Climate protection through automotive lightweight construction

FAT research on lightweight construction: composite construction is the future of autobody design

The heaviest part of an automobile is the autobody, comprising about 40 percent of the total weight. If CO2 emissions caused by traffic are to be further reduced in the future, lighter constructions and thus new ideas in autobody construction are needed.

In cooperation with manufacturers, suppliers and scientists, the Research Association of Automobile Technology (FAT) investigates new strategies for automotive lightweight construction. Experts say that a weight reduction of up to 50 percent can be achieved with the consequent use of automotive lightweight construction compared to conventional construction designs. If the weight of a midsized car is reduced by 100 kg, then fuel consumption is lowered by up to 0.3 l/100 km. If CO2 emissions are to be reduced, lightweight construction is a very important influencing factor.

The growing demand for more safety and comfort, improved mileage and low emissions constantly increase the requirements for lightweight construction. This is not only achieved with lightweight and high-strength materials but also with the optimal use of installation space and component loading. New ways of component calculation and functional integration are need here to go beyond classical construction methods.

While expensive materials like carbon fiber reinforced polymers (CRP) are often used in the premium segment, higher material costs in mass production can hardly be passed on to the consumer. Complicating this is the fact that the number of vehicle segments is increasing but they themselves are shrinking. That is why only lightweight construction strategies will be applicable in the long run, which ideally combine the features of cost, quantity, weight and function.  Much has already been achieved with new grades of steel. To derive optimal solutions from the existing framework conditions, innovative approaches must be evaluated in the trade-off between weight reduction and economic tenability. 

Under this premise, the trend is developing away from singular steel and aluminum designs towards modern composite construction. This is mainly being determined by developments in joining technologies. In the search for weight reductions, great hope is placed on the material magnesium. Its susceptibility for contact corrosion and low breaking strain, however, are currently blocking its broad application.

As in aerospace technology, the focus is increasingly on carbon fiber reinforced polymers (CRP) that are lightweight but can carry a heavy load. CRP are especially important in this connection because they are five times more tensile than steel and about 30 percent lighter than aluminum. They have the advantage that the fiber direction can be optimally aligned with the load application, thus achieving the greatest possible load transmission.  The disadvantage is that the material abruptly breaks when exceeding the breaking point and does not malleably warp like steel or aluminum. Calculating material fragmentation, for example, during a crash, requires new material and mathematical models, on which researchers at FAT are already intensively working. A greater use of CRP in automotive construction appears possible at least in the midterm. The cost structure must still be considered when using CRP. Due to high energy consumption in the production of CRP fibers from its precursor chemical polyacrilonitrile, the total ecobalance must be more intensively evaluated today.

Against the backdrop of CO2 reduction and the trend reversal in the weight of new generations of automobiles, the growth potential for innovative automotive materials is advancing at the highest level. The supply structure with regard to parts and raw materials provides good opportunities to automotive parts suppliers. Suppliers will sustainably increase their market share through new intelligent products and smart process developments.

The expansion of model variations of automobiles and the modulization of automotive parts offer suppliers new possibilities of developing alternative production procedures and composite applications. Close cooperation along the supply chain plays an important role here. OEMs, raw material suppliers and parts manufactures can effectively work together.

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First publication: 06.04.2009 Last modified: 27.02.2014