Carbon/biocomposite hybrid vehicle structures for reduced weight, cost and environmental impact (CARBIO)

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Carbon/flax fibre-reinforced hybrid composites offer advantages in terms of vibroacoustic, weight and cost when comparedto conventional steel and aluminium alloys which can be related to minimisation of emissions and fuel consumption.However, vibro-acoustic characteristics of epoxy-carbon fibres/flax hybrid composites and their co-relation to structuralstrength of the composite remain unexplored and a stumbling block in the application of the material technology tomanufacture better components. The increased application of both flax fibres and carbon fibre composites in automotivecomponents requires proper understand of vibro-acoustic problems and their effects in structural design andmanufacturing. The CARBIO project, therefore, involve investigating the vibro-acoustic levels for selected components/systems for determination of tuneable frequencies, determination and quantification of vibroacoustic coupling betweentemperatures variations, panels architecture and body assembly contributions and noise levels benefit againstbenchmarked fully epoxy/carbon fibre, steel and aluminium components.The study stems from the fact that with increasingly stringent environmental regulations and requirements, noise andvibration have become very important design considerations for automotive manufacturing. Modern vehicle customers areaware of their environmental needs and therefore demand the most economical car, the most comfortable to drive andobviously the cheapest. As a consequence, the automotive industry has become a consumer driven industry where noise,vibration and environmental harshness has become a measure of design excellence and vehicle performance, a factreflected strongly in vehicle sales. A rational approach to reducing noise and vibration is to improve the damping propertiesof the materials from which the car parts are manufactured. Currently, body panels are mainly manufactured from steeland aluminium alloy in conventional vehicles and epoxy - carbon/glass fibre- reinforced composites in high performancecars. More effective measures for noise and vibration reduction are desirable if the automotive industry is to achieve anacceptable driving environment and comfort as vehicle structural masses are reduced in response to environmentaldemands.The project acknowledge that hybrid composites with natural fibres are a key solutions to the vibroacoustic problem sincenatural fibres (flax) have much higher damping properties. In addition to the reduction of mass, composite materials offerconsistent potential advantages in terms of noise and vibrations reduction, impact resistance, energy absorption capability. They also offer advantages in the manufacturing process, such as cost reduction for producing low volume pieces and thepossibility of integration, i.e. structures which can be made with fewer sub-components. Composites also possess a uniquecapability: to be tailored in order to meet design requirements which are ill-matched for conventional materials, by properlychoosing the constituent materials and the orientation of the reinforcement fibres. This is of primary importance for theperformance optimization, the target objective being a minimization of the mass and/or of stress concentrations,guaranteeing the required performance. Use of thermoplastics and other lightweight materials also aligns UK OEMs withthe end of life vehicle EU directive in that by 2015 , vehicles must be constructed of 95% recyclable materials, with 85%recoverable through reuse or mechanical recycling and 10% through energy recovery or thermal recycling. It is envisagedthat the proposed project will give the UK automotive industry a leading edge in global industry.