ACA Study Demonstrates Composites' Benefits in Hybrid EVs

With hybrid electric vehicle (EV) sales forecast to exceed 1 million annually by 2012, the Automotive Composites Alliance (ACA, Arlington, Va.) announced on Jan. 17 the results of a benchmarking study of a prototype hybrid sedan to measure how composites can play a major role in hybrid EV development programs. The results generally show that in numerous hybrid EV applications, composites can provide significant savings in mass and tooling investment, as well as advantages in parts consolidation, corrosion resistance, opportunities for model differentiation and improvements in noise, vibration and harshness (NVH).

The ACA targeted seven applications for benchmarking, including hoods, fenders, deck lids, battery modules, floor pans, trunk compartments and front and rear bumper beam supports, says David Dyke, advanced engineering manager at Meridian Automotive Systems (Auburn Hills, Mich.), a member company of the ACA. In one portion of the study, the ACA study team disassembled and evaluated a prototype hybrid automobile. “We weighed and measured the components and discovered a lot of opportunities for improvements,” says Dyke.

ACA also compared a composite hood with a steel hood from a benchmark vehicle. The result was a 30 to 40 percent savings in mass and a 60 to 70 percent reduction in tooling investment. A similar comparison of fenders revealed a 25 to 35 percent reduction in mass and a 55 to 65 percent reduction in tooling investment. Importantly, the ACA’s benchmarking shows that the fenders could be consolidated into a single composite piece from four separate metal parts. ACA also pointed out that composites offered the opportunity for unique styling often not possible in metal, including the integration of wheel lip moldings.

The study further indicated that mass savings of 25 to 35 percent could be achieved in a benchmark decklid assembly by consolidating four metal parts into a two-piece composite construction. In this case, the move would result not only in reduced weight and greater fuel economy but also a 50 to 60 percent reduction in the tooling investment. ACA noted further that decklids that are compression molded from sheet molding compound (SMC) do not interfere with the transmission of RF waves. RF transparency would allow automakers to seamlessly integrate antennae for communication, navigation and audio systems into SMC decklid structures.

ACA’s study of floor pans, typically large structures welded together from numerous steel stampings, indicates the potential for a 30 to 40 percent mass reduction by using a lightweight core in a single-sandwich mold, with tooling investment savings of up to 60 percent. Improvements in stiffness and sound deadening also are possible.

“We think this was a valuable and worthwhile study,” says Dyke. “We are excited about the opportunities composites provide as hybrids continue to grow in acceptance.” Noting that the study validated ACA’s contention that composites technologies are right for hybrid vehicles, Dyke adds, “The ACA and its member companies are committed to providing composites solutions that will add the greatest value in hybrid vehicle applications.”

The ACA is an industry alliance of the American Composites Manufacturers Assn. (ACMA, Arlington, Va.). For more information on the study, visit ACA’s Web site: