list of basic terms for mechanical engineering

8/10/2019 List of Basic Terms for Mechanical Engineering

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List of basic terms for Mechanical Engineering

1. Torque or Turning Force

2. Couple3. Moment

4. Stress

5. Strain6. Spring

7. Specific Weight

8. Specific Volume

9. Specific Gravity10. Specific Heat

11. Viscosity

12. Buoyancy

13. Discharge of Fluid14. Bernoulli's Equation

15. Device for Fluid

16. Mach Number17. Hydraulic Machine

18. Draft Tube

19. Thermodynamics Law-zeroth law

First law

second law

20. Entropy21. calorific value of fuel

22. Boiler/Steam Generator

23. Superheater24. Air Preheater

25. Boiler Draught

26. Nozzle

27. Scavenging28. Supercharging

29. Turbocharging

30. Governor31. Flywheel

32. Rating of fuel-

S.I. engine

C.I. engine

33. Stoichiometric Mixture/ Stoichiometric Ratio34. Heat Transfer

35. Thermal Conductivity

36. Heat Exchanger37. Refrigeration

38. 1 tonne Refrigeration

39. Humidification40. Dehumidification


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41. Gear Train

42. Gyroscopic Couple

43. Heat Treatment44. Ferrous-Metal

45. Non-ferrous metal

46. Allowance47. Tolerance48. Clearance

49. Stiffness

50. Toughness51. Fatigue

52. Nuclear Fission

53. Nuclear Fussion

54. Welding55. Machine Tool

56. Cutting Tool

57. Indexing58. Jig

59. Fixture

Details

Torque or Turning Force:

It is the total amount of force which is required to create acceleration on moving substance.

Couple:

Two forces those acts on equally,parallely & oppositely on two separate points of same material.

Moment:

It is the amount of moving effect which is gained for action of turning force.

Stress:

It is the force that can prevent equal & opposite force. That means, it is the preventing force. If

one force acts on outside of a material, then a reactive force automatically acts to protest thatforce. The amount of reactive force per unit area is called stress. e.g. Tensile Stress, Compressive

Stress, Thermal Stress.

Strain:If a force acts on a substance, then in that case if the substance would deform. Then the amount

of deformation per unit length of that substance is called strain.

Spring:It is one type of device which is being distorted under certain amount of load & also can also go

to its original face after the removal of that load.

Its function:


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To store energy.

To absorb energy.

To control motion of two elements.

Stiffness:

Load per unit deflection. The amount of load required to resist the deflection.

Specific Weight:

Weight per unit volume of the fluid.

Specific Volume:

Volume per unit mass of the fluid.

Specific Gravity:

It is the ratio of specific weight of required substance to specific weight of pure water at 4 degreecentigrade temperature.

Specific heat:

The amount of heat required to increase 1 unit temperature of 1 unit mass.

Viscosity:Dynamic Viscosity:

The amount of resistance of one layer of fluid over other layer of fluid.

Kinematic Viscosity:

It is the ratio of dynamic viscosity to density.

Buoyancy:When a body is immersed in a liquid, it is lifted up by a force equal to weight of liquid displaced

by the body. The tendency of liquid to lift up an immersed body is buoyancy. The upward thrust

of liquid to lift up the body is called buoyancy force.

Bernoulli's Equation:

P/ +V/2g +Z = Constant

Where, P = pressure,V = velocity,Z = Datumn Head

Devices for fluid:

Venturimeter:It measures discharge of fluid.

Notches :

It measures discharge of fluid.


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Orifice meter:

It measures discharge of fluid.

Pitot tube :It measures velocity of fluid.

Mach Number:

It is the ratio of the velocity of fluid to the velocity of sound.

M=1 ----------------- Sonic flowM> (1-6) ----------- Super-Sonic flow

M>6 ---------------- Hyper-Sonic flow

Fluid discharge/Fluid flow:

Quantity of fluid flowing per second.

(through a section of pipe/ through a section of channel)

Q=AV

where, V= velocity of fluid,A= cross-sectional area of pipe/channelNote: 1m = 1000 L1 cusec = 1 ft/sec1 ft = 0.3048 m

Hydraulic Machine:Turbine,Pump,Compressor etc.

Draft tube:

It attaches with reaction turbine . Its function is to reduce energy loss from reaction turbine & italso reduce pressure at outlet which is must blow the atmospheric pressure.

Themodynamics Law:Zeroth Law

First Law of Thermodynamic

Second Law of thermodynamic

Zeroth Law:

If two body are in thermal equilibrium with a third body then these two body are also in thermal

equilibrium with each other.

First Law of Thermodynamics:In a closed system, work deliver to the surrounding is directly proportonal to the heat taken from

the surrounding.And also, In a closed system, work done on a system is directly proportonal to

the heat deliver to the surrounding.


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Second Law of Thermodynamics:

It is impossible to make a system or an engine which can change 100 percent input energy to 100percent output.

Entropy:

It is a thermodynamic property.

ds = dq/T

where, ds = change of entropy, dq = change of heat, T = Temperature.

In adiabatic process, entropy can not change. Actually,lacking or mal-adroitness of tranfering

energy of a system is entropy.

Calorific Value of fuel:It us the total amount of heat obtained from burning 1 kg solid or liquid fuel.

Boiler/Steam

Generator:It is a clossed vessel which is made of steel. Its function is to transfer heat to water to generate

steam.

Economiser:It is a part of boiler. Its function is to heat feed water which is supplied to boiler.

Superheater:

It is a part of boiler. Its function is to increase temperature of steam into boiler.

Air-Preheater:

It is a part of boiler. Its funtion is to preheats the air to be supplied to furnace and it recover heat

from exhaust gas.

Boler Draught:

It is an important term for boiler. It is the difference of pressure above and below the fire grate.This pressure difference have to maintain very carefully inside the bolier. It actually maintaind

the rate of steam generation. This depends on rate of fuel burning. Inside the boiler rate of fuel

burning is maintained with rate of entry fresh air. If proper amount of fresh air never entered into


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the boiler, then proper amount of fuel inside the boiler never be burnt. So, proper fresh air enters

into the boiler only by maintaining boiler draught.

Nozzle:

Nozzle is a duct of varying cros-sectional area. Actually, it is a passage of varying cross-sectional area. It converts steam's heat energy into mechanical energy. It is one type of pipe or

tube that carrying liquid or gas.

Scavenging:

It is the process of removing burnt gas from combustion chamber of engine cylinder.

Supercharging:Actually, power output of engine depends on what amount of air enter into the engine through

intake manifold. Amount of entry aiy if increased, then must be engine speed will increased.Amount of air will be increased by increasing inlet air density. The process of increasing inlet air

density is supercharging. The device which is used for supercharging is calledsupercharger.Superchargeris driven by a belt from engine crakshaft. It is installed in intake

system.

Turbocharging:

Turbocharging is similar to the supercharging. But in that case tubocharger is installed in exhaustsystem whereas supercharger is installed in intake system. Turbocharger is driven by force of

exhaust gas. Generally, turbocharger is used for 2-stroke engine by utilizing exhaust energy of

the engine, it recovers energy otherwise which would go waste.

Governeor:Its function id to regulate mean speed of engine when there are variation in the load. If load

incrases on the engine, then engine's speed must decrease. In that case supply of working fluid

have to increase. In the otherway, if load decrease on the engine, then engine' speed mustincrease. In that case supply of working fluid have to decrease.Governor automatcally, controls

the supply of working fluid to the engine with varying load condition.

Flywheel:

It is the one of the main parts of the I.C. engine. Its main function id to store energy in the time

of working stroke or expansion stroke. And, it releasesenergy to the crankshaft in the time ofsuction stroke, compression stroke & exhaust stroke. Because, engine has only one power

producing stroke.

Rating of fuel:


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S.I. Engine:

Octane number. Octane number indicates ability of fuel to resist knock.

C.I. Engine:

Cetane Number. Cetane number indicates ability of ignition of diesel fuel. That means, how

much fast ignites diesel fuel.

Stoichiometric ratio:It is the chemically correct air-fuel ratio by volume. By which theoratically sufficient oxygen

will be gotten to burn all combustible elements in fuel completely.

Heat Transfer:

It is a science which deals with energy transfer between material bodies as a result of

temperature difference.There are three way to heat transfer such as-

ConductionConvectionRadiation

Thermal Conductivity:

It is the quantity of heat flows between two parts of solid material by conduction. In this case

following consideration will be important fact-

Time------ 1 sec

Area of that solid material-------- 1 m

Thickness of that solid material------ 1m

Temperature difference between two parts of that material------ 1k

Heat Exchanger:It is one type of device which can transfer heat from one fluid to another fluid. Example-

Radiator, intercooler, preheater, condenser, boiler etc.

Refrigeration:

It is the process of removing heat from a substance. Actually, extraction of heat from a bodywhose temperature is already below the temperature of its surroundings.

1 tonne of refrigeration:

It is amount of refrigeration effect or cooling effect which is produced by uniform melting of 1

tonne ice in 24 hours from or at 0 degree centigrade or freezing 1 tonne water in 24 hours fromor at 0 degree centigrade.


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Humidification:

It is the addition of moisture to the air without change dry bulb temperatur.

Dehumidification:It is the removal of moisture from the air without change dry bulb temperature.

Gear Train:

Meshing of two or more gear. It can transmit power from one shaft to another shaft.

Heat Treatment:

Operation involving heating and cooling of a metal in solid state for obtaining desirablecondition without being changed chemical composition.Its object-increase hardness of

metal.increase quality of metal ( heat, corrosion,wear resistance quality )improve machinability.

Ferrous Metal:

1. Cast Iron - (2-6.67)%C, Si, Mn, P, S

2. Steel - (0-2)%C

3. Wrought Iron - 99.5% Fe

Non-Ferrous Metal:1. Brass - (Cu+Zn)

2. Bronze -

(Sn+Cu) ------ Tin Bronze

(Si+Cu) ------- Silicon Bronze

(Al+Cu) ------- Aluminium Bronze

Allowance:It is the difference between basic dimension of mating parts. That means, minimum clearance

between mating parts that can be allowed.

Tolerance:


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It is the difference between upper limit of dimension. It is also the permissible variation above

and below the basic size. That means maximum permissible variation in dimensions.

Clearance:

It is the difference in size between mating parts. That means, in that case the outside dimensionof the shaft is less than internal dimension of the hole.

Stiffness:

It is the ability to resist deformation.

Toughness:

It is the property to resist fracture.

Fatigue:When a material is subjected to repeated stress below yield point stress, such type of failure is

fatigue failure.

Nuclear Fission:

It is a nuclear reaction by which one big nucleous divided into two or more nucleous.

Nuclear Fussion:

It is also a nuclear reaction by which one big nucleous will produced by adding two smallnucleous.

Welding:

It is the process of joining two similar or dissimilar metal by fusion.

Arc Welding -

* need D.C current

* produced (6000-7000) Degree Centegrade Temperature

Gas Welding -

* Oxy - acetylene flame join metals

* Oxygen & acetylene gas works


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* produced 3200 Degree Centegrade Temperature

Machine Tool:

It is the power driven tool. It cut & form all kinds of metal parts.

Example - 1. Lathe2. Drill Press3. Shaper4. Planer5. Grinding6. Miling7. Broaching8. Boring

Cutting Tool:

Tool Materials for Cutting Tool:

1. High Carbon Steel

2. High Speed Steel (W+Cr+V)

3. Carbide (W Carbide+Ti Carbide+Co Carbide)

Indexing:

It is the method of dividing periphery of job into equal number of division. Actually, it is theprocess of dividing circular or other shape of workpiece into equal space, division or angle.

Jig:

It is one type of device which hold & locate workpiece and also guide & control cutting tool. Ituses in drilling, reaming and tapping.

Fixture:It is one type of device which hold and locate workpiece. It uses in miling, grinding, planning &

turning.

Posted byMd. Faisal at7:43 AM1 comment:

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list of basic terms for mechanical engineering

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