|Body in white is the next area of focus for downweighting. Source: ATG. Click to enlarge.|
Using aluminum in select automotive components could reduce vehicle body structure weight safely by as much as an additional 40% compared to today’s vehicles, according to a recent study by the University of Aachen (Germany) for the European Aluminium Association (EAA).
After producing the 40% upper limit figure, the study noted that in practice, additional aspects will have to be considered such as the joinability, the performance of the joints or nodes connecting the different components or the NVH performance. Therefore it may not be possible to fully exploit the indicated weight reduction potential of high strength aluminium alloys, the report cautioned. However, it also noted, similar restrictions may also apply to the substitution of ultra-high-strength steel grades for conventional steel grades.
It has to be mentioned that in contrast to perpetually mentioned arguments the weight reduction potential of aluminium is limited by strength requirements for few components, only. The reason is that even in state-of-the-art car bodies most of the steel components are still made from steel grades that show yield strength in ranges that aluminium can compete with. This situation can be regarded to change in the future only to a limited extent, since many components are not suitable for efficient high-strength material usage. For many components stiffness will maintain the decisive criterion.
It can be expected that in future body concepts mountable components will have the best chances to be made of light materials. If lightweight design becomes more important due to emission regulations the market penetration of aluminium closures in the middle class and the compact class is a realistic scenario.—Aachen study
The study, which aimed to identify the strength relevance in crash and the stiffness relevance of typical car body components in order to assess the remaining weight reduction potential by application of high-strength steel, analyzed 26 components in a compact-class vehicle.
The study found that weight reduction potential using high-strength steel was limited to an additional 11%; nearly 40% of the parts analyzed cannot be made thinner regardless of the grade of steel used. If high-strength steel were to be used to downweight these parts, their stiffness actually would be reduced and the car’s performance would suffer, whereas aluminum could be used without reducing stiffness or causing the car’s performance to suffer.
The Aluminum Association’s Transportation Group (ATG) said that this study, combined with other data on the benefits of aluminum, suggest a total of about 525 pounds of additional weight savings, which could result in 2.7 more miles per gallon or a nearly 10% further improvement in fuel economy over a typical auto today. This can be done while maintaining—if not further improving—vehicle safety.
The answer for cleaner, more efficient, affordable cars and trucks is a holistic approach to include low-weight, high-strength, affordable materials—like aluminum—matched with smart design, advanced powertrains and cleaner fuels.— Randall Scheps, ATG Chairman and Director of Ground Transportation, Alcoa Inc.