For decades, eddy current testing (ECT) is considered to be an extremely reliable and economic surface testing method. It is applied industrially for materials with high electrical conductivity for measuring and testing purposes up to series production. At high frequencies, ECT is also capable of testing materials with low electrical conductivity, such as carbon fiber reinforced plastics (CFRP).Due to the anisotropic and inhomogeneous character, eddy current propagation inside CFRP is highly complex. Capacitive interactions between fibers and displacement currents in the matrix material as well yield a chaotic electrical network. Whereas numerous reliability studies for ECT of homogeneous materials with high electrical conductivity exist, there is a lack regarding the reliability of ECT applied to CFRP.In this work, the Probability of Detection (PoD) of ECT is determined experimentally using two different probes working in the sub-MHz and MHz regime. Inspections were carried out on two CFRP parts with reference defects ranging from 0.5&nbsp;mm to 12&nbsp;mm in a depth of 1&nbsp;mm below the surface. Both CFRP plates show the same fiber volume content and only differentiate regarding the semi-finished fiber product. This enables not only a quantitative determination of the PoD and the influence of the fiber alignment, but also a comparison for different test frequencies.

Probability of Detection for High-Frequency Eddy Current Testing of Carbon Fiber Reinforced Plastics

Paper Proceedings: https://asmedigitalcollection.asme.org/qnde/QNDE2021/volume/85529

ASME 2021 48th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE2021)

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