Skip to content

Lightweight but crash safe: the ongoing challenge

Safety and lightweight construction no longer contradict each other – and new joining techniques mean OEMs can mix aluminium and steel to suit their needs, writes Rachel Boagey

The trend of vehicle lightweighting stems from increasingly stringent global regulations for efficiency and emissions, which are putting pressure on OEMs, and in turn, their suppliers. Future vehicles will have to be lighter with lower fuel consumption and CO2 emissions, and if OEMs do not dramatically reduce the average CO2 emissions of their cars, they will face hefty fines.

But with vehicles becoming lighter for efficiency purposes, is there a danger that their structural safety will get left behind?

Apparently not. With a new lightweight construction technology, researchers are making it possible to do both. According to Markus Wagner, a scientist at the Fraunhofer Institute for Material and Beam Technology (IWS) in Dresden, “Safety and lightweight construction need not contradict each other.”

Safe and lightweight

Ford F150 aluminium and steel frameThe 2015 F-150 is the only full-size, light-duty truck to earn the National Highway Traffic Safety Administration’s (NHTSA) highest rating, a five-star crash test rating, for the driver and passenger for all crash test modes and cab configurations. To build the 2015 model, Ford has incorporated new technologically advanced processes at the Dearborn Truck Plant to support the installation of the truck’s variety of new features, including its aluminium body panels.

Accompanied by Brian Kinnie, Assistant Plant Manager at Dearborn Truck, Megatrends took an exclusive behind-the-scenes tour of the Ford Rouge plant in Dearborn, Michigan. The facility houses production of Ford’s F-150, the most popular passenger vehicle in the US. During the tour, Kinnie explained the OEM’s choice to use aluminium for the truck body. “Why have a heavier box and cab when it’s equally as strong and safe for less weight?” said Kinnie.

The new F-150’s aluminum and high-strength-steel construction posed some unique challenges to truck’s engineers. “The team had to invent new ways to manage crash energy, because advanced materials like high-strength steel behave differently,” explained Matt Niesluchowski, the truck’s safety manager. “We found that changing certain shapes led to a weight reduction, while also improving crash performance.”

Kinnie continued, “Engineers added an extra crossmember and increased the use of high-strength steel to improve stiffness, durability and safety – while also helping reduce the frame’s weight by up to 60 pounds.”

In a statement, Vice President of Global Product Development at Ford, Raj Nair explained that the five-star rating achieved by the model is an example of One Ford collaboration and innovation. “Our truck team worked together for years to deliver this accomplishment, using an unprecedented combination of advanced materials throughout the all-new F-150. The 2015 model is engineered to be the safest F-150 ever, which matters to customers who depend on this truck to not only get the job done, but also get them safely home.”

A lightweighting battlefield

Chevrolet Silverado 1500 post crashA “battlefield” between aluminium and steel-intensive vehicles is emerging in the automotive industry, according to Louis Schorsch, Member of the Group Management Board and Chief Executive of ArcelorMittal. This is particularly true within the truck segment, he said, where “the most major – or obvious – battlefield is, with the announcement of the aluminium intensive F-150.”

But the choice of materials used for lightweighting purposes varies from OEM to OEM, with some opting for aluminium while others opt for high-strength steel.

General Motors, for example, continues to believe in steel, and recently added its new Chevrolet Silverado ‘Toughnology’ concept to its lightweighting portfolio.

Approximately 67% of each Silverado cab is constructed of steel, including stronger ultra-high-strength steel (UHSS) in the A-pillars, B-pillars, rockers and roof rails, as well strategic sections of the interior structure. UHSS is also used in areas of the rocker panels and underbody to help improve performance in crashes. Like the F-150, the 2015 Silverado 1500 crew cab model earned a five-star safety rating in crash tests.

Multi-material approach

At any one time, up to 80 new grades of high-strength steel are under development. Due to its fuel efficiency benefits as well as providing increased strength and safety properties, advanced high-strength steel is the fastest growing material in the automotive sector, and is due to further increase in coming years. ArcelorMittal expects orders for such advanced grades to rise from 20% of total automotive steel orders in Europe today to 35% in the next five years.

Megatrends spoke to Dr. Greg Ludkovsky, Vice President of Global Research and Development at ArcelorMittal, about the company’s recent developments in enabling OEMs to meet their fuel emissions targets, as well as increase safety. “No longer do you have to sacrifice things for strength. As well as being light and efficient, our third-generation steels make sure car occupants are safe and protected,” he said.

The battle between the two leading materials in the automotive industry rages on – and it looks set to continue for many years to come. The most likely scenario sees OEMs and suppliers continuing to use a multi-material approach to decrease the weight of their vehicles, while increasing efficiency and crucially, safety.

This article appeared in the Q2 2015 issue of Automotive Megatrends Magazine. Follow this link to download the full issue.

Welcome back , to continue browsing the site, please click here