Composites Under the Car

Weight savings of 50 to 60% can be achieved in chassis components by using composite materials instead of conventional metals. 

This bold claim comes from Stefan Sommer, CEO of driveline and chassis technology supplier ZF Group (zf.com). And he says the company is committed to developing the processes and manufacturing the composite products that make these high-percentage weight savings possible in the next decade. To achieve this, in July 2013, the company opened the ZF Composites Tech Center in Schweinfurt, Germany. In addition to composites-based processes and products, they are also developing multi-material construction capabilities. 

ZF is testing a prototype vehicle that uses composite structural underbody parts, such as a suspension strut and knuckle module made from fiber-reinforced plastics for damping and wheel guidance. The two parts weigh 40% less than traditional steel versions. There is also a front-axle stabilizer link made from a carbon fiber injection-molded polyamide and high-strength steel replaces a conventionally all-steel component, which provides a 16% weight reduction. 

Designing these chassis components from composite materials requires a different mentality than working with conventional metals, says Michael Hankel, ZF board member responsible for production, powertrain, chassis, and electronics. “The design is completely different than it is with steel or aluminum,” Hankel says, explaining that while the properties of the metals are essentially the same in all directions, with a fiber-based composite, the orientation of the fibers helps determine the performance properties of the material, which is important given specific applications. 

Hankel acknowledges that compared to metals, composite part processing time has been a roadblock for greater automotive application, but this is something that they’re beginning to overcome.

According to Sommer, there should be several composite-based chassis components on production models by 2020.—ZP