Collision protection and self-healing structures: Lightweight design ideas to mitigate the consequence of collision
While the future of lightweight design provides fodder for strategy debates, more and more innovations in carbon fibre reinforced plastic components are making headlines. This results, for example, in automotive engineers saying good-bye to the ‘simple bonnet plate. From research into textiles comes a proposal for an improved pedestrian collision protector in the form of an intelligent bonnet. In the Dresden based ITM working in cooperation with the Aachen Institutes for Textile Technology (ITA) and Motor Vehicles (ika) an integrated passive protection has been developed from textile spacer materials and incorporated in the bonnet of the VW ‘Golf V’. In addition to its mechanical function this insulating 3D structure has acoustic and thermal properties and is intended to absorb the impact of the collision between man and machine in such a way that the heady injury criterion (HIC) values, critical for survival, are met in line with EU regulations.
Textile research is also looking in other directions. One example is fibre composite materials that help components to repair any damage themselves. Just as the human body gradually heals itself following an injury, certain fibre composite materials are cable of regeneration after they become damaged. According to researchers at the Institute for Textile Chemistry and Chemical Fibres (ITCF) in Denkendorf, innovative new composites should restore their original material properties after a small crash for instance. It is said that special polymer technologies have already been able to achieve up to 30 continuous repair cycles – either independently or induced through UV light or heat. In addition self-healing materials enable totally new safety features: they could help to maintain and / or restore the functionality of tyres and windscreens for example.
Speeding up transfer on the agenda
One decisive factor for the development is the speed at which research is transferred to industry. One example of this development is the topic of manufacturing reproducible pre-forms. Mother: Institute of Textile Machinery and High Performance Material Technology (ITM) of the Technical University of Dresden; Father: the engine builder topcut bullmer GmbH from Mehrstetten (Baden-Württemberg) that has specialised for 80 years in the handling of pliable materials. Collaboration between research institute and small business has developed automated spreading concepts to apply adhesive locally for the production of pre-forms setting a further efficiency principle for the mass production of fibre composite structures. The core task was to establish a CNC controlled automated process chain including laying, spraying and cutting technology for multi-ply fabrics that need to be laid down without creasing as a single layer or stacked for further processing on/in the form of the finished component.
Another example is the automated drapability tester. When manufacturing fibre composite components, the drapability i.e. the ability of reinforcement textiles to adapt to the three dimensional form of the component contours specified in the design plays a decisive role. Anyone wanting to undertake large-scale production of high-precision, fibre-based semi-finished products in qualities that are reproducible requires, amongst other things, a standardised test methodology to characterise the drapability. Previous manufacturing parameter investigations by the Institute for Textile Technology of the RWTH University of Aachen in terms of their effect on the spherical formability of materials were taken up by Textechno Herbert Stein GmbH, based in Mönchengladbach, on the basis of ‘ZIM’ Central Innovation Programme, and in the space of only a year and a half had been incorporated in a test device that is so far the only one of its kind in the world. The DRAPETEST is now mass produced and makes it possible to identify qualitative draping errors in non-woven and woven fabrics.
Background picture: Source – S. George