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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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