FFMcracking: Coupled Criterion for Crack Initiation in Abaqus

This repository contains a Python script for Abaqus that applies the Coupled Criterion of Finite Fracture Mechanics in an automated manner to predict crack initiation. The script integrates with Abaqus to perform simulations and identify crack onset based on the coupled stress and energy criteria.

How It Works

The user needs to provide:

• An Abaqus input file (.inp) created with Abaqus CAE, where the geometry, material properties, boundary conditions, and mesh are defined. This input file can be generated following the standard Abaqus CAE workflow.
• A separate auxiliary file specifying the fracture and strength material properties.
• (Optional) Hypotheses about the crack initiation geometry, such as crack direction and initiation point. Providing more hypotheses will speed up the computation. If not specified, the script attempts to estimate the optimal crack geometry at initiation (feature under development).

The script calculates the load factor that, when applied to the loads in the user-defined model, leads to crack initiation, along with the corresponding crack geometry.

Features

Current Features

• Given a predefined crack geometry at initiation, computation of the load factor required to satisfy both the stress and energy criteria.
• Given a known initiation point and crack direction, automatic Bayesian Optimization to determine the optimal crack length and critical load factor.

Upcoming Features

• Crack propagation analysis: Computation of crack growth steps after initiation, following the coupled criterion of finite fracture mechanics.
• Multi-parameter optimization: Optimization of crack initiation direction and location, when unknown.
• Integration with Abaqus ODB output: Results will be saved directly in an ODB file.
• Crack initiation along bimaterial interfaces.
• Crack initiation in 3D solids.

Prerequisites

Before running the script, ensure you have:

• Abaqus 2020 or later

  Note: Abaqus 2014 has a known issue that limits the number of degrees of freedom when using XFEM.

Usage

The best way to learn how to use FFMcracking is by following the provided examples:

1. Example 1

   • Computes the load factor required for a fixed crack geometry at initiation.

2. Example 2

   • Uses Bayesian Optimization to determine the critical load factor for a problem where only the crack length is unknown.

More examples will be added as new features are developed.

How to Cite FFMcracking

If you use FFMcracking in your research, please cite the following reference:

@article{garcia2025,
  year = {2025},
  volume = {1},
  number = {},
  pages = {},
  author = {Israel G. García and Vladislav Manti\v{c}},
  title = {Implementación en un código comercial del Criterio Acoplado de la Mecánica de la Fractura Finita},
  journal = {Revista del Grupo Español de Fractura}
}

How to contribute

If you are interested in collaborating, we are willing to developing joints collaborations for:

• Developing new features from the list (see Features section or issues).
• Proposal of new features.
• Testing the script with new applications.

If you could be interested to collaborate with us, you have several options:

• Contact the the project administrator:
  Israel G. García with your ideas, motivation, etc.
• Open an issue.
• Fork the reposiroty and PR with your contribution.

Contact

For questions or contributions, please contact the project administrator:
Israel G. García