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Textural analyses of carbon fiber materials by 2D-FFT of complex images obtained by high frequency eddy current imaging (HF-ECI)

: Schulze, M.H.; Heuer, H.


Gyekenyesi, A.L. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.; American Society of Mechanical Engineers -ASME-:
Nondestructive characterization for composite materials, aerospace engineering, civil infrastructure, and homeland security 2012 : 12 - 15 March 2012, San Diego, California, United States
Bellingham, WA: SPIE, 2012 (Proceedings of SPIE 8347)
ISBN: 978-0-8194-9004-9
Paper 83470S
Conference "Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security" <2012, San Diego/Calif.>
Conference Paper
Fraunhofer IZFP ()

Carbon fiber based materials are used in many lightweight applications in aeronautical, automotive, machine and civil engineering application. By the increasing automation in the production process of CFRP laminates a manual optical inspection of each resin transfer molding (RTM) layer is not practicable. Due to the limitation to surface inspection, the quality parameters of multilayer 3 dimensional materials cannot be observed by optical systems. The Imaging Eddy-Current (EC) NDT is the only suitable inspection method for non-resin materials in the textile state that allows an inspection of surface and hidden layers in parallel. The HF-ECI method has the capability to measure layer displacements (misaligned angle orientations) and gap sizes in a multilayer carbon fiber structure. EC technique uses the variation of the electrical conductivity of carbon based materials to obtain material properties. Beside the determination of textural parameters like layer orientation a nd gap sizes between rovings, the detection of foreign polymer particles, fuzzy balls or visualization of undulations can be done by the method. For all of these typical parameters an imaging classification process chain based on a high resolving directional EC-imaging device named EddyCus® MPECS and a 2D-FFT with adapted preprocessing algorithms are developed.