Research and modelling of the multi-coil frequency division multiplexed eddy current methodology for the precise depth determination of characteristics in carbon fiber based structures

• Applicants: Professor Dr.-Ing. Chokri Cherif; Professor Dr.-Ing. Henning Heuer
• Subject Area: Measurement Systems ; Lightweight Construction, Textile Technology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 461706052

The outstanding mechanical properties of carbon fiber reinforced plastics (CFRP) are achieved by adjusting the orientation of the load-bearing high-strength and stiff carbon fibers exactly to the type and direction of the external loads acting on the structure. If the property potential of the fibers is fully exploited in this way, CFRP can be used to create load-bearing structures that are up to 70% lighter than steel and up to 30% lighter than aluminum with the same load-bearing capacity. The prerequisite for exploiting the property potential of the CFRP material, which is necessary for weight reduction, is precise knowledge of the fibre orientation in the component, which is usually constructed in several layers. Without this knowledge, manufacturing processes cannot be systematically optimized, draping processes and associated simulations cannot be checked and component design cannot be carried out reliably.With respect to this current deficit, the aim of the project is to investigate and model eddy current propagation and signals in eddy current testing of carbon fiber-based materials and the reconstruction algorithms for depth resolution based on them. On the one hand, extensive models of the electromagnetic behaviour of anisotropic carbon fibre-based materials and the modelling of eddy current sensors need to be scientifically researched. The characteristic material properties required for this are to be recorded by reliable and reproducible measuring methods and associated evaluation algorithms. On the other hand, in order to specifically influence the penetration depth and the propagation of eddy currents in the material, novel sensor configurations with several coils of different arrangements and sizes have to be developed and tested, which can be operated simultaneously in the frequency division multiplex method to be newly developed.With the achieved project results it will be possible to control forming processes with intelligent algorithms so that a load-adapted arrangement of the reinforcing yarn systems can be achieved.

• DFG Programme: Research Grants