Wednesday, October 7, 2009

Aluminum Versus Steel Versus Carbon-Composites

This was posted on Design News by Doug Smock..And I thought it was interesting...
Tesla & Chevy Volt: Aluminum Versus Steel Versus Carbon-Composites

What will be the material of choice for the bodies and structures of the first generation of electric cars? The Tesla Model S which is expected to debut in late 2011, will use aluminum alloy body panels. The highly publicized Roadster, which will cost twice as much, will use carbon composites.

The critical factor is processing time. Hand layup of fiber combined with cure times work fine for an aircraft such as the Dreamliner. But that won’t cut it for production models of cars, even if production only reaches around 20,000 units. As reported by Design News, Plasan Carbon Composites is developing new technology that will cut process times, but - at least as far as Tesla is concerned — it apparently won’t be ready for prime time in 18 months.

Companies such as Alcoa would love to see aluminum used for the bodies of higher-volume electric cars. But steel, albeit newer and lighter steels, will often be the material of choice because of cost considerations. One engineering analysis “shows that it takes 9 years or 122,460 miles, at a gas price of $2.53 per gallon for aluminum structured vehicle to offset the total cost for steel structured vehicle.” Certainly, aluminum will be an important player for many structural components in cars. As reported by Design News, GM engineers selected forged aluminum wheels for the Chevy Volt.

Plus..I also wanted to include a comment posted as well:

October 2, 2009
In response to: Tesla & Chevy Volt: Aluminum Versus Steel Versus Carbon-Composites
Melissa Clark commented:

On behalf of our client, The Aluminum Association's Automotive Transportation Group (ATG), I wanted to set the record straight about your assertion that, “…steel, albeit newer and lighter steels, will often be the material of choice [in next generation autos] because of cost considerations.” Fact is, using lightweight, high strength aluminum structures with alternative powertrain vehicles can improve a vehicle’s fuel economy, and a recent study - - commissioned by the Aluminum Association found aluminum-structured hybrid and diesel vehicles achieve more than 13 percent better fuel economy than their steel-bodied counterparts. As for cost, it’s well known that diesel and hybrid powertrains provide better fuel economy over standard internal combustion engines, but at increased costs to the consumer. Advanced powertrains also have a payback period of several years compared to gasoline engine of equivalent performance. Yes, it’s true that when aluminum is selected over heavier steel, the new, lighter platform typically costs more – at least up front. However, by reducing the weight of the vehicle, the power requirements can be correspondingly reduced, leading to a more affordable powertrain and vehicle overall. The fuel savings gained offsets the additional cost of the platform and powertrain within one to four years. As a result, aluminum’s value proposition is the automotive sector is increasingly nearly as fast as its usage, which is currently at an all-time high, and expected to continue rising in the years ahead.