Additional Steel Solutions

One of the major advantages of steel is the ability to create new materials with advanced properties. These are generally developed and proved through collaborative projects. SMDI automotive steel members through their research, development, design and application resources work in several major project areas including:

  • SMDI-sponsored design projects
  • SMDI-co-sponsored Auto/Steel Partnership (A/SP) enabling projects
  • SMDI-sponsored university programs
  • SMDI-Co-Sponsored WorldAutoSteel projects

SMDI-Sponsored Design Projects

One example of an SMDI design project is the SMDI lightweight twist beam shown in Figure 12. Completed by Multimatic Engineering with SMDI and OEM partners, from a baseline design, both u-beam and s-beam variants were developed and optimized for structure, dynamic performance, weight and cost. The u-beam was selected for the final design as it met all performance requirements with 30 percent mass reduction at a lower cost than alternative materials.

The design provides maximum mass reduction of 7.5 kg (30 percent) relative to the OEM baseline assembly and meets all structural and elasto-kinematic requirements. It also resulted in a slight (12 to 15 percent) cost premium relative to the OEM baseline at production volumes of 30k to 250k vehicles per year. This design was deemed production feasible based on expert manufacturing assessments.

Figure 12. SMDI’s Lightweight Twist Beam Concept Achieved 30 Percent Mass Reduction at a Lower Cost than Alternative Materials

Auto/Steel Partnership Enabling Projects

The Auto/Steel Partnership (A/SP) is a unique collaboration between the automotive and steel industries. They are collaboratively researching new applications for steel, defining local material properties for specific manufacturing strain paths and generating fatigue and corrosion resistance data to improve modeling predictions, vehicle performance and cost benefits. The 2016 A/SP project portfolio is shown in Figure 13 and consists mainly of projects to enable rapid implementation of AHSS solutions.

Figure 13.  A/SP Current Project Portfolio

Front Lower Control Arm Design Project

An example of a component design project through the A/SP is the front lower control arm shown in Figure 14. Three steel intensive designs were provided matching the weight of a best in class forged aluminum baseline. In addition, using the clamshell design a 34 percent cost reduction was achieved when evaluating an annual production of 250,000 vehicles. Because of the lower materials production emissions, this component also has a lower life cycle emissions over the aluminum baseline. This design solution has been implemented on multiple vehicles.

Figure 14. A/SP Front Lower Control Arm Project

Integrated Computational Materials Engineering (ICME) Project

The ICME project is a collaborative project with the U.S. Automotive Materials Partnership LLC and A/SP in response to a funding opportunity announcement by the Department of Energy (DoE) to develop lightweight third generation AHSS. Steel and automotive technical teams have joined in one of the most ambitiously-scaled A/SP projects. This project investigates modeling steel alloy design from the atomic scale through the engineering design and testing scale.

The project teams also include investigators from five universities: Brown University; Clemson University; Colorado School of Mines; University of Illinois; and The Ohio State University. Pacific Northwest National Laboratories (PNNL) staff also shared in the program. Analytical resources included EDAG and Livermore Software Technology Corporation (LSTC). Figure 15 shows the angstroms-to-autos progressive model flow and integration among the goals of this study.

(Source: USCAR – ICME project)

Figure 15. The Multi-Scale Nature of Steel Alloys and Linkage with Alloy Design for Performance

The researchers have made impressive progress during this extensive project. The full integration of all the models could take several years. This project also identifies the areas requiring additional research and development in future years.

University Programs

SMDI sponsors and has sponsored several university studies, including LCA modeling at the University of California, Santa Barbara, lightweight bumpers and wheel designs at Lawrence Technological University and science applied benchmarking at the University of Michigan.

FutureSteelVehicle (FSV)

The FSV is the most recently completed automotive lightweight demonstration project from WorldAutoSteel. The study used a whole vehicle structural and weight optimization 3-G Approach – gauge, grade and geometry. Previous studies only used a 2-G approach, grade and gauge, optimization. Significant mass savings was available by co-optimizing the geometry whether on a component or the full vehicle structure. Load path analysis optimization drives the full structure and geometry of efficiently designed vehicles.

In addition to optimizing the design of the vehicle for mass reduction, the FSV project included development of new AHSS grades to optimize grade and gauge reductions and improved manufacturing technologies to support the implementation of the new grades.

Rapid Adoption of FSV Technologies

Technology transfer of the FSV project results were completed to North American automakers and suppliers in 2011. Some of the new technologies introduced in the FSV began appearing in 2015 and 2016 model year vehicle programs. Because of the three- to five-year engineering cycle for introducing major program updates, the rapid adoption of this technology in a 2015 vehicle demonstrates the high value of AHSS solutions.

One of the first applications of an 1180 MPa grade was the a-pillar / roof rail on the 2015 Nissan Murano (Figure 16).

(Source: Great Designs in Steel 2015)

Figure 16. 2015 Nissan Murano – 1180 MPa A-Pillar / Roof Rail

Some of the improved manufacturing processes combined with increased use of AHSS are demonstrated in the 2015 Chevrolet Colorado, 2015 Ford Edge and the 2016 Acura TLX. Figure 17 shows the Colorado cab structure using 72 percent high-strength or AHSS to achieve mass reduction and improved stiffness. It also introduced a tailor-rolled, hot stamped b-pillar, shown in Figure 18.

(Source: Great Designs in Steel 2015)

Figure 17. 2015 Chevrolet Colorado Cab Structure

(Source: Great Designs in Steel 2015)

Figure 18. 2015 Chevrolet Colorado – Tailor-Rolled, Hot-Stamped B-Pillar

The Edge has an all steel body structure and closure applications. In the 2015 model year, it introduced the first application of a DP1000 hydroformed roof rail, shown in Figure 19, incorporating the a-pillar through the c-pillar and in the d-pillar for improved stiffness.

(Source: North American International Auto Show 2015)

Figure 19. 2015 Ford Edge – Hydroformed Roof Rail (shown in orange)

The TLX used a one piece, hot stamped door ring to achieve the desired rigidity without added mass. This component replaced four separate pieces avoiding the weld assembly and improving dimensional control as shown in Figure 20.

(Source: Great Designs in Steel 2015)

Figure 20.  2016 Acura TLX – One- Piece, Hot-Stamped Door Opening Panel