michelin tweel technology report

Seminar report 2015 Michelin Tweel Technology

1 Dept. of .Mechanical Engineering

CHAPTER-1

INTRODUCTION

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

encased in rubber. Sometimes, we get so used to a certain product that no true changes are

ever really made for years, decades even. So begins an article discussing the development of

airless tyres, something that has become more prevalent in the past few years. A few tyre

companies have started experimenting with designs for non-pneumatic tyres including

Michelin and Bridgestone, but neither design has made it to mass production.

Creating a new non-pneumatic design for tyres has more positive implications than

one might think. For one thing, there are huge safety benefits. Having an airless tyre means

there is no possibility of a blowout, which, in turn, means the number of highway accidents

will but cut significantly. Even for situations such as Humvees in the military, utilizing non-

pneumatic tyres has a great positive impact on safety. Tyres are the weak point in military

vehicles and are often targeted with explosives. If these vehicles used airless tyres, this

would no longer be a concern.There is also an environmental benefit to using this type of

tyre. Since they never go flat and can be retreaded, airless tyres will not have to be thrown

away and replaced nearly as often as pneumatic tyres. This will cut down landfill mass

significantly.

Because of the benefits, I believe that it is extremely important that research and

production of airless tyres is continued and increased. This type of innovation works well in

conjunction with several engineering codes of ethics, and thus should be embraced by

engineers everywhere. Cars are things that people use every day, so any improvements over

existing designs would affect the lives of the majority of people. Learning about such a

topic, therefore, I believe holds extreme value- especially for us freshmen engineering

students. In doing research into these kinds of topics that hold significant meaning, we can

see that what we will do can make a difference.

Airless tyres can be made with different spoke tensions, allowing for different

handling characteristics. More pliant spokes result in a more comfortable ride with

improved handling



CHAPTER-2

HISTORY

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. This report discusses

what such Airless Tyres are, why one would use it in place of traditional tyres, some of the

problems that may occur with an airless tyre and where one might see such Airless Tyre in

the future. When the tyre is put to the road, the polyurethane spokes absorb road impacts the

same way air pressure does in pneumatic tyres. The tread and shear bands deform

temporarily as the spokes bend, then quickly spring back into shape. Airless tyres can be

made with different spoke tensions, allowing for different handling characteristics. More

pliant spokes result in a more comfortable ride with improved handling. The lateral stiffness

of the tyre is also adjustable. However, you can’t adjust a such a tyre once it has been

manufactured. You’ll have to select a different one. For testing, Michelin equipped a n Audi

A4 with Tweels made with five times as much lateral stiffness as a pneumatic tyre, resulting

in “very responsive handling”. Non-pneumatic tyres (NPT), or Airless tyres, are tyres that

are not supported 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 tyre punctures are

likely. Michelin is currently developing an integrated tyre and wheel combination, the

"Tweel" (derived from "tyre" and "wheel," which, as the name "Tweel" suggests, are

combined into one new, fused part), that operates entirely without air. Michelin claims its

"Tweel" has load carrying, shock absorbing, and handling characteristics that compare

favorably to conventional pneumatic tyres.

Automotive engineering group of mechanical engineering department at Clemson

University is developing a low energy loss airless tyre with Michelin through the NIST ATP

project. Resilient Technologies and the University of Wisconsin–Madison's Polymer

Engineering Center are creating a "non- pneumatic tyre", which is basically a round

polymeric honeycomb wrapped with a thick, black tread. The initial version of the tyre is

for the SUVs and is expected to be available in 2012.Resilient Technologies airless tyres

have been tested and are used by the U.S. Army.



CHAPTER-3

TYRES

Airless tyres; Before the technology of airless tyres is discussed, it is important for

the reader to understand how standard pneumatic tyres function, and what advantages and

disadvantages there are to using them. A brief overview of the general concepts of airless

tyres will then follow.

Pneumatic tyres; The basic design of all pneumatic tyres is very similar, even though

there are many different types. They all include an inner core that holds pressurized air

which is then covered with a layer of rubber that comes in contact with the road, called a

tread. The tread helps keep traction with the road and prevents slipping and skidding. The

tread has the tendency to wear down over time, so if the tyre has not gone flat, a person will

usually replace it at this point.

A main reason for using pneumatic tyres is the deformation that occurs during

rotation. As the tyre rolls, the weight of the car pushing down on it causes the tyre to flatten

slightly. This, in turn, causes the tyre to have a larger surface area to be in contact with the

ground, which makes for better traction. It also gives a slight cushioning effect, making

running over small rocks or debris unnoticeable. Or, as writer for How Stuff Works Ed

Grabianowski puts it. If you’ve ever taken a ride in an old-fashioned carriage with wooden

wheels, you know what a difference a pneumatic tyre makes.

Pneumatic tyres have their advantages, but they also have their disadvantages as

well. The possibility of a blowout or flat (when air is let out suddenly from the tyre) is a

major concern because they have the tendency to cause severe accidents. The task o f

regulating tyre pressure is also a disadvantage because consumers are usually not very good

at it. Although it may help with traction to have the tyres a little flat, it comes at the price of

handling. When there is not enough air pressure in the tyre, the sidewalls flex causing the

tyre to not quite follow the desired line of steering. It is because of these disadvantages that

tyre companies have taken an interest in designing airless tyres.



3.1 AIRLESS TYRE (TWEEL)

Airless tyres or Non-pneumatic tyres (NPT), are the tyres that are not supported

by air pressure .These tyres are also called as Tweel which is a merger of the words tyre and

wheel. This is because the Tweel does not use a traditional wheel hub assembly. The Tweel

concept was first announced by Michelin back in 2005. it' s structure is a solid inner hub

mounted onto the vehicles axle, that is surrounded by polyurethane spokes. This forms a

pattern of wedges, which help to absorb the impacts of the road. These spokes look similar

to the ones found on bicycles and plays the shock-absorbing role of the compressed air as in

a traditional tyre. A sheer band is then stretched across the spokes, which forms the outer

edge of the tyre. It is the tension of the band and the strength of the spokes that replaces the

air pressure used on traditional tyres. When a vehicle drives over an obstacle, a sleeping

policeman for example, the tread and shear bands give way as the spokes bend, before they

quickly bounce back into shape.

Fig 3.1: Structural designation Schematic

3.2 WORKING OFAIRLESS TYRE

The Airless tyre (Tweel) doesn’t 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 tyre 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.



When the Tweel is running on the road, the spokes absorb road defects the same

way air pressure does in the case of pneumatic tyres. The flexible tread and shear bands

deform temporarily as the spokes bend, then quickly go back to the initial shape.

Different spoke tensions can be used, as required by the handling characteristics and

lateral stiffness can also vary. However, once produced the Tweel’s spoke tensions and

lateral stiffness cannot be adjusted.

Fig 3.2: Tyre on deforming when applying load

Fig 3.3: Tyre regains its shape when load is removed



3.3 DESIGN APPROACHES

There are many different approaches to the design of the supports. This accounts for

the main differences between the overall designs of each company’s version of the airless

tyre. The following are approaches to making an airless tyre by different companies. Some

solve more problems than others, but it should be noted that all show an extreme amount of

ingenuity that may cross over into different types of engineering.

3.3.1 NASA and the Apollo Lunar Rover

The first major attempt at creating an airless tyre was in 1970 for NASA’s Apollo

Lunar Roving Vehicle. The tyres were made of steel strands woven together to form the

shape, and then were coated with zinc. In order to gain traction, titanium chevrons were

added to the outer surface.

This design worked well on the moon, where comfort of the drivers was not an issue

(i.e. cushioning effect of pneumatic tyres), but it would not have been practical on earth.

The design would also be very expensive for a regular automobile, which is not attractive to

the average consumer.

Fig 3.4: Tyre of NASA and the Apollo Lunar Rover



3.3.2 Michelin Tweel Tyre

The next main attempt at creating an airless tyre was called the Tweel (combination

of tyre and wheel) by the tyre company, Michelin. Their design consisted of a thin rubber

tread with V-shaped spokes made of polyurethane.

There were extremely high hopes for this model when it came out. Columnist Don

Sherman of Car and Driver writes, introductory claims versus conventional pneumatic

radials were two to three times the tread life and five times higher lateral stiffness with o nly

a slight increase in rolling resistance. This development has very positive implications

because it means that the tyre would last about two times longer than a standard pneumatic

tyre before it would have to be retreaded. The only major problem with this model is at

highway speeds, the spokes tend to vibrate, causing excessive noise.

When asked about recent developments for the Tweel, Michelin refused comment,

either because they dropped the project, are working with the military, or do not want to

divulge findings to their competitors.

Fig 3.5: Michelin Tweel Tyre



3.3.3 Bridgestone Tyre

Another model for the non-pneumatic tyre came from the well-known tyre company,

Bridgestone. Although very similar in concept to Michelin’s Tweel, there are some key

differences.

The core is made of rigid aluminum and has thermoplastic spokes radiating outward

at an angle in opposite directions on each side. This creates more stability and less lateral

movement in the tyre. Bridgestone also fixed the vibration and noise problem in this way as

well. The main issue with their design was that debris had the tendency to get caught in the

gaps between spokes. In addition, the materials used in the tyres are recyclable, contributing

to the efficient use of resources. Further, by pursuing extremely low rolling resistance and

contributing to reductions in CO2 emissions through use of proprietary technologies,

Bridgestone believes it is possible to achieve even higher levels of environmental

friendliness and safety.

Bridgestone is pursuing this technological development with the aim o f achieving a

cradle to cradle process that proactively maximizes the cyclical use of resources from worn

tyres into new tyres and the use of recyclable resources.

Fig 3.6: Bridgestone Airless Tyre



3.3.4 Resilient Technologies, LLC

As stated before, the production of airless tyres would be extremely beneficial to the

military. The group Resilient Technologies, LLC is working with the military to develop

such a tyre for Humvees. To meet the requirements of heavy loads and rough terrain, these

tyres are quite industrial- looking. They consist of a thick outer tread with a honeycomb-like

structure inside. This allows for the load to be evenly distributed around the tyre.

The honeycomb design could be adjusted for any application where loss of air

pressure causes problems, where tyres face numerous hazards on a regular basis or where

business want to reduce downtime for tyre issues and maintenance, such as agricultural and

construction equipment.

This design causes the tyre to be very loud, making in unsuitable for regular

automobiles. For military purposes however, it is useful. It can withstand a large amount of

abuse, including blasts when under attack.

Fig 3.7: Tyre produced for military purposes by Resilient Technologies, LLC



3.3.5Scitech Airless Tyre

The most convenient design for everyday vehicles comes from a company called

SciTech. Their tyre fits on standard rims, unlike all previously mentioned models (which

are really a combination of a wheel and a tyre), and has the look of a regular pneumatic tyre

form the outside. Instead of supports radiating from the center, their supports are spring-

like. There are a hundred supports in every tyre and nine are in contact with the road at any

one time. There is also a secondary support system in order to distribute load to all of the

supports which have 550 pounds of strength each and are made of a thermoplastic glass

fiber composite material.

Because SciTech’s tyre has closed sidewalls and no spokes, there is no noise or

overheating issue as well as no problems with debris. A division of Scitech Industries has

announced a successful test of the company’s non-pneumatic airless tyre at an industry

laboratory in Ohio.

The company says the tyre achieved a cool and uniform 10-hour run at highway

speed at passenger car load. Mounted on a standard rim with a conventional tyre mounting

machine, the airless tyre is self-supporting, with internal glass fiber composite ribs

supporting the load. Built and cured in a conventional steam-bladder mold at a commercial

tyre factory, the composite rib and tyre construction are covered by worldwide patents.

Fig 3.8: SciTech Airless Tyre



3.3.6 Hankooki – flex tyres

A futuristic design concept, the Hankooki – Flex is an airless wheel and tyre, all in

one. Aiming to keep losses to a minimum when converting energy, Hankook Tyres

engineers have reconceptualised the automobile tyre. With the Hankook Tyres i-Flex, the

company presents the prototype of a non-pneumatic tyre that will help increase the overall

efficiency of vehicles thereby improving their energy balance. With 95 percent of its

construction being recyclable, the Hankooki-Flex is made from polyurethane synthetics,

with the tyre manufactured in conjunction with its rim as one unit. It is considerably lighter

than conventional wheel-tyre combinations and does not require air like conventional

pneumatic tyres, able to offer shock absorbency through the unique design.

Fuel consumption and noise emissions are thus optimized while simultaneously

increasing vehicle safety. it is Displayed at the Frankfurt show on an ABT-tuned

Volkswagen Up, the Hankook i-Flex tyre specification is 155/590 14 (155mm wide, 590mm

diameter, 14- inch ‘simulated wheel size). Through Hankook Tyres hands-on display and

video guides, visitors to the Frankfurt show can alter the colors’ of the Hankook i-Flex. At

the 65th IAA (International Automobile -Ausstellung), September 12-22, in Frankfurt,

premium tyre manufacturer Hankook Tyre will present its latest innovations, production-

ready prototypes and trend-setting tyre concepts designed to meet the demands of future

mobility, in Hall 8, Stand 24.

Fig 3.9: Hankooki -Flex tyres



3.4 Manufacturing of Tweel Tyre

Tweel tyres are produced in three steps: tread, hub, and polyurethane. In the first

step, the tread is constructed by a similar method as the tyre tread manufacturing process.

The tread on a Tweel tyre is exactly the same as a pneumatic tyre and is extruded in the

same way, and it is mated to layers of belts in the same manner as conventional tyres. The

process of rolling plies onto a drum to achieve the correct diameter currently is performed

manually, but the same basic process that is performed on tyres will be mimicked when the

Tweel production is fully automated. In this fairly simple process, rectangular sheets of

rubber and steel cord are rolled onto a steel drum, and the excess material from each sheet is

removed. Once the desired base thickness is achieved in this manner, the extruded tread is

rolled onto the top, and the entire assembly is vulcanized.

The second step is a very simple 4 kg steel hub casting that is well documented in

several databases including BUWAL250. In the third step, the hub and the tread are secured

concentrically and polyurethane is poured into a spoke and shear band mold while the entire

assembly spins so that the polyurethane will sufficiently fill the mold in the radial direction.

The energy needed to spin the Tweel assembly and polyurethane mold for just 5

minutes while the polyurethane is poured is considered irrelevant compared to the large

amount of energy required to heat and pressurize the ovens needed to cure the shear band

and then cure the entire assembly after the polyurethane is poured, so it can be ignored in

this inventory. Before the pouring process occurs though, all the surfaces that contact the

polyurethane are cleaned and covered with either an adhesive or a mold release for the shear

band and spoke mold, respectively. The quantities of these additives were supplied by

Michelin, and listed in table 3.1

Table 3.1: Cleaning, adhesive, and release agents used during manufacturing of one12 kg

Tweel Tyre

Additive Mass (g)

Ethyl acetate 26.7

Adhesive 3.3

Chemlok 7701 30

Stoner M-804 250



The polyurathene pre-polymers and curative are stored separately until they are

heated and combined at this point in the manufacturing process, but this chemical process is

considered part of the raw materials production in order to analyze which material is

causing the most amount of environmental harm. The combination of the heated pre-

polymers and curative could be considered in this Tweel manufacturing section, but in order

to organize the impacts of the raw materials it is treated as part of the raw material

production of polyurethane.

After the polyurethane is poured and the assembly is allowed to stop spinning, the

entire Tweel tyre (shear band, spokes, and hub) is placed into another oven. This final

curing occurs at 100°C degrees for 4 hours so that the desired polyurethane properties are

obtained and to assure all the components are securely bonded together. To save some

energy this curing process could take place at room temperature, but it would take much

longer to complete and during this time it would be susceptible to being bumped and

permanently damaged, so this possible environmental benefit to save the energy required to

heat the oven is not a plausible option for Michelin. So, this energy must be considered

along with all the other process inputs mentioned, and all of these are organized with the

rest of the life cycle inventory. The energy required to heat, mix, and cure the polyurethane

is allocated to the raw material production of polyurethane, so this 0.7 kWh is all the energy

that is needed in the Tweel manufacturing inventory.

3.5 Technical description of Tweel

Michelin's resilient, structurally supported non-pneumatic assembly, the Tweel™,

has performance capabilities like pneumatic tyres that are a substantial improvement over

any other airless tyre product. The key component of the technology is a structure called the

shear ring. The shear ring replaces the function of the crown belts and the air pressure that

normally carry the load in a radial tyre. The design of the shear ring consists of three

concentric layered elements.

There is an elastomeric annular band that is called the shear layer. The shear layer is

captured between two composite rings of the same width as the shear layer. The composite

rings have a circumferential tensile modulus of elasticity that is substantially greater than

the shear modulus of elasticity of the shear layer.



The main characteristic of the shear ring is that deflecting the circular unloaded

shape puts the elastomeric band in a state of shear deformation.

Fig 3.10: Shear Beam Cross Section

The shear deformation of the ring results in a uniform contact patch pressure

distribution again indicated in Figure 3.10. This uniform contact patch pressure is the first

key aspect of the technology. All prior non-pneumatic tyres, which carry load via

compression of structures between the contact patch and the wheel, have parabolic contact

patch pressure distributions that limit a number of performance criteria, such as: traction,

soft-soil flotation and tread life. The uniform contact patch pressure distribution delivered

by shear rings is equivalent to that of pneumatic tyres.

This allows the use of conventional tread materials and tread patterns that result in

traction and wear life similar to pneumatic tyres. Although the current embodiment of the

drive Tweel™ assembly for power chairs is 2¼" in width, the contact areas more

comparable to a 3" wide pneumatic tyre which has a rounded crown.

Further, the contact patch pressure of this technology can be low enough to offer the

prospect of satisfactory mobility in marginal soil conditions. The current estimate However,

any tyre, pneumatic or not, that must operate continuously at a low foot print pressure must

be made larger to provide the necessary footprint area without imposing excessive vertical

deflection. (Excessive deflection would cause too much shear strain and lead to early ring

failure.)The shear ring transmits the contact patch load to the top of the tyre like a

compression arch.



The ring is attached to the wheel via polyurethane spokes, which act only in tension

to transmit the ring load to the wheel. See the structural schematic in Figure 3.11 to

visualize the load path. The spokes buckle as they pass over the contact patch and therefore

provide little load transmission via compression. The transmission of load via the top of the

shear ring is the second key aspect of the technology.

Fig 3.11: Structural Schematic

The initial version of the Tweel™ assembly concept is shown in Figure 3.12. The

entire structure is utilized to carry the wheel load, making the resulting tyre much more

efficient than classic non-pneumatic tyres in the amount of load carried per unit mass of the

tyre/wheel system. Further, the absence of structures transmitting wheel loads directly to the

road in compression allows much higher levels of deflection without causing excessive

material strains. No prior non-pneumatic tyre design has been able to deliver this

combination of performance characteristics.

Fig 3.12: Tweel assembly



The design of the spokes and their relationship to the wheel control the forces

transmitted from the shear ring to wheel. Unlike pneumatic tyres, where all the forces

transmitted by the structure are proportional to the inflation pressure, the Tweel™ can be

made soft in one direction and stiff in another.

The lateral depth of the flat, vane style spokes contributes to the high lateral stiffness

of Tweel™ assemblies. This fact removes some of the classic constraints of design that are

inescapable when dealing with traditional pneumatic designs and, therefore, present a

tremendous opportunity for wheel assemblies for many applications with improved

handling and performance.

The shapes of pneumatic tyres are dominated by the constraints of being pressure

vessels. Although the belts in radial tyres allow their basic shape to be flattened into low

aspect ratio, low load carrying sport applications, there are currently no reasonable

structures that lead to tall and narrow pneumatic solutions, such as those in the dimensional

range of rear manual tyres and bicycle tyres. With more understanding and development of

the technology, this could change in the future. Because the spoke loads a llow the use of

unreinforced elastomeric materials, the complexity of the spoke design is limited only by

the cost of the mold. This allows substantial design flexibility in meeting the load

transmission characteristics required for each vehicle application. Further, the absence of

inflation pressure loads and simple, robust connections of the spokes to the wheel allow

more freedom in the wheel design.

The wheel can be compliant, carrying its own share of shock loads because the

spokes can be crushed against the outer wheel surface without damage. These additional

degrees of design freedom available to Tweel™ designers make up the third key aspect of

the technology. Tweels™ can be more easily designed to supplement or replace suspensions

in most applications than can pneumatic tyres and are far more tolerant of suspension

bottoming shock loads.

3.6 Components of Tweel Tyre

When mounted on a vehicle the TWEEL is a single unit consists of four pieces they

are The hub, Polyurathene spokes, Shear band, Tread band



Fig 3.13: Components Of Tweel Tyre

3.6.1 The Hub

The hub is generally made up of steel. Steel is made by reduction of iron, As seen in

the figure the hub is a part of the tweel and perform as a single unit. In a conventional tyre

the hub is a different part of steel made and fixed separately. Polyurathene spokes of a

Tweel tyre are molded directly to the steel hub with a bond that is not easily broken, Both

wheel and tweel use a steel hub weighing roughly 4 kg.

3.6.2 Polyurethane Spokes

Polyurathene Spokes is one of the most important part of the Tweel because it replaces the

air in a conventional tyre thereby avoiding the maintenance due to puncture, reduce the

downtime and provide a cushioned ride for the customers .The construction of the spokes in

the tweel is as follows.

3.6.3 Shear band

A solid inner hub mounts to the axle that’s 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 (the part that comes in contact with the road). The tension of the shear

band on the spokes and the strength of the spokes themselves replace the air pressure of a

traditional tyre. When the Tweel is put to the road, the spokes absorb road impacts the same

way air pressure does in pneumatic tyres.



3.6.4 Tread

The tread is constructed by a similar method as the tyre tread manufacturing process.

The tread on a Tweel tyre is exactly the same as a pneumatic tyre and is extruded in the

same way, and it is mated to layers of belts in the same manner as conventional tyres.

The process of rolling plies onto a drum to achieve the correct diameter currently is

performed manually, but the same basic process that is performed on tyres will be

mimicked when the Tweel production is fully automated. In this fairly simple process,

rectangular sheets of rubber and steel cord are rolled onto a steel drum, and the excess

material from each sheet is removed. Once the desired base thickness is achieved in this

manner, the extruded tread is rolled onto the top, and the entire assembly is vulcanized.

Fig 3.14: MICHELIN X TWEEL All terrain Tyre specification

3.7 Material Composition

The material composition of a conventional tyre and a tweel is recorded in the table.

From the following data it’s pretty much clear that the total weight of the conventional tyre

is maximum to be 14 kg but in case of Tweel its slightly more and reach up to 15.75 kg.



Table 3.2: Pneumatic Tyre Material Composition

Carcass Tread Total tire Hub

Raw Materials Wt % Wt % Wt % Wt%

Synthetic Rubber 15.78 41.72 24.17 0

Natural Rubber 24.56 3.53 18.21 0

Carbon Black 23.40 9.54 19.00 0

Silica 0.80 28.07 9.65 0

Sulpher 1.60 0.80 1.28 0

Zno 1.83 0.91 1.58 0

Oil 4.02 10.64 6.12 0

Stearic Acid 0.87 1.47 0.96 0

Recycled Rubber 0.60 0 0.50 0

Coated wires 17.2 0 11.4 0

Textile 7.0 0 4.7 0

Steel 0 0 0 100

Totals % 100.0 100.0 100 100

Weight (kg) 7.25 2.75 10.0 4.0



Table 3.3: Tweel Tyre Material Composition

Carcass Tread Spokes Hub Total

Raw Materials Wt % Wt % Wt % Wt% Wt%

Synthetic Rubber 0 41 0 0 1.15

Natural Rubber 0 4 0 0 0.10

Carbon Black 0 10 0 0 0.26

Silica 0 28 0 0 0.77

Sulpher 0 1 0 0 0.02

Zno 0 1 0 0 0.03

Oil 0 11 0 0 0.29

Stearic Acid 0 1 0 0 0.04

Recycled Rubber 0 0 0 0 0

Coated wires 10 0 0 0 0.62

Textile

Polyurathene

0

90

0

0

0

100

0

0

0

8.44

Steel 0 0 0 100 4.00

Totals % 100.0 100.0 100 100

Weight (kg) 6.35 2.75 2.65 4.0 15.75



CHAPTER 4

DISCUSSION SYNONYMS

4.1 Applications of Michelin Tweel tyre

1. They are used on some small vehicles such as riding lawn mowers and motorized

golf carts and wheel chairs .

Fig 4.1: I-BOT Wheel Chair

2. They are also used on heavy equipment such as Earthmovers, which are required to

operate on sites such as building demolition.

Fig 4.2: Michelin X Tweel SSL in Earth Movers



3. Military Usage Tweel deflects mine blasts away from the vehicle better than

standard tyres and that the Tweel remains mobile even with some of the spokes

damaged or missing.

Fig 4.3: Michelin Tweel Tyre in US Army Vehicle

4. The airless tyres are also used in All- terrain vehicle (ATV) made by polaris . These

tyres can suffer a shot from a .50-caliber rifle and still travel 350 miles, and also

drive 1,000 miles after running over a railroad spike. It will start at $14,999.

Fig 4.4: All-Terrain Vehicle (ATV) Made By Polaris

5. Six legged robotic lunar developed by NASA used on the moon which is able to roll

and walk over wide range of terrains uses the Tweel as shown in the figure. This

robot is mainly used for climbing hills and terrains.



Fig 4.5: NASA Lunar Rover

4.2 Advantages of Michelin Tweel Tyre

1. Eliminates air leaks or tyre blow outs.

2. With no air pressure you are left with consistent economy and handling.

3. Its flexibility provides an increase in surface area of contact.

4. No maintenance needed.

5. To lengthen tread life.

6. Facilitate recycling.

7. Makes Vehicle more Efficient have high lateral strength for better handling

without loss in comfort.

8. Vehicle remains under control even in emergency brake.

9. Remains mobile even with some of the spokes damaged or missing.

10. Durability & Long Life.

11. Can take gunfire or explosion.



12. Less environmental impact.

13 The injection-moulded polyurathene spokes are flexible; this allows them to

effectively absorb impacts by shortening when hitting a bump.

4.3 Disadvantages of Michelin Tweel Tyre

1. Lack of adjustability

One of the biggest disadvantages of the Tweel is that once it has been manufactured,

it cannot be adjusted. In this case if the car needed a different kind of setting, a whole new

set of Tweels will be required. On the plus side Tweels are made with five times the lateral

stiffness compared to pneumatic tyres, enabling very responsive handling.

2. Not as economic as pneumatic tyres

Michelin are currently working on enabling the Tweels to be as fuel efficient as

pneumatic tyres. Currently they are within 5% of the rolling resistance and mass levels.

3. Vibration

This could be one of the Tweels biggest downsides. Vibrations become considerate

once a vehicle is driving above 50 mph, while causing a lot of noise. Also disturbing is the

amount of heat the Tweels generate. Long distance journey with Tweels would be very

unpleasant unless these areas are improved upon.

4. Different Manufacturing process

Another problem is that creating airless tyres requires a totally different

manufacturing process. At this point of time, the tyre industry revolves around the

manufacture of traditional pneumatic tyres. To modify factories and service equipment

would be a major change, and the facilities just don’t exist yet.

4.4 Safety and Environmental Concerns

4.4.1 Safety

As stated before, the main danger of pneumatic tyres is the chance of a flat or blow

out that usually occurs at highway speeds. A blowout is when a tyre basically pops and

deflates rapidly. This causes the driver to lose control of the car and risk the possibility of

hitting another vehicle. With airless tyres, this is no longer an issue.



There is no chance for a blowout, and the driver does not have to be concerned

about changing a flat (also eliminates the need for a spare tyre).The assurance of never

having a flat tyre is also beneficial in areas such as construction, where there can be sharp

debris, and in the military. It is especially useful in the military because the tyres of

Humvees are often targeted when under attack, as they are the weakest part of the vehicle. If

the tyres are blown, the vehicle cannot go anywhere. Airless tyres in this sense can save the

lives of troops riding in Humvees because the tyres can take more abuse.

Better handling is also a benefit when it comes to safety. Although it does not vary

by much, it is important to have that extra stability in the tyre to make the car go exactly in

the direction in which it is steered. This is especially helpful in swerving to avoid an

obstacle such as an animal or another car. So for this reason, improved handling is not just

for a better driving experience.

4.4.2 Environmental concerns

Non-pneumatic tyres are also expected to have a positive environmental impact. As

of now, tyre companies must address the growing mountain of bald tyres defiling the

landscape and find a way to recycle or find something that lasts longer and can be recycled.

In the case of airless tyres, it can be the latter. SciTech’s airless tyre is said to be able to

outlast the car. This has enormous environmental implications because with so many cars

on the road, there are many old tyres that have to be disposed of. Because airless tyres

mostly use composite materials, there is only a small amount of rubber that actually goes

into it. Also, since the tread life of most models is longer than that of pneumatic tyres, the

rubber does not have to be replaced very often. This means that there will be less of it to

dispose of later.



CHAPTER-5

CONCLUSION

In concluding the goal and scope of this analysis it was found that Michelin's design

goal of a very low rolling resistance Tweel tyre could result in at least equivalent if not

more environmentally friendly performance than the most fuel efficient tyre on the market

today when the overall life cycles of both are considered due to its fuel savings. Both the

EcoIndicator99 and EDIP assessment methods agree that producing and disposing of a non-

pneumatic Tweel tyre contributes a slightly higher environmental load than the baseline

tyre, but the hypothetical Tweel tyre benefits from the10% fuel savings when it is used on a

vehicle. Due to the much higher contribution from the use phase (5 times higher impact

score, 10 times more carbon dioxide emissions, and 100 times more carbon monoxide), this

fuel saving would outweigh the environmental drawbacks of producing a large amount of

polyurethane and the additives needed to mold it and adhere it to the hub and the rubber

tread resulting in an overall environmental improvement if one replaces conventional tyres

with Tweel tyres. With the current knowledge available, the best estimate for the life cycle

comparison would be a 2 to 6% relative environmental savings with a 5.5 kg/T Tweel tyre

as compared to a conventional fuel efficient tyre with a rolling resistance of 6 kg/ton.



REFERENCE

[1] Bert Bras and Austin Cobert Life-Cycle Environmental Impact of Michelin

TweelTyre for Passenger Vehicles SAE INTERNATIONAL 2011-01-0093

Published 04/12/2011

[2] Anuj Suhag, Rahul Dayal ,International Journal of Scientific and Research

Publications, Volume 3, Issue 11, November 2013 1 ISSN 2250-3153

[3] Austin Cobert Environmental Comparison Of Michelin Tweel™ And Pneumatic

Tyre Using Life Cycle Analysis Georgia Institute of Technology December 2009

[4] Rhyne T. B., and Cron S. M., 2006, “Development of a Non-Pneumatic Wheel,” Tyre

Science and Technology, 34(3), pp. 150–169.

[5] Asnani, V., Delap, D., and Creager, C. 2009. The development of wheels forthe

Lunar Roving Vehicle. Journal of Terramechanics, Vol. 46, No. xx, pp. 89_103. doi:

10.1016/jjterra.2009.02.005.

michelin tweel technology report

Engineering

production of airless

development of airless

nonpneumatic tyres

tweel airless tyre

type of tyre

historythe pneumatic

tyre companies

place of traditional