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Lightweight Steel Wheels
Offer Stylish, Low Cost Solutions
Timothy Smith
Altair ProductDesign, Inc.
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Project Introduction
• Develop a steel wheel architecture that:
• has equivalent mass to a target cast aluminum wheel
• is 30% lower in cost
• Is stylish in it baseline form
• Provides an aesthetic upgrade path through the addition of wheel trim
Goal:
Background: • Currently automotive wheels utilize materials and process that have been in use for
many years
• Light weight wheels being costly
• Lower cost wheels limit aesthetic freedom
• A stylish, lightweight, low cost steel wheel could increase market penetration
Method: • Let me take you through the method we applied to achieve this goal
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Baseline Wheel
GMC Terrain Alum Wheel 10kg (22lbs.)
Target Application
Chevy Malibu Steel Wheel 10.7 kg + 0.66 kg (cover) = 11.36 kg
23.6 lbs + 1.46 lbs (cover) = 25 lbs
Design Surrogate
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Wheel Performance
MALIBU
St Wheel
TERRAIN
Al Wheel Packaging / Mass Target
Strength / Stiffness Performance
10 kg = 22 lbs
10.7 kg + 0.66 kg (cover) = 11.36 kg
23.6 lbs + 1.46 lbs (cover) = 25 lbs
Strength / Stiffness Performance
(not available)
AISI
St Wheel
Note: Considering that there was no steel wheel option for the Terrain, it was necessary to select
an existing steel wheel design surrogate to serve as a suitable baseline reference
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Generic Illustration of Design Process
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Package Space Development
GMC Terrain Wheel End Package Space
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Terrain’s Package Space
Malibu Steel Wheel
Terrain vs. Malibu Pkg Space
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Based on GM’s input, 3 loading conditions were studied:
• Radial Load (13,690 N = 3,076 lbs)
• Lateral Load (impact) (5,415 N = 552 lbs)
• Bending (2,730 N.m = 3,592 N @760mm)
Wheel Load Cases
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Topology Optimization Results
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Topography Optimization Results
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Inspiration
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Design Evolution
The evolution of the “drop center” design based on performance
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Bead Seat Concept Selected
Bead Seat concept proved to be very efficient in terms of mass and
performance and became our primary concept
• Mass: ~10kg
• Stiffness/Strength Performance similar to Malibu steel wheel
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Comparison: Malibu Vs SMDI Design
Malibu
Radial Load Stress Contour (MPa)
Bead Seat Design
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Comparison: Malibu Vs SMDI Design
Malibu
Bending Load Stress Contour (MPa)
Bead Seat Design
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Alternate Constructions Evaluated
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Comparison: Malibu Vs SMDI Concepts
Radial Load Stress Contour (MPa)
Bead Seat Concept – 490Y
Between spoke locations
Malibu – 300Y (rim)
yield
yield
yield
yield
yield
yield
Full Face – 420Y
At spoke locations
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Comparison: Malibu Vs SMDI Concepts
Malibu – 300Y (rim)
Lateral Load Stress Contour (MPa)
Bead Seat – 490Y Full Face – 420 Y
yield 1.5x yield
yield 1.5x yield
yield 1.5x yield
yield 1.5x yield
yield 1.5x yield
yield 1.5x yield
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Comparison: Malibu Vs SMDI Concepts
Bending Load Stress Contour (MPa)
Malibu – 380Y (disc) Bead Seat – 490Y Full Face – 420Y
yield 1.5x yield
yield 1.5x yield
yield 1.5x yield
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Formability – One Step
Malibu 6mm
380Y
r = 1.0
n = 0.17
Bead Seat– 5.8mm
490Y
r = 1.0
n = 0.144
Full Face – 5.4 mm
420Y
r = 1.0
n = 0.158
Thinning comparison
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Formability – One Step
Malibu
380Y
r = 1.0 / n = 0.17
Bead Seat- 5.8 mm
490Y
r = 1.0 / n = 0.144
Full face – 5.4 mm
420Y
r = 1.0 / n = 0.158
FLD comparison
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Gauge Optimization Study
Tailor-welded parts configurations:
Thicknesses are color-coded
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Retained Designs
SMDI
Concept
Bead Seat
SMDI
Concept
Full Face
2.1mm
5.8mm
5.4mm 1.8mm
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Final Design
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Wheel Dress Ideas
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Thank you!
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North American
Light Vehicle Metallic Material Trends
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