FutureSteelVehicle

Started in 2008, the FutureSteelVehicle (FSV) program built on more than a decade of work finding ways to decrease vehicle mass, reduce cost and meet comprehensive crash safety standards, all in pursuit of a smaller environmental footprint. FSV validated wide ranging research into the practical use of AHSS, innovative design and manufacturing technologies, and proposed specific examples for electrified vehicles (Figure 1).  FSV used Life Cycle Analysis (LCA) to select the steels and manufacturing techniques that result in the lowest total carbon footprint, going beyond accounting only for emissions in the use phase.

Figure 1: FutureSteelVehicle Battery Electric Vehicle Concept ^{W-11, W-12}

FutureSteelVehicle drew from a broad portfolio of steel types and grades, in a range of properties from mild to GigaPascal strength levels, applying a vast array of manufacturing processes. With advanced optimization algorithms, FSV incorporated hundreds of variables in the design process to identify a wide band of solutions. This approach integrated vehicle design, powertrain design and packaging, occupant space, passenger ingress/egress, driver sight angles, NVH, and aerodynamics to achieve a body structure that works in harmony with all vehicle requirements related to more stringent emissions and fuel efficiency standards while meeting safety (crash) standards and affordability.

The FSV project included structural variants for battery electric (BEV), plug-in hybrids (PHEV-20 and PHEV-40) and fuel cell (FCEV) powertrains, these same design attributes can be applied to conventional ICE-powered vehicles as well. Figure 2 highlights the FSV body materials breakdown.

Figure 2: Future Steel Vehicle Body Materials Usage

Lower Weight

Extensive use of a broad portfolio of AHSS grades, coupled with engineering design optimization, enabled a robust body structure that is feasible to produce and achieves 5-star crash performance against all global crash standards, while also exceeding mass reduction targets. A lower weight, mass-efficient body creates opportunities for downsizing sub-systems, including the powertrain, and promotes reductions in overall vehicle mass. As an example, the body structure mass achievement for the FSV BEV variant is 177 kg ^W-39, including the battery tray – a component unique to a Battery Electric Vehicle. This compares quite favorably with the 2010 VW Polo, at 231 kg, which was recognized as Car of the Year in Europe because of its mass-efficient design but carries a lighter ICE gasoline powertrain. Table 1 highlights some of the benchmarking comparisons.

Lower Cost

Steel is the most cost-competitive material for car bodies. It is economical to fabricate into components and sub-systems and to assemble into the total body-structure assembly. The resulting cost estimate of $1,115 to manufacture and assemble the complete FSV body validated this proposition and represents no cost penalty compared to vehicles at that time.

Lowest Total Lifetime Emissions

FutureSteelVehicle demonstrated the importance of Life Cycle Assessment as an integral element of a vehicle design process. In combination with optimizing the design for mass, cost, and functionality, FSV integrated into all analyses an accounting for its complete environmental footprint as measured in CO₂e. It more appropriately comprehends the entire lifetime carbon footprint of the vehicle, not simply the use phase. This includes the entire fuel production cycle (well to pump), the fuel usage cycle (pump to wheels), the production of raw materials, as well as disposal/recycling.

FSV demonstrated that the coupling of a lightweight, AHSS body structure with a battery-electric powertrain results in a 50 to 70 percent reduction in total life cycle emissions, compared to equivalently sized vehicles with conventional gasoline ICEs ^W-12. Furthermore, based on the new steels’ light weighting capabilities, steel is the only material to realize emission reductions in all life cycle phases. Table 2 summarizes total vehicle carbon footprint and emissions performance by life cycle phase.

Safety

The FSV design anticipated increasingly stringent crash safety standards over the decade following its release and was designed to meet European and U.S. 5-Star crash safety performance requirements over that time ^W-12. Using the latest holistic design and material optimization approaches combined with steel’s unmatched capabilities for design and manufacturing efficiency, the final FSV design comprised optimized, mass-efficient shapes that met or exceeded these global crash safety requirements.

Rationale

Automakers face conflicting constraints when designing new body structures:

• With escalating concerns about human-induced green-house gases, global legislators have passed increasingly stringent vehicle emissions regulations, with even more aggressive targets planned for the coming years. Lighter weight body structures promote reduced vehicle emissions.
• Fuel price increases lead to greater consumer sensitivity to vehicle fuel economy. Lighter weight body structures also promote improved fuel economy.
• One of the easiest ways to reduce vehicle weight is to use thinner metal. To maintain crash performance, this thickness reduction must be accompanied by an increase in the strength of the sheet metal grade.  Since thickness and stiffness are related, decreases in thickness must be accompanied by other methods to increase stiffness: either using a high-modulus material like steel, and/or using design features like darts or beads to lock in the shape.  The chosen grade must be sufficiently formable to successfully incorporate these features.
• Automaker marketing departments highlight spacious interiors. Greater room can be accomplished by making larger vehicles, but the extra weight does not support mass reduction. On the other hand, use of more formable steels is a cost-effective way to increase packaging efficiency.  New vehicle designs with complex geometries are aesthetically pleasing, but are difficult to form and join unless the chosen alloy has the necessary balance between strength and ductility.
• Global crash and safety regulations must be contemplated, especially if one body architecture will be used as the basis for vehicles intended for sale in multiple regions around the world. Increasing sheet metal thickness improves crash performance, so any reduction in thickness must be paired with using high strength grades where the deformation characteristics can be tuned to optimize crash energy management.
• All of these challenges must be addressed with sustainability in mind.

The global steel industry continues to develop new grades of steel defined by ever-increasing strength and ductility, continually reinventing this diverse material to address these challenges faced by automakers.  Advanced High-Strength Steels (AHSS) are characterized by unique microstructures and metallurgical properties that allow OEMs to meet the diverse functional requirements of today’s vehicles.

Worldwide working groups within WorldAutoSteel member companies created the AHSS Application Guidelines to explain how and why AHSS steels are different from traditional higher strength steels in terms of press-forming, fabrication and joining for automotive underbody, structural, and body panel applications. This website provides in-depth current information on a wide range of topics related to successful application of these steels.

Automotive companies around the world have adopted different specification criteria. Steel companies have different production capabilities and commercial availability. As a result, the typical mechanical properties provided on this website simply illustrate the broad range of AHSS grades that may be available worldwide.

In addition, regional test procedures will cause a systematic variation in some properties measured on the same steel sample. One example is total elongation, where both measurement gauge length and gauge width are a function of the standard to which the test is conducted (ASTM, DIN, or JIS, also known as ISO I, II, or III), with these differences impacting the measured value. In addition, property requirements can be defined relative to either the rolling direction or transverse direction. Therefore, communication directly with individual steel companies is imperative to determine grade availability along with specific test procedures, associated parameters, and steel properties.

• About
  • Rationale
    • ULSAB and the Early Steel Consortia
    • FutureSteelVehicle
    • Steel E-Motive
    • Emissions and Life Cycle Assessment
    • Performance Advantages
    • Current Vehicle Examples