ULSAS Steel Industry Suspension Study Shows Mass Savings of up to 34%

      Multi-Link Design Matches Mass, Shows Cost Savings of 30 Percent,
                        Compared to Aluminum Benchmark

    DETROIT, May 17 Results of a two-year design study of
automotive suspensions released today showed mass reductions of up to 34
percent at no increase in cost for four steel-intensive designs, compared to a
range of benchmarked steel suspensions.  The study also included a fifth steel
design that showed a 30 percent cost reduction with a small mass reduction,
compared to a current aluminum design.
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    All five designs meet or exceed a range of performance criteria including
those for ride and handling and NVH (noise, vibration, harshness),
manufacturability and packaging (the effect on underbody, occupant and luggage
space).
    Sponsored by a consortium of 35 of the world's leading steel companies and
conducted by Lotus Engineering Services, Inc., England, the UltraLight Steel
Auto Suspension (ULSAS) study demonstrates how the use of iterative, holistic
design, coupled with innovative use of high- and ultra high-strength steel
sheet, tubular and bar products, and advanced manufacturing technologies can
result in lighter weight, lower cost and better performing vehicle suspension
systems.
    The program is a companion to the UltraLight Steel Auto Body (ULSAB) study
released in 1998, the UltraLight Steel Auto Closure (ULSAC) study, which is
nearly complete, and ULSAB-AVC (Advanced Vehicle Concepts) study, which will
be complete in 2001.
    Peter Rawlinson of Corus Group - UK and Nick Sampson of Lotus Engineering
Services, Inc., today on behalf of the ULSAS Consortium presented the results
of the program at the Society of Automotive Engineers Automobile Dynamics and
Stability Conference in Detroit.
    "As was the case with ULSAB, ULSAS shows the potential of steel to reduce
weight, lower costs and improve performance," said Darryl C. Martin, senior
director, Automotive Applications, American Iron and Steel Institute (AISI).
"For our vehicle-making customers, these criteria are foremost.  We look
forward to meeting with them to help them understand how they can incorporate
in their suspension designs the advanced concepts that ULSAS demonstrates."
    Extensive use of high- and ultra high-strength steels in all five designs
made possible the substantial mass reductions.  Also contributing to mass
savings, as well as to cost savings and performance enhancements, are
strategic use of large, thin-wall sections, hydroforming, tailored blanks and
laser welding.
    From a design standpoint, Lotus Engineering rigorously pursued
opportunities for part consolidation and strategies to promote ease of
manufacture and lower tooling costs.  The design team also relied heavily on
representatives of the steel companies, who early in the program provided
expertise and advice concerning the steels, cost analysis and forming
simulations.
    Lotus benchmarked a representative, comprehensive range of automobiles
from Europe, Asia and North America.  Against these benchmarks, Lotus
engineers designed five different rear suspensions, each advancing the state
of the art of its respective type.
    The Twistbeam design was the star of the show -- with mass savings up to
32 percent at somewhat less cost.  The design differs from conventional
twistbeams because it features a transverse beam of thin-wall tube uniquely
profiled to save weight.  It sweeps in a U shape that provides continuity of
structure from hub to hub.  The design uses high-strength steel in the U-
shaped tube, trailing arm, spring pan, springs and hub mounting plate.  The
two forward facing arms are hydroformed.  The twistbeam design substantially
exceeded benchmark performance targets.
    This type of rear suspension is common in smaller cars, where passenger
and luggage space is critical but ride quality is less so.  However, because
the design would perform significantly better than any of the benchmarks, it
could be a leading suspension option for future small cars where good
handling, as well as space and packaging, are key criteria.
    The Strut & Links design achieved mass savings of 25 percent through
extensive use of high- and ultra high-strength steels, coupled with an
iterative design approach to optimize components.  The design also achieved
slightly lower cost and target-exceeding performance, and met all other target
criteria.
    Strut and links designs usually represent a low-cost approach with
compromises in ride and handling and in vehicle refinement.
    The Double Wishbone design achieved a mass saving of 17 percent with no
cost penalty, while exceeding performance targets.  All parts are high- and
ultra high-strength steel and the design features a stamped high-strength
steel fore and aft arm and forged steel upright, rather than a cast iron
upright in the benchmark design.
    Because they represent a reliable overall compromise, double wishbone
suspensions often are used in sports cars.
    The Multi-Link design is the only concept in the study whose benchmark is
aluminum intensive.  This suspension demonstrated a cost saving of 30 percent
while showing a slight mass advantage compared with its aluminum-intensive
benchmark.  All major parts are of high- and ultra-high-strength steel.  It
matched the other target criteria.
    Multi-link suspensions are more sophisticated and costly than the others
in the study, but provide superior ride and handling and vehicle refinement.
    Lotus also designed a Lotus Unique concept, which resulted in mass savings
of 34 percent and a modest cost advantage compared to a conventional double
wishbone system, to which it is similar.  Created from a clean sheet and
specifying the latest in steel materials and technologies, this design offers
performance advantages of more complex suspension systems, while simplifying
and minimizing the number of components.  Featuring extensive use of high- and
ultra-high strength steel, the design exhibits good performance with a
relatively efficient package.  The study showed it would be easy to
manufacture and assemble.
    Lotus conducted the ULSAS project in two phases.  First, Lotus engineers
carried out a comprehensive benchmark study to test and evaluate suspensions
in a variety of vehicles from North America, Europe and Asia.  The process
included road and track testing, detailed design reviews and weight, cost and
manufacturing studies.
    Based on those assessments, Lotus undertook a holistic review of
suspension system requirements, identified opportunities for application of
new steel technologies and established an extensive range of targets for the
design phase of the ULSAS project.
    ULSAS focused on rear suspensions because:

    *  Although both front and rear suspensions have equal potential impact on
vehicle handling and performance, rear suspensions have greater impact upon
occupant and luggage space.
    *  Most front suspensions on cars worldwide are of the McPherson strut
design, whereas different size and class cars from different automakers use a
wide variety of rear suspension types.
    *  Lightweighting, cost-saving and performance-improving concepts
developed in the study could apply equally to front suspensions.