Industry has consistently highlighted the need for improved eddy current and electromagnetic testing capabilities, and the ability to detect small surface breaking defects in safety critical applications such as in jet engine components is extremely important for safety but also potentially for cost savings in asset management.
Surface defects within poorly conducting materials (titanium, carbon fibre composites, etc.) are particularly difficult for eddy current testing, as it demands operation at extremely high frequencies. Visual inspection techniques (dye penetrant and magnetic particle) are limited in their ability to detect small defects, and sub-surface features.
This led the Ultrasound Group at the Department of Physics, University of Warwick into an investigation to discover whether is was possible to develop an eddy current based system which could operate at the frequencies necessary to identify small defects in poor electrical conductors.
By miniaturising the generation and detection electronics, and positioning them directly on top of the inspection coils, we were able to develop a system which could operate at frequencies of between 100kHz and 40MHz, easily high enough to detect defects as small as 0.25mm long in even the poorest conductors.
An added benefit to this configuration is a greatly increased signal-to-noise ratio, making the identification and characterisation of surface flaws extremely simple.