Advances in composites help make a sports car even faster.
By John Varrasi

Some presentations deserve more than a PowerPoint slide show. So when engineers with Automobili Lamborghini of Sant’Agata Bolognese, Italy, came to make their technical presentation at the 2009 ASME International Mechanical Engineering Congress in November, they brought along one of the company’s sleek Murciélago LP 670-4 SuperVeloce luxury sports cars.

The bright yellow Murciélago on exhibit at the Congress complemented a presentation examining recent research in the area of carbon-fiber composites for primary vehicle structures.

Lamborghini has used carbon-fiber composites in the production of the Murciélago since 2001. Indeed, carbon-fiber composites account for 31 percent of the structural weight of today’s Murciélago, and Lamborghini is interested in increasing the content of carbon-fiber in future model years. A challenge to meeting this new corporate strategy is to reduce the high costs associated with processing carbon composites.

Carbon-fiber composite materials are extremely lightweight, allowing engineers at Lamborghini to achieve optimum power-to-weight ratio. Carbon-based composites also are extremely durable, and have material properties that enable designers to shape and form the body components that give the SuperVeloce its distinctive appearance.

Engineers use sheets of fibers which are pre-impregnated with partially solidified polymer resin. The sheets are heated and pressurized under vacuum in an autoclave, which renders a solid structure in a distinct shape. The part is attached to the tubular steel frame of the vehicle with fasteners or high-strength adhesives.

In addition to the outer body panels, the floor of the Murciélago along with the wheel wells and the section that houses the transmission are constructed with carbon-fiber composites. With so much of the car consisting of composite materials, engineers at Lamborghini wrestled with ways to bring down materials costs, a good portion of which are associated with processing composites in a pressurized autoclave.

Yours for $475,000. The structure of the Lamborghini Murciélago LP 670-4
SuperVeloce luxury sports car, seen here on display at the 2009 ASME
International Mechanical Engineering Congress in November, is 31 percent
lightweight carbon-fiber composites.

To find cost-effective ways to process carbon-fiber composites, Lamborghini has turned to the Advanced Composite Structures Laboratory at the University of Washington, which also collaborates with The Boeing Company, the Federal Aviation Administration, and other partners on advanced materials research, experimentation, and development. Paolo Feraboli, the director of the laboratory, and his technical colleagues have begun experimenting with out-of-autoclave methodologies that demonstrate the potential to reduce raw material, processing, and labor costs—in addition to rendering a material featuring improved mechanical properties.

At the lab, the research thrust of the out-of-autoclave technique is to arrive at an approach to apply the essential resin to the sheets of fiber immediately prior to materials processing, in which case a pressurized autoclave is not required.

“Our focus is on applying a liquid-resin infusion process that cures the composite materials without the need for high amounts of heat and pressurization,” Feraboli said.

In processing the materials, the university lab has struck on a successful compromise between pure resin-transfer molding and vacuum-assisted molding. The lab refers to its approach as RTM-light, and it is being applied for the first time in the automotive industry.

“RTM-light is a great time and cost saver,” Feraboli said, “and we are seeing if the process renders carbon-fiber material properties that are an improvement over those of today.”

Maurizio Reggiani, Lamborghini’s vice president and chief technical officer, joined Feraboli for the presentation, which took place on Nov. 17 in Lake Buena Vista, Fla. The 2009 Congress featured nearly 350 technical sessions covering aerospace technology, manufacturing, micro devices, biotechnology, and other disciplines.

John Varrasi is senior staff writer in the Corporate Communications Department of ASME.