1. Mechanics and Physics of Solids Research Group, Modelling and Simulation Centre, The Univ. of Manchester, Oxford Rd., Manchester M13 9PL, GB
2. Nuclear FiRST Doctoral Training Centre, Manchester M13 9PL, GB, e-mail: craig.morrison@manchester.ac.uk
3. Mechanics and Physics of Solids Research Group, Modelling and Simulation Centre, The Univ. of Manchester, Oxford Rd., Manchester M13 9PL, GB.