Vehicle mass reduction strategies

The advantages of having a low vehicle mass are obvious. Even though the definition of what is a low mass seems to have changed, all companies are doing their share of lightweighting. This and the next few FOCUS articles will be about these strategies for mass reduction.

There are most often used strategies to achieve mass reductions are using different materials and/or different constructions for the load carrying members and body panels. Perhaps more important though are not the mass reductions for the load carrying members, but for the components mounted to them. The mass of these can be reduced by reducing the total number of components by integrating functions or by reducing the size of the components.

Aerospace has traditionally been regarded as the industry where lightweight constructions were most relevant and therefore it had the most innovations in this regard. This seems to be no longer the case, since the regulations have become so strict that most changes have become impossible. The regulations in automotive are more realistic and it is more costs which prevent introduction of new approaches. There are several industry and government collaborative research & development projects, such as the SuperLIGHT-CAR project, which try to find solutions which are cost-effective and give the desired result of mass reductions without compromises towards structural performance.

The good thing of these cooperations is that the best technologies from the partners are used in their most optimal use rather than whichever tech they specialised and invested in. The result is usually a vehicle which uses a combination of various alloys of aluminium and steel at the most convenient and effective locations, while all of a sudden it becomes acceptable to reduce performance. Normally this is not an option, because the market does not accept it, but for a research vehicle it is almost expected.

Volkswagen created a Golf with a 100kg lower mass than the production vehicle by using a higher amount of high-strength steel while also optimising the construction geometry. Ford recently did something similar and presented a lightweight research vehicle based on an existing Mondeo which was developed in cooperation with supplier Magna. This vehicle was a claimed 25% lighter than the original vehicle, though no absolute numbers were mentioned. This vehicle did not have the same performance as the original though, with a downsized engine and bicycle wheels and tires.

While it is promising to see the developments in regular vehicles, the most interesting technologies are still used in the more expensive sportscars. The mass reductions have the strongest effect on performance and the cost pressure is lower, while smaller production numbers allow for different manufacturing and assembly options.

Some production cars are already more advanced than race cars when production methods are considered. The resin-transfer-molding used in the manufacturing of CFRP tubs and body-panels is one example of this.

While any fiber-reinforced-plastic seems to be infinitely more advanced than metals, from a cradle-to-cradle perspective this picture changes considerably. Next week there will be more information about the developments regarding aluminium constructions and it will be clear that there is still a big opportunity for this material. ¤

This article first appeared on my now defunct website www.autoweekly.info on 2014-07-23.

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