Conformable EMAT arrays for inspection of defects in welds

About the Project

Electromagnetic acoustic transducers (EMATs) provide non-contact ultrasonic inspection solutions for electrically conducting materials and welded joints. The use of EMATs is couplant-free, non-contact, and does not require material surface preparation – but can suffer from low efficiency. EMATs make up for this by being extremely adaptable; Warwick have designed and built EMATs generating shear horizontal (SH) waves for welding defect inspections [1], high-temperature EMATs for material thickness gauging [2], as well as mini-EMATs (dimensions of around 3 to 5mm per side) [3,4] and miniaturised EMAT arrays for corrosion inspection in metallic samples [5,6] alongside the electronics for operation of the arrays. A recent preliminary study has also shown promising results when using EMATs on fusion pipe materials: miniature EMAT arrays were used to generate Rayleigh and SH-like waves on SS316 samples and measure reflections from slot defects in the weld. In addition, the EUROFER 97 ferromagnetic material used for fusion reactor cooling pipes gives extremely efficient generation, which would allow inspection using much smaller EMAT elements in an array. In contrast, EMATs have typically been considered not suitable for inspection of titanium, but recent advances have enabled inspection of welds in Ti-alloys despite low SNR [7]. EMAT arrays offer, in the longer-term, the potential for array operation at high temperature, or in other inaccessible environments. The PhD project will design, build, and test arrays of electromagnetic acoustic transducers (EMATs), made conformable to attach to different geometries. The array will be designed and controlled such that it can generate a range of ultrasonic waves to inspect for surface, near-surface, and volumetric flaws, with enhanced defect detection capabilities. Routes to production of high-temperature EMATs arrays will be investigated, to offer high-temperature ultrasonic inspection without the requirement for couplant or contact with the sample. The project is fully funded, with 50% funding from a Warwick Industrial Fellowship and 50% through NDEvR / RCNDE, who are enabling access to a number of companies who will help to guide the research. The project will involve;

• Guided by industry requirements, identification of suitable ultrasonic wavemodes for inspection of defects in chosen locations, including guided waves for remote inspection. This will be done using FEM of sample geometries and defect types for different generation modalities.
• Design EMAT arrays for generating chosen wavemodes, making them conformable (using flexible coils and magnet arrays rather than large fixed magnets); this step will use Huygens modelling to test different EMAT force geometries, followed by building and testing of the optimal solutions.
• Test arrays on simple geometries – e.g. plates, pipes with no features other than the weld / defects, and test efficiency and detection capabilities using calibration defects.
• Further FEM and design stage for complex geometries, producing mini conformable arrays.
• Test on samples with complex geometry.

Eligibility

You must have or expect at least an upper second class BSc honours, MSci or MPhys or equivalent in Physics or related subject

For students whose first language is not English, we require a score of 6.5 in IELTS or equivalent, for further information please see English Language Information & Entry Requirements

How To Apply

For further information on how to apply please see our postgraduate webpage Postgraduate - Department of Physics

Funding Notes

The project will provide a full UK-standard annual tax-free stipend of £ 21,805 rising with inflation, plus allocations for conference travel and consumables.

42 months funding