eigenvectors of stress tensor

[staurolite]

I would like to plot the eigenvectors of the stress tensor (i.e., the principal stresses), a seemingly routine operation. However, ElmerPost does not seem to have this ability. Gmsh has a postprocessor plugin to do this, but ResultOutputSolver cannot save Stress as a tensor (only as a set of scalars) form Gmsh to ingest. Do I really need to write out all the components as scalar fields, manually reassemble them into a tensor, and then feed the result into a postprocessor? I fear I may be re-inventing the wheel here. Can anyone tell me if there is already some Elmer-friendly code available to do this?

[raback]

Hi

I think that StressSolve can compute many kinds of stresses internally, also the principal ones.

I don't personally use Gmsh for postprocessing. It should not be big alteration to get the tensors there. Look at line ~1580 of ResultOutputSolver.src.

-Peter

[staurolite]

Thanks. I took at look at the StressSolve source, to find the undocumented features. Indeed, "Calculate Principal" correctly computes the magnitudes of the principal stresses. "Calculate PAngle" looks like it is supposed to calculate their directions, but it does not always seem to give meaningful results. In any case, it still does not produce principal stress vectors, only sets of scalars, which makes visualization difficult.

I don't usually use Gmsh for postprocessing either, but I thought its plug-in for eigenvectors might be useful in this case. In the end, however, it proved simpler just to program a filter for Paraview to successfully accomplish this, using vtu output from ResultsOutputSolver.