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Applications such as this bio-fiber door will help composites in lightweight applications to meet new fuel economy standards.
In April, the U.S. Department of Transportation (DOT) and the U.S. Environmental Protection Agency (EPA) jointly established new federal rules that set the first-ever national greenhouse gas (GHG) emissions standards for all new passenger cars and light trucks sold in the United States. The rules, which will significantly increase the fuel economy of the vehicles starting with the 2012 model year, will conserve about 1.8 billion barrels of oil, and reduce nearly a billion tons of GHG emissions over the lives of the vehicles covered and give lightweighting composites an opportunity to shine.
The final rules, issued by DOT’s National Highway Traffic Safety Administration (NHTSA) and EPA, establish increasingly stringent fuel economy standards under NHTSA’s Corporate Average Fuel Economy program and GHG emission standards under the Clean Air Act for vehicles produced in model years 2012 through 2016.
Starting with 2012 model year vehicles, the rules require automakers to improve fleet-wide fuel economy and reduce fleet-wide GHG emissions by approximately five percent every year. NHTSA has established fuel economy standards that strengthen each year, reaching an estimated 34.1 miles per gallon by 2016.
So what exactly does this mean for composites? A greater focus on fuel economy brings lightweighting to the forefront. With an oft-cited advantage of composites being a lighter alternative to substances such as metal, it only seems natural that composites emerge as a prime option to meet this directive.
John Schweitzer, senior director of government affairs for the American Composites Manufacturers Association (ACMA) says there’s a vehicle technology program at DOE that has a list of technologies for applications like hybrid engines and alternative fuel vehicles. “The problem is, it skips over glass composite materials and goes on to things like carbon nanotubes, lignum and magnesium. I think composites should be in that mix, but they’re not, even though they can offer a significant improvement in fuel economy through weight reduction.”
However, Jim deVries, manager of the manufacturing research department at Ford Research Laboratories, says conventional composites alone may not be enough. “Glass composites do not achieve the weight savings created in aluminum and magnesium, so I think the composites industry must look towards alternative reinforcements, ways to make conventional composites more lightweight.”
Which Fibers Win Out?
Carbon fiber represents a more commonplace solution to the lightweighting issue. “We see more emphasis on carbon fiber,” says Hamid Kia, group manager for polymer composites at General Motors. “The dollar-per-pound saved related to mass savings is going up because companies are more willing to pay more up front.”
The problem is that the material has always been too expensive. “Carbon fiber may be the next big composite material for the automotive industries, but for that to occur, the price of carbon fiber has to go down,” says deVries.
Natural fibers such as flax and hemp could play a larger role in achieving these standards, and composites are fully capable of being involved. “The need for renewable sources has been driving more emphasis on natural fiber and developing composites,” says Kia.
“This material is strong in its natural form and is rapidly renewing. It plays right into the green initiative that’s emerging,” says Mark Townsley, ground transportation engineer at the Composites Innovation Centre (CIC) in Winnipeg, Canada. CIC has an internal program of commercializing hemp bio-fibers, and the institution is hard at work on developing parts to meet this need.
Last December, CIC started work on a natural fiber battery door for a J4500 motor coach. Townsley, had worked at Motor coach Industries for over a decade and worked with them on manufacturing the product using a typical sandwich construction in a light RTM mold.
As one might expect with an emerging building material, there were challenges. “In the first tests, the permeability wasn’t as good as we wanted,” says Townsley. “We did mechanical and flex sandwich testing of the pure hemp material and found it wasn’t great when compared to glass. We went back and combined some glass fiber with it and managed to get some good parts using that technique, so we used the hybrid lay-up for the door.”
So far, the bio-materials are slightly heavier than fiberglass (about two percent). The material itself is lighter, but becomes heavier because it tends to soak up resin. “As we design the mats to become more permeable in the closed molding form, we hope to tailor it to weigh less than glass,” says Townsley.
Thanks in part to Townsley’s past employment, CIC has good connections with all local ground transportation manufacturers. “Transportation companies are keen on using the green products. It’s more important to people than many realize. It didn’t take much convincing to actually try them. Everybody’s game to try new things,” he says.
Of course, anyone can try something, but real-world adoption is a different matter. “There can be a lot of excitement generated in bio-based materials but in doing so, there is a lot of work that needs to be done to make these compatible with the automotive environment, whether it is humidity or heat or so forth,” says deVries.
For its part, CIC is also concerned about cost as they attempt to commercialize natural fibers on a global scale. “If it doesn’t compete price-wise to existing materials, we have to make sure it does,” says Townsley. “We’re very cognizant of what we have to do. Our stuff is being done on prototype lines and experimental lines, so it is more expensive now. These are low-quality experimental runs right now, but I have every confidence that they’ll cost less, especially with the rise of fuel costs to process existing materials. Those and transportation costs will factor into the lower costs.”
Projects like CIC’s bus cover are just the first step on the auto industry’s path to achieve better fuel economy. Lightweighting is a straightforward method in accomplishing that goal, and composites companies may do well to jump on the idea now and connect their product with that concept.
