IsoCoordsToLocalCoords + GetInternalStress Q4

[epsi1on]

Can you please update the code at line #493 of file Elements/TriangleElement.cs? I did not knew how BendingtressTensor does affect on CauchyStressTensor. Thank you so much

[rubsy92]

Hi @epsi1on

I added the code for the triangleElement, however you should be very careful with requesting the internal stress of a shell. As a user you don't know where the highest stress is (+thickness/2 or - thickness/2) so you would need to request both values and check which one is more critical. That's why I previously implemented the "SectionPoints" enum and the "UpdateTotalStress" method in the "FlatShellStressTensor" class. This enables the GetInternalStress method to determine the highest stress value and therefore I'd prefer not to put the obsolete tag on that method... After all it provides the best resemblance to Abaqus...

Cheers

[epsi1on]

yes, I've already seen the approach you've used, I'll remove the Obsolete attribute on the method. Thanks

[epsi1on]

I think we should bring this issue (highest stress) in a related example for triangle and q4 elements

[rubsy92]

Yes, I think that would be helpful. Maybe it's best to put that into the documentation? Or just as a text file in the code?

A good way to see the difference is combining a pre-stressed plate with bending. I.e. in-plane + out-of-plane loading. Then you can export the top/bottom/envelope values. I have the data, but I cannot access the documentation I guess.

[rubsy92]

I'm organizing/grouping the methods of the TriangularElement and the QuadrilateralElement a bit now. I'm also filling in the last methods which have a NotImplementedException. I'll probably make another commit today.

[epsi1on]

I think you've used the metric local coordinates, but usually iso parametric coordinates are used for getting stresses. Also in GetBMatrixAt and GetDMatrixAt iso parametric coords are used. public FlatShellStressTensor GetInternalStress(double localX, double localY, double localZ, LoadCombination combination, SectionPoints probeLocation)

Thanks

[rubsy92]

GetInternalStress expects iso coordinates, but I admit it's not clearly documented. I'll modify it.

[epsi1on]

Yes, I think that would be helpful. Maybe it's best to put that into the documentation? Or just as a text file in the code?

A good way to see the difference is combining a pre-stressed plate with bending. I.e. in-plane + out-of-plane loading. Then you can export the top/bottom/envelope values. I have the data, but I cannot access the documentation I guess.

documentation is also hosted in github: https://github.com/BriefFiniteElementNet/BFE.Net.devdocs It is entirely in rst format (reStructuredText), very similar to markdown. For adding new example, pls add new rst file in the docs/example in documentation repository then write example inside it. There are also several existing examples. I think i should combine that repository with main BFE repository.

[rubsy92]

See the new commit for:

• Organizing/grouping of the methods of the TriangularElement and the QuadrilateralElement

• Completing the methods which had a "NotImplementedException" in them

• Fixing the iso-coords misunderstanding

Are there still other methods for the shell elements which need completion?