“Lightweight construction is a key technology when it comes to reducing energy consumption and further improving safety,” affirms Dr Horst E. Friedrich.
Rib and space frame construction – reliable and lightweight
The body accounts for around a quarter of a vehicle’s overall weight and therefore offers great potential for optimisation. This is where the rib and space frame construction can be of help, combining conventional metal components with elements made of high-performance carbon-fibre-reinforced polymers
(CFRP). The length structures in this CFRP-dominated passenger cell (the so-called ‘Stuttgart model’) are still made of metal, but CFRP is used in the circular cross structure, the so-called ribs. The ribs are the load-bearing components in the passenger cell – lightweight, yet extremely stable – and replace the conventional A, B and C pillars in a vehicle. This innovative design ensures that the body structure weight can be reduced by up to 25 per cent and fuel consumption is diminished considerably.
|Carbon reinforced composite rib in crash test facility|
This rib and space frame architecture meets alternative power train requirements, particularly with regard to safety and flexibility. The structure developed by DLR engineers protects the tanks in a hydrogen vehicle much more effectively than conventional designs in the event of a side collision, for example. This is because the CFRP ribs are able to absorb about twice as much energy as metal components constructed in the same way. The basic passenger compartment structure is also extremely versatile. It can be adapted to different propulsion concepts and vehicle models without changing the underlying design principle.
New front end structure for enhanced safety in alternative fuel vehicles
The Institute of Vehicle Concepts team has developed a completely new type of front end structure to dissipate energy released during a collision more effectively. The core of the design concept is formed by innovative crash absorbers which are supported by a space frame structure. These com
ponents can be installed as side members in the front end structure of a vehicle, where they can replace existing structure solutions. In the event of a head-on collision, conventional crash absorbers fold together. The newly developed DLR model, on the other hand, involves a completely different deformation process: the crash energy pushes two aluminium tubes of different diameters together. In the process, the one tube peels off the uppermost layer of the other tube with the help of a ring-shaped metal cutter. Known as machining in metal processing, this process absorbs most of the energy released during a collision. The deformation process also takes place in a more controlled fashion. Thanks to the improved structural properties, damage can be minimised and safety can be increased for passengers, especially in vehicles with alternative drive architectures.
|Rohre des Crashabsorbers nach einem Zusammenprall|
State-of-the-art crash test system for auto components
When it comes to developing innovative vehicle concepts and the use of alternative materials such as carbon fibre polymers, computer simulations are often not enough on their own. The Institute of Vehicle Concepts has thus developed a special crash testing facility together with DSD, a company based in Graz, Austria. This system allows engineers to test large sections of vehicle bodies, such as the front structure of a car, even before a complete prototype is available.
The system consists of two test sleds on a rail. With a mass of up to 1,300 kilograms, the first sled can be accelerated up to 64 kilometres per hour. The second sled carries the body section being tested and is either fastened, so it remains stationary, or can move in the direction of the rail. This enables DLR researchers to re-create a side collision correctly, during which the vehicle is displaced. Each sled contains state-of-the-art data capturing systems, which measure the acceleration rate, the energies released and deformations.