Walmart wanted a greener truck. So, the multinational retailer teamed up with other companies to produce a concept vehicle and unveiled the resulting futuristic-looking tractor-trailer in 2014. It is the latest example of Walmart’s efforts to increase fleet fuel efficiency, something the company has boosted by 84 percent since 2005 on the way to its stated goal of doubling fuel efficiency by 2015.
Part of the advanced technology in the concept vehicle can be found in the trailer. Normally, these are constructed of aluminum, steel or plywood core fiberglass panels. Such trailers tip the scales at about 12,000 pounds, but the new trailer isn’t typical.
“The concept trailer panels were built almost exclusively with foam cores and carbon fiber,” says Wayne Durnin, vice president of sales and marketing at Fiber-Tech Industries. The Spokane, Ohio-based company supplied CFRP panels to trailer maker Great Dane of Savannah, Ga.
Durnin adds, “The one-piece fiberglass reinforced floor panel had been tested and approved with a 16,000-pound forklift rating. In combination with the one-piece CFRP sidewalls and roof panels, the new design saved almost 4,000 pounds compared to previous construction materials.”
Cutting the weight by a third had to be done without sacrificing the trailer’s weight-bearing capacity or interior volume. Those two parameters determine how much cargo can be carried in the trailer, which is constrained by government regulations to be a certain width, length, height and total weight when fully loaded.
For the concept trailer, there were other requirements as well. Importantly, the specifications for interior trailer volume dictated the walls be as thin as possible. Given the needed panel performance and requirement for cutting weight, Fiber-Tech engineers decided early on in the 3½-year project that the only solution was a ribbed foam core with carbon fiber. The strength of the resulting panels was such that the walls of the trailer were about half as thick as what they would have been with a traditional wood core and fiberglass approach, Durnin says.
Fiber-Tech has years of experience supplying panel materials to trailer manufacturers. The challenge was to come up with a manufacturing process that created full height (9 feet) and full length (53 feet) carbon fiber panels in a single step. The company’s engineering expertise and experience with similarly sized traditional fiberglass-wood core panels were vital in successfully devising an answer to that problem. The solution involved a combination of woven and stitched carbon fiber that laminated the foam core, which was about a half inch thick.
In addition to carbon fiber in the trailer, the truck also implemented a number of other advanced technologies. For instance, the tractor and the front of the trailer are shaped such that aerodynamic drag is cut by 20 percent, which leads to a 10 percent boost in fuel economy. The tractor engine is a hybrid, running either off of electric power, energy derived from a microturbine or a combination of both. The microturbine can run on natural gas or other fuels, burning these so cleanly that there’s no need for the exhaust treatment equipment found in conventional diesel engines. The concept engine also does not require heavy lubricants.