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Process monitoring for resins, carbon fiber fabrics, preforms and consolidated CFRPs by HF radio wave techniques

: Heuer, Henning; Schulze, Martin; Pooch, Matthias; Gäbler, Simone; Kupke, Richard

Fulltext urn:nbn:de:0011-n-3704968 (639 KByte PDF)
MD5 Fingerprint: 0c3a7e20452c788433ccb01ff180ac76
Created on: 27.1.2016

20th International Conference on Composite Materials, ICCM 2015. Proceedings. Online resource : 19-24 July 2015, Copenhagen, Denmark
Copenhagen, 2015
Paper 5206-4, 12 pp.
International Conference on Composite Materials (ICCM) <20, 2015, Copenhagen>
Conference Paper, Electronic Publication
Fraunhofer IKTS ()
CFRP; Carbon fibre; Non-destructive testing; High frequency eddy current; imaging impedance spectroscopy

Eddy current testing is well established for non-destructive testing of electrical conductive materials. The development of radio frequency (RF) eddy current technology with frequency ranges up to 100 MHz made it possible to extend the classical fields of application even towards less conductive materials like CFRP. It turns out that RF eddy current technology on CFRP generates a growing number of valuable information for comprehensive material diagnostic. Both permittivity and conductivity of CFRP influence the complex impedance measured with RF eddy current devices. The electrical conductivity contains information about fiber texture like orientations, gaps or undulations in a multilayered material. The permittivity characterization influenced by dielectric properties allows the determination of local curing defects on CFRP e.g. hot spots, thermal impacts or polymer degradation. An explanation for that effect is seen in the measurement frequency range and the capacitive structure of the carbon rovings. Using radio wave frequencies for testing, the effect of displacement currents cannot be neglected anymore. The capacitive structures formed by the carbon rovings is supposed to further strengthen the dielectric influences on eddy current measurement signal. This report gives an overview of several realized applications and should be understood as a general introduction of CFRP testing by HF Radio Wave techniques.