KARL MAYER Technische Textilien successfully takes part in FUTURE - a project for combining steel and carbon fibres in multiaxial textiles
The blend makes it all possible
Carbon-fibre-reinforced plastics (CFPs) represent a beacon of hope for the lightweight construction sector. These extensively used composite materials deliver excellent mechanical properties and, at the same time, have a low density, but their electrical conductivity is poor. This is a particular disadvantage for their use in aircraft. Protection against lightning is an absolute necessity for this demanding application at high altitudes. The CFP structures used until now have been combined with woven grid constructions made from copper to produce laminates that will guarantee safe flying, even in bad weather. But this solution is extremely complex, and the aim of this project was to find a simpler technique. The research project, which was publicly funded by the BMBF, was entitled “Funktionale Textilien und reproduzierbare Ergebnisse” (Functional Textiles and Reproducible Results) – FUTURE for short, under the direction of the project sponsor, Jülich.
It lasted from October 2014 to the end of September 2017 and was carried out by KARL MAYER Technische Textilien GmbH (Technical Textiles) in Naila. The partners in the project were the Institut für Verbundwerkstoffe, IVW (Institute for Composite Materials) in Kaiserslautern, AIRBUS in Munich and Quickstep in Ottobrunn.
The aim of the project – to develop a hybrid solution
The project involved developing carbon-steel-fibre hybrid structures as a replacement for the labour-intensive process for producing laminates. The first stage involved ideally producing spread tape-hybrid structures and bonding them in a second stage on the COP MAX 5 using warp knitting technology. The plan for the project, which was drawn up by KARL MAYER Technische Textilien, also involved the study of multiaxial textiles with 0° warp yarns made from steel. The steel material had to be combined with 0°/90° and +/- 45° carbon layers on the COP MAX 5 and processed into hybrid multiaxial textiles using a tricot construction. On the basis of the composite structures, the project partners hoped to achieve a similar or better protection from lightning in the finished components, and subsequently to guarantee a much better ductile behaviour in the event of a lightning strike, i.e. improved impact characteristics compared to the previous laminated system.
Successful preliminary work as a basis for subsequent work on the project
Implementing the project was definitely a worthwhile exercise for KARL MAYER Technische Textilien. Fundamental textile/technical facts were established during the investigations using both theoretical and practical principles.
The effectiveness of KARL MAYER’s spreading principle during spreading of the steel fibres and carbon-steel-fibre hybrids was again confirmed unequivocally. By using online spreading technology, which involves the use of TC 54 creels developed by KARL MAYER Technische Textilien, it was possible to lay and bond high-quality single-layered hybrid angled structures on the COP MAX 5.
The high quality of the textiles was confirmed yet again by carrying out basic tests. KARL MAYER’s specialists compared online and offline production on the COP MAX 5 in detail in order to produce products with first-class characteristics for use in the aerospace sector. At a layer weight of 110 g/m², the online-spread carbon multiaxial textiles had a better channel structure, homogeneity, thickness uniformity and appearance. The reason for this is that the previous tape winding and unwinding process, which was a source of quality problems, can now be dispensed with. Carbon fibre tows with the following characteristics were used in the tests and comparisons: TORAYCA® T 700S, 12K, sizing type 50C and 60E.
On the basis of the results of the experiments, carbon multiaxial textiles with a structure of 0°/90° and +/- 45° were produced and combined with steel rovings as the warp yarns. The steel-fibre-carbon hybrids produced were processed at the IVW in test samples and yielded some fundamental results, which would be useful in further scientific investigations.
"The FE project, on which this article is based, was carried out under the auspices of the Bundesministerium für Bildung und Forschung (Federal Ministry of Education and Research), no. 03X3042B. The author is responsible for the contents of this publication.”
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