The United States Council for Automotive Research LLC (USCAR, Southfield, Mich., USA), the collaborative automotive technology organization of Chrysler Group LLC, Ford Motor Co. and General Motors, announced on April 1 that it was recently awarded a U.S. patent for an automotive load-bearing composite floor pan developed by the U.S. Automotive Materials Partnership LLC (USAMP) Automotive Composites Consortium (ACC).
The U.S. patent applies to a multi-layered composite automotive floor pan that defines part of the passenger compartment and includes a high-elongation fabric layer sandwiched between glass fabric layers. The floor pan is configured to absorb or transfer dynamic external loads, or crash forces, which preliminary ACC testing has demonstrated, while maintaining the material integrity of the floor pan.
"The ACC composite underbody project has been a very successful collaboration among a remarkable array of suppliers and researchers from academia and the auto industry," says Libby Berger, project chair and staff researcher in General Motors' Chemical Sciences and Materials Systems Lab. "This patent is among the many great milestones of this project."
In addition to the three USCAR-based automakers represented by ACC, those involved in the project include: the U.S. Department of Energy, which provided partial funding for the project through a cooperative agreement with USAMP; Multimatic Engineering, Century Tool & Gage Inc., Continental Structural Plastics, Wolfden Products Inc., IBIS Associates, Camanoe Associates and researchers from the University of Massachusetts-Lowell.
With the U.S. automakers continually working to reduce vehicle weight and increase fuel efficiency, Berger said expanding the automotive use of sheet molding compounds (SMCs) for large lightweight structural components has great potential.
"If structural composite panels can move into production, one molded fabric SMC floor panel could replace up to 17 steel parts and shed up to 25 lb [11.3 kg] from the weight of a typical passenger car," she said.
Currently, SMC component manufacturers use chopped fiberglass and resin to mold a variety of parts such as wheel housing supports, instrument panels, and appearance-grade or surface-quality parts, such as trunk lids and doors. Fiberglass fabric, while more structurally robust, has unique and more complex forming requirements. How multiple layers are joined and preformed, and how deformation affects material properties are among the areas continuing to be researched by ACC.