Predictive modelling research
Models of deformation and failure processes in materials are being developed alongside novel experimental approaches to improve the reliability of predictions of materials performance in service. The establishment of a new high performance computer cluster is adding impetus to model development over all scale-lengths – including atomic-scale simulations, crystal plasticity finite element methods and continuum mechanics (including weld and fracture modelling).
Atomistic Modelling of Corrosion
Stephen O'Toole, PhD Student
The aim of this project will be to develop atomistic modelling tools to simulate the mechanisms of corrosion. A variety of techniques, including molecular mechanics, Monte Carlo, quantum mechanics and meso scale models, will be employed. These techniques, when combined in a multi-scale modelling approach, will allow the inclusion of atomistic level detail in models whose results will be on size and time scales which allow direct comparison with experimental results. These models will be applied to examine the properties and evolution of metal oxide surfaces, which are vital to the mechanisms of corrosion. They will also be used to look at surface coatings which provide a barrier to one or more of the mechanisms of corrosion.
Flow Assisted Corrosion Modelling
Anissa Amimer, PhD Student
Flow-accelerated corrosion is a type of corrosion that involves a coupling between chemistry and hydraulics. This degradation phenomena has been studied extensively.
At EDF, an empirical model (Berge's model, supported by experimental data) has been used to create a software package called BRT-CICERO, in order to predict the degree of flow accelerated corrosion damage for steels in various environments. However, this software rests on the assumptions made in Berge’s model.
Fracture Modelling using Continuum Damage Mechanics
Haiyan Li, PDRA
A continuum damage mechanics (CDM) model has been developed for nuclear graphite at the Manchester School of Engineering (MSE) in collaboration with the Institute of Nuclear Energy Technology (INET), Tsinghua University, China. The model is capable of predicting both the initiation and propagation of cracks in graphite components under mechanical loads, as well as under irradiation and radiolytic oxidation when used together with the User Material (UMAT) Subroutine for graphite in ABAQUS. Further details on Fracture Modelling using Continuum Damage Mechanics.
Multiscale Modelling of Fracture
Xinglong Zhao, PDRA
Current crack propagation models treat polycrystalline metals as homogeneous continua. In reality, deformation is heterogeneous, due to the elastic and plastic anisotropy of their constituent crystal grains. As a result intergranular and intergranular stresses are generated during elastic and elastic-plastic deformation. Local approach models (e.g. Beremin) use continuum mechanics as the basis for predicting cleavage probability in ferritic materials as a function of increasing load. However, intergranular heterogeneity due to plasticity is currently ignored.
Residual Stress Modelling
Philip Dai, PDRA
Finite element analysis offers a powerful technique for elucidating the factors that affect the formation and distribution of residual stresses in engineering components. For the useful application of this technique for welds in pressure vessel components it is necessary that developments be made to allow analyses of large complex structures and with the successful management of metallurgical effects (e.g. phase transformations and microstructural evolution)