Modeling Hyper-elastic Material

[Amir]

Hello
I’m trying to use the nonlinear model like the Ogden or Yeho model in SOFA instead of the elastic model(position ration and young module). I found the “TetrahedronHyperelasticityFEMForceField” class in SOFA but I don’t know how to import the equation coefficients. Please help if you have similar experience in this field
Thanks

[Hugo]

Hi @amir,

Another on which we need to work on the documentation.
From the code you can read (in Ogden.h):

Real k0=param.parameterArray[0];
Real mu1=param.parameterArray[1];
Real alpha1=param.parameterArray[2];

In the ParameterSet data of the TetrahedronHyperelasticityFEMForceField, you must therefore enter ParameterSet=”k mu alpha”. Let me know if it clarifies your point.

Best

Hugo

[Amir]

Hi @Hugo
Thanks for your help. can you address me some examples in the Sofa?
Thanks
Amir

[Hugo]

Yes @amir,

Please take a look at the scene TetrahedronHyperelasticityFEMForceField.scn

I am sure it will help.

Best

Hugo

[Amir]

Dear @ Hugo
Thanks. it was very helpful. another question is for using the hyperelastic modeling do I need a Flexible plugin? because I found the Ogden model in that plugin. and in the binary version is it possible to add this plugin?
Thanks

[Hugo]

Hi @amir

Not necessarily. The TetrahedronHyperelasticityFEMForceField is available in the core of SOFA, not in a plugin, and contains the Ogden model.

Best,

Hugo

[Owen]

Hi @hugo

I am trying to use the Ogden model for my simulation as well. I am very pleased to see the TetrahedronHyperelasticityFEMForceField contains Ogden, but I am struggling to set the parameters.

As you mentioned in your previous reply, in Ogden.h:

Real k0=param.parameterArray[0];
Real mu1=param.parameterArray[1];
Real alpha1=param.parameterArray[2];

Considering the equation of the strain energy density in the Odgen model, does it mean N is assumed to be 1 for the Ogden model on SOFA? I am wondering how to set the parameters if we have 3*mu and 3*alpha in an Odgen model where N=3.

Many thanks,
Owen

[Hugo]

Hi @qwe12050

I did not implement the class myself. You are perfectly right: it clearly appear that the only order available in the class TetrahedronHyperelasticityFEMForceField is the order 1 for Ogden. I am sorry about this. Changing the code could not be too difficult though.
Best,

Hugo

[Author]

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