Light-Weight Vehicle Discussion Steers Toward Carbon Fiber

TRAVERSE CITY, MI – The auto industry is looking to put vehicles on weight-loss diets in order to meet federal fuel-economy targets, and one way to do that is by using more carbon fiber, says Mansour Mirdamadi, chief engineer for Dow Automotive.

“You have to look at options, and one of them is carbon-fiber composites,” he says at the 2012 Center for Automotive Research’s Management Briefing Seminars here.

Beyond being lightweight, carbon fiber is strong, fatigue-resistant and impervious to corrosion. But it’s also expensive. That holds it back as a widely used material on mainstream cars. Its use on vehicles generally is limited to the bodies and chassis sections of Formula 1 race cars and costly exotics.

Still, many in the industry see carbon-fiber composites as an appealing way to reduce vehicle weight while also maintaining structural strength. Others doubt it will see much use by cost-conscious volume auto makers.

“You have to balance costs carefully,” says Dave Coleman, vehicle development engineer-Mazda North American Operations. “That’s what has kept us in steel for so long.”

Steel remains the material of choice at Ford, too, “but we will look at the benefits of all materials,” says James Morgan, the auto maker’s director-global body exterior.

Carbon fiber long has been a subject of discussion, debate and speculation as to its practical use in mass-produced vehicles. Twenty years ago, Ford built a concept car using carbon-fiber parts, but it never made it into production.

Will carbon fiber’s day come eventually? Morgan isn’t so sure. “A colleague of mine says it’s the material of the future – and always will be.”

But Mirdamadi says as innovative and improved uses of steel and aluminum “plateau,” the industry must look to other materials in its effort to build cars that weigh less in order to achieve greater fuel efficiencies.

“We are being pushed to introduce technology faster than it would happen in its own right,” says Jay Baron, CEO of the Center for Automotive Research, referring to U.S. government mandates for corporate average fuel economy to reach 54.5 mpg (4.3 L/100 km) by 2025.

Ironically, cars and trucks alternately have been losing and gaining weight. They lose mass when engineers, in the name of fuel efficiency, come up with ways to reduce the weight and size of components.

But they put on pounds when advanced safety features, often mandated by federal law, are installed.  Vehicles also are made heavier when auto makers add equipment such as advanced telematics systems in response to consumer demand.

“A lot of convenience stuff that’s put on cars adds weight,” says Greg Schroeder, a research analyst for CAR who also heads an industry group called the Coalition for Automotive Lightweight Materials (CALM).

The group is pressing its case to auto makers, some of which claim it’s a Tier 1-supplier issue at this point, he says. Others say vehicle-weight reduction may achieve fuel efficiency, but it competes with other technologies that also lower fuel consumption.

“The question for some people is, ‘Which way is cheaper?’” Schroeder says.

The coalition is promoting its cause by planning a first-ever awards program to recognize innovations in vehicle-weight reduction. The group is accepting nominations this year and plans to give out awards in 2013.

“If we honor weight reduction in cars, maybe we can inspire it,” says Tony Norton, a CALM member and director-business development for Altair Engineering.

Audi has made strides in vehicle-weight reduction by a greater use of aluminum, which is about 40% lighter than steel. The German auto maker particularly uses aluminum throughout the body of its flagship A8 sedan.

Audi now is working on a “multi-material body” for its TT model, says Manfred Sindel-quality manager. “Our strategy is improved performance and reduced weight.”

The future is in more mixed materials, he says, referring to aluminum, steel and others. “Magnesium is an interesting candidate, but not a proven one.”

The next-age material will be carbon-fiber reinforced polymers, Sindel predicts. “In preparation for that, Audi wants to build up our internal know-how for engineering and cost reductions. Long term, we would like to see high volume and high integration.”

But as a premium car company, Audi has the luxury of conducting research and development in expensive materials, says Mazda’s Coleman, noting Audis cost a lot more than Mazdas.

Upcoming Mazdas will “have a lot more aluminum,” Coleman vows. But those future vehicles will contain plenty of steel, too. “We look at what we can accomplish with the material we’re most familiar with.”

As the industry moves toward a greater use of mixed parts, questions are raised about best ways to adhere them to each other. “How do you best join carbon-fiber composites to steel?” says Mirdamadi, proposing auto makers and suppliers work together on composite-joining technology.

“The complicated thing is joining carbon-fiber composites,” Sindel says. “I’d like adhesive bonding, only if it worked. You need some other elements.”

An adhesive material needs to show structural holding power reliably and throughout the life of a vehicle, Mirdamadi says.

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