Struct mech stress

[Vybornak2]

Adding basic stress calculation functions based on #12 .

Currently did not implement generics as for the sake of simplicity.
Mypy precommit hook version has been upgraded to resolve np.linalg mypy errors.

Please check validity calculation functions @KarasTomas.

[Vybornak2]

Tests are missing and are yet to be implemented before merging of the PR.

[Copilot]

Pull Request Overview

This PR adds basic stress calculation functions for structural mechanics, introducing a new struct_mech module with comprehensive stress analysis capabilities. The implementation includes principal stress calculations, equivalent stress measures (von Mises, Tresca), and utility functions for handling Voigt notation tensors.

• Implements fundamental stress metrics including principal stresses, hydrostatic stress, von Mises stress, and Tresca stress
• Adds utility functions for Voigt notation handling and tensor conversions
• Updates pre-commit hook versions to resolve mypy compatibility issues with numpy.linalg

Reviewed Changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/fatpy/utils/voigt.py	New utility module for Voigt notation vector handling and tensor conversion
src/fatpy/struct_mech/stress.py	Main stress calculation module with principal stresses, equivalent stresses, and invariants
src/fatpy/structural_mechanics/eq_stresses.py	Removed placeholder content
.python-version	Added Python 3.12 version specification
.pre-commit-config.yaml	Updated pre-commit hook versions for compatibility

Comments suppressed due to low confidence (1)

src/fatpy/struct_mech/stress.py:1

• The if __name__ == "__main__": block contains commented-out test code and should be removed from production code. This type of debugging/example code belongs in tests or documentation, not in the main module."

"""Calculate fundamental stress metrics and invariants.

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[KarasTomas]

Overall the main changes are for the Voigt vector and tensor handling in utils/voigt.py.
The option for adding time as another dimension for stress data as well as component ordering should be further discussed.

[Vybornak2]

Changes implemented:

functions now utilize vectors of shape (... , 6)
stress_voigt replaced with stress_vector_voigt
signing function now handle edge cases
tests implemented

@KarasTomas please look at implemented tests, review the changes

[Copilot]

Pull Request Overview

Copilot reviewed 8 out of 12 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/fatpy/struct_mech/stress.py:1

• The eigenvalues from np.linalg.eigvalsh are returned in ascending order, but the function expects descending order. Using principals[0] and principals[2] assumes descending order (σ1, σ2, σ3), but eigvalsh returns ascending order. This should use principals[-1] and principals[0] or sort the eigenvalues first.

"""Calculate fundamental stress metrics and invariants.

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[KarasTomas]

The updated version correctly implements the variable stress vector dimension as requested.
Tests were also implemented.
Function docstrings were upgraded as well.

[Copilot]

Pull Request Overview

Copilot reviewed 8 out of 12 changed files in this pull request and generated 4 comments.

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[KarasTomas]

The stress functionality is ready for merge to main.