Study finds aluminum can reduce vehicle body structure weight safely by up to 40%
13 April 2011
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| 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.
I wonder if that 40% is inclusive of other weight savings. For example, if you reduce the weight of the car, then you can use a smaller engine which further reduces the weight and structural needs, and so on down to a diminishing point of return.
It would be interesting to know if this is just the base structure weight reduction they are talking about or it is even greater with all factors considered???
Posted by: DaveD | 13 April 2011 at 09:02 AM
DaveD...you can assume that the Aluminium Lobbies has included every factor to get to 40%. However, one thing is not at all sure, i.e. have they included all the extra energy required and GHG to produce aluminium?
Posted by: HarveyD | 13 April 2011 at 09:08 AM
The original Honda Insight used aluminum body panels and some Audi models do. It can be done, but it costs. The savings in fuel and GHG emissions probably offset any manufacturing difference compared to steel, if any.
Posted by: SJC | 13 April 2011 at 09:29 AM
Sheesh! You could make an aluminum car today! All you need is 10,000 beer cans. Bedump dump.
Seriously, It's a cost issue. Audi's A-3 aluminum version was a compact, great mileage...but too darn expensive for a compact.
The car companies will argue that modern steel alloys are getting so strong and purpose-engineered that they can use less steel now, save weight and still be safer. Maybe yes, maybe no. Those alloys cost a bit more and the weight of cars isn't changing much...so they aren't doing it in large yet. Given the cost of developing new chassis, savings will likely be on peripheral parts for another 5 years.
Posted by: HealthyBreeze | 13 April 2011 at 11:58 AM
Pontiac and Saturn showed that a space frame with polymer panels is cost effective, strong, light and safe. This has been shown on several models and the downside is panel gap to allow for expansion. I think people could live with that.
Posted by: SJC | 13 April 2011 at 12:33 PM
@DaveD
I think the quote at the end by Randall Scheps answers your question. That's what "holistic approach" means.
Posted by: ai_vin | 13 April 2011 at 02:31 PM
What about carbon fibre?
http://www.fiberforge.com/
http://green.autoblog.com/2007/09/04/video-rmis-hypercar-a-100-mpg-suv-featuring-amory-lovins/
http://www.thewebofhope.com/hypercar/
Posted by: ai_vin | 13 April 2011 at 11:26 PM
"However, one thing is not at all sure, i.e. have they included all the extra energy required and GHG to produce aluminum?"
Yes but it is highly recyclable and it does not rust away as readily.. saving tons of rustproofing compounds. In any case the car companies know how to do their jobs.
Posted by: Herm | 14 April 2011 at 09:58 AM
The public needs to be convinced. If it costs more, is it safe and durable? Is this something new or proven? You have to show the car was 3500 pounds and got 20 mpg and now it is 3000 pounds and gets 24 mpg. What are they getting for what they pay?
Posted by: SJC | 14 April 2011 at 10:08 AM
Screw this! I'm gettin' me one of them bamboo cars. Now THAT'S a light car!
Posted by: sheckyvegas | 14 April 2011 at 05:06 PM