The long road to a breakthrough for carbon fiber, trucks and GM

General Motors Co. drew attention at the start of March when it announced the option for a carbon fiber pickup bed on the 2019 GMC Sierra Denali, a first for the auto industry.

But the application of carbon fiber on the pickup truck was a seven-years-in-the-making project that called on the expertise of engineers at GM and leadership at Japanese materials firm Teijin Ltd., and supported by Continental Structural Plastics.

The Detroit automaker touted in a March 1 news release that the carbon fiber bed — called CarbonPro — marks the first time any automaker has used carbon fiber in a truck bed.

Since 2011, the automaker has worked with Teijin as a supplier of the chopped thermoplastic carbon fiber used on the truck. It has been a work-in-progress relationship for research and development of the material, which has seen "a long path and a long validation" for the application on the Sierra Denali, according to GM's Mark Voss.

"The thermoplastic material allows us to recycle any scrap that's [left] from the process. In fact, we have two parts in the pickup box on the next-gen Sierra that are made from 100 percent recycled material that's generated as scrap through this manufacturing process," he said during a March 7 phone interview.

Voss is the engineering group manager for advanced composites and pickup boxes — a professional title he said he was unable to use until the March 1 reveal of the next-gen Sierra Denali and SLT.

"If you look at the other carbon fiber usages, even globally, they're all traditional thermoset composites," he said. "This is breaking the paradigm not just for pickup boxes on the new Sierra; it's actually breaking some paradigms around carbon fiber material systems themselves."

Through the collaborative process, GM had engineers co-located at the Teijin facility in Auburn Hills, Mich., also home to composites supplier Continental Structural Plastics, which Teijin purchased in 2017.

"This was a very exciting global co-development project that resulted in an industry first for GM," Eric Haiss, executive vice president of CSP, said in a March 7 statement via email.

"Early on, the development of the project involved learning how to process the material, how to design with the material through extensive CAE [computer-aided engineering] work and then putting it through all of the application-specific testing to ensure that it met and exceeded customer expectations," he added.

Other steps in the co-development of the material, Haiss said, included modeling techniques, application and material validation, and manufacturing strategies and process.

"Then, when Teijin acquired CSP in 2017, we had the combined materials and manufacturing expertise needed to bring this carbon fiber box to production readiness," he said.

Teijin-owned CSP will be molding and manufacturing the carbon fiber box at its facility in Huntington, Ind. The material is made in Japan and shipped to the United States, the company said.

The use of carbon fiber offers several "distinct advantages" over traditional composites or metal, Voss said.

"It doesn't dent, so in terms of the damage and the usage of the pickup box, you can really throw bricks at this thing," he explained, adding that since the material doesn't corrode or rust either, the long-term life of the vehicle is increased.

The carbon fiber bed on the Sierra Denali is being touted by GM as a premium option from the automaker, breaking out from ongoing "truck wars," where the argument has typically been aluminum vs. steel or function vs. style.

"Increasing the functionality and durability of the box was one of the … target objectives we took on," Voss said. "The impact that may put a hole into an aluminum bed, may dent a steel bed, but it may not even put a scratch on the surface of this carbon fiber bed."

"It's that durable, it's that strong, it's that tough," he added.

The thermoplastic carbon fiber was validated in all weather conditions, such as hot, cold and humid environments.

Mass savings are another huge win for the material over sheet molding compound (SMC), steel, aluminum and various composites.

"We're saving 28 kilograms [62 pounds] of mass in comparison to the steel bed on the next-gen Sierra," Voss said. "There are significant mass savings that we really just couldn't achieve with any other material systems."

Overall, GM said the next-generation Sierra shaves off up to 360 pounds compared with the outgoing model.

"If you add in the fact that the box is actually bigger [at 63 cubic feet] — it's the most cargo volume of any short box in the industry," Voss said.

The carbon fiber bed also doesn't require a bed liner, enabling more mass savings. Compared with other industry executions, Voss said, GM's next-gen Sierra Denali is "looking at 100 pounds or so of mass that we could easily take off from the back of the truck," equivalent to the weight of, say, three or four bags of concrete or a couple packs of shingles.

In addition to carbon fiber, glass fiber-reinforced nylon is used on the CarbonPro box for the wheel houses.

The 2019 Sierra Denali with the option of a carbon fiber bed will be available later in the model year. Whether or not GM will offer carbon fiber options on a next-gen Silverado pickup or future vehicles remains to be seen.

"I like my job, so I won't talk about what the future holds," Voss quipped. "Time will tell."