stress tensor from coupled momentum method

[Pier Giuseppe Ledda]

Hi everyone,

I am familiarizing with SimVascular, in particular with the deformable wall model implemented with the Coupled Momentum Method.

I had a look at the outputs and I noticed that the stress tensor of the solid vessel is not an output of the simulation, while the displacement field as well as the tractions acting on the vessel walls are present.

I was wondering if there is a way to extract the stress tensor.

Thank you in advance for your answer,

Best regards,

PG Ledda

[Weiguang Yang]

Maybe you can do it in the post-processing. Since the wall nodal velocity is available, apply the membrane linear constitutive relationship to get the wall stress tensor:
\sigma=C:\epsilon,
where C is the material stiffness tensor and \epsilon is the strain rate tensor. See eqns 32-35 in Figueroa et al. CMAME, 2006.
For each vtu output file, use the unstructured gradient filter in paraview or paraview.simple python module can help with the calculation.
This is an idea off the top of my head. Hope it helps.

[Pier Giuseppe Ledda]

Dear Weiguang,

thank you for your suggestion. I implemented it in Paraview and the results look reasonable.

Best regards,

PG