Development/openporosityandmicrocracking

[ElisaCappellariEC]

Pull Request: Code Update with New Models and Features

This update introduces several key developments, including new models, additional options, and expanded testing capabilities.

New Models

• Densification Model (based on P. Van Uffelen’s thesis, iDensification=1)
  • Required if venting is enabled.
  • Currently active only in the Sciantix stand-alone version, in the coupling it is not needed thanks to idensi=2 of TU.
• Venting Model (iGrainBoundaryVenting)
  • Added new settings:
    • Claisse and Van Uffelen 2015 (setting 2)
    • Pagani et al. 2025 (setting 3)
• Microcracking Model (iGrainBoundaryMicrocracking = 2)
  • Cappellari et al. 2025.
  • Requires mechanical properties, which are now included in the matrix.
• Release Model (iReleaseMode = 1)
  • Introduced an alternative release mode.
  • Instead of using the similarity ratio (50% threshold), this mode applies a gradual release curve and solves the grain boundary with coalescence by Pastore 2013.

New Options

• iDensification: Enables the densification model.
• iReleaseMode: Selects the new gradual release approach.

New Scaling Factor

• The cent_parameter has been replaced by a diffusion-based release.
• For iRelease = 1, the scaling factor selects a vented fraction curve with three available options.
• By default, it uses the lower bound from Cappellari’s 2025 Gaussian Process Regression (GPR).

New Variables

• Added parameters from Pagani’s work:
  • Porosities: residual, open, as-fabricated.
  • Densification factor.

New Tests and Regression Updates

• Kashibe (1990, 1991):
  • Based on Cappellari (2025).
  • Tests the microcracking model (iGrainboundaryMicrocracking = 2 in gold results.
  • Included in regression.py.
• Baker 1977 - 1273K Porosity Evaluation:
  • Evaluates Pagani’s porosity model (Master’s thesis).
  • Implemented as a separate Python script in the regression folder.