EngD student 2008-2012
University: Imperial College London
Sponsoring company: Alstom Power Switzerland
EngD research: Investigation and Development of Transient Thermography for Detection of Disbonds in Thermal Barrier Coating Systems
The project explored the use of transient thermography for the detection of disbonds with minimum diameter 2mm located in a thermal barrier coating (TBC) system whose surface may be unpainted. The thesis quantifies the differences in thermal response using finite element analysis validated by experiments, and proposes a form of artificial disbond that gives a better representation of the thermal responses seen with real defects. Real disbonds tend to have a non-uniform gap between the disbonded surfaces across the defect, and the effect of this on the thermal response is evaluated using finite element simulations. It is shown that the effect can be compensated for by adjusting the diameter of the calibration defect compared to the real defect. The project demonstrated that unpainted blades can be tested satisfactorily by using a more powerful flash heating system assembled with an IR glass filter and a long wavelength IR camera. The problem of uneven surface emissivity can be overcome by applying the 2nd time derivative processing of the log-log surface cooling curves.
Current role: Senior Project leader, NDT section TWI
In the new role I am involved in various types of NDE project (single client, co-operative and EU). The projects include ultrasonic examination (standard and phase array), thermography and eddy current and will soon include digital radiography.
The EngD program significantly extended my technical knowledge in various types of NDE techniques. I have learnt computer programming in MATLAB, numerical simulations and various types of experimental techniques. As a non-native speaker and someone who obtained a first degree outside the UK, I have significantly improved my technical communication skill.
Very importantly, during the study I have met many experts in NDE from academia and industry and extended my professional network so that advice is available for technical issues encountered in my work.
