Directional eddy current probe configuration for in-line detection of out-of-plane wrinkles

TL;DR

This paper presents a novel directional eddy-current probe designed for real-time detection of out-of-plane wrinkles in carbon fibre composites during manufacturing, combining experimental and finite element analysis to optimize detection capabilities.

Contribution

The study introduces a new probe configuration with asymmetric and differential coils, enhancing the detection of out-of-plane wrinkles in composite materials during AFP manufacturing.

Findings

Optimal probe configuration identified with SNR >20 for wrinkles over 1.3 mm

Finite element modeling correlates eddy-current density with defect detectability

Experimental results validate the probe's effectiveness in real-time monitoring

Abstract

Real-time monitoring of carbon fibre composites during Automated Fibre Placement (AFP) manufacturing remains a challenge for non-destructive evaluation (NDE) techniques. An directional eddy-current (EC) probe with asymmetric transmit and differential receive (Tx-dRx) coils is designed, constructed and characterized to evaluate the detectability of out-of-plane wrinkles. Initial studies were conducted to determine suitable excitation frequencies and to analyse the impact of relative orientations of driver and pickup coils on wrinkle detectability. The probe configurations are evaluated experimentally and employ a new finite element modelling approach to better understand the relationship between eddy-current density and defect detection. The findings indicate that a probe configuration with an asymmetric driver coil normal to the material surface and aligned with the fibre directions, and with differential pickup coils 90 degrees to the scanning direction, shows the best capability for out-of-plane wrinkle detection, with SNR >20 for wrinkles over 1.3 mm in amplitude.