DETROIT — The math in favor of using more composites in future North American autos is easy to calculate.
Cutting weight means improving fuel economy — and the U.S. is facing a 2025 deadline to improve the Corporate Average Fuel Economy to 54.5 miles per gallon by 2025. Every 100 pounds of mass reduction adds up to an estimated 0.2 miles per gallon improvement, noted Saad Abouzahr, head of organic materials for Chrysler Group LLC, during an April 16 discussion about composites at the Society of Automotive Engineers 2013 World Congress in Detroit.
"Eventually, something is going to happen to tip the scale, and lightweighting is playing an important role," he said.
What is not so easy, though, is seeing how the industry will use multiple materials — including thermoset and thermoplastic composites — on high-volume production cars to drastically cut that weight.
"All the [automakers] are having problems addressing production of a multimaterial car," he said.
Although Chrysler, based in Auburn Hills, Mich., is using carbon fiber extensively on the current Viper sports car, it sees that production as a "great learning experience," rather than a specific example of where it will use carbon fiber in the future, Abouzahr noted.
Michael Wiseman, R&D director in the Americas for Honda Motor Co., agreed, noting six "challenge points" that suppliers and automakers must address before composites can become more mainstream for major part production:
• Improve ways to join multiple materials, including plastics and metal, through adhesives or welding.
• Improve the design community's understanding of ways to use composites.
• Raise production speed for composites, potentially up to one part every minute.
• Reduce and control costs.
• Improve software for simulation and production of composite parts.
The aerospace industry has done some important work on improving pre-production simulation, Wiseman noted, but airplane manufacturers are looking at different factors in their end products. An automaker, for instance, must test for specific crash data and know how body and structural panels would stand up to repeated low-speed bumps.
Until those issues are addressed, more-traditional materials will remain the fallback choice for future development.
"We haven't really seen a lot of follow through that will allow us to make … composites mainstream," Wiseman said. "I think everybody understands that right now the momentum is on the side of traditional steel for body structures."