Development of a standard procedure and a calibration standard for quality control of carbon fiber materials using Eddy Current techniques

Speaker:
Hillmann, Susanne; Fraunhofer IKTS; Germany

Authors:
Bor, Z.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS; Germany
Hillmann, S.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS; Germany
Hofmann, G.; BMW Group; Germany
Krüger, P.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS; Germany
Schulze, M.H.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS; Germany

ID: ECNDT-0262-2018
Session: Composite Material - EC
Room: G1
Date: 2018-06-14
Time: 09:40 - 10:00

Carbon fiber materials are currently the most innovative materials in many industries and are increasingly replacing conventional materials such like metals and steels. Especially companies in aerospace and automotive are increasingly establishing CFRP structures. Standard procedures secure, that a testing method will be applied at different places by different operators on similar materials in a similar way to receive comparable results as well as comparable quality of the testing process.

Due to its inhomogeneous character and varying properties in comparison to the conventional used metals and steels, the NDT-methods has to be optimized and adapted in large ranges to have a successful application of carbon fiber materials (CF-materials). Therefore, the existing standard procedures for application and evaluation of the testing data for many NDT methods cannot be used for the CF-materials and has to be either enlarged or new standard procedures has to be developed and validated.

In this article the development of a standard procedure for the quality control of carbon fiber materials during production process using Eddy Current technique is presented. The presented application is developed for detection of gaps, fold, fiber waviness, fiber cracks and fiber cluster in CF-materials with up to 11 layer in 4 different fiber directions. The development of the standard procedure includes techniques for reproducible parametrization of the measurement system, as well the development of a calibration block and its usages, and the evaluation of the measurement signal.
One scope is the development of a calibration strategy and a calibration block. The calibration block has to offer the possibility to be reproduced frequently now and in many years in constant properties in a narrow range. In this article we will present a promising solution of the testing procedure as well as a design of a calibration block, which is the basis for following analyzing and validation of the measurement system. The testing procedure as well as the calibration block and can be a basis for a standard procedure for this approach.