Monday, 15 January 2018

Young Modulus of Elasticity

Hello friends,

Today we are going to learn about elastic constant or more appropriate young modulus of elasticity. In our previous articles we have learnt about strain, stress and their types and relationship. In stress strain curve article, we have learnt about proportional limit and I have discussed about a constant there. This constant is known as young modulus of elasticity.

Don’t worry if you have missed that article. In this article we will to learn it from basic and also describe its value for some basic materials.

Let’s start the article.

Young modulus of elasticity:


Before learn about young modulus you should know about strain and strain. I am giving a brief introduction about them. If you want to learn them completely, kindly follow the link given below their definitions.

Stress:
Resistant Force applied per unit area of any cross section is known as stress. For ideal conditions, the applied force is equal to the resisting force so the ratio of the applied force to cross section area of any object is known as stress. It is the resistant force which resists the deformation in any body. For more detail click Stress and its Types

Strain:
The ratio of change in dimension to original dimension is known as stain. This dimension is taken only in one direction. In common words the change in length to original length under loading condition is known as strain. For more detail click Strain and its Types

Young Modulus of Elasticity:
For understanding this elastic constant, first read the diagram given below.

Young Modulus of Elasticity

It is stain strain curve for a ductile material. This diagram is obtain by applying an increasing load on a specified dimension specimen and observe its behavior and change in dimension. The region AB is known as proportional limit and AC is known as elastic limit. Under the elastic limit the stress is directly proportional to the strain. This law is known as Hooke’s law. The proportionality constant of Hook’s law is known as young modulus of elasticity.

According to the definition,

The ratio of direct stress to longitudinal stain under elastic limit is known as young modulus of elasticity. Its unit is same as that of stress which is newton per meter square (N/m2). This constant is independent on any constrain like dimension of object, applied load etc. and unique for every material. It is only depended upon material type and varied for material to material.

For practical observation let us now consider an object of length L having area of cross-section equal to A. If the force F acting on the wire, and the change in length due to loading is ∆L

Young Modulus of Elasticity

In Stress Strain terms, Young Modulus is given by-

Young Modulus of Elasticity

Signification or practical observation by Young modulus:

We have discussed that every unique material have unique value of young modulus. If a material has high value of this constant, it means that this material specimen or object required high value of force to little change in its original dimension. It is less elastic or that material got a little variation in its dimension for a high value of stress. It can say that the high value of modulus shows high rigidity of the material. The value of this modulus for steal is 210 GN/m2.

If a material has low value of this constant means the material is high elastic or it shows a very high deformation for small value of loading. The value of young modulus of aluminum is 70 GN/m2.

Table of Modulus of Elasticity for some common material:

S.No.
NAME OF MATERIAL
VALUE OF YOUNG MODULUS
( GN/m2 )
1.
Plastics
1 - 3
2.
Aluminum
70
3.
Brass
100 – 125
4.
Carbon Fiber
150
5.
Copper
120
6.
Glass
50 – 90
7.
Diamond
1200
8.
Gold
75
9.
Gray Cast Iron
120 – 130
10.
Iron
210
11.
Stainless Steel
180 – 190
12.
Tungsten Carbide
450 – 650
13.
Nylon
0  5

This is complete information about young modulus of elasticity at beginner level. If you have any query regarding this article, ask by commenting. If you like this article, don’t forget to share it on social network with your friends. Subscribe our website for more informative articles. Thanks for reading it.
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Friday, 12 January 2018

What will happen If we use Petrol in Diesel Engine or Vise Versa?

Are you planning to turn your garage into a laboratory, by adding diesel into patrol engine or patrol in a diesel engine? Well before you experiment with your vehicle's engine, let me give a little clarity of conditions, which will surely arrive.

There are less chances of your engine to start and there or it will start but won't last long, and finally, the engine will get a huge damage. Diesel engines are only suitable for diesel, whereas petrol engine works properly with petrol only.

Before discussing about conditions occur let take a quick look at some basic that will helps you to understand what will happen if we put petrol in diesel engine and vice versa.

Diesel engine:

There are lot of differences in the diesel and the petrol engines. Diesel engines basically works on diesel cycle. In a diesel engine, only air is induced in the combustion chamber via the suction pipe. The air in the combustion chamber is compressed by the piston. The compression ratio of the diesel engine is much higher than the petrol engine and the temperature if compressed air is increased at the end of compression due to the compression. Also, there is no carburation is present in the diesel. At the end of the compression stroke and at the beginning of the power stroke, a fuel injector atomizes the diesel and sprays it in the combustion chamber where compress air is present. When this spread diesel comes into contact with hot and compressed air, burning process of fuel begins and therefore the power stroke is obtained.



Petrol engine:

On the other hand, petrol engine works on the Otto cycle. In the petrol engine, carburetor prepares a homogeneous mixture of petrol and air, and this mixture is induced in the combustion chamber. Later in the combustion chamber, the piston compresses this mixture. At the end of compression stroke, the spark plug ignites this mixture and power stroke is obtained.The reason behind using the spark plug in the petrol engine is the auto igniting temperature of patrol and also its compression ratio. The auto igniting temperature of petrol is very high and on the other hand compression ratio of petrol engine is very low, this makes use of spark plug in igniting the fuel and air mixture.


For more information about these two engine read: Diesel Engine and Petrol Engine


Now, that we know, what these engines are and how they work. Now it will be easy for us to understand the outcome of using petrol in the diesel engine and vice versa.

If we use diesel in the petrol engine:


Well if you are going to use diesel in the petrol engine, then the suggestion is, not to do it. Diesel engines work on different principals than the petrol engines. It will surely not run and the reason behind it is the volatility of the diesel is lesser than the petrol. The carburetor cannot produce a fine vaporized mixture of air and diesel due to this low volatility. When this improper mixture reaches the combustion chamber, the spark is produced at the end of compression stroke but this spark won't be able to produce enough heat to burn the remaining mixture of air and diesel and this will lead the engine misfunctioning and engine will not start.

If we use petrol in the diesel engine:


There will be some differences in the results if we use petrol in the diesel engines. Well, in this situation there are chances that the engine may start for a while but this will lead excessive damage to the engine. The fire point of diesel is greater than patrol and compression ratio of the diesel engine is also greater than petrol. At the end of the compression stroke the mixture of petrol and air is released into the combustion chamber, but unlike diesel, it burns immediately causing rapid burning of patrol. Due to this rapid burning detonation and knocking takes place. Piston starts to move to BDC before reaching the TDC during the compression stroke, this will reverse the engine and causes vibrations and noise in the engine. This will damage the engine and may turn it into a dead wood.

Conclusion


After examining both the situations, ie if we will add diesel to petrol engine or patrol to the diesel engine, we can say it is not a good idea experimenting with your vehicles engine life. In both the cases you will lose your engine or get it damaged badly and it not recommended either by the manufacturers or any motor specialists.  both the engines are designed to run only with a specific type of fuel.

Well, now I guess your plans of experimenting with you vehicles engines are changed, I suggest the use of appropriate fuel type for the long and healthy life of your white mustang's engine life.

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Monday, 8 January 2018

Difference Between Petrol and Diesel

Petrol and Diesel are the liquid mixtures used as a fuel. Both are derived from the crude oil or petroleum products. Basically, these are hydrocarbons presents in the crude oil but having difference in the properties. The method used to derive petrol as well as diesel is same and called as ‘Fractional distillation’. These hydrocarbons are extracted from the crude oil based on the difference in their boiling points.



Petrol:

Petrol is a mixture of alkanes and Cycloalkanes generally derived by distillation of the crude oil. It has the length of the carbon atom chain ranges from 5 to 12. It is also known as gasoline and usually used in the internal combustion engine to give more speed to the engine. It is lighter and highly volatile liquid tends to makes less pollution.

Diesel:

Diesel is made up of alkanes and generally the carbon chain of it contains about 12 atoms. It is heavy and less volatile liquid having more viscosity. It is most suitable fuel for motor vehicle. It is safe to store as well as transport and usually used in CI engine.

Difference between Petrol and Diesel:


Petrol and diesel can be differentiate into following aspects. 

Difference Between Petrol and Diesel

Chemical Composition:

Petrol is basically a mixture from  7 (n-Heptane) or 8 (2,2,4-trimethylpentane) and Diesel has a mixture which has carbon chain from  8 (n-octane) to 21 (undodecane).

Chemical formula of the Petrol is C8H18 and Diesel has the chemical formula C12H23.

CO2 emission by the Fuel:

Diesel produces more CO2  than petrol. Diesel contains the higher proportion of the carbon atoms hence it produces about 13% more CO2 than petrol.

Energy content:

Diesel is denser fuel as compare to the petrol hence has more energy content than petrol. Petrol has the energy content of about 33.7 MJ/kg and it is approximately 36.7 MJ/kg in case of Diesel. Finally it can be said that diesel has around 16% more energy content than petrol.

Viscosity:

Petrol has less viscosity as compare to the Diesel. It can be increased at the lower temperature in case of Diesel but there will be no any change observed in case of petrol.

Volatility:

Petrol has types of additives and constituents which are responsible to make it more volatile therefore Volatility of the petrol is greater compared to the diesel.

Boiling ranges:

Boiling point of the petrol is lower than diesel. For the petrol it ranges between 350 degree C to 2000 degree C and it ranges 1800 degree C to 3600 degree C in case of the Diesel.

Fuel economy:

Petrol has lower fuel economy than Diesel and it can be seen better fuel economy for the Diesel.

Power:

Power of the Diesel fuel is higher than petrol. Petrol has the power of 34.6 mega joules per litre and diesel contains about 38.6 mega joules per litre. The petrol engine always runs at the higher RPM and Diesel engine requires more torque to run well.

Flammability:

It is always a dangerous practice to store the greater amount of the fuel which tend to be flammable and hazardous. Petrol is a greatly flammable fuel as compare to the Diesel due to high vapor pressure. Diesel is a less flammable fuel due to low vapor pressure, and it is easier to obtain during the requirements in disaster.

Types of ignition:

The Auto-ignition temperature of the petrol is 2460 degree C, and it requires Spark Plug for the sufficient ignition of the mixture of air and fuel.
Diesel has auto ignition temperature of around the 2100 degree C and Spark plug is not necessary for the ignition of the fuel. It simply works on the method of compression. The mixture of air and fuel get compressed with the help of high pressure which alternative increases the temperature of the mixture and helps it to ignite.

Calorific value:

The net calorific value of the Petrol fuel is about 44.4 MJ/kg and the calorific value of the diesel is around 43.4 MJ/kg

Flash point and fire point:

Flash point referred as the minimum temperature at which fuel gets available for ignition in the evaporated state. Flash point of the petrol is 430 degree C, and it is the 520-950 degree C for Diesel.
Fire point is the temperature at which vapor of the fuel tends to burn for the minimum five second. The fire point of petrol as well as Diesel is higher by 10 degree then flash point.

Octane and cetane rating:

Petrol is indexed by Octane number and generally it is the ability to resist auto ignition when used in the gasoline engine. It is used to measure the octane rating of the Petrol.
All the diesel engine is rated under the Cetane number. It measures how quickly the fuel start to burn inside the compressor. Combustion speed of the Diesel is depends upon the Cetane number

Price:

Diesel is cheaper than Petrol due to its availability compare to petrol.

These are all key differences between petrol and diesel. If you have any query regarding this article, ask by commenting. If you like this article, don't forget to share on social network with your friends. Subscribe our website for more informative articles. Thanks for reading it.
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Saturday, 6 January 2018

Cupola Furnace : Principle,Construction, Working, Advantages, Disadvantages and Application

Cupola Furnace is a melting device used to melt cast iron, Ni-resist iron, and some bronzes and It is used in Foundries. The cupola can be made of any size and the size of the cupola is measured in diameters which range from 1.5 to 13 feet. The shape of the cupola is cylindrical And the equipment is arranged in the vertical fitted with doors which swings down and Out to drop bottom.

The top is open or fitted with a cap to escapes gases or rain entering. The cupola may be fitted with a cap to control emission of gases and to Pull the gases into the device to cool the gases and remove all the Particulate Matter.

The cupola shell is made of steel and has a refractory brick and plastic refractory Patching material lining. The clay and sand mixture is used as a bottom line and the lining is temporary. The coal can be mixed with the clay lining so when it heats up the coal decomposes and the bond becomes friable. This makes opening up of the two holes easy. The bottom of the cupola lining is compressed against the bottom doors. Cooling jackets are also fitted with some of the cupola’s to keep the sides cool and with oxygen injection to make the coke fire burn hotter.

Cupola Furnace:

Principal:

The cupola furnace works on a simple principal that combustion of coke generates carbon dioxide and heat and this causes the iron to melt. The iron drains downward when get melted.

Afterwards, the carbon dioxide is reduced partly, reduced again by consuming energy and coke with carbon monoxide, carbon dioxide and supplied coke is present in the reaction equilibrium so it is possible to show a defined combustion ratio for the utilization of thermal energy for the coke combustion.

Finally, high concentration of carbon monoxide is present in the exhaust gas and it can be extracted from the furnace.

Construction: 

Cupola furnace constructed in the form of a hollow cylindrical vertical steel shell and it is lined from inside with a refractory material. This furnace is generally supported on four cast iron lags mounted on a concrete base.

Image Source

The bottom of the furnace is closed by two cast iron doors hinged to the bed plate of the furnace. A wind box cast iron encircles to the outside of the furnace bottom.This box is connected to the furnace blower pipe known as the blast pipe. Air which supplies the oxygen necessary to burn the fuels forced through the cupola by a blower.The top of the furnace is shielded by a mesh screen and topped with a cone-shaped spark arrester, which permits the free vent of the waste gas and deflects spark and dust back into the furnace.


Working

Basically, the operation of cupola furnace consists of following steps:

After building the cupola make sure it is dried completely before getting it to fire. Any slag around the tuyeres from previous runs needs to be cleaned properly.

Also, A broken part is repaired with the mixture of the silica sand and fire clay. Over the Brunt area, a layer of refractory material is applied To about thickness 6 inches or more is rammed on the bottom sloping toward the tap hole to ensure better flow of molten metal.

A hole opening of about 30 mm diameter and a tap hole of about 25 mm diameter is being provided there.

a fire of wood is ignited. When the wood burns well coke is dumped on the bed well from the top. Make sure that the coke gets burned too. A bed of coke about 40 inches is placed next to the sand.

Firstly The air blast is turned on At a lower blowing rate than as normal for provoking the coke. A measuring rod is also used which indicates the height of the coke bed. For about 3 hours firing is done before the molten metal required.

Now the charge is fed into the cupola. Many factors like charge composition, affect the final structure of the gray cast iron obtained. It composed of 10% steel,50% grey cast iron scrap, and 3% limestone as a flux.

Alternate layers are formed by these constituents. Besides limestone, fluorspar and soda ash are also used as flux material. The main function of flux is to remove the impurities in the iron and protect the iron from oxidation.

after the fully charged furnace, it is allowed to remain as such for about 1 hour. As this process goes in charge slowly gets heated up as the air blast is kept shut this time and because of this, the iron gets soaked up.

At the end of the soaking period, the air blast is opened. The topmost opening is kept closed till the metal melts. The sufficient amount of metal is collected. The contents of the charge move downwards as the melting proceeds.

The rate of charging is equal to the rate of melting. The furnace is kept full throughout the heat.

Closing feeding of charge and air blast is stopped when no more melting is required. The bottom plate swings to open when the prop is removed. The deposited slag is being removed.The cupola runs continuously and The melting period does not exceed 4 hours in most of the time. But can be operated for more than 10 hours.

Advantages:

  • Low cost of construction.
  • Low cost of maintenance.
  • Low cost of operation.
  • Very skilled operators are not required.
  • Simple in construction
  • Simple in operations.
  • Melting composition can be controlled.
  • Small floor area is required.

Disadvantages:

With a long list of advantages, cupola furnace also comes with few of limitations or disadvantages and they are listed below:
  • It is sometimes difficult to maintain the temperature in a cupola furnace.
  • Metal elements are converted to their oxides which are not suitable for casting.

Application:


Cupola furnace is a used widely as a melting unit for cast iron. Some of the characteristic that makes the cupola furnace a primary method used in melting irons in the foundries. Some of them are :

  • Cupola furnace is the only method which is continuous while operations.
  • The melting rate of cupola furnace is high.
  • It is easy to operate.Operating costs in use of cupola furnace is comparability very low to other methods for this purpose.

Although having such great factors, the use of cupola furnace is declining and people are opting for electric induction melting.

This is all about cupola furnace. If you have any query regarding this article, ask by commenting. If you like this article, don't forget to share it with your friends on social networks. Subscribe our website for more informative articles. Thanks for reading it. 
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Tuesday, 26 December 2017

What is Spring? What are Types of Springs?

Today we will learn about types of springs in mechanical used for various purposes. Spring is an elastic machine element that can deflect under the application of load. When the load is removed, it regains its original position. In other words, spring is a mechanical object made up of material having very high yield strength to restore elastic. It is used in various machines to absorb shocks or it also resist to transfer shocks and vibrations on various critical machine members.

Spring materials:

The material used to made springs are called a spring steel. Spring steels are mostly low-alloy manganese, low carbon steel or high carbon steel with very high yield strength. Examples of spring materials are as follows:

1. Oil Tempered Steel
2. Stainless Steel
3. Elgiloy
4. Carbon Value
5. Iconel
7. Monel
6. Titanium
7. Chrome Silicon

Why we need a Mechanical springs:

Springs are a very useful machine element. There are various regions to use spring. Some of them are given below.

  • To absorb shock load
  • To store energy
  • To measure force
  • To motive power
  • To Return motion
  • To control of vibrations
  • To retaining of rings


Types of spring in mechanical:


Based on the shape of the springs, it can be broadly classified into following types:


1. Helical Spring:


It is the most commonly used Mechanical springs.
In this type of spring a coil is wrapped in such a way that it resemble like a thread.
This type of springs is used for carrying Compression, Extension, and Torque forces.


According to the loading condition helical springs are classified into following four types.

  • Open coil springs (or) Compression helical springs
  • Closed coil springs (or) Tension helical springs
  • Torsion spring
  • Spiral spring 

a.) Tension spring:

Tension Springs are also called as Extension Springs.
Tension spring is opposite to compression spring.
Pull force is applied, resulting in extension of the spring.
These type of springs have hook or expanded eyes either one or both ends

Applications:
  • Lever mechanisms
  • Counterbalancing of garage doors
  • Weighing machine,
  • Vise-grip pilers
  • Garage door assemblies

b.) Compression spring:

These springs are open coil helical spring.
A helical coil is pressed or squeezes by load.
It resists compressive or push forces.
It also shows resistance to linear compressive forces.
Sometimes fluid behave as compression springs such as fluid pressure systems.

Application:
  • Motorcycle's suspensions.
  • Pen
  • Lock
  • Couches
  • Lighter

c.) Torsion spring

In this type of spring the load applied to coil is a torque or twisting force.
In other words, Helical springs which can hold and release angular energy.
Or these springs try to hold a system in place.
After twisting, the helical coil applies proportional force to opposite direction.
The torsion springs are used in application which rotates Less than 360 degree.
These springs have either clockwise or antilock wise rotation.

Applications:
  • Mouse trap
  • Rocker switches
  • Clothes pin
  • Automobile starters
  • Door hinges

d.) Spiral Springs

Spiral spring is also known as clock spring or Constant force spring.
A number of times band of steel wrapped around it to form this type of springs.
This type of springs releases a constant amount of force.
This types of springs are used in machines that need to rotate a number of times and the same time has to release same amount of load constantly.
These types of springs are used when more power is required.
Some of these springs are with thicker bond so that they can give fever rotations.
These types of springs are used in heavy duty applications

Applications:
  • Automotive seat recliners
  • Alarm timepiece
  • Watch
  • Window Regulators
  • DC Motors

2. Leaf springs 

Leaf springs are also called as s semi- elliptical spring or Cart spring.
It is one of the oldest forms of springs.
Leaf springs are long and flat slender arc -shaped.
These types of springs are used In Vehicle suspensions.
Location for axel is center of the arc.
And either end of loop is attached to the vehicle.
It spread the load over vehicle chassis.

Advantages
  • Leaf springs are easy to construct.
  • These springs are strong.
  • No need for separate linkage to hold the axle in position, leaf springs work as a linkage.
  • Rear axle location helps in reducing the extra weight.
  • Axle damping is control by leaf springs.
  • It reduces cost by eliminating the need of trailing arm and pan hard rod.
Applications:
  • Automobiles Suspension
  • Used by blacksmiths  (due to its relatively high quality steel.)


3. Belleville spring

A Belleville springs also known as a coned-disc spring, conical spring washer, disc spring, Belleville washer or cupped spring washer.
Belleville washers are mostly coin shape spring with a hole in center.
This disc springs are dynamically or statically loaded to its axis.
This spring required less space for installation but can bear a very large load.
These springs have more advantages compare to other springs.

Applications:
  • Slip Clutch
  • Overload Clutches
  • High Pressure Valve
  • Drill Bit Shock Absorber


4. Volute and conical spring

These springs are conical shape compression springs.
Conical springs are also known as tapered spring.
These springs used to provide stability and reduce solid height.

5. Special purpose spring:

As the name suggest this springs are made for special purpose use. Special purpose springs are made up from different types of material all together such as Air and water.

Other types of springs are:

1. Constant Spring
2. Variable Spring
3. Variable Stiffness Spring
4. Flat Spring
5. Machined Spring
6. Serpentine Spring
7. Cantilever Springs
8. Hairspring or Balance Spring
9. V-Spring
10. Gas Spring
11. Ideal Spring
12. Main Spring
13. Negator Spring
14. Progressive rate coil Springs

This is all about the types of springs. If you have any query regarding this article, ask by commenting. If you like this article, don’t forget to share it on social network. Subscribe our website for more informative articles. Thanks for reading it.
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