doc: add jax-fem example

[jacanchaplais]

Relevant issue or PR

Closes #4.

Description of changes

• Move vectoradd_jax example to a subdirectory of examples/
• Improve README for vectoradd_jax
• Add jax_fem example, with README, run script, and example JSON input for bar parameters

Suggested by @dionhaefner

• Explore whether we can use default values for arrays to make bar_params auto-populated
• Make the output a spatially resolved field (some FEM solution, eg. stress)
• Add related output plots

Testing done

None yet. Will need to test, since this is an extract of #9, and bits may be missing.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.95%. Comparing base (8e0ba97) to head (2d359c5).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #12   +/-   ##
=======================================
  Coverage   94.95%   94.95%           
=======================================
  Files           4        4           
  Lines         218      218           
  Branches       25       25           
=======================================
  Hits          207      207           
  Misses          8        8           
  Partials        3        3           

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[jacanchaplais]

@apaleyes I think the massive diff is sort of unavoidable because of examples/ directory being changed. The only file which was actually changed in the vectoradd_jax subdirectory was the README. Everything else under that directory is just copying the files. The actual diff is under examples/jax_fem/.

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[NolanBlack]

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2 out of 3 committers have signed the CLA.✅ (jacanchaplais)[https://github.com/jacanchaplais]✅ (dionhaefner)[https://github.com/dionhaefner]❌ @NolanBlackYou can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.

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[NolanBlack]

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[NolanBlack]

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what am I missing here? 🫠

[apaleyes]

@jacanchaplais @NolanBlack just wondering if this PR is done and just waiting for a review, before diving into said review. Any clues?

[jacanchaplais]

Hi @apaleyes! The data generation part is done, but the visualisation still needs to be performed. Not being an CAD / engineering guy, I don't know what a meaningful visual of the data would be. @dionhaefner mentioned he may assign himself the task for fun, but either way we'll need somebody to take the von Mises stress and come up with a nice PyVista visual for it to merge this PR.

[dionhaefner]

Should be stable from my side. @jacanchaplais want to give this a spin? The README likely needs to be updated too.

[jacanchaplais]

Seem to be getting errors due to the shape of the bar params. This occurs both with the provided bar_params.json file, and copying and pasting the example from the help text above the input.

[dionhaefner]

Should work now, good catch.

@NolanBlack Would you be able to verify whether the von-Mises stresses look reasonable? I have no intuition for this 😅

[jacanchaplais]

Should work now, good catch.

Works for me and looks cool! Thanks @dionhaefner! :)

[NolanBlack]

Should work now, good catch.

@NolanBlack Would you be able to verify whether the von-Mises stresses look reasonable? I have no intuition for this 😅

I pushed some fixes and polish. I think everything is okay now, at least this seams to make sense to me:

The only nit I still have is that the output stress should be perfectly symmetric about the x axis, but it is slightly off. Likely just interpolation errors when doing the surface->sdf->density translation. IMO this is too picky for the scope of this project, but I just wanted to document this :)