About the Project
3.5-year D.Phil. studentship
Project: Solid mechanics analysis of deformation of fusion reactor components during operation
Supervisors: Dr Ed Tarleton & Prof Sergei Dudarev
Irradiation-induced dimensional changes and build-up of stress in fusion reactor components due to irradiation are important factors affecting the reliability of reactor operation. Recent experimental work on ion irradiated tungsten performed at Oxford showed that irradiation-induced stresses can be large, up to several hundred MPa in magnitude. The aim of the on-going experimental and modelling research is to accurately predict irradiation-induced dimensional changes and their dependence on irradiation dose, temperature and material microstructure. This in turn requires the development of a computational framework for simulating effects of irradiation on the dimensional stability of fusion reactor components exposed to irradiation during its operation.
The project will explore an area of modelling and simulation that has so far not received attention. The analysis will involve the simulation of deformation of geometrically complex mesoscopic and macroscopic engineering parts. Examples include cantilevers, rings, pipes, shells and more complex components, exposed to fluxes of irradiation producing almost arbitrarily complex spatial distributions of radiation defects in materials. We have recently  developed a new method for computing the stress induced by defects through a body force applied in the finite element method. The body force is proportional to the gradient of the density of relaxation volumes of defects and dislocations, which has been extensively explored in [2-4]. The separation of scales between the defect and dislocation microstructures and dimensions of components enables applying the far field approximation when computing the body forces , hence reducing the problem of evaluation of stress and strain to the problem of homogenization of dislocation microstructure and evaluation of relaxation volume content associated with such a microstructure.
The studentship will involve the development of models linking the evolution of defect and dislocation microstructures, in a variety of geometries and defect populations, with the finite element method (FEM) for computing deformation and stresses using Abaqus; which is widely used commercial FE software.
 Dudarev, S. L., Mason, D. R., Tarleton, E., Ma, P.-W., & Sand, A. E. (2018). A multi-scale model for stresses, strains and swelling of reactor components under irradiation. Nuclear Fusion, 58(12), 126002. https://doi.org/10.1088/1741-4326/aadb48
 Dudarev, S. L. and Ma, P.-W. (2018). Elastic fields, dipole tensors, and interaction between self-interstitial atom defects in bcc transition metals. Phys. Rev. Materials 2, 033602. http://dx.doi.org/10.1103/PhysRevMaterials.2.033602
 Ma, P.-W. and Dudarev, S.L. (2019). Universality of point defect structure in body-centered cubic metals. Phys. Rev. Materials 3, 013605 http://dx.doi.org/10.1103/PhysRevMaterials.3.013605
 D. R. Mason, D. Nguyen-Manh, M.-C. Marinica, R. Alexander, A. E. Sand, and S. L. Dudarev (2019). Relaxation volumes of microscopic and mesoscopic irradiation-induced defects in tungsten. J. Appl. Phys. 126, 075112; https://doi.org/10.1063/1.5094852
Prospective candidates will be judged according to how well they meet the following criteria:
• A first class honours degree in Applied Maths, Engineering, Physics or Materials Science
• Excellent mathematical skills
• Good written English and spoken communication skills
The following skills are desirable but not essential:
• Ability to program in Matlab, Fortran, C++ and Python
• Familiarity with FEM and Abaqus
Informal enquiries are encouraged and should be addressed to Dr Ed Tarleton (edmund.tarleton[at]eng[dot]ox.ac.uk) or Prof Sergei Dudarev (Sergei[dot]Dudarev[at]ukaea.uk)
Candidates must submit a graduate application form and are expected to meet the graduate admissions criteria. Details are available on the course page of the University website.
Please quote 20ENGMM_ET2 in all correspondence and in your graduate application.
Application deadline: Applications will be considered as and when they are received and this position will be filled as soon as possible. The studentship will close on a Friday at a week’s notice. Please check the Courses open for studentships page (https://www.ox.ac.uk/admissions/graduate/courses/courses-open-for-studentships) for up-to-date information on the closing date.
Start date: October 2020
This studentship is funded through UKAEA/EUROfusion and UK Engineering and Physical Sciences Research Council (EPSRC) Doctoral Training Partnership and is open to UK students (full award – fees plus stipend). Full details of the EPSRC eligibility requirements can be found here.
Course fees are covered at the level set for UK/EU students (c. £7730 p.a.). The stipend (tax-free maintenance grant) is c. £15009 p.a. for the first year, and at least this amount for a further two and a half years.
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