Steel Industry Unveils Auto Door That is up to 42 Percent Lighter Than Benchmarks
24 May 2000
Steel Industry Unveils Auto Door That is up to 42 Percent Lighter Than Benchmarks
Industry Study Shows Important Advancements in
Structure, Technology and Materials
DETROIT, May 24 The UltraLight Steel Auto Closures (ULSAC)
Consortium today unveiled results of its Validation Phase, in which it
fabricated a frameless door that is 22 to 42 percent lighter in weight than a
range of benchmarked doors. The door meets or exceeds a range of performance
requirements and would cost no more to build than doors in the benchmark
group.
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The validated door weighs 23.15 pounds (10.5 kg) and would cost $66.50 to
manufacture in typical high-volume production (greater than 225,000 units per
year). The door meets or exceeds performance and structural requirements for
dent resistance, oil canning, upper and lower lateral stiffness, quasi-static
intrusion, and longitudinal door crush.
With use of high- and ultra high-strength steels and technologies such as
tailor welded blanks, stamping and hydroforming, the ULSAC door achieved 33
percent mass savings over the average benchmark from a wide range of door
structures. It is 42 percent lighter than the benchmarked average of
frameless doors only, and 22 percent lighter than the lightest benchmarked
unit, a framed door structure. The door achieved these results without
compromise to safety or structural performance.
The ULSAC study is an initiative of the global steel industry to
demonstrate the effective use of steel in producing lightweight, structurally
sound steel automotive closures that are manufacturable and affordable.
American Iron and Steel Institute (AISI) showed results and demonstration
hardware at a briefing for journalists today.
"This ULSAC door is evidence that our car company customers can use steel
to achieve necessary mass reductions in closures, while improving their
performance and reducing their cost," said Darryl C. Martin, senior director,
Automotive Applications, AISI. "This is the third major auto structural
design study we have completed during the past two years and, separately and
in combination, these initiatives have demonstrated significant mass reduction
at no increase in cost. We continue to increase the potential for steel to
remain our customers' material of choice when safety, affordability,
manufacturability and recyclability are key."
Based on a design from the Concept Phase of the ULSAC program, the
frameless ULSAC door is made from just nine major parts, which employ tailor
welded blanks, hydroformed tubular and stamped parts. The door features an
innovative structure that eliminates the need for a structural full inner
panel that is typical in current designs.
The structure comprises high-strength steel tube hydroformed latch and
hinge parts and two straight ultra high-strength steel tubes. These separate
components allow for selection of precise diameter, material grade and
thickness combination for each part -- independently of one another and based
entirely on functional requirements.
In an excellent example of functional consolidation, the two horizontal
tubes provide stiffness and work together as side impact intrusion beams,
simultaneously meeting both structural and crash energy management
responsibilities. In side collisions, they provide strength and absorption
capabilities to effectively manage impact energy forces. In a frontal
collision, these two parts provide excellent load carrying capabilities
between the A- and B-pillars. ULSAC's door outer panel uses relatively thin
and higher yield strength 0.7 mm, Bake Hardenable (BH) 260 MPa high-strength
steel, usage that pushes the envelope for this type of application. Car
companies have been using BH grades but not this thin and not at this yield
strength.
"As we have seen in our previous UltraLight projects, a key to success is
the use of high- and ultra high-strength steels," Martin said. "As in the
other projects, we did not have to sacrifice structural performance to reduce
weight. Rather, we looked at innovative ways to get smarter about how we use
steel. And, the results of the cost analysis show that the ULSAC door would
actually save a few dollars in the process."
To view the technical version of this release and complete set of images
visit the American Iron and Steel Institute's website at http://www.autosteel.org .
Detailed results of the ULSAC Validation Phase appear in the Consortium's
"April 2000 Engineering Report," which is available by calling
1-800-STEELWORKS. An overview of the Validation Phase will be available this
summer on AISI's website http://www.autosteel.org and the Consortium website,
http://www.ulsac.org .
The ULSAC study is a companion to the UltraLight Steel Auto Body (ULSAB)
study released in 1998, the UltraLight Steel Auto Suspension (ULSAS) study
released in May 2000, and ULSAB-AVC (Advanced Vehicle Concepts) study, which
will be complete in 2001.
The American Iron and Steel Institute (AISI) is a non-profit association
of North American companies engaged in the iron and steel industry. The
Institute comprises 46 member companies, including integrated and electric
furnace steelmakers, and 175 associate and affiliate members who are suppliers
to or customers of the steel industry. For more news about steel and its
applications, view American Iron and Steel Institute's web site at
http://www.steel.org .
The Automotive Applications Committee (AAC) is a subcommittee of the
Market Development Committee of AISI and focuses on advancing the use of steel
in the highly competitive automotive market. With offices and staff located
in Detroit, cooperation between the automobile and steel industries has been
significant to its success. This industry cooperation resulted in the
formation of the Auto/Steel Partnership, a consortium of DaimlerChrysler, Ford
and General Motors and the member companies of the AAC.
This release and other steel-related information are available for viewing
and downloading at American Iron and Steel Institute/Automotive Applications
Committee's website at http://www.autosteel.org . Automotive Applications
Committee member companies:
AK Steel Corporation
Bethlehem Steel Corporation
Dofasco Inc.
Ispat Inland, Inc.
LTV Steel Company
National Steel Corporation
Rouge Steel Company
Stelco Inc.
US Steel Group, a unit of USX Corporation
WCI Steel, Inc.
Weirton Steel Corporation
ULTRALIGHT STEEL AUTO CLOSURES (ULSAC) FACT SHEET
by the
Automotive Applications Committee
of
American Iron and Steel Institute
Program Objective Demonstrate the effective use of steel in producing
lightweight, structurally sound steel automobile
closure panels that are manufacturable in large
volumes and affordable.
Program Background ULSAC is a companion to the UltraLight Steel Auto
Body (ULSAB) study released in 1998 and the recently
completed UltraLight Steel Auto Suspensions (ULSAS)
study. The ULSAC program was commissioned by an
international consortium of sheet steel producers to
assist their automotive customers with viable
lightweighting solutions. The Consortium contracted
Porsche Engineering Services, Inc. to provide design
and engineering management for both the Concept and
Validation Phases of the program.
Concept Phase The Concept Phase was a study of automotive closures,
which includes: doors, hoods, decklids and hatches.
This Phase encompassed benchmarking, target setting
and conceptual design, which include FEA calculation
and cost analysis. The result of this phase was the
selection of a frameless door as the design example
for validation.
Validation Phase The Validation Phase includes additional
benchmarking, additional design, and the building of
demonstration hardware to validate the design
concepts. This includes managing detailed design
engineering, CAE analysis, design optimization for
manufacturing and assembly, supplier selection for
parts manufacturing and assembly, cost estimation and
cost model development and testing.
Technical
Highlights ULSAC achieved important results with a combination
of high- and ultra high-strength steel and
manufacturing technologies such as tailor welded
blanks, stamping and hydroforming. Specifics follow:
* Steel gauges range from .07 mm to 1.2 mm, and yield
strengths range from 140 MPa to 800 MPa, a unique
material combination for closures.
* The structure comprises high-strength steel tube
hydroformed latch and hinge parts and two straight
ultra high-strength steel tubes.
* The door inner front is a tailor welded blank which
incorporates the mirror flag inner and provides the
structural attachment points at the hinge area.
* Designers used a Functional Consolidation approach,
which is a concept in automotive design leading to
fewer parts. In the case of ULSAC the tubular
upper and lower components of the door inner also
serve as door intrusion beams -- a dual function.
Results The ULSAC door meets or exceeds all project
objectives:
Mass reduction:
* 33 percent lighter than a wide range of door
structures benchmarked in the Concept Phase
* 42 percent lighter than an average of frameless
doors benchmarked during the Validation Phase
* 22 percent lighter than the lightest unit, a
framed door structure
* No compromise to safety or structural performance
No cost penalty: Manufacturable in production
volumes of 225,000
Performance: Meets or exceeds targets for:
* Dent resistance
* Oil canning
* Upper and lower lateral stiffness
* Quasi-static intrusion
* Longitudinal door crush