Eddy-current inspection of complex geometries in carbon fibre composites

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To increase production rates advanced composite manufacturing methods have been developed, such as automated fibre placement (AFP) systems, allowing manufacturers to fabricate parts with greater geometric complexity for a range of industrial applications. These complex geometries introduce a number of manufacturing challenges for carbon fibre composites including; fibre misalignment of curvi-linear surfaces, ply bridging in internal corners and variations in fibre density. It is also in regions of complex geometries where high stress concentrations can occur thereby requiring rigorous non-destructive testing (NDT). However, these complex geometries present significant inspection challenges for some NDT techniques. Eddy current testing (ECT) is a staple of the NDT toolbox, offering high sensitivity to even very small discontinuities. However, eddy-current sensors are also highly sensitive to the local geometry of the material under inspection, leading to undesirable geometric signals at edges and corners where manufacturing errors are more likely to occur. These geometric signals limit the sensitivity of ECT measurements in these environments.This project will explore methods of eliminating or isolating geometric signals in ECT measurements to improve the signal-to-noise ratio of defect indications in these critical regions. Finite element models will be developed to simulate complex environments and optimise sensor design while advanced multi-frequency data-processing methods will be explored.It is anticipated that novel configurations of eddy current sensors will be developed to enable these inspections.The research will be primarily supervised by Dr Rob Hughes in the Bristol Ultrasonics and NDT group. The student will learn valuable skills in experimental ECT inspection techniques, data-processing, and modelling, and would ideally work closely with ECT probe manufacturers and/or industrial manufacturers. The work environment at Bristol will expose the student to a range of techniques and capabilities beyond Eddy Current approaches.