Lattice-Modelling of Nuclear Graphite for Improved Understanding of Fracture Processes

UoM administered thesis: Phd

  • Authors:
  • Craig Morrison

Abstract

The integrity of graphite components is critical for their fitness for purpose. Since graphite is a quasi-brittle material the dominant mechanism for loss of integrity is cracking, most specifically the interaction and coalescence of micro-cracks into a critically sized flaw. Including mechanistic understanding at the length scale of local features (meso-scale) can help capture the dependence on microstructure of graphites macro-scale integrity. Lattice models are a branch of discrete, local approach models consisting of nodes connected into a lattice through discrete elements, including springs and beams. Element properties allow the construction of a micro-mechanically based material constitutive law, which will generate the expected non-linear quasi-brittle response.This research focuses on the development of the Site-Bond lattice model, which is constructed from a regular tessellation of truncated octahedral cells. The aim of this research is to explore the Site-Bond model with a view to increasing understanding of deformation and fracture behaviour of nuclear graphite at the length scale of micro-structural features. The methodology (choice of element, appropriate meso length-scale, calibration of bond stiffness constants, microstructure mapping) and results, which include studies on fracture energy and damage evolution, are presented through a portfolio of published work.

Details

Original languageEnglish
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Award date1 Aug 2016