DLR Combines 3D Printing with Lightweight Construction Processes
Under the term AddComSTM (Additive Composite Structures), scientists at the DLR Institute of Composite Structures and Adaptive Systems in Braunschweig, Germany, are investigating how additive manufacturing processes can be integrated into existing production technologies. Multi-material, multi-scale materials, as well as structures and systems with integrated functions, that could not be efficiently produced up till now will therefore be easier and more cost-effective to implement in the near future according to the scientists. The DLR recently presented the first example applications.
The first components from the newly established laboratory in Braunschweig include wing ribs for a solar HALE (High Altitude Low Endurance) aeroplane, a flying platform that, due to its low weight, can be held aloft solely by solar energy from solar cells. The ribs were additively manufactured by a direct combination of endless carbon fibres and a thermoplastic according to the scientists. “The ribs would be milled out in a conventional design. 3D printing enables us to use the fibres in correct alignment with the direction of the forces, meaning that fewer fibres and less plastic have to be utilised”, explains Professor Hans Peter Monner of the DLR Institute of Composite Structures and Adaptive Systems.
The scientists see morphing structures as a further application. These could in the future be used for control surfaces and flaps on aircraft wings in order to achieve fuel savings. Combining solid and flexible materials now enables the additive manufacture of morphing wing edges with elastic air-pressure-controlled cells. “The air pressure cells are each equipped with a cavity and are simultaneously strong and flexible. That can’t be done with other manufacturing methods”, says Professor Monner.
Holistic methodology is necessary
In order to be able to further optimise the automated production of such additively manufactured components in the future, the experts at DLR believe that putting a special 3D print head on a common industrial robot, for example, would be feasible, enabling various manufacturing processes to be combined on one component. In Professor Monner’s vision, the production of today’s fibre composite components using fibre-carrying heads could practically merge with the new possibilities of 3D printing: “This requires a new holistic methodology with innovative approaches for material, concept, design, optimisation, manufacturing, production through to certification that considers the best combination of different manufacturing processes in each phase.” According to the Professor, the basic structure could be built using the traditional fibre placement process, and the new technology could additively “print into the component” additional functions, such as integrated lightweight and acoustically optimised structures, lightweight-construction-based crash systems, integrated antennas, integrated lighting or morphing properties.
The DLR Institute of Composite Structures and Adaptive Systems has had many years of experience in composite fibre manufacturing, such as in automated fibre placement (AFP). The Braunschweig Institute is now also to use additive manufacturing technologies: fused deposition modelling (FDM) and multi-jet modelling (MJM).