JEC COMPOSITES MAGAZINE - Issue #74 - July 2012 - 29

minutes depending on the part size, cycle times are still rather long with conventional matrix systems.

RTM demonstration part: roof module
The first demonstration part based on the various BASF materials suitable for RTM is a convertible roof module made up of several sections in a sandwich construction with carbonfibre-reinforced cover layers and a polyurethane foam core (Fig. 8). This roof segment forms the forward part of a three-section retractable hard top (RHT) folding roof concept which was conceived and designed by EDAG GmbH, Fulda, Germany, as a feasibility demonstrator for a generic fibre composite sandwich concept with system components from BASF optimized with each other. The central layer of the demonstrator sandwich structure is a closed-cell PUR structural foam from the Elastolit D range. It serves as a low-weight separator for the laminate cover layers, resulting in an exceptionally high component stiffness. In addition, it gives the roof module good insulating properties. On the exterior, the component is protected from UV radiation and other environmental

influences by a paint that contains the BASF Tinuvin CarboProtect additive. Upscaling this to a mass production process will require a pre-formed foam insert containing all the additional inserts, covered on both sides with the chosen textile structure, which is laid into the mould and fully impregnated in a single operation. The PUR foam system specially developed for this by BASF has a high pressure and temperature resistance, as well as low density. This ensures that the foam core is not compressed during the injection phase. As a fibre composite sandwich concept, the RHT roof segment weighs 2.9 kg in total, which represents a weight reduction of more than 35% compared to an aluminium construction and more than 60% compared to a steel one, whilst offering a comparable loading capacity under all typical design loading cases for vehicle roofs.

zers would not be in series production today without the ability to predict anisotropic part behaviour reliably, especially in a crash. To design and build the seat pan for the Astra OPC, the company’s engineers provided material descriptions for the virtual design of both the CFR laminate and the overmoulded ribbed areas of the part. This knowledge will be incorporated into an extension of the Ultrasim tool, making it possible to predict the behaviour of thermoplastic composite parts with continuous fibre reinforcement. For the same purpose, the company is expanding its expertise in the prediction of part performance by incorporating representation methods and material models for steelcord composites but also for such complex CFR structures as targeted by the reactive RTM systems.

Conclusion
Light but sophisticated high-performance fibre composite components and the associated composite raw materials will be able to replace even more metal, save weight and thus reduce energy consumption and CO2 emissions still further. With regard to cost-benefit considerations, various matrix materials, fibre types, reinforcing techniques, joining technologies, predictive modelling and processing technologies are currently being developed in parallel and rigorously investigated for their suitability for mass production. Without such multiple material systems, the next leap in automotive lightweight construction will not be possible. Thus, raw material manufacturers, part suppliers and OEMs will have to work together to establish the necessary competence to tackle these complex tasks and fully exploit the potential of the different approaches. n
More information: Lightweight-design@basf.com www.plasticsportal.eu

Not without high-end simulation
For many years now, BASF has developed, enlarged and intensively applied its meantime universally applicable simulation tool Ultrasim®. Reinforced plastic parts like lower bumper stiffeners, oil pans or stabili-

Feature Automotive

Fig. 8: RTM process demonstrator in the form of a convertible roof module

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JEC COMPOSITES MAGAZINE - Issue #74 - July 2012

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