Press Release: USCAR FABRIC DRAPING R&D SEEKS TO LIGHTWEIGHT LARGE STRUCTURAL COMPONENTS
SOUTHFIELD, Mich., Dec. 9, 2009 – While a fabric draping study may sound more like home decorating than automotive vehicle research, a team of scientists and engineers from USCAR – (the collaborative automotive technology organization for Chrysler Group LLC, Ford Motor Company and General Motors Company) – and the University of Massachusetts Lowell are in the midst of just that – conducting research to see how fabric weaves and directions may allow fiberglass fabric to be used to make larger lightweight structural components.
Sheet molding compound, also known as SMC, has been used to make a variety of lightweight structural components for many years. Today, using chopped fiberglass and resin, SMC component manufacturers mold a variety of parts such as wheel housing supports, instrument panels, and appearance-grade parts, such as trunk lids and doors.
With the U.S. automakers continually working to reduce vehicle weight and increase fuel efficiency, a fabric draping process now is being studied as part of the USCAR Automotive Composites Consortium Focal Project 4 (ACC-FP4), which is examining the viability of expanding the use of SMC compounds for large lightweight structural components that will carry crash loads.
Its target example is the underbody (or floorpan) of a large, rear-wheel drive car.
Fiberglass fabric is viewed as the preferable reinforcing material over chopped fiberglass if a large panel is to withstand structural and potential crash forces during the life of the vehicle.
One of the team’s main challenges is determining how fiberglass fabric will deform as it takes the shape of a part in the molding tool. While chopped fiberglass SMC flows easily within the heated tool, fiberglass fabric performs very differently.
At UMass Lowell, Professors James Sherwood and Julie Chen determined that computer simulations of the glass-fabric sheet molding compound are possible. The two professors and their research groups studied the deformation of the glass reinforcement fabric, both without resin and as compounded, into fabric SMC.
“They found that the simulation of the complex fabric SMC deformation behavior is possible with certain simplifying assumptions,” said Libby Berger, ACC-FP4 co-chair and staff researcher at General Motors’ Chemical Sciences and Materials Lab. “We also performed experiments to determine the shearing, tensile and frictional behavior of the material, as well as drape-ability of multiple layers of the fabric SMC.”
In essence, with the modeling advances, design engineers will be able to better predict how the forces of molding the component will affect the glass fabric SMC, thus understanding what geometries can be used to design a lighter weight structural underbody.
“Being able to predict the behavior of the fabric SMC is extremely useful in developing the processing of the structural underbody,” Berger said. “This technology will play an important role going forward with the underbody project and in the future use of structural composites in crash-critical automotive components.”
While the group has molded a smaller rear-compartment pan, a full-size molding test is expected within the next year. Provided the composite panels move into production, one molded fabric SMC floor panel can replace up to 17 steel pieces and shed up to 25 pounds from the weight of a typical passenger car.
Founded in 1992, USCAR is the collaborative automotive technology organization for Chrysler Group LLC, Ford Motor Company and General Motors Company. The goal of USCAR is to further strengthen the technology base of the domestic auto industry through cooperative research and development. For more information, visit USCAR’s Web site at www.uscar.org
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