Materials Performance Centre
Modeling Directions
Crystal Plasticity ModelingPrediction of intergranular strains and mechanical properties
• Relevant to stress corrosion cracking in stainless steels and Ni-base alloys
• Good expertise in Manchester, validated by X-ray and neutron diffraction
• Need parallelization to allow larger microstructures and studies of permutations in reasonable timescales
Grain Aggregate ModelingPrediction of intergranular stresses and strains• Relevant to stress
corrosion, and intergranular damage mechanisms
• Expertise developing in Manchester, using 3D microstructure data and diffraction-based validation
• Need to validate modeling approaches and address issues due to large model size.
Damage ModelingPrediction of microstructure effects on damage development• Relevant to stress corrosion
cracking, for example• Development of current
work on crystal aggregates, derived from tomography
• Work done so far in partnership with other institutes
• Need to develop further in Manchester
Image-Based Modeling
Dimensional Change of Graphite• Models constructed from
tomography data, with crystal anisotropy deduced from pore orientations
• Model validation against in-situ tomography of thermal dimensional change
• Aim to predict irradiation induced dimensional change
• Currently limited by model size
Image Based Modeling
Issues• How large a volume do you need to
model?• What resolution mesh do you
need?• As resolution of XMT systems
improves, data sets and mesh sizes expand
• Research Needs– Development of visualisation
methodologies– Development of serial mesh
generation– Any size mesh (so far up to 320 GB
data set)– Development of parallelised FE code– Development of XFEM
Example: fibre composite
Model
Stress Development
Grain Boundary ModelingPrediction of Diffusion and Segregation• Relevant to stress corrosion
and sensitisation kinetics• Requires molecular
dynamics methods• Currently little expertise in
Manchester in this area, but development of capability is needed to support other work
• Work being done with collaborators
Flow Assisted Corrosion
)][].([. 022 FeFeKFACrate eq
Oxide
Water H2
H2 Steel
Fe 2+
Fe 2+
Fe 2+
Fe 2+
C0
CbulkCs
• Iron oxidation to give Fe(II) or magnetite Fe3O4 at the internal metal-oxide interface
• Diffusion of soluble species• (Fe2+ and H2) across the porous
Oxide layer • Dissolution and reduction of
magnetite into solution• Removal of the soluble iron
species (and hydrogen), transported into the bulk of the flowing solution
Other Areas
• Multiscale modeling– Integration of microstructural models with
fracture propagation models
• Coupled modeling– Development of crack tip chemistry– Influence of residual stress on crack tip
deformation