Phil Petcher

I am a PhD student in the ultrasound group within the physics department at the University of Warwick. Supervised by Dr. Steve Dixon, my research interest is the imaging of defects in metals. Funding for my work is provided by the EPSRC (Engineering and Physical Sciences Research Council) and Corus.

Profile

After completing an undergraduate degree in Physics (MPhys) at the University of Warwick, I started working as a researcher at QinetiQ, specifically in the field of electronic surveillance. Having learnt a great deal there, I decided to apply my new skills to a PhD. Find out more on the "Profile" page, including a CV and details of my professional development.

Research - Time of Flight Diffraction and Imaging (ToFDI)

Below is a non-specialist summary of my PhD project. It contains minor technical inaccuracies, but nothing serious. To avoid such inaccuracies would require introducing terms that would then limit it to the specialist. Find out more on the "Research" page, including far more technical information, conferences I have attended, and publications I have produced.

ToFDI for the Non-specialist

Non-contact ultrasound combined with sophisticated computer software is being used to develop a new imaging technique for testing steel during production at steelmaker Corus. The technique, Time of Flight Diffraction and Imaging (ToFDI), should reduce costs and improve yield by early detection of manufacturing faults.

Testing steel while it is very hot is impossible with contact ultrasonic transducers, such as those commonly used when assessing the progress of a pregnancy. Lasers are inappropriate for medical ultrasound, but generate waves in steel bars whilst metres away, by boiling off a small surface layer. An Electro-Magnetic Acoustic Transducer (EMAT) receives ultrasound in metals by detecting the motion of charged particles and can be placed millimetres from the surface, far enough away to survive if appropriately cooled and protected. Compression waves (like sound waves in air) and shear waves (which only exist in solids) are generated by the laser, bounce off defects, and are detected by EMATs.

ToFDI uses a single laser and a series of EMATs scanning over a surface. Custom software calculates where each wave could have come from, and by combining all the waves observed, any defect location can be determined. Using both wave types means defects are more likely to be detected and are seen at greater resolution. Defects are displayed in an image representing the sample, making it easy to analyse anything of significance compared to prior methods.

Good progress is being made, but the work is currently limited to a laboratory environment at room temperature. The final objective is for fast and automated detection, identification, positioning and sizing for all defects in a sample with known basic characteristics, such as wave speeds.