# HDPE hyperelastic modelling in Abaqus

Dear Dr.Bergstorm,

Thank you for your time, I am trying to model HDPE PE-100 temperature dependent behavior under compression and tension as a hyperelastic material. I have conducted tensile and compression tests and tried to curve fit the combined data (uniaxial) to abaqus hyperelastic models, however, the only stable model is marlow, which does not accept both compression and tenisle data except for trusses, beams, and rebars.Â

Therefore, I have tried defining the uniaxial test data in Abaqus using the tensile test data and the biaxial data using the equibiaxial tension data which is the same as the compression test data (but positive), using the equivalency of stress state mentioned in abaqus manual (abaqus 6.14 , 22.5.1 hyperelasticity). Moreover, I tried fitting the test data with all the strain energy potentials functions in Abaqus (Ogden (N=1 to N=6), Polynomial (N=1 & 2), Reduced polynomial (N=1 to N=6), etc..), However, I did not get any good fit plus the fact that most of the fits were unstable. Finally, I tried the free two week version of Mcalibration software to get a good and stable fit for my data but with no luck.

I currently do not know what to do in order to obtain a stable and good hyper-elastic fit for both my tensile and compression test data in Abaqus. I really appreciate any help.

Thanks and sorry for the long post.

Â

Can you post your MCalibration (mcal) file here? If you do, then I can take a quick look and see what hyperelastic material model that I would recommend.

-Jorgen

Hello Dr.Bergstorm,

I am the same user as (aheshahin) who asked this question, for some reason, the website has banned my previous account (aheshahin). Anyway, this is the link to the MCal file on google drive. The data are taken from my tesnile and compression experiments at 23 C, from -0.1 engineering stain to 0.1 engineering strain. I really appreciate your help. https://drive.google.com/file/d/1PbPFINOorrAc7N4p5sH3vL9ASDEdtkUH/view?usp=sharing

Kind regards,

Ahmed

I just downloaded yourfile. Here it is.

Also, I changed some settings on the forum. You should now be able to attach the file, and you should not be banned again. Sorry for that issue.

I will review your file soon...

-Jorgen

There are some issues with your experimental data.

At time=0, the strain needs to be 0 and the stress needs to be zero. Your file has a very large negative stress at time=0. See attached screenshot.

If you performed both a compression and a tension test then you should create a MCalibration "Load Case" for each experimental test.

I suspect that the reason you could not calibrate an accurate material model is caused by this experimental data issue.

-Jorgen

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