AUG 2018


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45 CF SMC Front Chassis Subframe Illustration / Karl Reque Ford/Magna High-volume, Lightweight CFRP Front Subframe › Weight reduction of 34% compared to stamped steel equivalent. › Parts reduction of 82%, replacing 54 stamped steel parts with two compression molded composite components and six overmolded stainless steel inserts. › Optimized SMC material duo: chopped carbon fiber SMC achieves complex molded geometry while 0°/90° noncrimp fabric (NCF) patches resist high attachment loads at select locations. Wagner, "so you need more section in the members. We defined how much the new design could change from the baseline dimen- sions and shared some initial topology optimization with Magna." Topology optimization (TO) is a CAE analysis that optimizes material placement within a given design space — including loads, boundary conditions and constraints — with the goal of maxi- mizing performance and minimizing weight. "We started with our own TO for understanding the critical load paths," says Cordoba. ese involved loads at subframe attachment points, including control arms and engine loads, as well as road loads, engine torque twists and crash requirements. "We had to look at our different stiffness vs. steel and the prop- erties we wanted to have," recalls Krull. Because composites offer many resin, fiber and fiber orientation choices, their proper- ties can be specifically tailored, but "it is more complex than just plugging in the properties of steel," he points out. "Plugging in properties" refers to entering material data into software tools. "We used all of the standard software, including COMPRESSION MOLDED TOP PART Aluminum extrusion Co-molded, 6-ply NCF carbon fiber SMC patch Overmolded stainless steel sleeve (body mount attachments) Chopped carbon fiber SMC Integrated composite crush cans COMPRESSION MOLDED BOTTOM PART Overmolded stainless steel inserts (steering gear attachments)

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