Add constrained mixture material model

[mrp089]

@schwarz-e has a C++ implementation of the constrained mixture model (CMM) that takes the deformation gradient and returns the stress tensor and tangential stiffness matrix. Currently, this is called from a Python code.

We have a unique opportunity to take this CMM implementation and put it into svFSIplus as a material model, which hasn't been done before in any large-scale FEM code. The challenge is that we need to store a bunch of information on each integration point, which is currently all implemented in a vessel struct. Also, we need to test if the linearization of the stress tensor is correct.

I think this could be an interesting first svFSIplus project for me.

PS: Happy issue #2!

[ktbolt]

@mrp089 This would indeed be a good first project.

You may want to wait until I add documentation describing the C++ implementation, I will do that next week. I would also like to give a presentation to explain things.

It is unfortunate that there is already a CMM, the Coupled Momentum Model, used in the FSI code. Perhaps we could refer to the Constrained Mixture Model as the Stifled Amalgamation Model (SAM) ?

[mrp089]

@schwarz-e, it's yours!

[lpapamanolis]

@mrp089 @ktbolt Just to let you know I have started working on this. If I understood well, this issue is just to add the CMM in svFSIplus. To fully integrate the FSG framework in svFSIplus, we would need an additional loop (long growth and remodelling timescale) between the Fluid and Solid (CMM) domains, which would be outside the scope of this issue. If that's the case, I can follow-up with a plan on how to integrate this in svFSIplus in a new issue.