Using carbon fiber, thermoplastic resin and state-of-the-art computer design techniques, a team of researchers led by Clemson University, in cooperation with NETL, has developed a lightweight vehicle door that boosts fuel efficiency while still meeting federal safety requirements.

The project team reduced the weight of a steel door by 32% and then subjected the door to a battery of tests to ensure it complied with Federal Motor Vehicle Safety Standards and safety requirements set by Honda, another project partner.

“The development of this new door is significant because it could play a major role in helping automakers build safe, lighter vehicles that use less fuel and produce fewer emissions without reducing performance,” said David Ollett, NETL project manager.

According to the U.S. Department of Energy’s (DOE) Vehicle Technologies Office, a 10% reduction in vehicle weight can result in a 6% to 8% fuel economy improvement because it takes less energy to accelerate a lighter vehicle. Furthermore, the Vehicle Technologies Office stated that using lightweight components and high-efficiency engines enabled by advanced materials in one-quarter of U.S. vehicles could save more than 5 billion gallons of fuel annually by 2030.

Clemson, working with partners at Honda North America, University of Delaware, LANXESS and Proper Tooling, redesigned a base steel vehicle door.

The new design utilizes carbon fiber and thermoplastic panels and stiffeners combined with select high-strength steel and aluminum components. The use of carbon fiber fabrics enables the thickness and strength of the door panels to be tailored specifically to design needs, which is often difficult when using stamped metal panels.

Using the optimized reinforced inner and outer door panels reduces the door’s structural components from 17 to eight, saving 22 pounds per door.

“Reducing the weight of light-duty passenger vehicles is critical to improving the efficiency of our cars to address climate change. By using this technology, a reduction of 88 pounds per vehicle (four doors multiplied by 22 pounds each) is possible,” Ollett said.

An additional project goal was to maximize the recyclability of the door to meet European recyclability standards. By using a carbon fiber-thermoplastic matrix, the composite components can be ground into a molding compound, re-melted and reused in new components in the same manner as steel and aluminum.

The lightweight door developed by the research team was subjected to numerous static tests as well as critical safety tests, including side-impact tests to determine performance in a broadside or side-impact collision. The Insurance Institute for Highway Safety reports that side-impact accidents accounted for 23% of vehicle occupant deaths in car accidents in 2020. Testing was performed by Honda North America at its research center near Columbus, Ohio.

The test consisted of a 3,015-pound sled impacting the side of the stationary test vehicle at 38.5 mph (62 km/hr). The test demonstrated the ability of the door to withstand and minimize intrusion into the driver area of the vehicle.

The total project cost for the almost eight-year research effort was $5.36 million, with $2.25 million provided by DOE and $3.11 million provided by the project team. Technical program monitoring and management was provided by NETL.

NETL is a U.S. Department of Energy national laboratory that drives innovation and delivers technological solutions for an environmentally sustainable and prosperous energy future. By leveraging its world-class talent and research facilities, NETL is ensuring affordable, abundant and reliable energy that drives a robust economy and national security, while developing technologies to manage carbon across the full life cycle, enabling environmental sustainability for all Americans.

Video and images provided by Clemson University.