Change in Tyre Technology

8/3/2019 Change in Tyre Technology

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PROGRESS IN TIRES

FHWA Workshop

25 Oct 2007

John Melson

Michelin Americas R&D


2/21

Michelin Tire Corporation 2

Topics

In the beginning rough roads and early tires The bias tire, how it works, and how it led to

The radial tire

Truck tires and how they perform- why radials hitthe sweet spot for modern vehicles and roads

Why low aspect ratio radial tires are difficult

The new hybrid and how it advances design one

step further


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Rigid wheel no tire: the wheel is forced to

mount the obstacle and then drop

Wheel with tire: the tire deforms over the

obstacle, less vertical motion, more energyrecoverd

Early days: Rough roads

Rigid wheel response

Tire with high

inflation pressure

Tire with low

inflation pressure

A 1888 patent by J.B. Dunlop described how a

pneumatic tube attached to a rigid rim could ease

rolling over rough ground significantly.


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Membrane Equilibrium Shape

RADIUS&ANGLEPOSEBIAS

0

222

0

2222

RADIAL

22)(cos

)(cos221

)cos(

cp

ep

ec rr

rrr

rr

r

R

pR

N

r

N

Radius of curvature is determined

by

N

N

Curvature and casing cord length determine shapeShape of casing + mechanical properties of casing section

determine footprint/contact pressures and thus

performance in wear, traction,

r

BIAS CASING

N

N


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Building

on drum Conformed to largerradius

ply angles decrease

Bias Construction Parameters and Inflated Shape

BiasAngle

H/W

90 105

42 85

32 80

28 75

24 65

r0r

Rolling direction

Contact Patch progression

High H/W to Low H/W


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Bias Casing Properties

Simple construction, many reinforcing materials can be used Lower bias angles provide higher cornering stiffness because more

of the length of the casing is involved in steering or braking

Pure radial has poor performance contact patch shape / contact stressdistribution bad, cornering stiffness is very low

Shearing between plies in sidewall where large deformationimposes high displacements between cables which are close toeach other.

Cord paths (except for radial) are non geodesic with normalbuilding methods so static shears between plies are induced with

inflation Contact area shape and stress are largely determined by bias angle.

Some level of adjustment can be made by varying rubber thickness


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Crown Belts (2)

Casing Ply (900)

Shear Coupling

Bead Wirer

, p

BELTED RADIAL CONSTRUCTION, LOAD BEARING STRUCTURES

Y

-1.00

-0.50

0.00

0.50

1.00

-1.00 -0.50 0.00 0.50 1.00

Crown Belt to Carcass Shear

N/N parameter

R large

R small

pR

N

r

N

)cos(

NN


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Radial Casing Properties

Flat crown, flexible sidewall

Geodesic casing -> less fatigue, lower rolling losses

Casing shape has more design parameters variability

better contact area shape, better contact stress distribution

better wear life, traction, rolling losses


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Typical Radial Contact

Stresses

Radial construction can

distribute normal stresses

more evenly.

Allows tuning of tangential

stresses to improve abnormal

wear resistance

Stress measurements on shoulder block of dual tire

-4

-2

0

2

4

6

8

10

-150-100-50050100150

Position, mm

Stress,

bar(daN/cm2)


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Tire Treads and Tread Compoundshave evolved rapidly

Tread patterns and compounds needed to deal withwet traction and soft soil conditions.

Wear forms and wear rate must be optimized

Tread compounds and mechanics interact the mosteffective designs optimize the two together

The casing evolves slowly, the tread evolves rapidly

Customer perception importantif it doesnt look

traction it hasnt got traction.


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A recent tread innovation example:

Using interlocking sipes to modifycontact stresses


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Truck Rims:Tube Type/Flat Seat/Multipiece:

Rim flange removable, rim pieces locked in

place by tire pressure and mechanicalengagement.

Subject to explosive failure throwing metal

pieces.

Tube increases tire running temperature

Tubeless/150 Drop Center

Single piece rim, casing ply forces provide leverage to seal tire on rim. Lower

operating tire operating temperature, higher bead stresses, low probability of thrown

metal fragments from rim or tire failure.

150 slope

Sealing Pressure

Rim Load

Casing Tension

Another major change: Rims and Wheels & Tires


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Truck tire naming by epochTube Type Bias Ply Tires almost always on multi-piece rims

10.00-20/22/24 XXX

Tire width ininches(10,11, 12..)

Rim Diametereven integers 20,22,24 = tube

type multi-piece rim

Tire type usuallya tread name

10.00R 20/22/24 XXX

R =Radial(different load/pressure)

Tubeless Tires almost always onsingle piece rims (150 drop centerfor truck)

11R22.5 / 24.5 XXX

Tire width ininches(10,11, 12..)

no decimal

Rim Diameterhalf inch sizes

275/80R22.5 / 24.5 XXX

Most recently metric width and aspect ratio added

Tire Section Height/Width

Tires were ~ 90 series


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Michelin Tire Corporation

14

H/W what limits?

Trucking profits from lower H/W:

Double wide tire (275/80 -> 445/50 or 455/45) NA trucking

Lower diameter tires (315/80 -> 315/60) European evolution

Belted radial constructions have most endurance when70 < H/W < 90.

Low H/W in belted construction pushed towards higherinflation pressures to control endurance side effects ->greater contact stress level, less even stress distribution

in contact.


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15

Circumferential (00

)reinforcing

Increase width, lower H/W

Height

constant with

respect to dual

equivalent tire

Three way hybrid of radial casing, small angle bias belt at shoulder and circumferential

(00) reinforcing at center

Reduces shear stresses at shoulder -> lower inflation pressure for equal crown

endurance

Better contact stress distribution in wide casing construction

The answer: Circumferential reinforcement

A 445/50R22.5 casing

R ->

p

r

N


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16

Rolling Resistance (10-3)

First tires

First Radialtires

Green X

Energy 3

Energy

FirstMetalique

Tires

First cablereinforced

tires

30

25

20

15

10

5

0

1880 1900 1920 1940 1960 1980 2000 2020

Bandage plein

Pass Tire

Truck Tire

Railroad wheel

Metro/subway tire

Research materials

(Shell eco marathon)

Order of magnitude in 2002 :

- Passenger car : 8,5 -13 x10-3

- Truck Tires : 4,5 (Xone) - 10 x10-3

- Motorcycle : 2,5 - 5x10-3

Rolling Resistance Evolution 1910 - 2002

Xone


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17

z

z

x FPK

F

FR

R/R0

Fz/Fz0

P/P0

Rolling Resistance Behavior:

, Determined by combination of mechanical effects

of tread and casing behavior.

Rubber Compounds vary magnitude of R0

at P0

and Fz0

~ -0.2

~ -0.1

for a dual truck tire at road velocities

RR behavior: pressure

effect is strong, Load

effect weaker

Actual Tire Rolling Resistance Ranges - Class 8

0.00

2.00

4.00

6.00

8.00

10.00

12.00

TireRR

t(kg/1000kg)

New tires Recap tires

Steer Drive Trailer

act. bic

XON

act.

act.

bic bic

bic "best in class"

XONXONE

XONE New Wide-baseact. 2000 avg.

Xone/duals


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18

Center Reinforced Low H/W (Xone)Design Goals

Better optimization of vehicle grossweight/volume, wear, rollingresistance and endurance than 80H/W tire & rim

=

lower cost of ownership Equal operating temperature (short

term endurance)

85

54

66

78

Equivalent vehicle handling(braking, acceleration,

cornering, stability) in all

situations.

Modified axle shown -> better roll over

Standard axle + 2 off set wheel -> equal roll over


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19

What customers want

Safety

Vehicle stability stopping,cornering, emergencymaneuvers


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20

What customers want

Life cycle cost minimized Purchase cost

Wear life

Fuel consumption

Payload maximization Maintenance

Vehicle down time

Pressure maintenance

Repairability / Retreadability


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21

Behind the evolutionsEnabling material technologies

Vulcanization Sulfur linking of rubber polymer chains

Carbon Black (Early

nanoparticle technology)Further reinforcement of rubber tuning ofcompound viscoelasticity, elasticity, abrasionresistance

Synthetic rubbers, naturaland synthetic blends

More rubber properties tuning possibilities

Rubber/brass bonding Structural bond needed to make a belted radialpossible, brass plated steel + special rubber mixprovides high quality bond

Silica Used with or in place of carbon black-newadherence/wear/rolling resistance trade off

Open steel cableconstructions

Permits 00 reinforcing in crown without cablerupture

Documents

Change in Tyre Technology