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