Material-efficient lightweight construction for resource-efficient mobility

© Fraunhofer IWU

Carbon-fiber-reinforced plastics (CFRP) are increasingly used as structural materials in automobile construction. Because they are much lighter than metallic materials, they reduce the vehicles’ fuel consumption and carbon dioxide emissions. Their production, however, is oil-, cost- and energy-intensive: Up to now, CFRP components for vehicles are mainly manufactured as monocoque constructions made of layered textile semi-finished products. Cutting the individual layers of laminate to size, however, produces a lot of waste. In addition, they are designed to bear the same load across their whole surface. If individual points are exposed to higher loads, the layers must be increased here, which has previously only been possible with high additional production costs.

The semi-finished products of the “MAREMO” project consist of fiber composites that are manufactured tailored to their respective load and in near-net-shape preforms. These semi-finished products produce hardly any waste and are made of recycled materials. Individually-tailored fiber carbon bands, so called towpregs, are applied to the base material of flat fleece. The towpreg layer is thickened depending on the load. Parts not exposed to higher loads are left without continuous fiber reinforcement.

A recycled fiber fleece from the Fraunhofer Institute for Machine Tools and Forming Technology IWU was selected as the base material. The production of the efficient semi-finished products should take place in an automated process, in which component-specific tape patterns are placed on and attached to the base material.

The research partners match the fiber reinforcements with the demands on components. Suitable deposit patterns for the towpregs are derived from the component design. The components are constructed at Wethje Carbon Composites GmbH and Fraunhofer IWU. The prototype is an automobile structure specified by BMW. The experiences of the three-year project result in practical construction and design instructions.