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