Model for EPS material

**jakko** · 2009-01-06, 10:05

Hello all,

I like to fit a material model on the measured EPS data (see attachment) in ABAQUS. The problem is that a *Hyperfoam model can not be combined with any plasticity and a Mullins effect can not be used in a crushable foam model. Can anyone tell me what to do?

Regards Jakko

**Jorgen** · 2009-01-08, 04:38

You might be able to combine a traditional hyperelastic material model with a plasticity or Mullins effect model.

If that is not accurate enough then you can switch of a more accurate and advanced user-mateiral model, e.g. the Micromechanical Foam Model (MFM).

**jakko** · 2009-01-08, 06:26

What are the drawbacks of a traditional hyperelastic material compared to the Abaqus Hyperfoam model? It seemed to me that you are not very enthusiastic about the FeFp model in ABAQUS (according to your review), is there a specific reason why you think it will work for this specific case?

Is it possible to simulate plasticity in the Micromechanical Foam Model?

**Jorgen** · 2009-01-25, 05:26

The hyperfoam model in Abaqus is very similar to the standard hyperelastic Ogden model. The reason I sometimes recommend the hyperfoam model for foam materials is simply based on experience. I have used it multiple times and it works relatively well for low density soft polymer foams.

Besides that, there is really only one reason it migth work better than the other hyperelastic material models. The reason is that it has the ability to specify the volumetric response a sum of different terms. This can potentially improve the predictions.

You are also right about the FeFP model - it's not my favorite at this time.

It should be possible to accurately predict the experimental data that you provided using the Micromechanical Foam Model (MFM), and yes, the MFM can simulate plasticity.

-Jorgen

**jakko** · 2009-01-26, 03:09

How do I get this MFM model? Do I need to have more testdata than a compression and sheartest to fit the model?

**Jorgen** · 2009-01-26, 18:46

The MFM is only commercially available. Send me a message if you want more info.

The MFM model can be calibrated using compression and shear data. It is typically important to also have confined compression data in order to calibrate the volmetric response of the model.

**rpls2004** · 2009-02-08, 08:53

hiiii
i am doing a EPS modeling using the ABQUS, i seen your compression stress strain graph,,,,
i will be really happy if kindly let me know what is the density and the young modules, v ratio, ,,ect,,,
thanks