Lightweight trains are in tests.

Researchers at the Fraunhofer Institute for Chemical Technology ICT in Germany recently developed an extremely resilient polyurethane-based sandwich material. It is intended to replace steel or aluminum in train or car components, while being more lightweight and just as strong.

To test the material, ICT manufactured a train component subject to significant stresses — the housing for a diesel engine. The housing is located between the car and the tracks. It shields the engine against flying stones, protects the environment from leaking oil, and, in the event of a fire, stops flames from spreading. In fact, the housing meets the flame retardant and fire-safety standards for railway vehicles.

Says Jan Kuppinger, a scientist at the ICT, “Using the new material reduced the housing’s weight by over 35% and cuts costs by 30% because of reduced fuel consumption.” The new material’s sandwich construction increases component stability. The outer facings are layers of glass-fiber-reinforced polyurethane. The core is paper honeycomb. Researchers incorporated additives into the polyurethane to meet fire-safety standards. They also improved the fiber-spraying manufacturing process by developing a mixing chamber that lets complex structures be produced in almost any size. The diesel engine housing, for example, is about 4.5 × 2 meters.

“This is the first time fiber spraying has manufactured such a large and complex component that also satisfies structural requirements,” says Kuppinger. Previously, it was impossible to determine the precise thickness of the polyurethane top layers. But now researchers use computer tomography to inspect the manufactured layers and then ensure the correct thickness. If future tests prove successful, it will be possible to use the material to make roof segments, side flaps, and wind deflectors for automobiles and commercial vehicles and ramp-up manufacturing to turn out volumes between 250 and 30,000 units.

Resources: Fraunhofer Institute for Chemical Technology ICT, www.fraunhofer.de/en.html