To reduce the weight of its cars, German vehicle manufacturer Porsche has replaced steel and carbon-fibre body parts with components made from natural materials 

Porsche has begun to use organic materials in its automotive manufacturing applications. The brand’s new, low-volume, 718 Cayman GT4 Clubsport model features body parts made from natural-fibre composites. The doors of the vehicle, as well as its rear wing, have been fashioned using vegetable fibre in a move that’s seen as a sustainable alternative for the production of lightweight vehicle bodies.

Co-developed by the Fraunhofer Institute for Wood Research and Hannover University’s Institute for Bio Materials – with support from the German Ministry of Food and Agriculture – the organic composite is being used by Porsche in series production to replace components previously made from lightweight steel and carbon-reinforced plastic – until now materials perceived as being among the most practical to reduce vehicle mass.

According to a statement released by the Fraunhofer Institute, registration statistics globally indicate that new cars are progressively becoming heavier, due to improved safety functions and the addition of electronic equipment.

“This weight gain means higher levels of fuel consumption, aspects contrary to the general goal of reducing CO2 emissions. Weight is also an important factor for e-cars, since they require large, heavy batteries in order to maximise range. Accordingly, new developments in lightweight design are an absolute prerequisite for truly efficient e-cars.”

In recent years, lightweight steel and carbon-fibre reinforced plastic have become popular choices among motor manufacturers as a means of reducing vehicle mass – but the solution has a number of disadvantages. “First, the materials pose substantial challenges in machining, repairs and recycling. Second, their manufacture is highly energy intensive, subtracting from the positive environmental aspect of weight reduction,” says the statement.

Accordingly, researchers at the Fraunhofer Institute for Wood Research began experimenting with materials made from organic fibre to see if they could be used instead to reduce component weight. “They investigated various readily available ecological materials in terms of their technical properties, availability and cost-efficiency,” says the statement.

“Natural fibre-reinforced plastics turned out to be the answer. As components in organic composites, vegetable fibres represent a sustainable alternative for lightweight vehicle bodies. The biogenic component improves the ecological impact during manufacturing, use and disposal.

“And, economically speaking, the use of renewable raw material is beneficial because natural flax, hemp, wood and jute fibre are less expensive than carbon fibre, requiring less energy to manufacture. Thus, the advantages of weight reduction don’t come with a prohibitive price tag. Additional benefits include good acoustic damping properties and a reduction in splintering – an important factor in the event of a collision.”

The arguments appear to have been convincing enough for Porsche. Joining forces with the brand’s motorsport division, researchers at Fraunhofer initially tested organic materials for series readiness under extreme conditions on the race track, using a Cayman GT4 Clubsport that belonged to the Four Motors racing team.

“The third generation of the car has been on the race track since 2015. The tests combine the advantage of extreme stress with a vehicle that is also street-legal. The partnership with Porsche has enabled development under the realistic conditions,” says project manager Ole Hansen.

Experience gained on the track has resulted in the development of parts for the new 718 Cayman GT4 Clubsport – Porsche’s first car in series production to feature doors and a rear wing made from organic fibre. The car weighs 1 320 kg – the composite material is said to have reduced the weight of the components by about 60 percent compared to steel.

According to the statement, the material consists of a thermoset polymer matrix reinforced with organic fibre mesh. It is said to exhibit high tensile strength and is particularly fine. Also, it can be draped, easily fitting part shapes.

The simplicity with which it can be produced to precise dimensions facilitates machining and quality assurance. “These aspects are an important prerequisite for high-volume production,” says Hansen. “We believe that these ecologically beneficial organic materials will soon fulfil that role.”

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