Engineers at Clemson University are tackling the lightweighting challenge by developing new applications for carbon-fiber composites and other nontraditional materials.
Composites are widely used to make airplanes, boats, sporting goods and other products because they can be made up to 10 times stronger than steel and a fifth the weight. However, composites traditionally cost more than aluminum and steel.
Affordability has been the biggest barrier to the widespread use of composite materials for automotive applications. But, recent tariffs on imported aluminum and steel could spark increased interest from automakers.
“The difference in the cost [could be] reduced substantially,” says Srikanth Pilla, an assistant professor of automotive engineering who also serves as director of the Clemson Composites Center. “If the mindset changes for the OEMs, there might be more opportunities for more parts to be made from composites. From a technology standpoint, it’s definitely there. But, cost-wise, there is always a push back.”
“Incentives similar to the ones that lower the cost of biofuels and electric vehicles could make a difference,” notes Pilla. “Just like [there are] incentives for electric vehicles [if there were incentives] for lighter vehicles, composites [could make] a big push into the automotive sector.”
As part of a $6 million grant from the U.S. Department of Energy, Pilla and his colleagues are developing a driver’s side front-door that will be made entirely out of thermoplastic composites. The goal is to make the high-strength steel door of a Honda Accord sedan 43 percent lighter, without sacrificing safety and structural integrity.
The Clemson engineers are also attempting to keep the cost increases often associated with nontraditional materials down to $5 for every pound of weight saved. Other challenges include meeting or exceeding standards governing fit, function, safety, stiffness, crash performance, recyclability, and noise, vibration and harshness.
Pilla expects to have a prototype door ready by early 2020. He also plans to develop a complete automation platform for mass-producing composite auto parts.
“Parts consolidation will play a key role in reducing assembly time,” claims Pilla. “We’re using adhesive bonding and polymer injection forming to join parts within the door system.”
While Pilla and his team are using the car door as a model to investigate affordable weight targets, he says the proposed technologies could also be applied to fabricate most of a vehicle’s structural, semistructural and interior components.
“Up until now, most people have only been looking at composites for nonstructural automotive applications,” explains Pilla. “But, the technology we have developed for doors and closure systems could be transferred to other types of car parts, such as body panels and roofs.
“At the very fundamental level, we’re also looking at high-temperature, under-the-hood applications,” adds Pilla. “Some possible candidates for carbon-fiber composites include engine fan belt and manifold systems.”
In addition to carbon-fiber composites, Pilla has worked with foams, polymers and other types of lightweight materials. For instance, he has studied ways that materials derived from trees could be used to produce lighter and stronger auto parts.
“Cellulose nanocrystals are central to the research,” explains Pilla. “They are rod-like structures 20,000 times smaller than the diameter of a human hair and suspended in liquid. They are made from trees removed during forest restoration projects that prevent wildfires.”
Pilla and his colleagues have focused on glove box and fender applications. But, he believes the technology could eventually be applied to a wide variety of automotive components, such as bumpers and instrument panels.
“The parts would be biorenewable,” says Pilla. “They could either be recycled or channeled to a composting facility instead of a landfill when their time on the road is done.”