Automotive Design
automotive industry typically cost up to $25/kg - which is lower than the $35/kg for high modulus grades used in the aerospace industry. But the aerospace industry makes larger parts, which leads to better economies of scale. “There is also a lack of general engineering expertise among automotive OEMs,” he says. “Most have invested in metal assembly plants, and are not keen on making more capital expenditure on a new technology.” He says that
automotive companies are likely to adopt a ‘hybrid’ approach, and use a range of materials - including aluminium, high strength steels and thermoplastic composites - to deliver weight savings. And while CF materials
Fig. 3. Cazuc: “Lightweighting is a primary factor to reduce CO2
emissions.”
are most likely to save weight - to help meet future emissions targets - they are difficult to recycle. The End of Life Vehicles (ELV) Directive insists that 85 per cent of all vehicles must be recyclable by 2015. This would be more difficult if CFRP parts were involved, he says.
Mondal estimates that 90 per cent of CFRP automotive
applications will use carbon-epoxy composites, with the rest composed of carbon fibres embedded in thermoplastics such as polyamide, polyurethanes and Peek - depending on the application. “Under-bonnet parts are most likely to use CF-reinforced
PA, because epoxy does not have high enough chemical or heat resistance,” says Mondal. Beyond 2017, he believes that efforts to reduce cycle times
for CF parts will continue to improve. “Many carbon fibre producers are looking to bring
cycle times below five minutes,” he says. “This is still long compared with steel, but at the same time the cost of carbon fibre is likely to come down.”
Carbon adoption
The US, whose automotive industry has suffered recently, will be slowest to adopt these measures, he believes. Japan, a global centre of CF production, will be faster, but Europe is leading the charge to adopt CF technologies - with BMW at the front of the queue. This year, BMW intends to roll out two new mass-
production cars - the i3 ‘Megacity’ electric vehicle, and the i8 hybrid ‘supercar’ - that rely heavily on carbon fibre-reinforced plastic (CFRPs). It has been able to do this because it has automated the processes used to make carbon fibre textiles, and to shape them into automotive components. BMW is using resin transfer moulding (RTM) to reduce production time for each CFRP part to less than 10 minutes
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Fig. 4. The ACOMPLICE project is developing composite materials for use in mainstream cars.
In the Thermoplastics category, MVC of Brazil and Arkema of France won for their ‘Sofia Project’, in which a PMMA- based thermoplastic resin formulation is used to make bodies for buses, vans or cars using resin transfer moulding (RTM). The resin has several advantages over traditional thermoset resins, including lower weight, better mechanical properties, and better surface quality. The main body parts will be made of a sandwich structure with a low-density PU core, bonded together with structural adhesives. Saving weight by specifying new materials is not the only
way to meet the tough new emissions standards: greater engine efficiency and reduced rolling resistance of tyres are arguably more important. But the number of methods available means that incremental weight savings can be made across the car - adding up to a substantial overall reduction. ●
- much faster than the 20 to 30 minutes that was needed just a few years ago. The CFRP part in the Megacity car will be the ‘passenger cell’, which sits on top of an aluminium chassis. The CFRP part is half the weight of an equivalent steel part, says the company. BMW has definite plans to transfer it within the company. “More and more car projects, starting from 2105 and
2016, will use carbon fibre as a structural element to reduce weight,” says Joerg Pohlman, joint managing director of SGL- Automotive Carbon Fibers - a joint venture between BMW and carbon fibre producer SGL. BMW’s vehicle concept was one of three automotive-
themed winners at this year’s JEC Composites Awards. It was the winner of the Special Prize for its LifeDrive architecture - which was designed and built specifically for electric vehicles. In the Automotive category itself, ECM of France won for
its self-supporting composite structure for a light urban electric vehicle. It was designed and manufactured using thermoset resin and glass fibre reinforcement to replace a traditional steel body-in-white. The prototype meets industrial feasibility criteria and results in 30-40 per cent weight savings. Further development using carbon fibre could improve this further. The key benefits are: weight reduction at acceptable cost
for the automotive industry; reduced vehicle emissions due to reduced car weight; design of vehicle parts with integrated functional aspects; reduced number of parts to build a car; and savings on investment and assembly costs.
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