AUG 2018


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AUGUST 2018 44 CompositesWorld FOCUS ON DESIGN Teaming to define what automotive CFRP could be Ford and Magna explore a high-volume chassis front subframe built from co-molded chopped fiber and noncrimp fabric SMC ยป Carbon fiber-reinforced plastic (CFRP) body frame/chassis components have been used in high-end sports and racing cars for decades. eir performance and lightweight enabled more recent expansion into higher volume produc- tion models, including BMW's i3, i8 and 7 Series models, as well as Audi's new R8 and A8 luxury sedans. However, most of these parts, including roof rails and cross members, lower side sills, B-pillars and rear walls, use continuous fiber. Ford Motor Co. (Dearborn, MI, US), in a joint research project with Magna Interna- tional (Aurora, ON, Canada), has developed a carbon fiber composite subframe made using a sheet molding compound (SMC) that combines continuous and chopped fiber SMC. e appli- cation is novel, because the subframe, located in the front of the car, supports the engine and chassis components, including the steering gear and the lower control arms that hold the wheels and, therefore, takes significant loads. "ere were dozens of engineers involved in this project," says Brian Krull, global director of innovation for Magna Exteriors. "We had struc- tural engineers, manufacturing engineers, testing engineers, product engineers and computer aided engineering (CAE) specialists, as well as support from different departments at our customer, Ford, including vehicle modeling and simula- tion." e Magna Composites Center of Excellence in Toronto also supported this project, "as did our body and chassis team at Cosma," adds Cosma International global director of R&D Gabriel Cordoba. "We wanted to explore what the challenges would be to use CFRP parts on a high-volume production vehicle," recalls David Wagner, technical leader at Ford Motor Company. "e goal was to make as much of the structure CFRP as possible while using manufacturing that could accommodate high-volume production [200,000 vehicles/year] see how much weight that would take out and where the limits and challenges would be." From initial discussions to completed design, the project spanned a little over one year. Prototype subframes were delivered to Ford at the end of 2017 and are now undergoing tests. Redefining the design envelope e Ford Fusion's stamped steel subframe served as the baseline. "Ford provided the design space for the project โ€” the vehicle-level design inputs โ€” and held weekly design meetings," says Wagner. Cosma then took that packaging environment, Cordoba explains, "and began exploring what weight savings we could achieve. How could we retrofit the design into that space but still meet stiffness, strength and durability requirements?" Stiffness vs. package space was an early challenge. "You typi- cally drop modulus when you move from steel to composite," notes High-volume CFRP front subframe OEM Ford teamed with Magna International to explore how much weight could be removed in a high- volume (200,000/yr) vehicle front subframe by using as much carbon fiber as possible โ€” revealing limits, challenges and new technology solutions. Source (all photos) | Magna International By Ginger Gardiner / Senior Editor

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