Slimming diet for car and co.

Lightweight components and new welding technology save weight and energy

XXL Laser Beam Welding System © Fraunhofer IWS
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Down with the weight - that is the motto of automobile and aircraft manufacturers. For the heavier a car or plane is, the more fuel it needs. Lightweight, yet safe, stable and reliable - that's how the models of the future must be. Researchers at the Fraunhofer Gesellschaft are therefore working with partners from industry to develop new components such as car doors, which are made of lightweight construction materials.

Air conditioning, navigation system, airbags, power steering, antilock braking system - new cars are equipped with more and more electronic refinements and security systems. But the higher demands on comfort and safety have their price: the weight of the vehicles and thus also the fuel consumption increases. In order to reduce the fuel consumption, car manufacturers put on a significant weight reduction. Lightweight construction materials such as aluminum, magnesium and fiber composite materials are designed to help slimming down - without sacrificing safety, comfort and reliability.

How this works is shown by Fraunhofer researchers using the example of a lightweight door. The new car door is 18 percent lighter than currently used models and yet safe. The door consists of a hydroformed aluminum frame. The necessary side impact protection is provided by an aluminum foam core. "The use of hydroforming, aluminum foaming, plastic and gluing as the joining technique of the different components not only saves weight. It is also possible to achieve a more homogeneous load on the components and the connection points, "explains Axel Storz from the Fraunhofer Technology Development Group TEG about the advantages of the new lightweight door. In addition, functional integration reduced the number of components from 23 to 18. This simplifies manufacturing and reduces costs.

Laser welding makes planes easier

Even aircraft manufacturers look at every kilogram. Especially for wide-body aircraft of the XXL generation - such as the Airbus A 380 - operating costs must remain manageable. To save weight, the new Airbus A 380 fuselage parts are no longer riveted, but put together in a large laser beam welding in the Airbus plant Nordenham in one step with stiffening elements. That saves about 100, 000 rivets.

"When laser welding, you can do without the wide rivet base in the outer skin of the aircraft and at the Stringerfuß. At the same time, the sealant between the riveted parts is eliminated. This reduces the structural weight by five percent, "explains Professor Berndt Brenner from the Fraunhofer Institute for Material and Beam Technology IWS in Dresden. In the future, the experts expect that by further improvements in material and welding technology, a maximum weight savings of up to 15 percent could result. Another advantage of the new production technology: the welded joint delivers greater compressive and shear strength despite the lower weight. Laser welding also shortens production times. Laser welding can produce six meters per minute. The riveting speed, however, is only about 20 to 40 centimeters per minute. display

New laser welding system developed

In a joint project of Airbus Deutschland GmbH, the Fraunhofer Institute for Material and Beam Technology IWS in Dresden, the Schuler Held Lasertechnik GmbH Dietzenbach and the ibs Automation GmbH Chemnitz, the researchers developed and tested a so far unique laser beam welding system. Together, IWS and Airbus Germany engineers want to further reduce the weight of aircraft. To do so, they are testing new machine concepts, developing weldable metallic constructions and developing welding processes for even lighter aluminum alloys.

"Lightweight construction is the technically and economically feasible maximum weight reduction with sufficient rigidity, dynamic stability and operational stability, " says Thomas Hollstein of the Fraunhofer Institute for Mechanics of Materials IWM, summarizing the requirements for the development of lightweight construction concepts must be considered. He coordinates the Fraunhofer Perspectives topic Integrated Lightweight Systems . In this project, the Fraunhofer-Gesellschaft bundles the lightweight construction expertise of its institutes. The goal is to reduce the weight of components using innovative materials, processes and concepts.

(Fraunhofer-Gesellschaft, 05.04.2006 - DLO)