material properties for FSI simulation

amsys · June 22, 2016, 08:57

I am carrying out an FSI simulation using ANSYS CFX and mechanical on a pipe like structure. I have uniaxial stress vs strain data for my hyperelastic material (silicone), see screenshot attached.

It seems my simulation is failing because of the material properties as I have tried running the model with more rigid materials where it has ran without error. I have tried increasing the mesh stiffness value to no avail. I am pretty confident that my mesh is good. I am not sure if I am fitting the right hyperelastic model, I have tried the Neo-Hookean as I believe it is used when the material exhibits a strain in the order of 40% which my data does (0-5[mm^-1]) but I have also tried Mooney-Rivlin which doesn't seem to make a difference.

The error that is returned is:

| CFX encountered the error: Read. Fatal error occurred when reque- |
| sting Total Mesh Displacement for FSI_Interface. |

Any suggestions would be welcome.

ghorrocks · June 22, 2016, 09:15

Does it run when you use a linear elastic material with the same elastic modulii of the start of your stress/strain curve? What about if you use the highest or lowest gradients of your stress/strain curve?

Be aware that FSI simulations are difficult and when you make them non-linear like this it becomes difficult^2. So you should expect to have some difficulties on a simulation like this.

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June 22, 2016, 09:15		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Does it run when you use a linear elastic material with the same elastic modulii of the start of your stress/strain curve? What about if you use the highest or lowest gradients of your stress/strain curve? Be aware that FSI simulations are difficult and when you make them non-linear like this it becomes difficult^2. So you should expect to have some difficulties on a simulation like this.