Inspiration from Nature

DaimlerChrysler is using a new concept vehicle to examine the great potential of bionics for automobile development, and has achieved outstanding results for fuel consumption and emissions with a combination of pioneering diesel engine technology and innovative emission control methods.

To realise the Mercedes-Benz bionic car, the engineers at the Mercedes-Benz Technology Centre and the DaimlerChrysler Research department have for the first time looked for a specific example in nature which not only approximates to the idea of an aerodynamic, safe, comfortable and environmentally compatible car in terms of details, but as a formal and structural whole.

The example arrived at was the boxfish.

With an accurately constructed model of the boxfish the engineers in Stuttgart were able to achieve a wind drag coefficient of just 0.06 in the wind tunnel.

In order to use this great potential for automobile development purposes, specialists at DaimlerChrysler first created a 1:4 car model whose shape was substantially based on the boxfish.

During tests in the wind tunnel, a drag coefficient of 0.095 – a previously unprecedented value in automotive engineering – was measured for this clay model. It corresponds to the values achieved with highly streamlined shapes (Cd 0.09) and other aerodynamically ideal forms.

DaimlerChrysler utilised the findings from this research during the development of the Mercedes-Benz bionic car, a fully functioning and roadworthy compact car with a length of 4.24 metres and space for four occupants plus luggage.

With a Cd value of just 0.19, this concept vehicle is among the most aerodynamically efficient in this size category.

In addition to superb aerodynamics and a lightweight construction concept derived from nature, the 140-hp diesel engine and innovative SCR technology (Selective Catalytic Reduction) greatly contribute to fuel economy and a further reduction in exhaust emissions. In the EU driving cycle the concept car has a fuel consumption of 65.7 mpg – 20 less than a comparable series-production car.

The Body structure: nature’s construction principles for rigidity and light weight

Both the external armour-plating of the boxfish and the bone structures of other creatures show how nature achieves maximum strength with the minimum use of materials. Bone structures are always in accordance with the actual loads encountered.

In the case of the human thigh bone, for example, the position and strength of the bone matter is precisely right for the tensile and pressure loads which the limb must withstand.

It is not only bone structures but also tree branches and roots that grow according to biological laws – a perfect lightweight construction strategy on the part of nature.

In consultation with bionics experts, DaimlerChrysler researchers have developed a computer-assisted process for transferring the growth principle used by nature to automobile engineering. It is based on the SKO method (Soft Kill Option).

Computer simulation is used to configure body and suspension components in such a way that the material in areas subject to lower loads can be made less resistant, and can perhaps even be eliminated ("killed") completely, while highly stressed areas are specifically reinforced. This bionic SKO process enables an optimal component geometry to be identified which meets the requirements of lightweight construction, safety and durability in equal measure.

The hexagonal scales of the boxfish likewise obey the principle of maximum strength for the least weight. Transferred to the external panelling of a car door, this natural construction principle produces a honeycomb pattern with up to 40 percent more rigidity.

If the entire bodyshell structure is configured according to the SKO method, its weight is reduced by around 30 percent – while retaining its exemplary stability, crash safety and handling dynamics. In this area too, bionics can therefore make a further major contribution to greater fuel economy.

The Mercedes-Benz bionic car study will have its world premiere at this year’s DaimlerChrysler Innovation Symposium in Washington.

Technical Data

(Source: Mercedes-Benz)