Fully Funded M2A EngD Scholarship: The Effect of Peening on Isothermal and Non-Isothermal Fatigue Behaviour in Nickel Disc Alloy RR1000

Start date: October 2019

Supervisor: Dr M Whittaker

Sponsoring company: Rolls Royce Plc

The project provides opportunity to expand on areas of thermo mechanical fatigue research, and to consider an associated critical issue in high performance nickel alloys, that of surface treatments.

Large scale testing programmes undertaken at Swansea University demonstrate the requirement for optimisation of surface treatment prior to lifing programmes for critical parts, where shot peening is used to improve fatigue life and resistance to handling damage. However, the complex interaction of residual stress with the work hardening layer can significantly influence crack nucleation in comparison to polished specimens, as residual stresses relax at high temperatures leaving only a rougher surface more suitable for cracks to initiate. Producing an optimum surface finish to deliver appropriate protection whilst also minimising fatigue life debit over polished specimens is of great strategic importance. It is hoped that guidelines established for current alloys can be used to inform future lifing programmes, minimising the need for expensive large-scale testing.

In service temperatures of new alloys continue to increase, and the influence of thermo mechanical fatigue behaviour on operations cannot be ignored. Exploratory studies indicate significant reductions in fatigue lives at temperatures approaching 750°C and oxidation and mean stress effects become increasingly significant.

The Research Engineer will:
• Explore the complex interaction of creep, oxidation, thermo mechanical fatigue and surface finish on crack nucleation at high temperatures, through testing involving variations in phase angle, strain rate, peak cycle temperature and dwell time;
• Explore appropriate lifing methodologies for complex geometries under thermo mechanical fatigue loading;
• Use high temperature test data to assess feasibility of using isothermal data in the prediction of thermo mechanical fatigue behaviours, as a cost saving measure;
• Consider any shortfalls identified and to develop new lifing approaches to take account of peak cycle temperature and phase angle, in order to deliver improved predictions.

Eligibility
We welcome applications from candidates with an Engineering or Physical Science degree (minimum level 2:1), or a combination of degree and equivalent relevant experience to the same level, to join the M2A community of research engineers.

Please visit our website for more information on eligibility.