air gap piston design and analysis

8/18/2019 air gap piston design and analysis

1/56

MODELLING AND ANALYSIS OF AIR GAP INSULATING PISTON

DEPT. OF MECHANICAL ENGINEERING, MTIET Page 1

CHAPTER-01

1.1 INTRODUTION

It is well known fact that about 30% of the energy supplied is lost through the coolant and the 30% is wasted through friction and other losses, thus leaving only about

30% of energy utilization for useful purposes. In view of the above, the major thrust in

engine research during the last two decades has been on the development of low heat

rejection engines. The Low Heat Rejection (LHR) engine has been given considerable

attention recently as engine builders struggle to find remaining avenues to improve

economy and lower emissions. The concept of air gap insulated piston has been explored

by providing 2mm air gap within the piston by using bolted type piston. The bolted airgap insulated piston provides complete sealing of air gap necessary for continued

insulation. The design evolved provides high insulation combining adequate durability.

In order to provide high insulation and reliability, proper designing of the air gap piston

has to be ensured. The pistons with 2 mm thickness of air gap are designed with two

different materials. The invar alloy 36 insulation provides betterment in fuel

consumption at normal operating condition than a conventional piston engine and also

the delay period tends to reduce the emissions levels of Hydrocarbons and carbon

monoxide. The combustion rate is increased because of insulation and hence there is

reduced vibration and noise level.

1.2 INTRODUCTION ABOUT PISTON

In an IC engines piston is one of the main component. The heat

energy developed by the expanding of gases is transmitted by piston inside

the cylinder. During this process, some amount of heat is loosed by

absorbing the piston and some other purpose. Approximately one third of the

total fuel energy was converted into useful work and two third has been

lost By providing insulation on the piston surface the heat loss through the

piston can be reduced. Since the piston is made up of aluminum pistons,

with high thermal conductivity the heat from the piston can be reduced

by applying thermal barrier coatings like ceramics whose thermal

conductivity is less and can withstand high pressures and high


2/56



temperatures in the cylinder. These maintain high piston overhead

temperatures which is favorable for reducing knocking tendency, and to

improve combustion efficiency. The ceramics are zirconium and alumina is

having desirable properties such as good thermal insulation. These coatingscontrol and manage heat for optimum performance ,by converting energy .

1.3TYPES OF PISTON :

1.3.1Internal combustion engine Pistons

Fig 1 : Internal combustion engine piston

An internal combustion engine is acted upon by the pressure of the expanding combustion

gases in the combustion chamber space at the top of the cylinder. This force then acts

downwards through the connecting rod and onto the crankshaft. The connecting rod is

attached to the piston by a swivelling gudgeon pin (US: wrist pin). This pin is mounted

within the piston: unlike the steam engine, there is no piston rod or crosshead (except big two

stroke engines).

The pin itself is of hardened steel and is fixed in the piston, but free to move in the

connecting rod. A few designs use a 'fully floating' design that is loose in both components.

All pins must be prevented from moving sideways and the ends of the pin digging into the

cylinder wall, usually by circlips.

Gas sealing is achieved by the use of piston rings. These are a number of narrow iron rings,

fitted loosely into grooves in the piston, just below the crown. The rings are split at a point in

the rim, allowing them to press against the cylinder with a light spring pressure. Two types of

ring are used: the upper rings have solid faces and provide gas sealing; lower rings have

https://en.wikipedia.org/wiki/Internal_combustion_piston_enginehttps://en.wikipedia.org/wiki/Combustion_chamberhttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Gudgeon_pinhttps://en.wikipedia.org/wiki/Crossheadhttps://en.wikipedia.org/wiki/Circliphttps://en.wikipedia.org/wiki/Piston_ringhttps://en.wikipedia.org/wiki/File:BHB_Hiduminium_piston_(Autocar_Handbook,_13th_ed,_1935).jpghttps://en.wikipedia.org/wiki/Piston_ringhttps://en.wikipedia.org/wiki/Circliphttps://en.wikipedia.org/wiki/Crossheadhttps://en.wikipedia.org/wiki/Gudgeon_pinhttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Combustion_chamberhttps://en.wikipedia.org/wiki/Internal_combustion_piston_engine


3/56



narrow edges and a U-shaped profile, to act as oil scrapers. There are many proprietary and

detail design features associated with piston rings.

Pistons are cast from aluminium alloys. For better strength and fatigue life, some racing

pistons may be forged instead. Early pistons were of cast iron, but there were obvious benefits for engine balancing if a lighter alloy could be used. To produce pistons that could

survive engine combustion temperatures, it was necessary to develop new alloys such as Y

alloy and Hiduminium, specifically for use as pistons.

A few early gas engines had double-acting cylinders, but otherwise effectively all internal

combustion engine pistons are single-acting. During World War II, the US

submarine Pompano was fitted with a prototype of the infamously unreliable H.O.R. double-

acting two-stroke diesel engine. Although compact, for use in a cramped submarine, thisdesign of engine was not repeated.

1.3.1.1Trunk pistons

Trunk pistons are long relative to their diameter. They act both as a piston and

cylindrical crosshead. As the connecting rod is angled for much of its rotation, there is also a

side force that reacts along the side of the piston against the cylinder wall. A longer piston

helps to support this.

Trunk pistons have been a common design of piston since the early days of the reciprocating

internal combustion engine. They were used for both petrol and diesel engines, although high

speed engines have now adopted the lighter weight slipper piston.

A characteristic of most trunk pistons, particularly for diesel engines, is that they have a

groove for an oil ring below the gudgeon pin, in addition to the rings between the gudgeon

pin and crown.

The name 'trunk piston' derives from the 'trunk engine', an early design of marine steam

engine. To make these more compact, they avoided the steam engine's usual piston rod with

separate crosshead and were instead the first engine design to place the gudgeon pin directly

within the piston. Otherwise these trunk engine pistons bore little resemblance to the trunk

piston; they were extremely large diameter and double-acting. Their 'trunk' was a narrow

cylinder mounted in the centre of the piston.

1.3.1.2 Crosshead pistons

Large slow-speed Diesel engines may require additional support for the side forces on

https://en.wikipedia.org/wiki/Casting_(metalworking)https://en.wikipedia.org/wiki/Aluminium_alloyhttps://en.wikipedia.org/wiki/Forginghttps://en.wikipedia.org/wiki/Cast_ironhttps://en.wikipedia.org/wiki/Y_alloyhttps://en.wikipedia.org/wiki/Y_alloyhttps://en.wikipedia.org/wiki/Hiduminiumhttps://en.wikipedia.org/wiki/Gas_enginehttps://en.wikipedia.org/wiki/Double-acting_cylinderhttps://en.wikipedia.org/wiki/Single-acting_cylinderhttps://en.wikipedia.org/wiki/World_War_IIhttps://en.wikipedia.org/wiki/USS_Pompano_(SS-181)https://en.wikipedia.org/wiki/Hooven-Owens-Rentschlerhttps://en.wikipedia.org/wiki/Crossheadhttps://en.wikipedia.org/wiki/Piston#Slipper_pistonshttps://en.wikipedia.org/wiki/Trunk_enginehttps://en.wikipedia.org/wiki/Marine_steam_enginehttps://en.wikipedia.org/wiki/Marine_steam_enginehttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/Marine_steam_enginehttps://en.wikipedia.org/wiki/Marine_steam_enginehttps://en.wikipedia.org/wiki/Trunk_enginehttps://en.wikipedia.org/wiki/Piston#Slipper_pistonshttps://en.wikipedia.org/wiki/Crossheadhttps://en.wikipedia.org/wiki/Hooven-Owens-Rentschlerhttps://en.wikipedia.org/wiki/USS_Pompano_(SS-181)https://en.wikipedia.org/wiki/World_War_IIhttps://en.wikipedia.org/wiki/Single-acting_cylinderhttps://en.wikipedia.org/wiki/Double-acting_cylinderhttps://en.wikipedia.org/wiki/Gas_enginehttps://en.wikipedia.org/wiki/Hiduminiumhttps://en.wikipedia.org/wiki/Y_alloyhttps://en.wikipedia.org/wiki/Y_alloyhttps://en.wikipedia.org/wiki/Cast_ironhttps://en.wikipedia.org/wiki/Forginghttps://en.wikipedia.org/wiki/Aluminium_alloyhttps://en.wikipedia.org/wiki/Casting_(metalworking)


4/56



the piston. These engines typically use crosshead pistons. The main piston has a large piston

rod extending downwards from the piston to what is effectively a second smaller-diameter

piston. The main piston is responsible for gas sealing and carries the piston rings. The smaller

piston is purely a mechanical guide. It runs within a small cylinder as a trunk guide and also

carries the gudgeon pin.

Fig 2 : Cross head Piston

Because of the additional weight of these pistons, they are not used for high-speed engines.

1.3.1.3Slipper pistons

Fig 3 :Slipper piston

A slipper piston is a piston for a petrol engine that has been reduced in size and weight as

much as possible. In the extreme case, they are reduced to the piston crown, support for the

piston rings, and just enough of the piston skirt remaining to leave two lands so as to stop the

piston rocking in the bore. The sides of the piston skirt around the gudgeon pin are reduced

away from the cylinder wall. The purpose is mostly to reduce the reciprocating mass, thus

making it easier to balance the engine and so permit high speeds. A secondary benefit may be

some reduction in friction with the cylinder wall, since the area of the skirt, which slides up

https://en.wikipedia.org/wiki/Crossheadhttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/File:Ricardo_slipper_piston_(Autocar_Handbook,_13th_ed,_1935).jpghttps://en.wikipedia.org/wiki/File:Ricardo_slipper_piston_(Autocar_Handbook,_13th_ed,_1935).jpghttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/Crosshead


5/56



and down in the cylinder is reduced by half. However most friction is due to the piston rings,

which are the parts which actually fit the tightest in the bore and the bearing surfaces of the

wrist pin, the benefit is reduced.

1.3.1.4Deflector pistons

Fig 4 :Two-stroke deflector piston

Deflector pistons are used in two-stroke engines with crankcase compression, where the gas

flow within the cylinder must be carefully directed in order to provide efficient scavenging.

With cross scavenging, the transfer (inlet to the cylinder) and exhaust ports are on directly

facing sides of the cylinder wall. To prevent the incoming mixture passing straight across

from one port to the other, the piston has a raised rib on its crown. This is intended to deflect

the incoming mixture upwards, around the combustion chamber .[1] Much effort, and many

different designs of piston crown, went into developing improved scavenging. The crowns

developed from a simple rib to a large asymmetric bulge, usually with a steep face on the

inlet side and a gentle curve on the exhaust. Despite this, cross scavenging was never as

effective as hoped. Most engines today useSchnuerle porting instead. This places a pair of

transfer ports in the sides of the cylinder and encourages gas flow to rotate around a vertical

axis, rather than a horizontal axis.

1.3.1.5 Steam engines

Cast-iron steam engine piston, with a metal piston ring spring-loaded against the cylinder

wall. Steam engines are usually double-acting (i.e. steam pressure acts alternately on each

side of the piston) and the admission and release of steam is controlled by slide valves, piston

valves or poppet valves. Consequently, steam engine pistons are nearly always comparatively

https://en.wikipedia.org/wiki/Piston_ringshttps://en.wikipedia.org/wiki/Two-stroke_enginehttps://en.wikipedia.org/wiki/Scavenging_(automotive)https://en.wikipedia.org/wiki/Cross_scavenginghttps://en.wikipedia.org/wiki/Combustion_chamberhttps://en.wikipedia.org/wiki/Piston#cite_note-Irving.2C_13-3https://en.wikipedia.org/wiki/Piston#cite_note-Irving.2C_13-3https://en.wikipedia.org/wiki/Piston#cite_note-Irving.2C_13-3https://en.wikipedia.org/wiki/Schnuerle_portinghttps://en.wikipedia.org/wiki/Steam_enginehttps://en.wikipedia.org/wiki/D_slide_valvehttps://en.wikipedia.org/wiki/Piston_valvehttps://en.wikipedia.org/wiki/Piston_valvehttps://en.wikipedia.org/wiki/Poppet_valvehttps://en.wikipedia.org/wiki/File:Two-stroke_deflector_piston_(Autocar_Handbook,_13th_ed,_1935).jpghttps://en.wikipedia.org/wiki/Poppet_valvehttps://en.wikipedia.org/wiki/Piston_valvehttps://en.wikipedia.org/wiki/Piston_valvehttps://en.wikipedia.org/wiki/D_slide_valvehttps://en.wikipedia.org/wiki/Steam_enginehttps://en.wikipedia.org/wiki/Schnuerle_portinghttps://en.wikipedia.org/wiki/Piston#cite_note-Irving.2C_13-3https://en.wikipedia.org/wiki/Combustion_chamberhttps://en.wikipedia.org/wiki/Cross_scavenginghttps://en.wikipedia.org/wiki/Scavenging_(automotive)https://en.wikipedia.org/wiki/Two-stroke_enginehttps://en.wikipedia.org/wiki/Piston_rings


6/56



Fig 5 : Steam Engine Piston

thin discs: their diameter is several times their thickness. (One exception is the trunkenginepiston, shaped more like those in a modern internal-combustion engine.) Another

factor is that since almost all steam engines use crossheads to translate the force to the drive

rod, there are few lateral forces acting to try and "rock" the piston, so a cylinder-shaped

piston skirt isn't necessary.

Fig 6 : Early (c. 1830) piston for a beam engine. The piston seal is made by turns of wrapped

rope.

https://en.wikipedia.org/wiki/Trunk_enginehttps://en.wikipedia.org/wiki/Trunk_enginehttps://en.wikipedia.org/wiki/Beam_enginehttps://en.wikipedia.org/wiki/File:1830s_beam_engine_piston_with_rope_seal,_Coalbrookdale_Museum_of_Iron.jpghttps://en.wikipedia.org/wiki/File:Piston,_sprung_ring_(Heat_Engines,_1913).jpghttps://en.wikipedia.org/wiki/Beam_enginehttps://en.wikipedia.org/wiki/Trunk_enginehttps://en.wikipedia.org/wiki/Trunk_engine


7/56



1.4 ENGINE SPECIFICATIONS:

Bore 80mm

Stroke 110mm

BHP 5

Compression Ratio 16.5: 1

Radius of Dynamometer 215mm

Efficiency of dynamometer 0.8

Type of Loading DC generator loading

Orifice Diameter 2cm

Co-efficient of Discharge 0.6

Speed of the Engine 1500rpm

Fuel Used Diesel

Calorific Value 10500 kcal/kg

Specific Gravity 0.836

Piston Material Aluminum

Table 1 : ENGINE SPECIFICATIONS


8/56



1.5 ENGINE PARTS :

1.5.1 CYLINDER HEAD :

Fig 7 :Cylinder Head

In an internal combustion engine, the cylinder head (often informally abbreviated to

just head) sits above the cylinders on top of thecylinder block. It closes in the top of thecylinder, forming the combustion chamber. This joint is sealed by a head gasket. In most

engines, the head also provides space for the passages that feed air and fuel to the cylinder,

and that allow the exhaust to escape. The head can also be a place to mount the valves, spark

plugs, and fuel injectors.

For a four-stroke engine, key parts of the engine include the crankshaft (purple), connecting

rod (orange), one or more camshafts (red and blue), and valves. For a two-stroke engine,

there may simply be an exhaust outlet and fuel inlet instead of a valve system. In both typesof engines there are one or more cylinders (grey and green), and for each cylinder there is

aspark plug (darker-grey, gasoline engines only), a piston (yellow), and a crankpin (purple).

A single sweep of the cylinder by the piston in an upward or downward motion is known as a

stroke. The downward stroke that occurs directly after the air-fuel mix passes from

thecarburetor or fuel injector to the cylinder (where it is ignited) is also known as a power

stroke.

https://en.wikipedia.org/wiki/Internal_combustion_enginehttps://en.wikipedia.org/wiki/Cylinder_(engine)https://en.wikipedia.org/wiki/Cylinder_blockhttps://en.wikipedia.org/wiki/Combustion_chamberhttps://en.wikipedia.org/wiki/Head_gaskethttps://en.wikipedia.org/wiki/Poppet_valvehttps://en.wikipedia.org/wiki/Spark_plughttps://en.wikipedia.org/wiki/Spark_plughttps://en.wikipedia.org/wiki/Fuel_injectorhttps://en.wikipedia.org/wiki/Four-stroke_cyclehttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Camshafthttps://en.wikipedia.org/wiki/Poppet_valvehttps://en.wikipedia.org/wiki/Two-stroke_cyclehttps://en.wikipedia.org/wiki/Spark_plughttps://en.wikipedia.org/wiki/Gasolinehttps://en.wikipedia.org/wiki/Pistonhttps://en.wikipedia.org/wiki/Crank_(mechanism)https://en.wikipedia.org/wiki/Carburetorhttps://en.wikipedia.org/wiki/Fuel_injectorhttps://en.wikipedia.org/wiki/File:Cylinderhead.JPGhttps://en.wikipedia.org/wiki/Fuel_injectorhttps://en.wikipedia.org/wiki/Carburetorhttps://en.wikipedia.org/wiki/Crank_(mechanism)https://en.wikipedia.org/wiki/Pistonhttps://en.wikipedia.org/wiki/Gasolinehttps://en.wikipedia.org/wiki/Spark_plughttps://en.wikipedia.org/wiki/Two-stroke_cyclehttps://en.wikipedia.org/wiki/Poppet_valvehttps://en.wikipedia.org/wiki/Camshafthttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Four-stroke_cyclehttps://en.wikipedia.org/wiki/Fuel_injectorhttps://en.wikipedia.org/wiki/Spark_plughttps://en.wikipedia.org/wiki/Spark_plughttps://en.wikipedia.org/wiki/Poppet_valvehttps://en.wikipedia.org/wiki/Head_gaskethttps://en.wikipedia.org/wiki/Combustion_chamberhttps://en.wikipedia.org/wiki/Cylinder_blockhttps://en.wikipedia.org/wiki/Cylinder_(engine)https://en.wikipedia.org/wiki/Internal_combustion_engine


9/56



A Wankel engine has a triangular rotor that orbits in an epitrochoidal (figure 8 shape)

chamber around an eccentric shaft. The four phases of operation (intake, compression, power,

and exhaust) take place in what is effectively a moving, variable-volume chamber.

1.5.2Valves

All four-stroke internal combustion engines employ valves to control the admittance of fuel

and air into the combustion chamber. Two-stroke engines use ports in the cylinder bore,

covered and uncovered by the piston, though there have been variations such as exhaust

valves.

1.5.2.1 Piston engine valves

In piston engines, the valves are grouped into 'inlet valves' which admit the entrance of fueland air and 'outlet valves' which allow the exhaust gases to escape. Each valve opens once per

cycle and the ones that are subject to extreme accelerations are held closed by springs that are

typically opened by rods running on a camshaft rotating with the engines' crankshaft.

1.5.2.2 Control valves

Continuous combustion engines — as well as piston engines — usually have valves that open

and close to admit the fuel and/or air at the startup and shutdown. Some valves feather to

adjust the flow to control power or engine speed as well.

1.5.3 Exhaust systems

Internal combustion engines have to effectively manage the exhaust of the cooled combustion

gas from the engine. The exhaust system frequently contains devices to control pollution,

both chemical and noise pollution. In addition, for cyclic combustion engines the exhaust

system is frequently tuned to improve emptying of the combustion chamber. The majority of

exhausts also have systems to prevent heat from reaching places which would encounterdamage from it such as heat-sensitive components, often referred to as Exhaust Heat

Management.

For jet propulsion internal combustion engines, the 'exhaust system' takes the form of a high

velocity nozzle, which generates thrust for the engine and forms a colimated jet of gas that

gives the engine its name.

https://en.wikipedia.org/wiki/Wankel_enginehttps://en.wikipedia.org/wiki/Epitrochoidhttps://en.wikipedia.org/wiki/Four-strokehttps://en.wikipedia.org/wiki/Two-strokehttps://en.wikipedia.org/wiki/Camshafthttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Exhaust_Heat_Managementhttps://en.wikipedia.org/wiki/Exhaust_Heat_Managementhttps://en.wikipedia.org/wiki/Propelling_nozzlehttps://en.wikipedia.org/wiki/Propelling_nozzlehttps://en.wikipedia.org/wiki/Jet_(fluid)https://en.wikipedia.org/wiki/Jet_(fluid)https://en.wikipedia.org/wiki/Propelling_nozzlehttps://en.wikipedia.org/wiki/Propelling_nozzlehttps://en.wikipedia.org/wiki/Exhaust_Heat_Managementhttps://en.wikipedia.org/wiki/Exhaust_Heat_Managementhttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Camshafthttps://en.wikipedia.org/wiki/Two-strokehttps://en.wikipedia.org/wiki/Four-strokehttps://en.wikipedia.org/wiki/Epitrochoidhttps://en.wikipedia.org/wiki/Wankel_engine


10/56



1.5.4 Cooling systems

Combustion generates a great deal of heat, and some of this transfers to the walls of the

engine. Failure will occur if the body of the engine is allowed to reach too high a

temperature; either the engine will physically fail, or any lubricants used will degrade to the point that they no longer protect the engine. The lubricants must be clean as dirty lubricants

may lead to over formation of sludge in the engines.

Cooling systems usually employ air (air-cooled) or liquid (usually water) cooling, while some

very hot engines using radiative cooling (especially some rocket engines). Some high-altitude

rocket engines use ablative cooling, where the walls gradually erode in a controlled fashion.

Rockets in particular can use regenerative cooling, which uses the fuel to cool the solid parts

of the engine.

1.5.5 Piston

A piston is a component of reciprocating engines. It is located in a cylinder and is made gas-

tight by piston rings. Its purpose is to transfer force from expanding gas in the cylinder to

the crankshaft via a piston rod and/or connecting rod. In two-stroke engines the piston also

acts as a valve by covering and uncovering ports in the cylinder wall.

1.5.6 Propelling nozzle

For jet engine forms of internal combustion engines, a propelling nozzle is present. This takes

the high temperature, high pressure exhaust and expands and cools it. The exhaust leaves the

nozzle going at much higher speed and provides thrust, as well as constricting the flow from

the engine and raising the pressure in the rest of the engine, giving greater thrust for the

exhaust mass that exits.

1.5.7 Crankshaft

Most reciprocating internal combustion engines end up turning a shaft. This means that the

linear motion of a piston must be converted into rotation. This is typically achieved by a

crankshaft.

1.5.8 Flywheels

The flywheel is a disk or wheel attached to the crank, forming an inertial mass that stores

rotational energy. In engines with only a single cylinder the flywheel is essential to carry

energy over from the power stroke into a subsequent compression stroke. Flywheels are

https://en.wikipedia.org/wiki/Air-cooledhttps://en.wikipedia.org/wiki/Water-cooledhttps://en.wikipedia.org/wiki/Rocket_enginehttps://en.wikipedia.org/wiki/Ablativehttps://en.wikipedia.org/wiki/Regenerative_cooling_(rocket)https://en.wikipedia.org/wiki/Reciprocating_enginehttps://en.wikipedia.org/wiki/Cylinder_(engine)https://en.wikipedia.org/wiki/Piston_ringhttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Two-stroke_engineshttps://en.wikipedia.org/wiki/Valvehttps://en.wikipedia.org/wiki/Porting#Two-stroke_portinghttps://en.wikipedia.org/wiki/Inertiahttps://en.wikipedia.org/wiki/Inertiahttps://en.wikipedia.org/wiki/Porting#Two-stroke_portinghttps://en.wikipedia.org/wiki/Valvehttps://en.wikipedia.org/wiki/Two-stroke_engineshttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Piston_ringhttps://en.wikipedia.org/wiki/Cylinder_(engine)https://en.wikipedia.org/wiki/Reciprocating_enginehttps://en.wikipedia.org/wiki/Regenerative_cooling_(rocket)https://en.wikipedia.org/wiki/Ablativehttps://en.wikipedia.org/wiki/Rocket_enginehttps://en.wikipedia.org/wiki/Water-cooledhttps://en.wikipedia.org/wiki/Air-cooled


11/56



present in most reciprocating engines to smooth out the power delivery over each rotation of

the crank and in most automotive engines also mount a gear ring for a starter. The rotational

inertia of the flywheel also allows a much slower minimum unloaded speed and also

improves the smoothness at idle. The flywheel may also perform a part of the balancing of

the system and so by itself be out of balance, although most engines will use a neutral balance

for the flywheel, enabling it to be balanced in a separate operation. The flywheel is also used

as a mounting for the clutch or a torque converter in most automotive applications.

1.5.9 Starter systems

All internal combustion engines require some form of system to get them into operation.

Most piston engines use a starter motor powered by the same battery as runs the rest of the

electric systems. Large jet engines and gas turbines are started with a compressed air

motor that is geared to one of the engine's driveshafts. Compressed air can be supplied from

another engine, a unit on the ground or by the aircraft's APU. Small internal combustion

engines are often started by pull cords. Motorcycles of all sizes were traditionally kick-

started, though all but the smallest are now electric-start. Large stationary and marine engines

may be started by the timed injection of compressed air into the cylinders — or occasionally

with cartridges. Jump starting refers to assistance from another battery (typically when the

fitted battery is discharged), while bump starting refers to an alternative method of starting bythe application of some external force, e.g. rolling down a hill.

1.5.10 Heat shielding systems

These systems often work in combination with engine cooling and exhaust systems. Heat

shielding is necessary to prevent engine heat from damaging heat-sensitive components. The

majority of older cars use simple steel heat shielding to reduce thermal

radiation and convection. It is now most common for modern cars are to use aluminium heat

shielding which has a lower density, can be easily formed and does not corrode in the same

way as steel. Higher performance vehicles are beginning to use ceramic heat shielding as this

can withstand far higher temperatures as well as further reductions in heat transfer.

1.5.11 Lubrication systems

Internal combustions engines require lubrication in operation that moving parts slide

smoothly over each other. Insufficient lubrication subjects the parts of the engine to metal-to-

metal contact, friction, heat build-up, rapid wear often culminating in parts becoming friction

https://en.wikipedia.org/wiki/Starter_motorhttps://en.wikipedia.org/wiki/Air_motorhttps://en.wikipedia.org/wiki/Air_motorhttps://en.wikipedia.org/wiki/Auxiliary_power_unithttps://en.wikipedia.org/wiki/Bump_startinghttps://en.wikipedia.org/wiki/Thermal_radiationhttps://en.wikipedia.org/wiki/Thermal_radiationhttps://en.wikipedia.org/wiki/Convectionhttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/wiki/Steelhttps://en.wikipedia.org/wiki/Lubricationhttps://en.wikipedia.org/wiki/Moving_partshttps://en.wikipedia.org/wiki/Friction_weldinghttps://en.wikipedia.org/wiki/Friction_weldinghttps://en.wikipedia.org/wiki/Moving_partshttps://en.wikipedia.org/wiki/Lubricationhttps://en.wikipedia.org/wiki/Steelhttps://en.wikipedia.org/wiki/Densityhttps://en.wikipedia.org/wiki/Convectionhttps://en.wikipedia.org/wiki/Thermal_radiationhttps://en.wikipedia.org/wiki/Thermal_radiationhttps://en.wikipedia.org/wiki/Bump_startinghttps://en.wikipedia.org/wiki/Auxiliary_power_unithttps://en.wikipedia.org/wiki/Air_motorhttps://en.wikipedia.org/wiki/Air_motorhttps://en.wikipedia.org/wiki/Starter_motor


12/56



welded together e.g. pistons in their cylinders. Big end bearings seizing up will sometimes

lead to a connecting rod breaking and poking out through the crankcase.

Several different types of lubrication systems are used. Simple two-stroke engines are

lubricated by oil mixed into the fuel or injected into the induction stream as a spray. Earlyslow-speed stationary and marine engines were lubricated by gravity from small chambers

similar to those used on steam engines at the time — with an engine tender refilling these as

needed. As engines were adapted for automotive and aircraft use, the need for a high power-

to-weight ratio led to increased speeds, higher temperatures, and greater pressure on bearings

which in turn required pressure-lubrication for crank bearings and connecting-rod journals.

This was provided either by a direct lubrication from a pump, or indirectly by a jet of oil

directed at pickup cups on the connecting rod ends which had the advantage of providinghigher pressures as the engine speed increased.

1.5.12 Control systems

Most engines require one or more systems to start and shut down the engine and to control

parameters such as the power, speed, torque, pollution, combustion temperature, and

efficiency and to stabilise the engine from modes of operation that may induce self-damage

such as pre-ignition. Such systems may be referred to as engine control units.

Many control systems today are digital, and are frequently termed FADEC (Full Authority

Digital Electronic Control) systems.

1.5.13 Diagnostic systems

Engine On Board Diagnostics (also known as OBD) is a computerized system that allows for

electronic diagnosis of a vehicles' powerplant. The first generation, known as OBD1, was

introduced 10 years after the U.S. Congress passed the Clean Air Act in 1970 as a way to

monitor a vehicles' fuel injection system. OBD2, the second generation of computerized on-

board diagnostics, was codified and recommended by the California Air Resource Board in

1994 and became mandatory equipment aboard all vehicles sold in the United States as of

1996.

1.6 LOW HEAT REJECTION ENGINE :

The thermal barrier coated engines are otherwise known as low heat rejection (LHR)

engines. Due to the insulation of the cylinder wall the heat transfer through the cylinder wallsto the cooling system is reduced which change the combustion characteristics of the diesel

https://en.wikipedia.org/wiki/Friction_weldinghttps://en.wikipedia.org/wiki/Crank_pinhttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Crank_shafthttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Journal_bearinghttps://en.wikipedia.org/w/index.php?title=Pickup_cup&action=edit&redlink=1https://en.wikipedia.org/wiki/Pre-ignitionhttps://en.wikipedia.org/wiki/Engine_control_unithttps://en.wikipedia.org/wiki/FADEChttps://en.wikipedia.org/wiki/FADEChttps://en.wikipedia.org/wiki/Engine_control_unithttps://en.wikipedia.org/wiki/Pre-ignitionhttps://en.wikipedia.org/w/index.php?title=Pickup_cup&action=edit&redlink=1https://en.wikipedia.org/wiki/Journal_bearinghttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Crank_shafthttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Crank_pinhttps://en.wikipedia.org/wiki/Friction_welding


13/56


14/56



CHAPTER 2

2.1 LITERATURE SUMMARY AND WORK :

To Understand the scope of the project , the literature survey is a must . Here in this project we had used the piston of KIRLOSKAR DIESEL ENGINEThe literature survey for

this project is as follows .

2.1.1 INTRODUCTION

Fig 8 :Nicholas August Otto, (German) Inventor of Piston (1866)

A piston is a component of reciprocating engines, reciprocating pumps, gas

compressors and pneumatic cylinders, among other similar mechanisms. It is the moving

component that is contained by a cylinder and is made gas-tight by piston rings. In an engine,

its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via

a piston rod and/orconnecting rod. In a pump, the function is reversed and force is transferred

from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the

https://en.wikipedia.org/wiki/Reciprocating_enginehttps://en.wikipedia.org/wiki/Pumphttps://en.wikipedia.org/wiki/Gas_compressorhttps://en.wikipedia.org/wiki/Gas_compressorhttps://en.wikipedia.org/wiki/Pneumatic_cylinderhttps://en.wikipedia.org/wiki/Cylinder_(engine)https://en.wikipedia.org/wiki/Piston_ringhttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Fluidhttps://en.wikipedia.org/wiki/Fluidhttps://en.wikipedia.org/wiki/Connecting_rodhttps://en.wikipedia.org/wiki/Piston_rodhttps://en.wikipedia.org/wiki/Crankshafthttps://en.wikipedia.org/wiki/Piston_ringhttps://en.wikipedia.org/wiki/Cylinder_(engine)https://en.wikipedia.org/wiki/Pneumatic_cylinderhttps://en.wikipedia.org/wiki/Gas_compressorhttps://en.wikipedia.org/wiki/Gas_compressorhttps://en.wikipedia.org/wiki/Pumphttps://en.wikipedia.org/wiki/Reciprocating_engine


15/56



cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in

the cylinder wall.

2.2 PROBLEMS OF PISTON FAILURE:

The main challenge for the free-piston engine is engine control, which can only besaid to be fully solved for single piston hydraulic free-piston engines. Issues such as the

influence of cycle-to-cycle variations in the combustion process and engine performance

during transient operation in dual piston engines are topics that need further investigation.

Crankshaft engines can connect traditional accessories such as alternator, oil pump, fuel

pump, cooling system, starter etc.

Rotational movement to spin conventional automobile engine accessories such as alternators,

air conditioner compressors, power steering pumps, and anti-pollution devices could becaptured from a turbine situated in the exhaust stream.

Cracks in the top of a piston (crown) in petrol engines are usually the result of excessive

combustion pressure caused by excessive compression or over advanced ignition timing.

These conditions cause excessive combustion pressure, which in turn causes the piston crown

to crack as the piston is operating outside the pressure it was designed to work under. In

diesel engines this damage can be caused by a condition called thermal fatigue.

Thermal fatigue occurs when an engine is consistently operated under full heavy load

followed by light load. The constant drastic changes in combustion temperature eventually

results in thermal cracks of the piston crown.

Piston skirt cracking is usually a result of constant excessive loading of the engine and high

mileage fatigue or in some cases faulty piston design. The manufacturer usually corrects the

later by supplying a superseded part.

Incorrect fitting of pistons to rods can cause stress fractures, which develop into serious skirt

cracking early in the life of a repaired engine. Piston skirt cracking is not a common engine

fault and is almost totally eliminated out of modern piston design

Cracked ringlands are usually caused in detonation or pre-ignition. Detonation causes

excessive combustion temperature and pressure. By design the ring lands are one of the

weaker positions on a piston and can crack under this type of stress. The land can completely

crack away in sections. Rings will also crack under these conditions.

https://en.wikipedia.org/wiki/Valvehttps://en.wikipedia.org/wiki/Porting_(engine)#Two-stroke_portinghttps://en.wikipedia.org/wiki/Porting_(engine)#Two-stroke_portinghttps://en.wikipedia.org/wiki/Valve


16/56



2.3 PREVIOUSLY PUBLISHED JOURNALS ON AIR GAP

PISTON :

1. Structural and Thermal Analysis of Conventional and Air Gap Insulated Piston forLow Heat-Rejection Engines by authors PAVANI KUMARI, DR.SUNEEL

DONTHAMSETTY. Published on February-2015

2. Thermal Analysis of Piston for the Influence on Secondary motion by authors Vinay

V. Kuppast, Dr.S.N.Kurbet, H.D.Umeshkumar, Adarsh B.C published on May - June

2013

3. PERFORMANCE EVALUATION AND EMISSION CHARACTERISTICS OF

LOW HEAT REJECTION ENGINE USING AIR GAP INSULATION by authors M.IRSHAD AHMED, C. THAMODHARAN, P. RAMAN published on June-July 2013.

4. COMPARATIVE PERFORMANCE OF DIFFERENT VERSIONS OF LOW HEAT

REJECTION DIESEL ENGINES WITH MOHR OIL BASED BIO-DIESEL by

authors T. Ratna Reddy, M.V.S. Murali Krishna, Ch. Kesava Reddy & P.V.K.Murthy

published on October-2012.

5. The Performance Study of Alcohol in an Air Gap Ceramic Insulated Diesel Engine

with Brass Piston by authors S Sunil Kumar Reddy, V.Pandurangadu, M.Venkat Rao

published on June-2014.

6. Design Analysis and Optimization of Piston using CATIA and ANSYS by authors

Ch.Venkata Rajam, P.V.K.Murthy, M.V.S.Murali Krishna, G.M.Prasada Rao

published on January-2013.

7. Design Analysis and Optimization of Internal Combustion Engine Piston using CAE

tool ANSYS by authors Aditya Kumar Gupta, Vinay Kumar Tripathi published on

November 2014 .


17/56



CHAPTER-03

3.1 INTRODUCTION ABOUT INVAR MATERIAL :

Invar, also known generically as FeNi36 (64FeNi in the US), is a nickel –

iron alloy notable for its uniquely low coefficient of thermal expansion (CTE or α). The

name Invar comes from the word invariable, referring to its relative lack of expansion or

contraction with temperature change. It was invented in 1896 by Swiss physicist Charles

Édouard Guillaume. He received the Nobel Prize in Physics in 1920 for this discovery, which

enabled improvements in scientific instruments.

Like other nickel/iron compositions, Invar is a solid solution; that is, it is a single-phase alloy,

consisting of around 36% nickel and 64% iron.

Common grades of Invar have a coefficient of thermal expansion (denoted α, and measured

between 20 °C and 100 °C) of about 1.2 × 10−6 K −1 (1.2 ppm/°C), while ordinary steels have

values of around 11 – 15 ppm. Extra-pure grades (


18/56



3.1.1 APPLICATIONS :

Invar is used where high dimensional stability is required, such as precision instruments,

clocks, seismic creep gauges, television shadow-mask frames,[3] valves in motors,

and antimagnetic watches. In land surveying, when first-order (high-precision) elevationleveling is to be performed, the Level staff (leveling rod) used is made of Invar, instead of

wood, fiberglass, or other metals. Invar struts were used in some pistons to limit their thermal

expansion inside their cylinders.

3.1.2 VARIATIONS :

There are variations of the original Invar material that have slightly different coefficient of

thermal expansion such as:

Inovco, which is Fe – 33Ni – 4.5Co and has an α of 0.55 ppm/°C (from 20 – 100 °C).

FeNi42 (for example NILO alloy 42), which has a nickel content of 42% and α ≈

5.3 ppm/°C, is widely used as lead frame material for electronic components, integrated

circuits, etc.

FeNiCo alloys — named Kovar or Dilver P — that have the same expansion behaviour

as borosilicate glass, and because of that are used for optical parts in a wide range of

temperatures and applications, such as satellites.

3.1.3 EXPLANATION OF ANAMALOUS PROPERTIES :

All the iron-rich face-centered cubic Fe – Ni alloys show Invar anomalies in their measured

thermal and magnetic properties that evolve continuously in intensity with varying alloy

composition. Scientists had once proposed that Invar's behavior was a direct consequence of

a high-magnetic-moment to low-magnetic-moment transition occurring in the face centered

cubic Fe – Ni series (and that gives rise to the mineral antitaenite); however, this theory was proven incorrect.[5] Instead, it appears that the low-moment/high-moment transition is

preceded by a high-magnetic-moment frustrated ferromagnetic state in which the Fe – Fe

magnetic exchange bonds have a large magneto-volume effect of the right sign and

magnitude to create the observed thermal expansion anomaly.

Few people realize that the nickel-iron alloy, Invar, plays a crucial part in so many of

their household controls and office appliances. This role was established soon after its

discovery 100 years ago in 1896. Invar is the forerunner of a family of controlled expansionnickel-iron alloys which form the essential part of bimetals and thermostats. Invar itself is

https://en.wikipedia.org/wiki/Shadow_maskhttps://en.wikipedia.org/wiki/Invar#cite_note-3https://en.wikipedia.org/wiki/Invar#cite_note-3https://en.wikipedia.org/wiki/Invar#cite_note-3https://en.wikipedia.org/wiki/Antimagnetic_watchhttps://en.wikipedia.org/wiki/Surveyinghttps://en.wikipedia.org/wiki/Level_staffhttps://en.wikipedia.org/wiki/Kovarhttps://en.wikipedia.org/wiki/Borosilicate_glasshttps://en.wikipedia.org/wiki/Satellitehttps://en.wikipedia.org/wiki/Antitaenitehttps://en.wikipedia.org/wiki/Invar#cite_note-5https://en.wikipedia.org/wiki/Invar#cite_note-5https://en.wikipedia.org/wiki/Invar#cite_note-5https://en.wikipedia.org/wiki/Geometrically_frustrated_magnethttp://www.jlcelectromet.com/alloy364248.htmhttp://www.jlcelectromet.com/alloy364248.htmhttp://www.jlcelectromet.com/alloy364248.htmhttp://www.jlcelectromet.com/alloy364248.htmhttps://en.wikipedia.org/wiki/Geometrically_frustrated_magnethttps://en.wikipedia.org/wiki/Invar#cite_note-5https://en.wikipedia.org/wiki/Antitaenitehttps://en.wikipedia.org/wiki/Satellitehttps://en.wikipedia.org/wiki/Borosilicate_glasshttps://en.wikipedia.org/wiki/Kovarhttps://en.wikipedia.org/wiki/Level_staffhttps://en.wikipedia.org/wiki/Surveyinghttps://en.wikipedia.org/wiki/Antimagnetic_watchhttps://en.wikipedia.org/wiki/Invar#cite_note-3https://en.wikipedia.org/wiki/Shadow_mask


19/56



still used today in vast numbers of household appliances, from electric irons and toasters to

gas cookers and fire safety cutoffs. In the office, computer terminals and TV screens make

extensive use of Invar and other Ni-Fe alloys for shadow masks, frames, and cathode ray tube

gun parts.

Other applications for these special alloys are continuing to be found in industry for advanced

electronic components, filters in mobile phone networks and even as tank membranes for

massive liquefied natural gas transport ships.

3.1.4 DISCOVERY AND NOBEL PRIZE :

When Invar was discovered in 1896, its unique property of low and linear expansion over a

wide temperature range allowed the production of effective bimetals which could be used insafety cut-off devices for gas cookers and heaters. For his work on the nickel-iron system and

the discovery of Invar, Charles Edouard Guillaume of Imphy was awarded a Nobel prize for

Physics early in the 20th century.

One of the traditional uses for Invar has been for the thermostat of electric immersion heaters,

used for a variety of domestic and commercial water heating systems. Operation of the

thermostat is based upon differential expansion between a brass tube and an inner Invar rod,

the resulting movement being used to actuate a microswitch. The set temperature is

commonly adjustable in the range between 48-83°C.

3.1.5 PHYSISCAL PROPERTIES :

Invar is a 36% nickel iron alloy which has the lowest thermal expansion among all metals and

alloys in the range from room temperature up to approximately 230°C. The Invar alloy is

ductile and easily weldable, and machinability is similar to austenitic stainless steel. It does

not suffer from stress corrosion cracking.

The mean coefficient of thermal expansion (CTE) of Invar from 20-100°C is less than 1.3 x

10-6°C-1. The Curie point is 230°C, and density is 8.1 kg.m-3.

http://www.jlcelectromet.com/alloy364248.htmhttp://www.jlcelectromet.com/http://www.jlcelectromet.com/alloy364248.htmhttp://www.jlcelectromet.com/alloy364248.htmhttp://www.jlcelectromet.com/alloy364248.htmhttp://www.jlcelectromet.com/alloy364248.htmhttp://www.jlcelectromet.com/http://www.jlcelectromet.com/alloy364248.htm


20/56



3.2 Invar Alloy Properties

(Also know as Invar 36, NILO 36, Pernifer 36, and Invar Steel)

TABLE 2 :Invar Alloy Physical Properties

Density lb/cu in 0.291

Specific Gravity 8.05

Curie Temp °F 535

°C 279

Melting Point °F 2600

°C 1427

Electrical Resistivity Micro-ohm-cm 84

Micro-ohm-cm 495

Thermal Conductivity W/cm °C 0.10

BTU-in/sq. ft-hr- 72.6

Specific Heat Cal/g- °C 0.123

BTU/lbm- °F 0.123

Thermal Expansion ppm/°F (75°F to 842°F) 4.9

ppm/°C (25°C to 450°F) 8.9

TABLE 3 :Invar Alloy Mechanical Properties

Tensile Strength

Ksi 75

MPa 518

Yield Strength Ksi 40

MPa 276

Elongation % in 2 in. 34

Typical Hardness Ann. Rockwell HRB 80

Modulus of Elasticity Mpsi 20.5

kMPa 141


21/56



TABLE 4 :Invar Alloy Chemistry maximum % unless noted

Iron Bal

Nominal Nickel 36

Nominal Cobalt 0.5

Carbon 0.05

Silicon 0.40

Sulfur 0.015

Chromium 0.25

TABLE 5 :Invar Alloy Linear Coefficient of Thermal Expansion

Degree C Degree C

30-100 0.8 - 1.6 30-450 8.5 - 9.2

30-150 -- 30-475 --

30-200 1.3 - 2.1 30-500 9.7

30-250 -- 30-525 --

30-300 4.92 30-550 --

30-325 -- 30-600 11.4

30-350 6.2 - 7.0 30-700 12.7

30-375 -- 30-800 13.5

30-400 7.8 30-900 13.9

30-425 -- 30-1000 --


22/56



CHAPTER-04

4.1 AIR GAP PISTON :

Air gap insulated pistons are generally used in diesel engines to keep the combustionchamber at optimum high temperature. The air gap in between piston crown and piston body

has low thermal conductivity. Due to this, the temperature in the piston crown is high, when

compared to conventional piston. Due to this surface temperature of the combustion chamber

is very high, the air inducted into the combustion chamber is rapidly exposed to high

temperature and it is more than the conventional piston. When the air is inducted to the

combustion chamber its temperature is raised because of the average temperature of the

combustion chamber is raised. Due to this the fuel which is injected in to the combustionchamber attains the self ignition temperature quickly and so the combustion occurs smoothly.

The pressure rise in the uncontrolled combustion is very less and the maximum temperature

of the cycle is comparatively less. The complete burning of fuel occurs smoothly in the

controlled phase. K. Kumarasekaran et al 1 made a novel design of an air gap insulated piston

has been proposed which is expected to give a larger life compared to the existing designs.

The new composite piston is made of a crown piece which is fitted to the base of a piston

through a gasket by an interference fitting and locked by oral shaped riveted radially

Fig 10: Air Gap Piston


23/56



The air gap piston has a conventional skirt and ring pack together with a crown piece

whose contact with the piston body is arranged to provide adequate mechanical strength with

the minimum of conductive heat transfer. At relatively low temperatures, heat transmission

across the air gap is controlled by conduction and convection at a very low level. However, as

the temperature of the crown rises, radiative heat transfer becomes predominant, and in the

most advanced designs special precautions have to be taken to minimize this. From the

operational viewpoint the location of the principal insulating region in the piston is very

important. According to the principles set out. If the insulation can be situated above the ring

pack later can operate at normal, or even reduced, temperature relative to an insulated piston.

4.2 Some of the merits by using air gap insulated piston are:

4.2.1 Reduction of Delay Period: Due to the average temperature in combustion chamberincreases, the air temperature which is inducted into the chamber also increases which helps

the fuel to attain self ignition temperature quickly and mixes with air readily and atomized

easily.

4.2.2 Reducing the Emission: As we know that if the delay period is lowered, the complete

combustion occurs smoothly which results in reduction of emission.. The overall combustion

is dominated by the controlled phase for combustion. The premixed combustion resulting

from the shorter delay period, lower the CO, HC and SMOKE emission and even reduces the particulate emissions.

4.2.3 Reduction in Noise level: It is clear that the overall combustion is dominated by the

controlled phase of combustion. So the abnormal pressure rise due to uncontrolled

combustion is minimized and the knocking is reduced. This helps engine to run smoothly

without noise.

4.2.4 Fuels with higher viscosity can be used: The air inducted during the suction stroke is

exposed to the walls of the combustion chamber. This raises the air temperature that helps the

atomization and mixing fuels. So, the fuels with high viscosity can also be used.

4.2.5 Increase in thermal efficiency: The conduction through the piston is desirably

reduced. This increases the thermal efficiency of the cycle.

4.3 MANUFACTURING OF PISTON

The manufacturing process of pistons has changed considerably since the inception of the

internal combustion motor. Modern piston manufacturing is fully automated with little or no

human intervention. This is not the case with JP Pistons. JP Pistons strength lies in our


24/56



ability to manufacture very low numbers of pistons at a time (for example, 10-20). This

ability means that we do not, and cannot, compete with the massive automated facilities of

the manufacturers of mass produced pistons for modern vehicles. It also means that they

cannot do what we do either. What is laid out below is the way that we make pistons. We use

many modern manufacturing processes, but also older methodologies which ensures our

position as a niche manufacturer.

4.3.1 FoundryThe foundry is the beginning of the piston. At the foundry the die is prepared by heating it to

operating temperature for approximately one hour. This process allows the die to readily

accept the molten material when it is poured.

Fig 11 : METAL POURING INTO CAST

The material used is a 10% silicon content aluminium.


25/56



Fig 12 : DIE USED IN CASTING

The dies used are 5 piece and three piece. These dies are made from cast iron with steel

inserts for the gudgeon pin holes and the cores. The cores dictate the placement of the

gudgeon pin and can be located to give offset pins or square pins

Fig 13 : PROCESS OF REMOVAL

The process starts by heating the material to 700 degrees Celsius. This is well above the

melting point of the aluminium, but below its boiling point. The material is then scooped up

with a ladle from the crucible (the pot that holds the molten material). This is then poured

into the die through the sprue. The material is then allowed to cool before it is removed from


26/56



the die and placed into a bin of hot water. This water is used to facilitate a more even settling

of the hot metal. After the castings have had time to cool they are placed into a heat treatment

plant overnight. This process tempers the casting and ensures the piston will have improved

qualities.

After it is removed from the heat treatment the casting has its runner removed.

This process takes little time and is fully automated.

Fig 14 : RUNNER

4.3.2 PIN BORING

At this stage of the piston manufacturing process the casting has the gudgeon pin hole rough

machined and the locating bung machined. The bung . This process is where the casting is

machined on the base to allow placement of the casting in other machines. This is carried out

on a simple lathe.

Fig 15 : PIN BORING


27/56



Pin boring is done in conjunction with the bung turning, as one casting is removed from

having the bung face machined it is placed on the pin borer. The pin borer is only a rough

machining process which allows the reamer to enter the gudgeon hole later.

4.3.3 CNC Turning

Turning of the casting is carried out on CNC (Computer Numeric Control) machinery.

This equipment is the most accurate and fastest available for this application with very tight

tolerances and extremely fast spindle speeds. The castings are placed in the lathe on a bung

and held in place by a solid rod through the gudgeon pin hole. A draw bolt is activated in the

chuck which draws the rod toward the chuck and holds the piston in place.

The lathe is then started and the machining cycle begun. This cycle is programmed

into the lath in a basic language called G-Code (this code is not the only one available). G-

Code has basic commands to tell the lathe to move to certain positions (X,Y,Z co-ordinates),

Fig 16 : CNC MACHINING

at particular spindle speeds (eg S2500 means spindle speed 2500rpm), at particular feed rates

(eg G01; rapid traverse) and other commands such as M01 (repeat programme) and

others. As you can see this is a simple system to learn and implement. After the piston is

machined it is removed from the lathe and the part number stamped on the crown (top) of the

piston.


28/56



Fig 17 : FINISHING PROCESS

The piston is now ready for the finishing processes.

4.4 FINISHING PROCESS

The first stages of the finishing process include drilling, slotting, valve and crank relieving.

4.4.1Drilling

Drilling includes all oil holes in places such as the gudgeon pin bosses and oil ring grooves.

4.4.2 Slotting

Slotting is where slots are placed in the skirt or in the oil ring groove.

4.4.3 Valve relieving

This process is done on a mill and invloves setting the machine up for the process, choosing

the correct cutter and completing the job. Since there are so many different types of valve

reliefs it is impossible to have a specialised machine set up to do one job.

4.4.4 Crank relieving

Crank releiving is carried out on a specialised machine which scallops the skirt of the piston

to the required shape and depth by using two opposed cutters placed on a common shaft.


29/56



4.4.5 Grinding

This process involves the final size being machined on the piston. The grinder machines the

skirt of the piston only and in the majority of cases is cam ground. Cam grinding ensures the

piston will "grow" evenly in the bore of the engine. A perfectly round piston will expandunevenly during use because of the uneven placement of material in the casting (gudgeon pin

bosses and ribbing used for strenghtening).

Fig 18 : Grinding

4.4.6 Reaming :

The final machining process for the piston is that of reaming. This process involves the piston

being placed in a bath of oil and reamed at different sizes to reach the final size required.

Since the pin boring process is only rough it is necessary to ream the pin bore a number of

times to achieve the surface finish and size required. Reaming is not a fast process and is only

partially automated (there are automatic feeds on the reaming machines). Tolerances

achieved on the finished reamed surface is 0.4Ra.

Fig 19 : Reaming


30/56



4.4.7 Pin Fitting and Final Inspection

At this stage the piston is cleaned, fitted with the appropriate gudgeon pin, stamped with the

pistons' oversize and any other markings, and then sent to despatch.

Fig 20 : Pin Fitting and Final Inspection

4.5 CALCULATIONS FOR PISTON DESIGN:

The Physical and material properties of Aluminum Alloy are given below: [4]

Density – 2770 (Kg/m3)

Poisson Ratio – 0.33

Young Modulus – 7.1x1010 (Pa)

Tensile Ultimate Strength – 3.1x108(Pa)

Tensile Yield Strength – 2.8x108(Pa)

Compressive Yield strength – 2.8 x108(Pa)

Calculations : Analytical Design

mp = mass of the piston (Kg)

V = volume of the piston (mm3)

th = thickness of piston head (mm)

D = cylinder bore (mm)

pmax = maximum gas pressure or explosion pressure (MPa)

σt = allowable tensile strength (MPa)

σut = ultimate tensile strength (MPa)

F.O.S = Factor of Safety = 2.25

k = thermal conductivity =174.15(W/m C)

Tc = temperature at the centre of the piston head (0C)


31/56



Te = temperature at the edge of the piston head (0C)

HCV = Higher Calorific Value of fuel (KJ/Kg) = 47000 KJ/Kg (petrol)

BP = brake power of the engine per cylinder (KW) =4KW. Value obtained experimentally

considering the following conditions. N=1500rpm, Compression Ratio (rc) =16.5, fully

loaded condition.

m = mass of fuel used per brake power per second (Kg/KW s) =0.25/3600 (Kg/KW s).Value

obtained experimentally considering the following conditions:B.P=4KW, CV=47000Kj/kg

(petrol), N=1500, fully loaded condition.

C = ratio of heat absorbed by the piston to the total heat developed in the cylinder = 5% or

0.05

b = radial thickness of ring (mm)

Pw = allowable radial pressure on cylinder wall (N/mm2) = 0.042 MPa

h2 = axial thickness of piston ring (mm)

t1 = thickness of piston barrel at the top end (mm)

t2 = thickness of piston barrel at the open end (mm)

do = outer diameter of piston pin (mm)

Engine Specifications:

Engine make: Kirloskar

Bore Diameter: 80mm

Stroke Length: 110mm.

Calculation of Dimensions Of Piston For Analysis:[8]

Thickness of Piston Head (tH) : The piston thickness of piston head calculated using the

following Grashoff’s formula,

tH =D √ (3p)/ (16σt) in mm

P= maximum pressure in N/mm²=8 N/mm².

This is the maximum pressure that Aluminium alloy can withstand.D= cylinder bore/outside diameter of the piston in mm= 80mm.

σt=permissible tensile stress for the material of the piston.

= σt =280/2.25=124.4 MPa.

tH= 8.9mm.

Heat Flow through the Piston Head (H)

The heat flow through the piston head is calculated using the formula

H = 12.56*tH * k * (Tc-Te) KJ/secWhere


32/56



k=thermal conductivity of material which is 174.15W/mC

Tc = temperature at center of piston head in °C.

Te = temperature at edges of piston head in °C.

(Tc-Te)=75°C for Aluminium alloy.

On the basis of the heat dissipation, the thickness of the piston head is given by:

H = [C x HCV x m x BP]

= 0.05 x 47000 x 0.25/3600 x 4

=0.6527 KJ/s

tH = H/(12.56 x k (Tc – Te))

= Hx1000/12.56 x 174.15 x 75

=3.98mm.

Comparing both the dimensions, for design purpose we will be considering the maximum

thickness, hence required thickness of piston head is 8.9mm.

Radial Thickness of Ring (t1):

t1 = D√3pw/σt

Where,

D = cylinder bore in mm=80mm.

Pw= pressure of fuel on cylinder wall in N/mm². Its value is limited from 0.025N/mm² to

0.042N/mm². Here Pw value is taken as 0.042N/mm² while σt= 124.4Mpa for aluminum

alloy.

(t1): 3mm.

Axial Thickness of Ring (t2)

The thickness of the rings may be taken as

t2 = 0.7t1 to t1

=0.7 t1=2.1mm.

Number of rings (nr)

Minimum axial thickness (t2)

t2= D/( 10*nr )

nr = 3.86 or 4 rings.

Width of the top land (b1)

The width of the top land varies from

b1 = tH to 1.2 tH

=1.2 tH = 1.2 x8.9 =10.68mm.


33/56



Width of other lands (b2):

Width of other ring lands varies from

b2 = 0.75t2 to t2

=0.75 t2= 0.75x2.1=1.575mm.

Maximum Thickness of Barrel at the top end (t3):

Radial depth of the piston ring grooves (b) is about 0.4 mm more than radial thickness of the

piston rings(t1),therefore

b = 0.4 +t1 =0.4+3 =3.4 mm

t3 = 0.03*D + b + 4.5 mm

t3=0.03*80+3.4+4.9=10.7mm.

Thickness of piston barrel at the open end (t4):

t4= 0.25 t1 to 0.35 t1)

t4=0.25*10.7=2.675mm

Piston pin diameter (do):

do=0.03D=24mm.

Theoretical Stress Calculation:

The piston crown is designed for bending by maximum gas forces Pzmax as uniformly loaded

round plate freely supported by a cylinder. The stress acting in MPa on piston crown:

σb=Mb/Wb=Pzmax(ri/δ)2

Where ,

Mb = (1/3) Pzmax ri3 is the bending moment, MN m;

Wb = (1/3) riδ2 is the moment of resistance to bending of a flat crown, m3;

Pzmax = Pz , is the maximum combustion pressure, MPa;=5Mpa.

This value varies from 2Mpa-5Mpa in case of aluminium alloy.

ri = [D / 2 - (s + t1 + dt)] is the crown inner radius, m.;

Where, Thickness of the sealing part s = 0.05D= 0.05X80=4mm.

Radial clearance between piston ring and channel :dt= 0.0008m

Radial thickness of ring (t1) =3mm.

Therefore, ri=[0.08/2-(0.004+0.003+0.0008)]=0.0322m

Thickness of piston crown δ=(0.08 to 0.1)XD= 0.085X80=7mm.

σb= 5X[(0.0322/0.007)^2] Mpa= 105.8Mpa.

Hence required theoretical stress obtained from calculation is 105.8Mpa.


34/56



CHAPTER-05

5.1 INTRODUCTION TO PRO-ENGINEER WILDFIRE 5.0

PTC Creo, formerly known as Pro/ENGINEER , is a 3D CAD/CAM/CAE feature- based,associative solid modeling software. It is one of a suite of 10 collaborative applications

that provide solid modeling, assembly modelling, 2D orthographic views, finite element

analysis, direct and parametric modeling , subdivisional and NURBS surfacing , and NC and

tooling for mechanical designers.

Creo Elements/Parametric compete directly with Solidworks, CATIA, and NX/Solid Edge. It

was created by Parametric Technology Corporation (PTC) and was the first of its kind to

market. The application runs on Microsoft Windows.

The UNIX version was discontinued after 4.0,[2] except x86 64 UNIX on Solaris.[3]The name

changed to Creo 1.0 after Pro/ENGINEER Wildfire 5.0 (rebranded PTC Creo

Elements/Pro),[4] took place on October 28, 2010, which coincided with PTC’s announcement

of Creo, a new design software application suite. Creo Elements/Pro will be discontinued

after version 2 in favor of the Creo design suite.

Creo Elements/Pro (formerly Pro/ENGINEER), PTC's parametric, integrated 3D

CAD/CAM/CAE solution, is used by discrete manufacturers for mechanical engineering,

design and manufacturing.

Pro/ENGINEER was the industry's first rule-based constraint (sometimes called "parametric"

or "variational") 3D CAD modeling system.[5] The parametric modeling approach uses

parameters, dimensions, features, and relationships to capture intended product behavior and

create a recipe which enables design automation and the optimization of design and product

development processes. This design approach is used by companies whose product strategy is

family-based or platform-driven, where a prescriptive design strategy is fundamental to the

success of the design process by embedding engineering constraints and relationships to

quickly optimize the design, or where the resulting geometry may be complex or based upon

equations. Creo Elements/Pro provides a complete set of design, analysis and manufacturing

capabilities on one, integral, scalable platform. These required capabilities include Solid

Modeling, Surfacing, Rendering, Data Interoperability, Routed Systems Design, Simulation,

Tolerance Analysis, and NC and Tooling Design.

https://en.wikipedia.org/wiki/3D_modelinghttps://en.wikipedia.org/wiki/CADhttps://en.wikipedia.org/wiki/Computer-aided_manufacturinghttps://en.wikipedia.org/wiki/Computer-aided_engineeringhttps://en.wikipedia.org/wiki/Solid_modelinghttps://en.wikipedia.org/wiki/Solid_modelinghttps://en.wikipedia.org/wiki/Assembly_modellinghttps://en.wikipedia.org/wiki/Technical_drawinghttps://en.wikipedia.org/wiki/Finite_element_analysishttps://en.wikipedia.org/wiki/Finite_element_analysishttps://en.wikipedia.org/wiki/Mechanical_engineeringhttps://en.wikipedia.org/wiki/PTC_Creohttps://en.wikipedia.org/wiki/SolidWorkshttps://en.wikipedia.org/wiki/CATIAhttps://en.wikipedia.org/wiki/Siemens_NXhttps://en.wikipedia.org/wiki/Solid_Edgehttps://en.wikipedia.org/wiki/Parametric_Technology_Corporationhttps://en.wikipedia.org/wiki/Microsoft_Windowshttps://en.wikipedia.org/wiki/UNIXhttps://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-2https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-2https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-2https://en.wikipedia.org/wiki/X86-64https://en.wikipedia.org/wiki/UNIXhttps://en.wikipedia.org/wiki/Solaris_(operating_system)https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-3https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-3https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-4https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-4https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-4https://en.wikipedia.org/wiki/Creo_(design_software)https://en.wikipedia.org/wiki/Parametric_Technology_Corporationhttps://en.wikipedia.org/wiki/Mechanical_engineeringhttps://en.wikipedia.org/wiki/3D_CADhttps://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-5https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-5https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-5https://en.wikipedia.org/wiki/Parametric_feature_based_modelerhttps://en.wikipedia.org/wiki/Numerical_controlhttps://en.wikipedia.org/wiki/Numerical_controlhttps://en.wikipedia.org/wiki/Parametric_feature_based_modelerhttps://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-5https://en.wikipedia.org/wiki/3D_CADhttps://en.wikipedia.org/wiki/Mechanical_engineeringhttps://en.wikipedia.org/wiki/Parametric_Technology_Corporationhttps://en.wikipedia.org/wiki/Creo_(design_software)https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-4https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-3https://en.wikipedia.org/wiki/Solaris_(operating_system)https://en.wikipedia.org/wiki/UNIXhttps://en.wikipedia.org/wiki/X86-64https://en.wikipedia.org/wiki/PTC_Creo_Elements/Pro#cite_note-2https://en.wikipedia.org/wiki/UNIXhttps://en.wikipedia.org/wiki/Microsoft_Windowshttps://en.wikipedia.org/wiki/Parametric_Technology_Corporationhttps://en.wikipedia.org/wiki/Solid_Edgehttps://en.wikipedia.org/wiki/Siemens_NXhttps://en.wikipedia.org/wiki/CATIAhttps://en.wikipedia.org/wiki/SolidWorkshttps://en.wikipedia.org/wiki/PTC_Creohttps://en.wikipedia.org/wiki/Mechanical_engineeringhttps://en.wikipedia.org/wiki/Finite_element_analysishttps://en.wikipedia.org/wiki/Finite_element_analysishttps://en.wikipedia.org/wiki/Technical_drawinghttps://en.wikipedia.org/wiki/Assembly_modellinghttps://en.wikipedia.org/wiki/Solid_modelinghttps://en.wikipedia.org/wiki/Solid_modelinghttps://en.wikipedia.org/wiki/Computer-aided_engineeringhttps://en.wikipedia.org/wiki/Computer-aided_manufacturinghttps://en.wikipedia.org/wiki/CADhttps://en.wikipedia.org/wiki/3D_modeling


35/56



Creo Elements/Pro can be used to create a complete 3D digital model of manufactured goods.

The models consist of 2D and 3D solid model data which can also be used downstream

in finite element analysis, rapid prototyping, tooling design, and CNC manufacturing. All

data are associative and interchangeable between the CAD, CAE and CAM modules

without conversion. A product and its entire bill of materials (BOM) can be modeled

accurately with fully associative engineering drawings, and revision control information. The

associativity functionality in Creo Elements/Pro enables users to make changes in the design

at any time during the product development process and automatically update downstream

deliverables. This capability enables concurrent engineering – design, analysis and

manufacturing engineers working in parallel – and streamlines product development

processes.

5.2 SUMMARY OF CAPABILITIES :

Creo Elements/Pro is a software application within the CAID/CAD/CAM/CAE category.

Creo Elements/Pro is a parametric, feature-based modeling architecture incorporated into a

single database philosophy with advanced rule-based design capabilities. It provides in-depth

control of complex geometry, as exemplified by the trajpar parameter. The capabilities of the

product can be split into the three main headings of Engineering Design, Analysis and

Manufacturing. This data is then documented in a standard 2D production drawing or the 3D

drawing standard ASME Y14.41-2003.

5.2.1 PRODUCT DESIGN

Creo Elements/Pro offers a range of tools to enable the generation of a complete digital

representation of the product being designed. In addition to the general geometry tools there

is also the ability to generate geometry of other integrated design disciplines such as

industrial and standard pipe work and complete wiring definitions. Tools are also available tosupport collaborative development.

A number of concept design tools that provide up-front Industrial Design concepts can then

be used in the downstream process of engineering the product. These range from conceptual

Industrial design sketches, reverse engineering with point cloud data and comprehensive free-

form surface.

https://en.wikipedia.org/wiki/Finite_element_analysishttps://en.wikipedia.org/wiki/Rapid_prototypinghttps://en.wikipedia.org/wiki/Data_conversionhttps://en.wikipedia.org/wiki/Bill_of_materialshttps://en.wikipedia.org/wiki/Engineering_drawinghttps://en.wikipedia.org/wiki/Concurrent_engineeringhttps://en.wikipedia.org/wiki/Trajparhttps://en.wikipedia.org/wiki/Production_drawinghttps://en.wikipedia.org/wiki/ASME_Y14.41-2003https://en.wikipedia.org/wiki/Pipinghttps://en.wikipedia.org/wiki/Pipinghttps://en.wikipedia.org/wiki/ASME_Y14.41-2003https://en.wikipedia.org/wiki/Production_drawinghttps://en.wikipedia.org/wiki/Trajparhttps://en.wikipedia.org/wiki/Concurrent_engineeringhttps://en.wikipedia.org/wiki/Engineering_drawinghttps://en.wikipedia.org/wiki/Bill_of_materialshttps://en.wikipedia.org/wiki/Data_conversionhttps://en.wikipedia.org/wiki/Rapid_prototypinghttps://en.wikipedia.org/wiki/Finite_element_analysis


36/56



5.3 DESIGN PROCEDURE FOR AIR GAP PISTON

5.3.1 Design of PISTON

The following steps are used in modeling of piston in pro-e wildfire 5.0

Step 1: Open pro-e wildfire 5.0 software ,select a new file and windows opens then select part

and click ok

Step 2: Go to status bar ,select insert and go to helical sweep-click protrusion


37/56



Step 3: In attribute window select variable pitch ,thru axis, choose right handed and click

done

Step 4: Select the front plane and click okay in the direction window (menu manager)

Step 5: Now select default in the sketch view (menu manager)

Step 6: Take reference line on the plane using line (reference) command


38/56



Step 7: Draw a line with 25mm center of the point.

Step 8: Draw an arc in the end of the line and the arc distance is 25mm.

Step 9: Then below of the line 5mm thickness draw another arc.

Step 10: Then second end of the arc line draw a line with 15mm.

Step 11: Then the extra line will be trim by trim option

Step 12: Draw line 15mm and divide 3mm slots for piston rings.

Step 13: Then select line option draw16mm a line from end of the piston ring slot


39/56



Step 14: At end point of this line draw a arc of 15mm radius for the piston ring.

Step 15: Then select line option draw7mm a vertical line from end of the piston ring slot

Step 16 : At end of this line draw a slot of 5mm for spring ring.


40/56



Step 17: Then select line option draw15mm a vertical line from end of the piston ring slot

this line ends the bottom end of the piston

Step 20 :The wall thickness 10mm select the extrude option ,reveled with 80mm dia.


41/56



Step 21 : At last the get 80mm dia ,110mm length and 10mm wall thickness piston with 4

rings slots .

5.3.2DESIGN OF PISTON PLATE:

Step 1 : draw a line 16mm on center of the point .

Step 2: draw a arc with distance of 25mm and draw a another arc with 5mm distance .

Step 3 : draw a 15mm line .

Step 4: draw a 9mm thickness and extrude 5mm

Step 5: revolved the option and finally it get the piston plate.


42/56



CHAPTER-06

6.1 INTRODUCTION TO ANSYS 14.0

ANSYS is general-purpose finite element analysis (FEA) software package. FiniteElement Analysis is a numerical method of deconstructing a complex system into very small

pieces (of user-designated size) called elements. The software implements equations that

govern the behavior of these elements and solves them all creating a comprehensive

explanation of how the system acts as a whole. These results then can be presented in

tabulated, or graphical forms. This type of analysis is typically used for the design and

optimization of a system far too complex to analyze by hand. Systems that may fit into this

category are too complex due to their geometry, scale, or governing equations.ANSYS is the standard FEA teaching tool within the Mechanical Engineering

Department at many colleges. ANSYS is also used in Civil and Electrical Engineering, as

well as the Physics and Chemistry departments.

ANSYS provides a cost-effective way to explore the performance of products or

processes in a virtual environment. This type of product development is termed virtual

prototyping.

With virtual prototyping techniques, users can iterate various scenarios to optimize

the product long before the manufacturing is started. This enables a reduction in the level of

risk, and in the cost of ineffective designs. The multifaceted nature of ANSYS also provides a

means to ensure that users are able to see the effect of a design on the whole behavior of the

product, be it electromagnetic, thermal, mechanical etc.

6.2 GENERIC STEPS TO SOLVING ANY PROBLEM IN ANSYS

Like solving any problem analytically, you need to define (1) your solution domain,

(2) the physical model, (3) boundary conditions and (4) the physical properties. You then

solve the problem and present the results. In numerical methods, the main difference is an

extra step called mesh generation. This is the step that divides the complex model into small

elements that become solvable in an otherwise too complex situation. Below describes the

processes in terminology slightly more attune to the software.


43/56



6.2.1 Build Geometry

Construct a two or three dimensional representation of the object to be

modeled and tested using the work plane coordinate system within ANSYS.

6.2.2 Define Material Properties

Now that the part exists, define a library of the necessary materials that composes the

object (or project) being modeled. This includes thermal and mechanical properties.

6.2.3 Generate Mesh

At this point ANSYS understands the makeup of the part. Now define how the

modeled system should be broken down into finite pieces.

6.2.4 Apply Loads

Once the system is fully designed, the task is to burden the system with constraints,

such as physical loadings or boundary conditions.

6.2.5 Obtain Solution

This is actually a step, because ANSYS needs to understand within what state (steady

state, transient …etc.) the problem must be solved.

6.2.6 Present the Results

After the solution has been obtained, there are many ways to present ANSYS results,

choose from many options such as tables, graphs, and counter plots.

6.3 SPECIFIC CAPABILITIES OF ANSYS

6.3.1 Structural

Structural analysis is the most probably the most common application of the finite

element method as it implies bridges and buildings, naval, aeronautical and mechanical

structures such as ship hulls, aircraft bodies and machine housings, as well as mechanical

components such as pistons, machine parts and tools.

6.3.1.1 Static Analysis

Used to determine displacements, stresses, etc. under static loading conditions. ANSYS


44/56



can compute both linear and nonlinear static analyses. Nonlinearities can include plasticity,

stress stiffening, large deflection, Large strain, hyper elasticity, contact surfaces and creep.

6.3.1.2 Modal Analysis

A modal analysis is typically used to determine the vibration characteristics (natural

frequencies and mode shapes) of a structure or a machine component while it is being

designed. It can also serve as a starting point for another, more detailed, dynamic analysis,

such as a harmonic response or full transient dynamic analysis.

Modal analyses, which being one of the most basic dynamic analysis types available

in ANSYS, can also be more computationally time consuming than a typical static analysis.

A reduced solver, utilizing automatically or manually selected master degrees of freedom isused to drastically reduce the problem size and solution time.

6.3.1.3 Harmonic Analysis

Used extensively by companies who produce rotating machinery, ANSYS Harmonic

analysis is used to predict the sustained dynamic behavior of structures to consistent cyclic

loading. Examples of rotating machines which produced or are subjected to harmonic loading

are:

Gas turbines for Aircraft and Power Generation

Steam Turbines

Wind Turbines

Water Turbines

Turbo-pumps

Internal Combustion engines

Electric motors and generators Gas and fluid pumps

Disc drives

A harmonic analysis can be used to verify whether or not a machine design will

successfully overcome resonance, fatigue and other harmful effects of forced vibrations.

Transient Dynamic Analyses – Used to determine the response of a structure to

arbitrarily time varying loads. All nonlinearities mentioned under Static Analysis above areallowed.


45/56

MODELLING AND ANALYSIS OF AIR GAP

air gap piston design and analysis

Documents

Transcript of air gap piston design and analysis