Hardware Fabrication Validates Advanced Design for Steel Closures
16 February 2000
American Iron and Steel Institute: Hardware Fabrication Validates Advanced Design for Light Weight, Low Cost Steel Closures for Vehicles
Complete Results Due in May
Advanced Materials, Manufacturing Processes Foster
Successful Try-Outs of ULSAC Concept
DETROIT, Feb. 16 -- Comparisons of finite element analysis
and initial measurements of demonstration hardware indicate that the
UltraLight Steel Auto Closures (ULSAC) frameless door design has achieved the
program's aggressive design objectives for improving mass and structural
efficiency.
Preliminary results indicated a mass savings of approximately 27 percent,
compared to a benchmark average of similar doors in eighteen 1997-model year
vehicles from Asia, Europe and North America.
Porsche Engineering Services of Troy, Mich., which is conducting the ULSAC
study on behalf of a consortium of the world's leading steel producers,
fabricated the demonstration hardware to validate its initial design.
In building the frameless door demonstration hardware, PES successfully
stamped outer panels in thicknesses of 0.6 mm and 0.7 mm high strength steel
sheet and used different grades and yield strength levels, including bake
hardenable (210, 260 MPa), dual phase (500, 600 MPa), rephosphorized (260 MPa)
and isotropic (260 MPa).* These gauges are relatively thin in comparison to
typical door outers on current automobiles.
Use of these grades and gauges represent significant advancements and lead
directly to the substantial weight savings and structural performance that are
the hallmarks of the project. Three of the six grades (bake hardenable 210,
260 MPa and dual phase 600 MPa), which are state-of-art steels for closures
and representative grades for comparison purposes, will undergo dent testing.
With the fabrication and testing of demonstration hardware, the ULSAC
project is nearly complete. Final results will be available in May in a
comprehensive engineering report detailing the design, CAE results, physical
testing, material and manufacturing specifications, economic analysis and cost
model, and other key data. Available at the same time will be demonstration
hardware consisting of assembled doors and sets of individual parts.
The validation phase of the ULSAC project seeks not only to validate the
design, but to demonstrate manufacturing feasibility. The validation work
encompasses:
-- Detail design optimization and CAE analysis of structural performances
-- Forming simulation of stamping and hydroformed parts
* Bake hardenable steels increase in strength when undergoing a "baking"
treatment, such as that used to cure automotive paints.
Dual phase steels have two principal metallurgical phases, or structures.
These steels rapidly increase in strength as they are formed into automotive
parts.
Rephosphorized steels have small additions of phosphorus that provide an
economical means to increase the strength of automotive sheet steels.
Isotropic steels have nearly the same strength and properties in all
directions.
-- Build of door structure assemblies, for testing and demonstration
hardware
-- Comparative testing for dent-resistance and oil-canning (dimple
testing)
-- Testing for structural performance
-- Validation of forming simulation with strain analysis
-- Documentation of manufacturing parameters such as press environment,
lubrication, tonnage, etc.
-- Documentation of material properties
-- Documentation of dimensional control data
-- Economic analysis to evaluate cost effectiveness
PES and its sub-contractor Schuler/SMG (Stuttgart, Germany) will conduct
additional try-outs using an active hydromechanical sheet forming process. If
successful, this alternative forming approach could yield door outer panels
with favorable dent resistance. Results of the sheet hydroforming try-outs
will be available in early 2001.
Other fabrication highlights include PES's successful use of an ultra high
strength steel tube of 1.5 mm wall thickness and 600 MPa yield strength for
the door intrusion beam. PES also effectively incorporated hydroformed high
strength steel for hinges and latch tubes, which additionally achieved
excellent fit in the door assembly.
A comprehensive discussion of this information is available in ULSAC
Technical Transfer Dispatch #1 on http://www.autosteel.org .
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 is comprised of 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 website 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