Finite Element Modelling of High-Frequency Eddy Current for CFRP’s Orientation Evaluation

Abstract

The performance of CFRP is influenced by the proper stacking of various layers of carbon fibres oriented at different angles and by the curing process. In these multi-layer structures, fibre misorientation (off-axis) and fibre waviness can happen during manufacturing, leading to reduced performance and structural failures during operation. High-frequency ECT has demonstrated its capability for detecting the orientation-related features, including fibre orientation and waviness, in previous work. However, the electromagnetic modelling of orientation-related features was not fully explored in the community, which hinders the optimisation of the ECT configuration for achieving high detectability and sensitivity. In this work, finite element modelling is used to determine the ECT response of a planar CFRP component containing multiple plies. The structure of CFRP is modelled by 2D waves as the function of orientation and its conductivity tensor. The virtual ECT test was then implemented in the modelling. Then, the tools of the chain are proposed, including Radon transform, and 2D FFT for orientation characterisation. The simulated and experimental data are validated through the chain’s tools. The results demonstrate that the electromagnetic resistive characteristics of the CFRP structure can be modelled with the proposed approach compared with experimental data. The orientation inversion techniques Radon transform can estimate the orientations from the impedance data. The overall strategy has provided the methodology for modelling the heterogenous EM properties of composites.