Novel material could make cars lighter and cheaper to run

Developed by a team at the Fraunhofer Institute in Germany, the polyurethane-based sandwich material is said to make components 35% lighter than their steel and aluminium counterparts, and be just as strong. "To demonstrate the material, we manufactured a component that is subject to significant stresses and which has to fulfill a number of requirements – the diesel engine housing for a train," said Jan Kuppinger, a scientist at the at the Fraunhofer Institute for Chemical Technology. "This housing is located beneath the passenger compartment, i.e. between the car and the tracks. "Not only does it shield the engine against flying stones and protect the environment from any oil that might escape, but in the event of a fire, it also stops the flames from spreading, thus meeting the flame retardant and fire safety standards for railway vehicles. According to Kuppinger, the researchers opted for a sandwich construction to ensure component stability. They began by incorporating various additives into their polyurethane, altering it in such a way as to ensure it would meet fire safety standards. They then optimised a standard manufacturing process called fiber spraying by developing a mixing chamber. This allowed even more complex structures to be produced in any required size, something not previously possible. The researchers overcame the obstacle of not being able to determine the precise thickness of the polyurethane top layers by utilising computer tomography. This, according to Kuppinger, helped them inspect the manufactured layers before a specially adapted evaluation routine could be applied to establish exact thickness. The scientists' diesel engine housing demonstrator was said to pass initial strength tests with 'flying colours'. The researchers are now looking to trial the component in a proper test field. If that proves successful, Kuppinger says it will then be possible to use the material to make roof segments, side flaps and wind deflectors for the automobile and commercial vehicle industry, and to ramp up the manufacturing process to produce medium volumes of between 250 and 30,000 units.