Fractures in nuclear graphite

Expanding PhD Research to Nuclear Power Plant Safety

PhD research, initially focused on bone fatigue fracture prevention, has been uniquely applied to enhance the structural integrity assessment of nuclear power plants in the UK. Key highlights of this interdisciplinary application include (Athanasiadis et al., 2023):

• Industrial Collaboration: Temporarily pausing my PhD to contribute to a project on modelling fracture in irradiated graphite bricks in Advanced Gas-Cooled Reactors. This project involved collaboration with EDF Energy and Jacobs.

• Extension of MoFEM: Extending the functionality of MoFEM, developed during my PhD, to efficiently map heterogeneous fields and enhance postprocessing features for High-Performance Computing (HPC) capabilities.

• Industry Interaction: Gaining valuable experience through technical sessions and progress meetings with industrial partners.

• Workshop Organization: Organizing two workshops at the University of Glasgow in 2020, aimed at training partners in using our code for simulations.

• Impact on Nuclear Safety: Facilitating the use of novel technology for simulations supporting safety cases for the UK’s nuclear power plants operations, thanks to sustainable development practices within the MoFEM team.

• REF2021 Impact Case Submission: Submitting an impact case to REF2021, demonstrating significant cross-disciplinary applications of the research.

Configurational Mechanics in Heterogeneous Materials

“Configurational Mechanics for Modelling Continuous Crack Propagation in Heterogeneous Materials” extends the principles of configurational mechanics to modelling crack propagation in brittle, heterogeneous materials. Key aspects of this work include:

• Theoretical Basis: Utilizing principles of configurational mechanics, based on the local form of the first law of thermodynamics, for establishing equilibrium conditions for the crack front.

• Crack Propagation Direction: Applying the principle of maximal energy dissipation to determine the direction of crack propagation in line with configurational forces.

• Handling Heterogeneous Materials: Extending previous formulations to include the influence of spatially varying material stiffness, introducing an additional force influencing the crack front movement.

• Monolithic Solution Strategy: Simultaneously solving for material and spatial displacements, enabling discrete displacement discontinuity resolution without the need for mesh refinement or enrichment techniques.

• Advanced Numerical Techniques: Implementing arc-length procedures for dissipative loading path tracing and mesh smoothing for maintaining mesh quality.

• Demonstration of Efficacy: Validating the performance of this formulation through numerous numerical simulations, showcasing both accuracy and robustness.

This research marks a significant contribution to both the fields of engineering mechanics and nuclear safety, demonstrating the versatility and impact of the methodologies developed during bone fracture research.