MORE COMPOSITES IN MORE VEHICLE STRUCTURES MEANS MORE STYLE AND LESS WEIGHT
The value of composites in making vehicles much lighter has been acknowledged for many years by those who build racing cars and sport and luxury vehicles. Now composites are preparing to play an ever larger role in the design of vehicle structural, semi-structural and A-class body parts, prompted by government regulations that set stricter mileage standards for vehicles all over the world: lighter-weight steels will not be sufficient to decrease the vehicle weight more than 20 percent
Faurecia develops a liftgate made entirely of composite materials. The liftgate can be fashioned from carbon fibers or glass fibers and thermoset or thermoplastic resins – or a combination of these materials. The displayed liftgate is a plastic composite liftgate reinforced with carbon fibers, and has a structural inner lining using a thermoset resin and an outer shell of thermoplastic.
Faurecia chooses the right combination of composite resins for each structural application, and their use in the composite liftgate provides a high-performance, lightweight hatch that sets a new standard for weight savings.
Compared to steel, the carbon composite liftgate structure concept that Faurecia is exhibiting is 50 percent lighter, weighing just 15.4 pounds, and 30 percent lighter than the equivalent solution in metal when fully equipped. Weight savings result from the material itself and from the ability to accommodate electrical cables by a groove molded into the lining and wiper motors by an open cavity formed in the production process. The number of fasteners, hinges and latches is reduced. Additionally, the inherent stiffness and lightness of the composite liftgate allows designers to remove one of the two stabilizers required for conventional rear doors, eliminating even more weight.
OVERALL, THE FAURECIA COMPOSITE LIFTGATE OFFERS A NUMBER OF WEIGHT-SAVING AND DESIGN-IMPROVEMENT ADVANTAGES:
- The use of composite materials
- Interior of the liftgate mass tinted directly, allowing for elimination of interior trim components without painting operation
- Fewer parts to assemble with only one stabilizer instead of two
- Integration of features to make assembly easier, such as the groove for cables
- The ability to produce shapes, such as the rear window, that are more complex than those fashioned from metal or glass
- A liftgate that is easier to open and close than its steel counterparts
Typically, the floors of today’s passenger vehicles are stamped from steel, producing a relatively heavy structural component. Faurecia is working with a major automaker, however, to develop a composite rear floor and trunk floor made entirely of glass-fiber composite materials. This concept floor extends from the rear seat back to the fascia and integrates seat-belt attachments and mechanisms for the rear seat. Designers also could integrate other features, such as a rear-battery tray that would be a separate, weight-adding component for a steel floor. All this results in more flexible performance with less weight.
DEVELOPING SUCH A LIGHTER-WEIGHT REPLACEMENT PRESENTS NUMEROUS CHALLENGES, INCLUDING:
- The need to match existing vehicle floor performance in managing stresses, strains and load
- The ability to attach a composite floor to a steel body and effectively seal it from leaks, noise and vibrations
- The requirement that the composite floor be price-competitive
Faurecia has succeeded in meeting these challenges with a concept load floor that saves 40 to 45 percent in mass compared to the steel floor it replaces. When measured against the same floor made of aluminum, the composite version still would reduce mass by 15 percent.
Another advantage of the Faurecia composite floor is that it can tolerate the temperatures of electro-coating, so automakers do not need to change manufacturing processes.
At the same time that Faurecia is designing a lighter-weight floor, its engineers are designing ways for it to be integrated into the vehicle at the assembly plant. Faurecia is working on both a thermoset solution and a thermoplastic version to determine the best materials for the environment and vehicle performance.
Faurecia’s commitment to carbon-fiber composites extends all the way to the top—of both the company and the car. Faurecia features an exposed-carbon roof at NAIAS 2015 as an example of how its processes can significantly reduce weight while improving attractiveness.
The most widely used method of creating large carbon-fiber parts involves fibers that have been pre-impregnated (pre-preg) with epoxy resin to produce a woven look. Faurecia chooses a different process: resin-transfer molding (RTM), which offers exceptional strength-to-weight characteristics and a best-in-class smoother, sleeker finished product. When used to create hoods or roofs, RTM yields a very nice, even and complete layer over the top of the fabric that does not leave the visual impression of an extra-thick clear coat that often is seen with pre-preg.
The exposed-carbon roof, with a beautifully rich weave of fibers, reduces the roof weight by as much as 60 percent compared to steel. Furthermore, the carbon roof can be customized for sport and luxury vehicles. For a particular vehicle model, an OEM can request a pattern that is tight and small or a larger weave and can specify the direction of the weave.
Today, the cost of the exposed-carbon roof remains considerably higher than that of steel or aluminum, but Faurecia is working with resin and fiber suppliers on ways to lessen material expenses considerably through faster resins curing and low-cost fibers.
Less weight and more attractiveness make the exposed-carbon roof a sleek alternative for luxurious vehicles.
In its exhibit, Faurecia has brought forward the BMW 3-Series GT bumper as an example of the way that a plastic bumper can harmonize with the sporty personality of the car that wears it. It improves the aerodynamics of the car while accentuating its sporty appearance with a distinctive front fascia that matches the prominent contoured headlights. Faurecia manufactures, paints, assembles and delivers this complete bumper in five finishes: Base, Modern, Luxury, Sport and the optional M Sport package.
The M Sport package features an exclusive optional exterior paint shade, Estoril Blue metallic, which casts a distinctive stylish look and road presence to the BMW3-Series Gran Turismo.