compression stress-strain data.  Now, I'd like to see if it attempted to fit the lateral strain.  If, by default, it doesn't, how to invoke?  Is it even necessary to fit the lateral strain?  Are there any videos or blogs on the subject?

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Posts: 6
Topic starter
(@slaterim)
Active Member
Joined: 3 years ago

Sorry, I didn't mean to offend:  by "it", I meant the MCalibration software.

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Posts: 3998
(@jorgen)
Member
Joined: 5 years ago

That is a good question. By default, MCalibration only tries to match the experimental stress-strain response. But if you have transverse strain data, then you can instruct MCalibration to also use/fit that data during the calibration. To do this all you need to do is to specify a fitness weight for the transverse strain for the desired load cases. By default the fitness weight for the transverse strain is set to 0. Here's an image.

/Jorgen

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(@slaterim)
Joined: 3 years ago

Active Member
Posts: 6

@jorgen,

I had multiple replicates for both lap shear and compression and had MCalibrate combine them into one average curve each.  How can I be certain that it took the average of the transverse strain as well?  And how can one see the fitting to the transverse strain?  Is there a virtual experiment to help with this?  Sorry if some or all of this does not make sense.

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(@slaterim)
Joined: 3 years ago

Active Member
Posts: 6

There is one selection for column heading for lateral strain.  I take it that if a user would input engineering longitudinal strain then it would be assumed that the lateral strain is also engineering.  Would the lateral strain be assumed as true if true longitudinal strain were input?  It isn't clearly stated anywhere.

For foam, is there an advantage of inputting the true values over the engineering values?

I also see that there is a POLYUMOD - Three Network Foam model.  How does one purchase the user material Fortran code needed for this model in ANSYS?  It isn't built-in, correct?

Thanks for any help in with these questions.

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Posts: 6
Topic starter
(@slaterim)
Active Member
Joined: 3 years ago

Thank you for response.  That helps.

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