[Insight-users] Simulating Soft-Tissue Deformation with itk::fem

[Luis Ibanez]

Hi Ryan,

    Are you using the LinearElasticy in the Materials ?

That should provide the internal forces that you are needing.

It may be a matter of finding the appropriate values for the
elasticity.

Please NOTE that, when applied to images, the FEM framework
must be seen as a "Virtual" model. You should not be using
the material properties of real tissue. Instead, you should
use property values that are in the appropriate order of
magnitude of the External Forces and the scale of distances
in the image.


    Regards,


       Luis


-----------------
Ryan Barr wrote:
> Hi, I've been using the itk::fem framework to simulate soft tissue 
> deformation for a vtkUnstructuredGrid model. I am using the 
> SolverHyperbolic class and it works as far as applying external forces 
> goes. My problem is that there is no "internal" force counteracting 
> external forces. For example, if I apply a LoadGravConst to a beam with 
> Boundary Conditions on its ends, then the middle continues to sag more 
> and more every dTime. At no point does the fem model become stable. 
> Furthermore, when any external forces are removed (such as LoadGravConst 
> or LoadNode), then the model remains as it was and never returns to its 
> original shape.
> 
> Changing material properties simply affects how great the displacement 
> is for each dTime.
> 
> Am I missing something, doing something wrong, or is this simply not 
> implemented (I know itk::fem framework is aimed at segmentation)?
> 
> Thanks,
>  Ryan
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