The Tweel tire is an airless tire design concept developed by the French tire company Michelien. Its significant advantage over pneumatic tires is that the Tweel does not use a bladder full of compressed air , and therefore it cannot burst, leak pressure, or become flat. Instead, the Tweel assembly\'s inner hub connects to flexible Polyurethane spokes which are used to support an outer rim and these engineered compliant components assume the shock-absorbing role provided by the compressed air in a traditional tire.
I choose Tweel tire as my topic, because I am interested in automobiles and wheels are one of the most important part of vehicle. And the fuel efficiency of vehicle is mostly depended on its wheel after the engine system. So that we can control the fuel efficiency up to certain limit using the most suitable tires. And also we can save more money.
Tweel tires are one of the latest inventions in the mechanical engineering. It has some particular features that make them unique from the normal tires (pneumatic tires) .
The name is a combination of the words tire and wheel because the Tweel doesn’t use a traditional wheel hub assembly. 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 tire (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 tire. The tread is then attached to the shear band. The Tweel looks sort of like a very large, futuristic bicycle wheel. When the Tweel is put to the road, the spokes absorb road impacts the same way air pressure does in pneumatic tires. The tread and shear bands deform temporarily as the spokes bend, then quickly spring back into shape. Tweels 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 Tweel is also adjustable. However, you can’t
adjust a Tweel once it has been manufactured. You’ll have to select a different Tweel. Tweels made with 5 times as much lateral stiffness as a pneumatic tire, resulting in very responsive handling.' 'T he Tweel tire is within five percent of the rolling resistance and mass levels of current pneumatic tires. That translates to mean within one percent of the fuel economy of the tires on your own car. And the high rolling resistance can provide fast and smooth braking to the vehicle.
The mechanism of fast breaking is like this, when you apply brake the Tweel’s shear band and the flexible polyurethane spokes temporarily deforms in to a plain parallel shape normal to the road. So that it can provide more friction to the surface and enables fast breaking.' 'Other economic benefits of Tweel tires are very low maintenance, airless, durable, and it has very high loading capacity while compared to the pneumatic tires.' 'The material used for the manufacturing of Tweel tires is not so different from the pneumatic tires.
The spokes are made up of polyurethane. Polyurethane is chosen to make the spokes because it has a property of fastest shape recovery flexibility and also good tensile strength. So that it can easily take heavy loads.' '80-90% 0f shape recovery of Polyurethane is obtained at 30-45 wt % of hard segment content .
The solid housing of the Tweel tires are made up of Reinforced Carbon Fibre. The reason behind choosing Reinforced Carbon Fibre is because of its high strength-to-weight ratio.' 'But the Shear band of the Tweel tires is made up of Rubber and Carbon black, the same material used for the manufacture of Pneumatic tires.
While considering the Pneumatic tires it is made of an airtight inner core filled with pressurized air. A tread, usually reinforced with steel belting or other materials, covers this inner core and provides the contact area with the road. The pressure of the air inside the tire is greater than atmospheric air pressure, so the tire remains inflated even with the weight of a vehicle resting on it. The tire’s air pressure provides resistance against forces that try to deform the tire, but it gives to a certain degree -a cushioning effect as the tire hits bumps in the road. If you’ve ever taken a ride in an old-fashioned carriage with wooden wheels, you know what a difference a pneumatic tire makes.
Pneumatic tires do have drawbacks, especially in high-performance or highly dangerous applications. The main problem, of course, is that a puncture of the tire results in total failure. A blowout at high speeds can lead to a dangerous car accident. Army planners are concerned with tires getting blown out by gunfire or explosion shrapnel. A vehicle crew’s worst nightmare is getting trapped in a fire zone because their tires are all flat. Obviously, an airless tire can\'t be disabled by a single puncture.
Carbon nanotube is one of the most suitable materials that will replace Reinforced Carbon Fibre in future for manufacturing the solid hub of the Tweel tire in future.
Because it is 20 times stronger than Reinforced Carbon Fibre and also lighter. And it is always better to make the solid hub of Tweel tires stronger and rigid as much possible. Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics and other fields of materials science and technology. Owing to the material\'s exceptional strength and stiffness, nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material.
In addition, owing to their extraordinary thermal conductivity, mechanical, and electrical properties, carbon nanotubes find applications as additives to various structural materials. For instance, nanotubes form a tiny portion of the material(s) in some (primarily carbon fibre baseball bats, golf clubs, car parts or Damascus steel.
Mechanical Properties of Carbon nanotubes
Carbon nanotubes are highly elastic. The Young’s Modulus is a measure of elasticity . the Young’s Modulus of Carbon nanotubes is about 1800 Gpa wher as it is about 210 Gpa for steel.
Carbon nanotubes exhibit large strength in tension. They are about 20-times stronger than steel. The yield stress is a measure of strength. Carbon nanotubes can withstand larger strain than steel.' 'They also can be bent without breaking.
Nanotubes are members of the fullerene structural family. Their name is derived from their long, hollow structure with the walls formed by one-atom-thick sheets of carbon, called grapheme. These sheets are rolled at specific and discrete
(\"chiral”) angles and the combination of the rolling angle and radius decides the nanotube properties; for example, whether the individual nanotube shell is a metal or semiconductor. Nanotubes are categorized as single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). Individual nanotubes naturally align themselves into \"ropes\" held together by van der Waals forces, more specifically, pi-stacking.
Applied quantum chemistry, specifically, orbital hybridization best describes chemical bonding in nanotubes. The chemical bonding of nanotubes is composed entirely of sp2 bonds, similar to those of graphite. These bonds, which are stronger than the sp3 bonds found in alkanes and diamond, provide nanotubes with their unique strength.
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