Uniaxial equivalent stress amplitude functionality

[KarasTomas]

Pull request following issue #40 and is prepared for other stress based uniaxial fatigue criteria like #44 , #45 and #46.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 13 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...tress_life/damage_params/uniaxial_stress_eq_amp.py	0.00%	13 Missing ⚠️

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[Vybornak2]

typo in the file name iniaxial

[Vybornak2]

This function seems to implement DRY principle, but to me seems a bit clunky and hard to extend

reason might be, that it is trying to do multiple things, so it does not have 1 responsibility only, thus it branches in its logic and is harder to fit to use cases.

think it through if it could not be improved

[Vybornak2]

I would convert ArrayLike to np.ndarray here and check for positive values
It is more explicit and does not create too much boilerplate code

In this case validate function seems as overkill to me

[Vybornak2]

I am not saying that we have to do that. Just going through cases of usage of validate function

[Vybornak2]

** 0.5 might be more readable than np.sqrt but it does not matter as much, just is more consistent with the mathematical formulas

[Vybornak2]

what about case, where user inputs real values, where some are simply too high, so some results are negative?
Is it okay to disallow user from calculating all values ?

I personally would rather raise warning and exclude it from this validation function

[Vybornak2]

validate function requires more then it brings value

[Vybornak2]

I would recommend using test classes to separate different test baste on function tested

[Vybornak2]

Test class than would be more generic, where each test case within the test class repeats for each tested function

class TestFunctioon1:
    def test_feature1():
        pass
    
    def test_feature2(): ...
 
# now same thing for class TestFunction2

[Vybornak2]

it puts a bit more structure into the test file, so it is easier to navigate
also you can run tests based on the test class and more

[Vybornak2]

Additionally the things should be added / considered:

• additional eq methods (please contact @MartinNesladek)
• STW for HCF docstring should include usage requirements and reference to SWT LCF (for now create issue placeholder until implementation)
• for each equivalent stress function should be specified what is it equivalent of (R = -1 standard or R=0, ....) and potentially other descriptive information
• consider/consult whether we should raise error for some conditions when mean stress is lower then zero or rather return stress amp as is