Steel Market Development Institute, Great Designs in Steel 2013
Bumper Group Technology Presentation, Presented by
Presentation Title: Next Generation of Roll Formed Bumper Beams: How
geometric optimization and processing ingenuity will allow steel to compete on
mass with aluminum bumper cross sections
Abstract:
Shape recently completed development on the MonoLeg bumper beam, Figure 1 below, which
can level the playing field against Aluminum bumper beams, saving 5-10% mass from current
state of the art roll formed AHSS beams.
Figure 1
Shape is committed to helping OEMs achieve their mass reduction targets by optimizing its cross
section geometries and utilizing the highest AHSS material grades in the world. Focused on
taking full advantage mechanical characteristics of martensitic steel grades, Shape has
developed a bumper beam cross section called the MonoLeg. This beam section was designed
for high torsion strength. This enables it to perform equivalently with extruded aluminum beams
during impacts to the IIHS bumper barrier, which often imparts a torsion load. Shape’s MonoLeg
bumper beam accomplishes this by doublings the J-value (torsion constant) of a typical roll
formed B section bumper. This, combined with the higher mechanical properties of AHSS, puts
the MonoLeg on par with aluminum window pane sections of similar mass, see table 1 below.
Laser welding and section forming methods implemented for the manufacture of the section were
new to Shape and required a disciplined approach to process development. Beams made from
1300, 1500 and 1700 MPa martensitic steels validated the section design through static and
dynamic testing. Mass competitiveness with Aluminum has been demonstrated on several case
studies for various OEMs. Given the wide range of bumper design attributes and performance
criterion, there are a wide range of comparisons that can be made, in general our internal studies
have shown that compared to an equivalent mass Aluminum beam, the JG value for the
MonoLeg is 90% of Al, and the bending characteristics sYS * Z exceeds Aluminum by up to 10%,
resulting in nearly equivalent back of beam strokes during IIHS bumper barrier impact. See IIHS
Bumper Barrier impact results below for the Aluminum beam and MonoLeg beam highlighted in
Table 1 above.
Figure 2
Tom Johnson
tjohnson@shapecorp.com
616.850.3649
Joe Matecki
mateckij@shapecorp.com
616.850.3799
Brian Oxley
oxleyb@shapecorp.com
616.844.3476