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Reducing car weight and cutting down greenhouse gas emissions

A new lighter weight car frame unveiled by EU-funded ‘SuperLight-Car’ project could provide the structure on which to rebuild Europe’s ailing auto industry – and reduce greenhouse gas emissions.

The Superlight Car conference © Ahmed ElAmin
Superlight Cars in Wolfsburg
© Ahmed ElAmin

A prototype of a new lightweight automobile frame was unveiled by SuperLight-Car at a conference on 26-27 May 2009 in Wolfsburg, Germany. The prototype was created using a variety of materials, and design and manufacturing techniques that Europe’s automakers can develop further.

Due to the current economic crisis, European car manufacturers are restructuring their operations to meet the new challenges that lie ahead. These include changing consumer demands, concerns about climate change, and environmental laws requiring their products produce less greenhouse gas emissions.

The reduction of fuel consumption and CO 2 emissions is one of the most important challenges facing the automotive industry, said Martin Goede, the project’s coordinator and a manager at Volkswagen’s research unit.

“One way to reduce consumption is by reducing a car’s weight,” he says. “Thus, the project goal is to provide the basis to save millions of tonnes of fuel and carbon dioxide due to significantly reduced vehicle weight.”

About one-third of a passenger car's total fuel consumption directly depends on its weight: For example, a weight reduction of 100 kg represents a fuel savings of between 0.3- 0.5 litres for every 100 km driven according to industry estimates.

The project’s challenge was to develop technologies and design concepts that would allow up to 30% weight reduction in the frame of a typical compact class passenger car, while keeping within the cost range for manufacturing such popular models. Volkswagen’s Golf V model was used as the standard for comparing weigh reduction and testing.

Multi-material design

Overall the project achieved its aim, with the prototype weighing in at 171 kg, representing a 39% reduction, or 110 kgs. As Goede told the 140 conference participants, the project partners developed a multi-material design for the prototype. The best material was chosen for each component.

The difficulty was to reduce weight by developing new material and manufacturing processes that did not increase manufacturing costs, while fulfilling a wide range of automotive requirements in areas such as stiffness, crash performance, fatigue and corrosion resistance, and other performance requirements, he said.

All this, while ensuring that a multi-material lightweight design could be mass produced on the production line. Light alloy hot forming aluminium and magnesium was used for the frame’s external panels, hot formed steel for the door apertures, fibre-reinforced thermoplastic for the roof cross beam and rear floor, cast aluminium for the rear longitudinal strut, and reinforced polymer for the seat cross-member. The steel parts made up 50% of the frame’s weight, aluminium 35%, magnesium 8% and plastic 7%.

Project partners also developed new moulding and joining technologies for vehicles, and an assembly plant design for the production of 1 000 cars a day.

Overall, the project provides a prototype to Europe’s car industry that advanced multi-material concepts that combine steel, aluminium, magnesium, plastics and composites can significantly reduce weight.

Manufacturing achievements

Project partners also achieved other technical objectives. They created a library of multi-material architectures and concepts for the development of light weight mass-produced vehicles. They developed forming technologies for aluminium, steel, magnesium and reinforced plastics, along with joining technologies such as welding, brazing, adhesive bonding and mechanical joining. They also created simulation tools for analysing cost, static, crash, fatigue and life cycle of lighter weight vehicles. They also produced and validated a front-end structure demonstrator.

“The principle idea is to use the best material for the appropriate functions,” Goede said. “In addition to the development of metals and light metals, the research on fibre-reinforced plastics will play a major role. In the area of joining technologies, mechanical joining as well as adhesive and hybrid methods will complement the approved welding technologies.”

Now, the goal is to achieve an overall cost efficient lightweight design. The prototype can be used by vehicle manufacturers to reduce the costs. The current cost analysis for the project’s prototype indicates it is currently outside the cost parameters for producing a compact passenger car.

Crossing the line

Participants examine new lightweight frame. © Ahmed ElAmin
Participants examine new
lightweight frame.
© Ahmed ElAmin

In an interview, Goede noted that another project achievement is the continuing collaboration of seven competing European car makers: Volkswagen (as coordinator), Fiat, Opel, Renault, Volvo, Porsche and Daimler. Volkswagen broke down the barriers by sharing the crash and simulation modelling data of its Golf V car.

“This was the starting point for a good project,” he said. “You are working with competitors and you need to treat everybody honestly. At the start you have to give more than you get. In the end you get more back. We now have strong partners for the further development of the prototype and intensive communication networks that will remain in place after the project is finished.”

He expects that the principles, techniques and materials developed by the project will be on the road in the next decade.

“I am convinced that the techniques and design principles could be transferred into series manufacturing projects over a longer period,” he said. “The steel technologies are advanced and available. The aluminium solutions in sheet production are ready to be used. The techniques for casting and thermoplastic polymers will be available after 2012. The innovative technique of using magnesium and carbon fibre reinforced polymer needs further verification but they should be ready to be used by 2015.”

Reducing CO2 emissions

Gundolf Kopp, a speaker at the conference on behalf of the German Aerospace Centre (DLR), a project partner, noted that reducing the weight of cars on the road would be a significant step in reducing CO 2 emissions. About 23% of these emissions is produced by all transport sectors across the globe.

“In addition, the driving behaviour of lighter vehicles is considered to be more agile and safe,” he said. “Optimisation of the weight of all vehicle components has therefore become very important.”

The SuperLight-Car project was co-funded through the EU’s Sixth Research Framework Programme. It brought together 37 partners from across Europe, including seven competing auto manufacturers and suppliers such as Arcelor, Hydro, Corus and Comau.

The project also coordinated with other major research and technological development projects through the umbrella of the European Council for Automotive Research (EUCAR) as part of the European Commission’s roadmap for reducing CO2-emissions and mitigating climate change.