Steel is very much in the game for next-generation, electric vehicle designs. There’s been plenty of focus on lightweight materials, such as aluminum or carbon fiber reinforced plastics, that reduce weight of the new alternative cars. But past experience says to never rule out steel as a dominant structural and panel material. Two of the reasons are the experience automotive design engineers have with steel, and even more significantly, the significant investment in steel-forming assets.
Plus the steel technical groups have responded well to pressure from traditionally lighter materials.
Now comes news from The Steel Market Development Institute (SMDI) that a three-year collaboration with World Auto Steel called the Future Steel Vehicle (FSV) program is yielding positive results.
FSV features steel body structure designs that reduce mass by more than 35 percent over a benchmark vehicle and reduce total life cycle emissions by nearly 70 percent. This is accomplished while meeting global crash and durability requirements.
The FSV program uses optimized advanced high-strength steel (AHSS) body structures for four proposed 2015 to 2020 model-year vehicles: battery electric (BEV) and plug-in hybrid electric (PHEV-20) for A-/B-Class vehicles; and plug-in hybrid electric (PHEV-40) and fuel cell (FCV) for C-/D-Class vehicles.
The FSV program includes more than 20 new AHSS grades of materials expected to be commercially available in 2015 to 2020. The FSV material portfolio includes dual phase (DP), transformation-induced plasticity (TRIP), twinning-induced plasticity (TWIP), complex phase (CP) and hot-formed steels, which reach into gigapascal-strength levels.
FSV’s BEV concept weighs 188 kg; the A-/B-Class PHEV20 vehicle weighs 175 kg, and the larger C-/D-Class vehicle versions weigh 201 kg.
New designs in the concepts include:
- Front Rail Subsystem for automotive front crash structures. The unusual section shape of the rails is a result of the design optimization methodology that improved the effectiveness of each steel element to achieve minimum mass and best crash management performance. It is manufactured using a laser-welded blank with varying gauges of TRIP steel.
- Shotgun Subsystem resembles a shotgun-type weapon and provides superior performance in both full frontal and offset crash simulations. The Shotgun is comprised of a three-piece hot formed steel tailor-welded blank of varying thicknesses and is manufactured using hot stamping with tailor quenching.
- Rocker Subsystem is manufactured using roll-formed CP steels of gigapascal strength. Resembling a skeletal bone, the rocker enabled excellent results in four different side crash simulations that are a combination of global requirements.
“Achievement of such aggressive weight reduction accomplished with advanced steels and design optimization will set a new standard for vehicle design approaches for the future,” says Ronald Krupitzer, vice president, automotive market for SMDI, said. ”
The following illustration, provided courtesy of the AISI, shows the three-piece “shotgun” subsystem.