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Products and solutions, 2002-09-11, 02:00 AM

Potential for lightweight construction in commercial vehicles through the use of aluminum - Weight reductions of up to 50 percent

Weight reduction is a major issue in passenger car developments today, as exemplified by the use of aluminum for entire vehicle bodies or key body assemblies. Statistics also show that increasing proportions of lightweight materials such as aluminum, magnesium and plastic are being used in car construction. By contrast, such materials have so far featured far less in commercial vehicles. This is mainly due to the much higher and more complex loads placed on individual components. However, the use of aluminum in commercial vehicles offers great potential. In addition to savings on fuel due to reductions in weight, there are other advantages that could contribute to improved economy in the transport of freight. These include greater loading capacity and thus a reduction in journeys, aluminum`s superior corrosion resistance and the higher resale value of aluminum vehicles.

ThyssenKrupp Umformtechnik has long been working on the use of aluminum in commercial vehicles. To achieve high weight reductions at acceptable extra cost, the basic design of the vehicle needs to be rethought to make the most of aluminum`s specific advantages and strengths. Building on these basic considerations, a study was carried out on the use of aluminum in commercial vehicles using a large transporter van as an example. Aluminum-compatible designs were developed for most of the assemblies, various concepts were compared and the potential weight savings calculated. The total estimate resulting from the key profitability figures conveys the likely benefits associated with the use of aluminum in commercial vehicles.

Extensive design studies on sliding doors for van loading compartments showed that these components are particularly well suited to lightweight construction. Depending on the design and the technical requirements, weight savings of between 30 and 50 percent can be achieved versus comparable steel designs. For sliding doors in particular, weight optimization has the additional advantage of making them easier to open and close as well as allowing hinges and locks to be made lighter. For large volumes, aluminum sheet designs represent the best option in terms of both technology and economy. For smaller volumes and special designs, solutions utilizing extruded sections and castings are more economical.

One important aspect here is the need to adapt joining techniques to the special requirements of the aluminum material.

When it comes to using aluminum for structural components, extruded sections are the ideal solution. Their cross-sections and thicknesses can be optimally adapted to match localized loads. Such sections also offer numerous possibilities for integrating functions and allow great flexibility in terms of size (wheelbases and body heights). For example, the sections can incorporate fastening systems for a simple method of securing loads and for installing clothes rails, shelves or other logistical elements. Thanks to the modular structure, various body shapes, e.g. roof heights, overhangs or wheelbases are possible. In this way, customized vehicle designs can be built on the basis of standard elements.

For design reasons, the large panel areas will continue to be made of sheet metal components. New options for further optimizing weight or economy are opened up by the use of sandwich materials or pre-painted sheets. However, it is important that panel molds and tooling also be designed to allow simple adaptation to these sizing concepts. Assembly methods also need to be adapted in line with the specific properties of aluminum and planned batch sizes. The spot welding process typically used for steel components is replaced for aluminum by bonding, riveting and clinching. In the future, laser welding will also play an increasing role in the assembly of aluminum bodies. Solutions devised so far show that the use of aluminum can be economical if the design takes account of the material`s special properties. When this is the case, weight savings of up to 50 percent can be achieved at additional costs that remain within acceptable limits. Of particular importance here are the sensible use of extruded sections and the choice of suitable joining methods.

Picture: Prototype of an aluminum transporter van.
<small>Copyright: ThyssenKrupp Automotive</small>

Picture: The sliding door for the load compartment is between 30 and 50 percent lighter than comparable steel designs.
<small>Copyright: ThyssenKrupp Automotive</small>

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