Is Carbon Fiber the Future of Truck Bodies?
While cost remains an obstacle to widespread acceptance of carbon-body trucks, this lightweight, durable, and strong material can facilitate fleet vehicle downsizing, promote fuel-efficient engines, and help extend lifecycles.
July 2010, Work Truck - Feature
Carbon Fiber: Lighter than Steel, But as Strong & Rigid
Carbon fiber is a material consisting of extremely thin fibers, thinner than human hair, about 0.005-0.010 mm in diameter and composed mostly of carbon atoms. Several thousand carbon fiber strands are twisted together to form a "yarn," which is woven, molded, and coated with a stiff resin or plastic to form a composite material weighing significantly less than steel, yet offering comparable strength and rigidity.
Carbon fiber is used in spacecraft, satellites, aircraft, Formula One racecars, architectural structures, and in other applications requiring light materials capable of withstanding high stress.
How does carbon fiber compare with other lightweight materials, such as aluminum and fiberglass?
Aluminum is significantly lighter and more corrosion-resistant than steel. However, aluminum usually costs more, although recent market conditions have significantly narrowed the gap. The downside to aluminum is that it's not as strong or durable as steel and is often more expensive to repair.
Compared to aluminum, carbon fiber is lighter and offers similar corrosion-resistant capabilities, but is considerably more durable, with strength on par with steel.
Much of the Chevrolet’s Silverado ZR2 concept pickup body is constructed of carbon
fiber, including the front fenders, extractor-style hood, rocker extensions, and tailgate.
What about fiberglass? "Carbon fiber is stronger than fiberglass and a little bit lighter," says Paul. "The carbon fiber will have a lot of the same characteristics as fiberglass, but will be about 10-15 percent lighter and to what degree stronger, I don't know yet because we're still in the [research and development] phase with carbon fiber."
Paul offers this example as a frame of reference: "The weight of a typical 8-foot steel service body is 1,248 lbs. The weight of our [composite] body, which is a hybrid of aluminum and fiberglass, is 590 lbs. We believe we can build a body out of carbon fiber for around 400 lbs.," says Paul.
That's a more than an 800-lb. increase in payload with carbon fiber, compared to steel, without sacrificing strength.
Overcoming the Cost Barrier Depends on Further Development
Despite the promise of carbon fiber in the truck body market, one major obstacle stands in the way: cost.
"I don't see [carbon fiber] around the corner yet. It's at least 10 years out," says Johnson. "It's not really an available technology [to body companies] at the moment because of cost, but I think eventually it will be."
According to the 2008 Progress Report on Lightweighting Technologies by Oak Ridge National Laboratory (ORNL) - a science and technology laboratory managed for the U.S. Department of Energy (DOE) by UT-Battelle, LLC - carbon fiber is too expensive at $20 per pound for large-scale automotive use. The cost must be cut to $5 per pound before significant use of carbon fiber is seen in the automotive industry.
What will drive down the cost to a more acceptable level? In December 2009, the U.S. government earmarked funds to ORNL to find the answer. Through the American Recovery and Reinvestment Act, the DOE allocated $34.7 million to establish the Carbon Fiber Center at ORNL. The project will further the research, development, and commercialization of low-cost carbon fiber.
Ray Boeman, director of ORNL Advance Transportation Systems Programs, says ongoing research focus areas include identifying low-cost carbon fiber precursors (raw materials), developing advanced technologies for converting precursors to carbon fiber, and testing low-cost composite design and manufacturing capabilities.
"The new technology center's capabilities are expected to advance these research efforts, while enabling development of new innovations and commercialization opportunities," says Boeman. "The facility will be highly flexible and instrumented to demonstrate and evaluate the scalability of science and technology for lowering carbon fiber costs at least 50 percent and improving affordability of carbon fiber in high-volume applications."
According to Paul, if carbon fiber costs drop low enough for major automotive OEMs to sign on, the heightened demand and resulting material standards would make the ultra-lightweight material more financially viable for the specialty vehicle market.
"What the U.S. government is trying to do is to take carbon fiber out of the aerospace sector and put it into the automotive sector, where it's more mainstream. What you'll find, as with any new technology, is that it will be more expensive the first go-around, probably adding a premium of an additional $1,000-2,000 [to the price of the body]. And then, as it becomes more and more used in the process, it will start to get cheaper," says Paul.
"The OEMs are using fiberglass and other composite materials on their fenders, doors, and so forth. But it is slow getting into the specialty vehicle market, because [the carbon fiber industry] is such a disorganized market, with so many players," Paul adds. "You have a lot of different products and theories out there. I suspect that as carbon fiber reaches GM, Kenworth, International, and Freightliner through carbon-fiber leaf springs and other components of the vehicle, you'll start to see the price of carbon fiber go down. Then that $1,000-$2,000 premium won't be there."