1. Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, C31 Coates Building, University Park, Nottingham NG7 2RD, UK
2. Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Manufacturing Building, University Park, Nottingham NG7 2RD, UK
3. Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, A63 Coates Building, University Park, Nottingham NG7 2RD, UK e-mail:
4. Repair Technology, Rolls-Royce plc, Derby DE24 8BJ, UK