air.pdf

SEETHI SAHIB MEMORIAL POLYTECHNIC COLLEGE

TIRUR-5

DEPARTMENT OF AUTOMOBILE ENGINEERING

2015-2016

Seminar report on

AIRLESS TYRE

Submitted by:-

FASIL K K

Roll No: 5

Reg. No. : 12050196

Seminar Report 2014-2015 Airless Tyre

2

Dept. of Automobile Eng. S.S.M Polytechnic College, Tirur

SSM POLYTECHNIC COLLEGE

TIRUR

DEPARTMENT OF AUTOMOBILE ENGINEERING

2014-2015

CERTIFICATE

This is to certify that this is the bonafide record of seminar on Airless

tyre has been presented by Fasil K K, sixth semester automobile,

SSMPTC, Tirur on. In partial fulfillment of the

requirement for the award of the Diploma in Computer Engineering under

Directorate Of Technical Education, Kerala State during the year 2014-

2015.

Staff in charge: Head of Section:

External Examiners: Internal Examiner:

Place:

Date:


3


ACKNOWLEDGEMENT

First of all I would like to praise the god for blessing me to com-

plete this seminar successfully. I am deeply incepted to Mr. Naina Mo-

hammed Basil (Head of department in automobile engineering, Seethi

Sahib Memorial Polytechnic College, Tirur) for providing me the op-

portunity to present the seminar on this topic.

I extended my unexplainable gratitude towards all of my teachers;

& librarians who gave me a lot of information and supports for this

seminar. I gave my heart full thanks to my friends & family, whom of-

fered me all kind of supports for this.


4


CONTENTS

ABSTRACT

INTRODUCTION

PROBLEM IN CONVENTOINAL TYRE

DESIGN OF TWEEL AIRLESS TYRES

APPLICATIONS

FUTURE OF TWEEL TECHNOLOGY

CONCLUSION

REFERENCE


5


ABSTRACT

Non-pneumatic tires (NPT), or Airless tires, are tires that are not sup-

ported by air pressure. They are used on some small vehicles such as riding lawn

mowers and motorized golf carts. They are also used on heavy equipment such

as backhoes, which are required to operate on sites such as building demolition,

where tire punctures are likely. Tires composed of closed-cell polyurethane foam

are also made for bicycles and wheelchairs.

Michelin is currently developing an integrated tire and wheel combina-

tion, the "Tweel" (derived from "tire" and "wheel," which, as the name "Tweel"

suggests, are combined into one new, fused part), which operates entirely with-

out air. Michelin claims its "Tweel" has load carrying, shock absorbing, and han-

dling characteristics that compare favorably to conventional pneumatic tires. The

automotive engineering group of the mechanical engineering department

at Clemson University is developing a low energy loss airless tire with Michelin

through the NIST ATP project.

Resilient Technologies and the University of WisconsinMadison's Pol-

ymer Engineering Center are creating a "non-pneumatic tire", which is basically

a round polymeric honeycomb wrapped with a thick, black tread. The initial ver-

sion of the tire is for the Humvee and is expected to be available in 2012. Resil-

ient Technologies airless tires have been tested and are used by the U.S. Army.

And is also the first group to make a commercially available mass-produced air-

less tire after their acquisition by Polaris, albeit, only as coupled with their vehi-

cle.


6


INTRODUCTION

For more than 100 years, vehicles have been rolling along on cushions of

air encased in rubber. The pneumatic tyre has served drivers and passengers well

on road and off, but a new design by Michelin could change all that the tweel

airless tyre .The tweel (a portmanteau of tyre and wheel) is an experimental tyre

design developed by the French tyre company Michelin. The tyre uses no air,

and therefore cannot burst or become flat. Instead, the Tweel's hub connects to

flexible polyurethane spokes which are used to support an outer rim and assume

the shock-absorbing role of a traditional tyre's pneumatic properties.


7


PROBLEM IN CONVENTOINAL TYRE

LOWER ROLLING RESISTANCE

The increasing concerns over the green-house effect will in the near future

require more attention to rolling resistance than ever before; in fact from an al-

ready high attention to a very high attention.

The trend towards lower rolling resistance has been obvious for many

years. Significant progress was reported in the recent Tyre Energy Efficiency

Report in reducing rolling resistance, as measured for new passenger tyres, over

the past 25 years. More tyre models today, when measured new, have rolling

resistance coefficients below 0.009, and the most energy-efficient tyres have co-

efficients that are 20 to 30 percent lower than the most energy efficient radial

models of 25 years ago [TRB 286, 2006].

Another trend is the increased popularity of run-flat tyres; mostly having

stiffer sidewalls or some material added that can avoid running a flat tyre on the

rim. The above-mentioned Tyre Energy Efficiency Report concluded that run-

flat tyres weigh more than conventional radial tyres which increases their ma-

terial and production cost and they tend to exhibit higher rolling resistance.

This author thinks that this may turn the trend back to more traditional designs,

or turn the interest over into designs which have run-flat capabilities without

increased rolling resistance.

The increasing popularity and more frequent governmental support for

hybrid or electric vehicles will also require lower rolling resistance since this

directly affects the distance one can run in the electric mode. Finally, it shall be

mentioned that labeling of energy efficiency (in practice rolling resistance) of

tyres is likely to happen in the near future.


8


INCREASING CONCERN FOR LOW NOISE

Both rolling resistance and noise emission are expressions of energy

losses in the rolling of tyres. It is not surprising that these characteristics are at

large positively correlated; although exceptions exist. Nevertheless, it is this au-

thor's conclusion that exterior noise and rolling resistance will drive the tyre de-

velopment to a large extent in the coming years [Sandberg, 2003]. Probably, the

present focus on high-speed and high-power performance, which both are in

some conflict with low noise and rolling resistance (and thus air pollution), will

at last have to give in to the latter performances.

Another present trend is the high priority put on the visual appearance of

tyres, as a selling argument; in particular for "sporty" vehicles. The styling trend

was heavily criticized recently as being in conflict with good technology by one

of the foremost tyre experts in the world, Dr. Joe Walter, in a column in Tire

Technology International [Walter, 2006]. It is likely that this trend will be broken

when it is in conflict with the increasing environmental demands. Vehicle man-

ufacturers will have to face the possible effects of this which may be uncomfort-

able to some.


9


DESIGN OF TWEEL AIRLESS TYRES

The Tweel consists of a cable-reinforced band of conventional "tyre" rub-

ber with molded tread, a shear band just below the tread that creates a compliant

contact patch, and a series of energy-absorbing polyurethane spokes. The rectan-

gular spokes can be designed to have a range of stiff nesses, so engineers can

control how the Tweel handles loads. The inner hub contains a matrix of deform-

able plastic structures that flex under load and return to their original shape. By

varying the thickness and size of the spokes, Michelin can generate a wide array

of ride and handling qualities. The tread can be as specialized as any of today's

tyres and is replaceable when worn.


10


HOW IT WORKS

The Tweel doesnt use a traditional wheel hub assembly. A solid inner

hub mounts to the axle and is surrounded by polyurethane spokes arrayed in a

pattern of wedges. A shear band is stretched across the spokes, forming the outer

edge of the tyre. On it sits the tread, the part that comes in contact with the surface

of the road. The cushion formed by the air trapped inside a conventional tire is

replaced by the strength of the spokes, which receive the tension of the shear

band. Placed on the shear band is the tread, the part that makes contact with the

surface of the road.


11


ADVANTAGES

One of the greatest advantages of this technology would be the fact that

the tyre is service-free. No more air pressure check, no more flat tires and no

more blow-outs mean a lot less to worry about when driving car. It is also con-

ceived to last longer. Also, the balancing between traction and comfort could

become a thing of the past. Thats because Michelin has found that it can tune

Tweel performances independently of each other, which is a significant change

from conventional tires. This means that vertical stiffness (which primarily af-

fects ride comfort) and lateral stiffness (which affects handling and cornering)

can both be optimized, pushing the performance envelope in these applications

and enabling new performances not possible for current inflated tires.

It doesnt require maintenance and it is risk-free, the Tweel tyre could be

a good choice for special vehicles like those used in the army, in the construction

business or even in the exploration of other planets. In 2009, Michelin has de-

veloped for NASA a Tweel-based tyre to be used in the latest generation of lunar

rover vehicles. The Michelin Lunar Wheel maintains flexibility and constant

ground pressure, allowing the vehicle to move through loose soil and craters. In

addition, it combines low mass and high payload capacity, making it 3.3 times

more efficient than the original Apollo Lunar Rover wheels. Its textile tread en-

ables the rover to maintain traction at very low temperatures.

Tweel technology could also penetrate the personal mobility market. At

the public demonstration of the Tweel, Michelin placed prototypes on the iBOT,

a personal mobility device for physically impaired people, and the Segway Cen-

taur, a four-wheeled ATV-type vehicle that uses Segways self-balancing tech-

nology.


12


DISADVANTAGES

It is not the perfect tire. At least not yet. One of its biggest flaws is vibra-

tion. Above 50 mph, the Tweel vibrates considerably, thus generating noise and

heat. A fast moving Tweel is reportedly unpleasantly loud. Long distance driving

at high speeds generates more heat than Michelin engineers would like. Thats

why, for the moment, the first applications of the Tweel are in low-speed vehi-

cles, such as construction vehicles. The Tweel is perfect for such use because the

ruggedness of the airless design will be a major advantage on a construction site.

Michelin is also exploring military use of the Tweel, which would be ideal in

combat situations, where conventional tyres are an easy target.

Another big obstacle in the Tweels way is the tire industry itself. Making

Tweels is quite a different process than making a pneumatic tire. The retooling

of the many tire factories, plus the equipment necessary to service the new tire

around the world represents also an important obstacle to the broad adoption of

airless tires. Because of these drawbacks, Michelin is not planning to roll out the

Tweel to consumers any time soon.

Last but not least, another challenge for the Tweel could be the drivers

themselves who would see their beloved radial tires and rims replaced by a not

so good looking Tweel. Of course, Michelin could place some covers to hide the

spokes, but the psychological impact on the consumer should not be neglected.

It might be the inventor of the Tweel, but another company is working on a sim-

ilar project. Resilient Technologies is developing their own airless tire, known

as the NPT (non-pneumatic tire). That company is using a more aggressive de-

velopment and marketing strategy aimed at military use. The NPT is based on a

different configuration of spokes, but the general idea is the same as Tweel's.


13


APPLICATIONS

Given the high speed problems with the Tweel, the first commercial ap-

plications will be in lower-speed, lower-weight vehicles such as wheelchairs,

scooters, and other such devices. The iBOT mobility device and Segway's Con-

cept Centaur were both introduced with Tweels. Michelin also has additional

projects for Tweel on small construction equipment, such as skid steer loaders,

for which it seems well-suited.

The first large-scale applications may be in the military where a flat-proof

tyre would be advantageous. Military testing has indicated that the Tweel de-

flects mine blasts away from the vehicle better than standard tyres and that the

Tweel remains mobile even with some of the spokes are damaged or missing.

NASA has contracted Michelin to develop a wheel for the next generation

Lunar Rover based on the Tweel. This has resulted in the Lunar Rover Initiative

AB Scarab wheels. The first large-scale applications may be in the military where

a flat-proof tyre would be advantageous.


14


FUTURE OF TWEEL TECHNOLOGY

For Michelin, Tweel is a long-term vision that represents the next step in

a long path of industry-changing innovations. Fifty years ago, Michelin invented

the radial tyre and there is no question that radial tyre technology will continue

as the standard for a long time to come. Michelin continues to advance the per-

formance of the radial tyre in areas such as rolling resistance, wear life and grip.

In the short-term, the lessons learned from Tweel research are being ap-

plied to improve those conventional tyre performances. In the future, Tweel may

reinvent the way that vehicles move. Checking tyre pressure, fixing flats, high-

way blow-outs and balancing between traction and comfort could all fade into

memory.


15


CONCLUSIONS

It is concluded that tyres featuring low noise and low rolling resistance

will be required in the near future and that the interest in and need for improved

characteristics in this respect will receive much more attention and priority in the

tyres of the next 10 years than for present market tyres.

If the climate changes will force a sudden and dramatic change in trans-

portation and vehicle emissions policies, which is not an unlikely scenario, the

tyre and vehicle manufacturer who fails to consider unconventional solutions

may suddenly find itself in an inferior position to the one who can see and actu-

ally explore the possibilities of new technologies.

There are possibilities to reduce noise and rolling resistance further than

today by traditional tyre design measures; in particular if the extreme high-speed

demands (speeds in excess of 200 km/h) can be abandoned.

It is further concluded that there are several possibilities for a break-

through in tyre design for low noise and low rolling resistance within the next 10

years or so, provided sufficient resources are spent on developing the concepts

presented above.


16


REFERENCES

Sandberg, U.; Ejsmont, J. A.; Kropp, W. and Larsson, K. (2003):

"Low noise tires A co-operation project in northern Europe", Paper

N494, Proc. of Inter-Noise 2003, Seogwipo, Korea.

Sandberg, Ulf (2003): "The road to quieter tires". Article in Tire Tech-

nology International '03, Annual Review 2003, UKIP Media & Events,

Dorking, Surrey, U.K.

air.pdf

Documents