High-Performance Leaf Springs for Commercial … Leaf Springs for Commercial Vehicles New Generation...

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ARISTOTLE UNIVERSITY OF THESSALONIKI LABORATORY OF MACHINE ELEMENTS & MACHINE DESIGN G. Savaidis, M. Malikoutsakis High-Performance Leaf Springs for Commercial Vehicles New Generation Design 8 th International Congress of Spring Industry (ESF 8) September 2015, Prague, Czech MAN TRUCK & BUS SA Chr. Ertelt , F. Schwaiger

Transcript of High-Performance Leaf Springs for Commercial … Leaf Springs for Commercial Vehicles New Generation...

Page 1: High-Performance Leaf Springs for Commercial … Leaf Springs for Commercial Vehicles New Generation Design ... - Serial and new leaf spring suspension design

ARISTOTLE UNIVERSITY OF THESSALONIKI

LABORATORY OF MACHINE ELEMENTS & MACHINE DESIGN

G. Savaidis, M. Malikoutsakis

High-Performance Leaf Springs for Commercial VehiclesNew Generation Design

8th International Congress of Spring Industry (ESF 8)

September 2015, Prague, Czech

MAN TRUCK & BUS SAChr. Ertelt, F. Schwaiger

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A R I S T O T L E U N I V E R S I T Y

Outline

1. Introduction- Targets and aspects of modern suspension design- Scope

2. Theoretical investigations- Serial and new leaf spring suspension design - FE analyses (kinematics, stresses)

3. Driving tests - performance verification

4. Conclusions

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A R I S T O T L E U N I V E R S I T Y

Introduction

Overall targets of the new MAN TGX-Generation

1. Economical

2. Body-friendly

3. Maximum Comfort

4. Reliable

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A R I S T O T L E U N I V E R S I T Y

Introduction

Contribution of the SUSPENSION team

Reduction of number of leaves, reduction and unification of components

for driver and cargo Spring rate

High kinematics/steering performance,high durability performance

1. Economical

2. Body-friendly

3. Maximum Comfort

4. Reliable

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A R I S T O T L E U N I V E R S I T Y

IntroductionPrincipals of leaf spring suspension

Driving direction

Middle

buffer

S-buffer

Leaf spring

(stretched)

Shackle

FRAME

Shock Absorber

Steering

gear

Drop arm

Drag link

Steering

lever

Track rod

Wheel jointClamped area

determines the performance of the vehicle in terms of suspension and guidance

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A R I S T O T L E U N I V E R S I T Y

Introduction

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A R I S T O T L E U N I V E R S I T Y

Design requirementsDesign requirements – Schematic representation of the wheel joint‘s orbits

BRAKINGMAXIMUM VERTICAL LOAD

IntroductionKinematics of leaf spring suspension

UNLOADED CONDITION

o Requirement: Compatibility of the two orbits

Drop arm

Drag link

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A R I S T O T L E U N I V E R S I T Y

Introduction Design requirements

o Specific dimensions introduced by the vehicle setting

o Reduction of number of leaves

o Spring rate R=Force/Displacement within a specific range (comfort)

o Compatibility between joint’s orbit due to leaf-spring and joint’s orbit due to steering rod

o Durability: Acting stresses < permissible stresses

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A R I S T O T L E U N I V E R S I T Y

Reduction of number of leaves

Reduction / unification of components

High kinematics/steering performance

High durability performance

MAN TGX–New Generation Front Axle SuspensionFor payloads 7.5to, 8to and 9.2to

Introduction Suspension - Technical targets

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A R I S T O T L E U N I V E R S I T Y

Introduction Suspension - Technical scope

Front axle payload 7.5to

Serial Monoleaf, stepped eye type, eye lever e=17mm, Rate Rserial288±7%

1: Monoleaf, berliner eye, e=10mm,R1Rserial

2: ... R2= 0.88·Rserial

One new buffer

New Proposals

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A R I S T O T L E U N I V E R S I T Y

Introduction Suspension - Technical scope

Front axle payload 8.0to

Serial 2-leaf spring, stepped eye, e=17mm, Rserial=260±7% [N/mm]

2-leaf spring, stepped inclined eye, e=0mm, R=Rserial

One new buffer

New Proposals

Monoleaf, stepped eye, e=17mm, R=1.16·Rserial

One new buffer

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A R I S T O T L E U N I V E R S I T Y

Introduction Suspension - Technical scope

Front axle payload 9.2to

Serial 3-leaf spring, stepped eye, e=15mm, Rserial=300±7% [N/mm]

2-leaf spring, stepped eye, e=17mm, RRserial

One new buffer

New Proposal

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A R I S T O T L E U N I V E R S I T Y

FE Analysis

Geometric non-linear analysis:

- Original clamping components included (hats, U-bolts, middle plates)

- 50-60k elements/leaf, typical element length ~5mm

- Bushings modeled as steel cylinders (further investigations needed)

- Rubber silencers modeled with hyperelastic material data

- Contact modeling with friction (steel-steel μ=0.1, steel-rubber μ=0.8)

- U-bolts pretension considered

- Buffer modeled as spring element (non-linear F-s curve)

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A R I S T O T L E U N I V E R S I T Y

Wheel joint kinematics

-44 -42 -40 -38 -36 -34 -32 -30 -28 -26 -24 -22 -20 -18

-320

-300

-280

-260

-240

-220

-200

-180

-160

-140

-120

-100

-80

-60

-40

-20

wheel joint curve

Wheel Joint Kinematics ComparisonC

oo

rdin

ate

z (

mm

)

Coordinate x (mm)

empty load

nominal load (payload)

maximum vertical load

maximum braking load

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A R I S T O T L E U N I V E R S I T Y

Kinematics results

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A R I S T O T L E U N I V E R S I T Y

Stress results - 7.5to

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A R I S T O T L E U N I V E R S I T Y

Driving tests

• TGX-driving tests in Papenburgwith serial and new (prototype) springs

• test drivers, test engineers,

• 19 criteria covering the areas of:- driving comfort- straight-ahead driving behavior- cornering behavior- steering behavior

• Grades from 1 to 10

05X-5278 , 18.480

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A R I S T O T L E U N I V E R S I T Y

Driving test – 7.5to

0,90

0,95

1,00

1,05

1,10

1,15

1,20driving comfort

straight driving behaviour

steering behaviour

cornering

A: Serial 7,5t single leafspring, Rate 288N/mm,front eye at z=-100mm

B: Serial 7,5t single leafspring, Rate 288N/mm,front eye at z=-140mm

C: New berlin eye type7.5t single leaf spring,Rate 288 N/mm, fronteye at Z=-140mm

D: New berlin eye type7.5t single leaf spring,Rate 260 N/mm, fronteye at Z=-140mm

Grades normalized, series = 1.00

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A R I S T O T L E U N I V E R S I T Y

Driving test – 8.0to

0,90

0,95

1,00

1,05

1,10

1,15

1,20driving comfort

straight driving behaviour

steering behaviour

cornering

E: Serial 8.0t 2-leafspring, Rate 260N/mm,front eye at Z=-100mm

F: Serial 8.0t 2-leafspring, Rate 260N/mm,front eye at z=-140mm

G: New 8.0t 2-leafspring, Rate 260N/mm,front eye at z=-140mm

Grades normalized, series = 1.00

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A R I S T O T L E U N I V E R S I T Y

Summary / Conclusions

Systematic (… ICEAF III, IJSI) design of new front axle suspension for the new TGX-Generation, for 3 axle payloads: 7.5to, 8to, 9.2to

Achievement of better driving performance by:- Optimized Adjustment of steering gear/front leaf eye position- Adjustment of eye type (berliner, stepped) and eye lever e- Reduction of spring rate

Reduction of components:- 1 wind-up buffer for all axle loads- Reduction of number of leaves for 9.2to (proposal for 8.0to)

One steering configuration throughout all axle payloads

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A R I S T O T L E U N I V E R S I T Y

Acknowledgements

MAN Truck & Bus is gratefully acknowledged for the financial support of the theoretical investigations

BETA CAE is gratefully acknowledged for the provision of pre- and post-processing software