College of Engineering
Tel: +44 (1792) 295573
Senior Lecturer, College of Engineering
Specialist Subjects: Thermo-mechanical fatigue, Creep lifing, Titanium alloys, Nickel Alloys, Crystallographic texture, Fatigue Lifing, Fatigue/Creep/Environment Interactions
2012 – Senior Lecturer, , Materials Research Centre, Swansea University
2007 - RCUK fellow, Materials Research Centre, Swansea University
2003 - 2007 Research Officer, Materials Research Centre, Swansea University
Within the gas turbine engine, the high transient thermal stresses resulting from throttle movement from idle to high settings give rise to the phenomenon of thermo-mechanical fatigue (TMF). These effects have been widely explored for turbine blade materials, typically single crystal nickel alloys. More recently however, a combination of thinner disc rims and further increases in turbine entry temperature has lead to a situation where TMF in disc materials cannot be ignored. Turbine discs will usually be manufactured from polycrystalline nickel alloys, and as such it is now considered critical that TMF effects in this system of alloys is fully characterised. Research within the Institute of Structural Materials in collaboration with Roll-Royce plc leads the way in the development of modelling approaches to TMF through a range of cutting edge experimental techniques.
Modern creep lifing approaches
Traditional creep lifing techniques based on power law equations have shown themselves to be extremely limited, particularly in the prediction of long term data based only on short term experimental data. More recently, alternative approaches such as the Wilshire equations and hyperbolic tangent methods have been proposed which offer a new insight into the field. Ongoing research within the Institute of Structural Materials focuses on the development of the Wilshire equations in particular, their relationship with microscopic behaviour of engineering alloys and their application to a range of materials that currently includes copper, aluminium alloys, steels, titanium alloys, nickel superalloys and titanium aluminides.
Premature failure of titanium based engineering components in the 1970s brought to attention the phenomenon of dwell effects at low temperatures in these alloys, loosely termed ‘cold creep’, which are currently still a major concern for designers. Ongoing research at the Institute of Structural Materials seeks to address the issue through targeted mechanical testing and microscopic evaluation. The presence, extent and effect on mechanical properties of cold dwell related features such as ‘quasi-cleavage’ facets are investigated with the resultant effect on both creep and fatigue life also studied.
Conferences, invited papers
Invited Book Chapter
1. MT Whittaker “Titanium in the Gas Turbine Engine” Ed.E. Benini, Publ. INTech (ISBN 978-953-307-324-8).