Airless Tyre

Anyone who has ever driven a car run on a flat tire, but what if your tires could never go flat? In recent years a number of companies and inventors have been working on creating airless tires that would be impossible to puncture. Non-pneumatic tires (NPT), or Airless tires, are tires 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 tire puncture is likely. Tires composed of closed-cell polyurethane foam are also made for bicycles and wheelchairs. The main advantage of airless tires is that they cannot go flat, but they are far less common than air-filled tires.

The most well known design in this field is the Michelin Tweel, a combination wheel and tire. The design was one of the first to emerge, bringing the idea of non-pneumatic tires to the public's attention. But Michelin has been slow to roll out the technology beyond the test phase.in light of this; a company called resilient technologies has also been working on an airless tire. The company recently announced that prototypes of their honeycomb-like tires will ship in 2011 for use in the US military. This will no doubt help the airless tire field, as will other startup companies working on the task like Britek.

AIRLESS TIRES
Non-pneumatic tires (NPT), or Airless tires, are tires that are not supported by air pressure. Airless tires generally have higher rolling friction and provide much less suspension than similarly shaped and sized pneumatic tires. Other problems for airless tires include dissipating the heat buildup that occurs when they are driven. Airless tires are often filled with compressed polymers (plastic), rather than air.
 

The Tweel (a portmanteau of tire and wheel) is an experimental tire design developed by the French tire company Michelin. The tire uses no air, and therefore cannot burst or become flat. Michelin is currently developing an integrated tire and wheel combination, the "Tweel” that operates entirely without air. Automotive engineering group of mechanical engineering department at Clemson University is developing a low energy loss airless tire with Michelin through the NIST ATP project. The Tweel would be the most radical change in the tire industry since the radial tire was invented nearly 60 years ago. Other changes include no more deadly blowouts. And in time, no more used-tire mountains or the need for as many shredding and recycling stations.

The Tweel is durable. Forget a nail, an armored vehicle with Tweel can go over an exploding landmine and keep moving. But for the car, the Tweel is still just a concept. On a test drive on tweels, a sedan handles well enough. The biggest problem is noise, once the speed hits about 50 mph. The noise gets worse the faster you go.

WORKING

 

 

When the Tweel is put to the road, the spokes absorb road impacts the same way air pressure does in pneumatic tires. 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 tire's pneumatic properties. 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. For testing, Michelin equipped an Audi A4 with Tweels made with five times as much lateral stiffness as a pneumatic tire, resulting in very responsive handling.
 

Michelin reports that the Tweel prototype 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. Since the Tweel is very early in its development, Michelin could be expected to improve those numbers.

THE FUTURE OF AIRLESS TIRES
The first large-scale applications may be in the military where a flat-proof tire would be advantageous. Military testing has indicated that the Tweel deflects mine blasts away from the vehicle better than standard tires 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.[3] This has resulted in the Lunar Rover Initiative AB Scarab wheels. The Tweel does have several flaws (aside from the name). The worst is vibration. Above 50 mph, the Tweel vibrates considerably. That in it might not be a problem, but it causes two other things: noise and heat. A fast moving Tweel is unpleasantly loud. Long-distance driving at high speeds generates more heat.
 

Another problem involves the tire industry. Making Tweel is quite a different process than making a pneumatic tire. The sheer scale of the changes that would need to be made to numerous factories, not to mention tire balancing and mounting equipment in thousands of auto repair shops, presents a significant (though not insurmountable) obstacle to the broad adoption of airless tires.

 

CAD-CAM Technology

(CIM) computer integrated manufacturing is a recent technology being tried in advance computer and it comprises a combination of software and hardware for product design, product planning, product control, product equipment and product process.

In this CIM technology CAD/CAM play an effective role. CAD/CAM system is ideally suited for designing and manufacturing mechanical components of free from complex 2-dimensional and 3-dimensional shapes.

CAD/CAM technology plays an important role in functioning of robots. In CAD/CAM system the robot work data is prepared from CAD data from the first designing process. This system is a kind of off-line teaching system. Since an actual robot is not used to input data for path creation, the coordinate system data must be corrected and simulations necessary before loading a created data.

 

 

 

Robots are inevitable for application in the field where the work is extremely difficult or impossible for human being to perform.

Some of such examples are: Work requiring speed, precision or function exceeding human ability, or that which requires entering a sterile environment, vacuum, outer space, or around a nuclear reactor, places that a man cannot enter easily or at all.

Computer Aided Design and Computer Aided Manufacture is the way things are made these days. Without this technology we wouldn’t have the range and quality of products available or, at least, they wouldn’t be available at a price most of us can afford.

Hand-building and manual techniques still very much have their place and Design Education needs to treasure and foster these skills so that future generations will have the ‘hands-on’ skills to understand the man-made world and provide the next generation of engineers, designers and technicians.

All of these professionals will be using CAD/CAM techniques or CAD/CAM products in their work, alongside practical hands-on skill. Design and Technology education has to reflect modern practice so it is crucial that students have the opportunity to use real CAD/CAM tools in their designing and Making.

USES

Computer-aided design is one of the many tools used by engineers and designers and is used in many ways depending on the profession of the user and the type of software in question.

CAD is one part of the whole Digital Product Development (DPD) act ivity within the Product Lifecycle Management (PLM) processes, and as such is used together with other tools, which are either integrated modules or stand-alone products, such as:

• Computer-aided engineering (CAE) and Finite element analysis (FEA)
• Computer-aided manufacturing (CAM) including instructions to Computer Numerical
• Control (CNC) machines
• Photo realistic rendering
• Document management and revision control using Product Data Management (PDM).

CAD is also used for the accurate creation of photo simulations that are often required in the preparation of Environmental Impact Reports, in which computer-aided designs of intended buildings are superimposed into photographs of existing environments to represent what that locale will be like were the proposed facilities allowed to be built. Potential blockage of view corridors and shadow studies are also frequently analyzed through the use of CAD.

CAD has been proven to be useful to engineers as well. Using four properties which are history, features, parameterization, and high level constraints. The construction history can be used to look back into the model's personal features and work on the single area rather than the whole model. Parameters and constraints can be used to determine the size, shape, and other properties of the different modeling elements.

The features in the CAD system can be used for the variety of tools for measurement such as tensile strength, yield strength, electrical or electro-magnetic properties. Also its stress, strain, timing or how the element gets affected in certain temperatures, etc.

Solar Based Refrigerator

As the trend changes the consumption of electricity also increases, to reduce this we can use renewable sources such as solar energy which is world’s most rich, stable and clean source of energy having large potential and also we see that in present refrigerator system which produce cooling effect by refrigerants like CFC’s, HCFC’s, Freon, ammonia which gives a maximum efficiency but the main disadvantage is that it causes the global warming ozone depletion. Now this problem can be overcome by Peltier effect and thereby protecting the environment. In this paper to introduce the portable refrigerator using peltier module with solar energy as supply which overcomes the disadvantages of existing refrigerator with increase in population and environment degradation there is an alarming rate for thermoelectric couple system have come to rescue as these are environmental friendly, affordable and compact in size.

 

Solar Panel
Solar panels are used to convert solar radiation into electrical energy. Photovoltaic (PV) modules are used.

Charge Controller
A charge controller or charge regulator is basically a voltage and/or current regulator to keep batteries from overcharging. It regulates the voltage and current coming from the solar panel going to the battery.

Battery
Solar powered refrigeration equipment, or so called off grid photo voltaic systems, run on direct-current electricity provided by solar energy. Batteries are used to store energy. In off grid PV systems batteries are essential to providing power during periods of low or no sunlight.

Advantages

High reliability.
Precise temperature control.
It occupies less space.
Eco friendly.
Noise less operation.
No Freon’s or other liquid or gaseous refrigerants required.
Low cost and high effectiveness.
Design is very simple.

Disadvantages

COP is less as compared to conventional refrigeration system.
In rainy season it cannot be possible to charge battery from solar.
It also depends on climatic conditions.

Applications

To keep medicines in rural area
Hospitals.
Small scale industries

Conclusion

Solar power nowadays is playing a major role in meeting the energy requirements of our country.It is being developed at a very fast rate and its applications in many areas are being explored. The fridge is intended at exploring the same and provides an efficient and economical solution to the areas where there is no electricity and cooling is required. This project main objective was to develop a mini compressor less solar fridge .By this we decided to conclude our solar based refrigerator project.

 

Gear Trains: Types & Gear Ratio

A gear train is a mechanical system formed by mounting gearson a frame so that the teeth of the gears engage. Gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission of rotation from one gear to the next.

Types of gear train are given below:

• Simple gear train
• Compound gear train
• Reverted gear train
• Epicyclic gear train

Simple Gear Train:
 

If there is only one gear mounted on each shaft, the gear train is known as simple gear train. that is, each shaft has only one gear.

Usually when two gears mate, they rotate opposite to each other. When we use three gears each mounted on separate shaft, the direction of rotation of the last gear will be same as that of the direction of rotation of first gear. Suppose the number of gears are increased to four the direction of rotation of first and last gear will be opposite to each other. A typical simple gear train is shown in the figure 1.
 

So from above we can conclude that in a simple gear train, if the no of gears is odd then the direction of rotation of first and last gear will be the same, it it is even, direction of rotation will be opposite. 

The speed ratio is given by, (N1/N2) = -(T2/T1), where, N1 is the speed of the driver, N2 is the speed of driven gear, T1 is the no of teeth on driver gear and T2 is the no of teeth on driven gear.

Compound gear train:

If there is more than one gear on a shaft, the gear train is said to be compound gear train. Here speed of rotation of the gears mounted on a shaft will the same and also the direction. By using this arrangement, the power will be transmitted to the shaft which is placed not in the row. The system is compact here. Also we can reduce the size of the gears using this arrangement. This is illustrated in the Figure 2.

 

Reverted gear train:

 

If the axes of driver shaft and driven shaft is co-axial, then the gear train is termed as reverted gear train. This is kind of compound gear train. This is illustrated in the figure 3. So reverted gear train may be called as a compund gear train but all compound gear train can not be a reverted gear train. This reverted technology is very much useful when the power is to be transmitted within the less space. 

 

Epicyclic gear train:

 

This is important gear train compared the said above. In this case, One of the gear is rotating over and around another gear. Epi means over, Cyclic means around. There is an arm connecting such two gears. This gear train finds great application in various field. This is illustrated in the figure 4.

Modes of Heat Transfer – Conduction, Convection & Radiation

Heat is a form of energy which transfers between bodies which are kept under thermal interactions. When a temperature difference occurs between two bodies or a body with its surroundings, heat transfer occurs. In this article, we are going to deal with the different modes of heat transfer. Heat transfer occurs basically in three modes:

1. Conduction
2. Convection and
3. Radiation

CONDUCTION:

 
Conduction is the mode of heat transfer occurs from one part of a substance to another part of within the substance itself or with another substance which is placed in physical contact. In conduction, there is no noticeable movement of molecules. You might be think that then how this heat transfer occurs? The heat transfer occurs here by the two mechanisms happen.

By the transfer of free electrons. (Good conductors like metals have a plenty of free electrons to make conductive heat transfer. The atoms and molecules having energy will pass those energy they have with their adjacent atoms or molecules by means of lattice vibrations.

Now we can think how this conduction occurs in gases and liquids. In the cases of gases, the molecules having energy in the form of kinetic energy and during their random movements, they exchange their momentum and energy by colliding with others. By doing so, the first molecule loses the energy while the second one gains it. This is how energy is transferred in the case of gases.

In the case of liquids also, the working is similar to that of gases. Here, the only difference is that, the molecules in liquids are more closely packed and hence inter molecular forces came into action in the case of liquids.

Fourier Law of Conduction:

Q = -kAdT/dx
Where:  Q is the heat flow rate by conduction
              K is the thermal conductivity of the material
              A is the cross sectional area normal to direction of heat flow and
              dT/dx is the temperature gradient of the section.

CONVECTION:

Conductive heat transfer occurs within a fluid itself and it is carried out by transfer of one fraction of the fluid to the remaining portion. Hence unlike conduction, transfer of molecules occurs during convection. Since movement of particles constitutes convection, it is the macro form of heat transfer. Also convection is only [possible in fluids where the particles can moved easily and the rate of convective heat transfer depends on the rate of flow to a great extend. Convection can be of two types:

Natural convection: In this type of convection, the movement of particles which constitutes convection occurs by the variation in densities of the fluids. As we already know, as temperature increases, the density decreases and this variation in density will force the fluid to move through the volume. This cause convection to occur.

Forced Convection: The difference between natural convection and forced convection is that in forced convection, a work is done to make movement in the fluid. This is done using a pump or blower.

Newton’s Low Of Cooling:

Q = hA(Ts-T∞)
Where:  Ts is the surface temperature
              T∞ is the fluid temperature
              h is the heat transfer coefficient

RADIATION:

Radiation is the third mode of heat transfer. This mode of heat transfer didn’t require any medium to occur. Every matter having a temperature above absolute zero will emit energy in the form of electromagnetic waves and called radiation. It is the same way the energy of the Sun reach us. The key features about radiation are it do not require any medium and also laws of reflection is applicable for radiation.

Stefan- Boltzman Law:

Q = A∑Ts⁴
Where:  Ts is the absolute temperature of surface
              ∑ is the proportionality constant.