Multiaxial vibration fatigue

[jasasonc]

This pull request includes several changes to the FLife package, including new modules for multiaxial vibration fatigue, multi-point models and visualization. Change of the input type for SpectralData object from tuple to dictionary.

New modules:

• EquivalentStress class for calculating uniaxial equivalent stress from multiaxial stress states. Also supports the calculation for the whole FEM model and critical point selection. The following multiaxial criteria are currently available:

  • Maximum normal stress on critical plane
  • Maximum shear stress on critical plane
  • Maximum normal and shear stress on critical plane
  • EVMS: Equivalent von Misses stress
  • Carpinteri-Spagnoli criterion
  • Frequency-based multiaxial rainflow criterion
  • Thermoelasticity-based criterion
  • EVMS adaptation for out-of-phase components
  • Nieslony criterion, combining von Mises and hydrostatic stresses
  • Equivalent Lemaitre stress
  • LiWI approach
  • COIN-LiWI method

• visualize for visualizing FEM models and interactively displaying equivalent stresses and critical point selection

Input type change:

• SpectralData object is now created by passing a dictionary input instead of tuple. Type of input signal (PSD or time history) is defined with correct keys. This improves clarity and allows for future upgrades. Backward compatibility is handled.

[jankoslavic]

@jasasonc thank you! This is a great PR. I have invited @azorman to review this PR and give suggestions. Let's wait some time.

[azorman]

It looks to me you did a great job. I would just check the FLife.rst and code.rst files in docs/source folder, which are used for generating the documentation.

[jankoslavic]

@azorman, @jasasonc Thank you! Any more suggestions?

[jankoslavic]

looks ok to me

[jankoslavic]

@jasasonc please add your name to the authors (second place); add also the MSSP thermoelasticity as multiaxial criteria article (which was the reason for this code) to the references in readme. Please also change the version to 2.0.0; this is a big step!

[jasasonc]

@jankoslavic done. I think we are ready to merge.

[jankoslavic]

@jasasonc great PR. Thank you!