Article · Composites Part B Engineering · August 7, 2025

Design and comparison of directional transmit to differential receiver eddy-current probe for in-line monitoring of automated fibre placement

Meirbek Mussatayev, Qiuji Yi, Paul D. Wilcox, Robert R. Hughes

Abstract

Automated fibre placement (AFP) manufacturing systems help to increase the production rates of Carbon Fibre Reinforced Polymers (CFRP), however, the in-line inspection of AFP remains a challenge for the Non-Destructive Evaluation field. This paper reports on a directional eddy-current testing (ECT) probe developed and tested for in-line detection of common AFP composite prepreg defects such as in-plane waviness and out-of-plane wrinkles. A directional transmit and differential receiver sensor previously developed for detection of out-of-plane wrinkling in cured carbon fibre composites was evaluated and adapted for the detection of in-plane waviness in un-cured CFRP. A figure-8-shaped transmitter coil is employed to increase current density along the fibre direction. Differential receiver coil designs with different aspect ratios were evaluated over a range of suitable frequencies to optimise the probes for sensitivity to in-plane fibre waviness. An advanced finite element modelling approach was employed to simulate the probes above CFRP tapes containing waviness and the results compared to experimental findings. The results demonstrate that a design using square differential receiver coils is most sensitive to in-plane wrinkling, while a lift-off study revealed that the ECT probe can be operated up to 0.3 mm from the material surface while maintaining effective detection of fibre waviness.

Non-Destructive Testing TechniquesElectrical and Bioimpedance TomographyUltrasonics and Acoustic Wave Propagationautomated fiber placementeddy current testingin-line inspection

Design and comparison of directional transmit to differential receiver eddy-current probe for in-line monitoring of automated fibre placement

Abstract

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