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1 “In pursuit of Global Competitiveness” A PROJECT ON THERMAL ANALYSIS OF BRAKE DISCFor the degree of Bachelor of Engineering (Mechanical) 2014-2015 Submitted By Mr. PENGKAM KENGLANG LUNGCHANG(BE06F02F065) Mr. PARAG DESHATTIWAR (BE10F02F068) Mr. KAHANI MENJO (BE11F02F064) Mr. TOSHIF RUIKAR (BE11F02F046) Mr. SANJEET KUMAR (BE11F02F065) In partial fulfilment of Bachelor of Engineering (Mechanical Engineering) Under the guidance of Dr. R.K SHRIVASTAVA Department of Mechanical Engineering Government College of Engineering, Aurangabad (2014-2015)

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Page 1: Thermal analysis of brake disc   2015

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“In pursuit of Global Competitiveness”

A PROJECT ON

‘THERMAL ANALYSIS OF BRAKE DISC’

For the degree of Bachelor of Engineering (Mechanical)

2014-2015

Submitted By

Mr. PENGKAM KENGLANG LUNGCHANG(BE06F02F065)

Mr. PARAG DESHATTIWAR (BE10F02F068)

Mr. KAHANI MENJO (BE11F02F064)

Mr. TOSHIF RUIKAR (BE11F02F046)

Mr. SANJEET KUMAR (BE11F02F065)

In partial fulfilment of

Bachelor of Engineering

(Mechanical Engineering)

Under the guidance of

Dr. R.K SHRIVASTAVA

Department of Mechanical Engineering

Government College of Engineering, Aurangabad

(2014-2015)

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CERTIFICATE

This is to certify that, the seminar “THERMAL ANALYSIS OF BRAKE DISC”

submitted by Penkam K. Lungchang, Parag Deshattiwar, Toshif Ruikar, Kahani Menjo,

Sanjeet Kumar is a bona fide work completed under my supervision and guidance in partial

fulfilment for award of Bachelor of Engineering (Mechanical) Degree of Government College of

Engineering (An Autonomous Institute of Government of Maharashtra) affiliated to Dr.

Babasaheb Ambedkar Marathwada University, Aurangabad, Maharashtra.

Place: Aurangabad

Date:

Dr. R. K. Shrivastava

Guide & Head of Department,

Department of Mechanical Engineering,

Govt. College of Engineering,

Aurangabad

Dr. P. S. Adwani

Principal,

Government College of Engineering,

Aurangabad

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CONTENT

1. INTRODUCTION 1

2. LITERATURE REVIEW 2

3. BACKGROUND THEORY

3.1 BRAKING SYSTEM 4

3.2 HEAT TRANFERENCE 9

3.3 MATERIAL USED FOR BRAKE MANUFACTURING 10

3.4 MANUFACTURING PROCESS OF DISC BRAKE 12

4. FINITE ELEMENT METHOD

4.1 INTRODUCTION 15

4.2 GENERAL PROCEDURE 15

4.3 CONVERGENCE REQUIREMENT 17

4.4 ADVANTAGES OF FEM 18

4.5 LIMITATIONS OF FEM 18

4.6 APPLICATION OF FEM 18

5. FEA SOFWARE – ANSYS

5.1 INTRODUCTION 19

5.2 EVOLUTION OF FEA 20

5.3 OVERVIEW OF THE PROGRAM 20

5.4 REDUCING THE DESIGN & MANUFACTURING COST USING ANSYS 22

5.5 PROCEDURE FOR ANSYS ANALYSIS 23

5.6 BUILD THE MODEL 24

5.7 MATERIAL PROPERTIES 24

5.8 OBTAIN THE SOLUTION 24

6. DISC BRAKE CALCULATIONS

6.2 ASSUMPTION 28

6.2 CALCULATION FOR INPUT PARAMETER 28

6.3 ANALYTICAL TEMPERATURE RISE CALCULATIONS 30

7. FEM MODELS OF BRAKE DISC WITH MESHING 32

8. RESULT 35

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9. DISCUSSION 41

10. CONCLUSION 42

APPENDIX A

43

APPENDIX B 44

APPENDIX C 45

APPENDIX D 46

APPENDIX E 47

APPENDIX F 48

APPENDIX G 49

APPENDIX H 50

APPENDIX I 51

REFERENCE 52

ACKNOWLEDGEMENT 53

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LIST OF FIGURES

Fig.

no.

Description Page

no.

1. DISK BRAKING SYSTEM OF TWO WHEELER 6

2.1 MATERIAL ANALYSIS 11

2.2 INCLINED ROW DRILLED DISC 12

2.3 CURVED ROW OF DRILLED DISC 12

2.4 CROSSED ROW OF DRILLED DISC 13

2.5 SLOT DISC 13

2.6 SLOT AND DRILLED DISC 13

2.7 INCLINED ROW OF SLOTTED DISC 14

2.8 MINIMUM LIGMENT LENGTH FOR VARIOUS PATTERN 14

5.1 SCHEMATIC DIAGRAM OF A DISC BRAKE

7.1 MESHING OF MODEL 1 31

7.2 MESHING OF MODEL 2 32

7.3 MESHING OF MODEL 3 33

8.1 TEMPERATURE DISTRIBUTION PLOT FOR SS MODEL NO. 1 34

8.2 HEAT FLUX PLOT SS MODEL NO. 1 34

8.3 TEMPERATURE DISTRIBUTION PLOT SS MODEL NO. 2 35

8.4 HEAT FLUX PLOT SS MODEL NO. 2 35

8.5 TEMPERATURE DISTRIBUTION PLOT SS MODEL NO. 3 36

8.6 HEAT FLUX PLOT SS MODEL NO. 3 36

8.7 TEMPERATURE DISTRIBUTION PLOT CI MODEL NO. 1 37

8.8 HEAT FLUX PLOT CI MODEL NO. 1 37

8.9 TEMPERATURE DISTRIBUTION PLOT CI MODEL NO. 2 38

8.10 HEAT FLUX PLOT CI MODEL NO. 2 38

8.11 TEMPERATURE DISTRIBUTION PLOT CI MODEL NO. 3 39

8.12 HEAT FLUX PLOT CI MODEL NO. 3 39

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LIST OF TABLES

TABLE

NO.

DESCRIPTION PAGE

NO.

6.1 CALCULATION FOR INPUT PARAMETERS 30

6.2 MATERIAL PROPERTIES FOR STAINLESS STEEL AND CAST IRON 30

9.1 MAXIMUM AND MINIMUM TEMPERATURE DISTRIBUTION 40

9.2 MAXIMUM AND MINIMUM TOTAL HEAT FLUX 40

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LIST OF ABBREVIATION

ABBREVIATION ILLUSTRATION

FE FINITE ELEMENT

ANSYS ANALYSIS SYSTEM

CATIA COMPUTER AIDED THREE DIMENSIONAL INTERACTIVE

APPLICATION

HSS HIGH SPEED STEEL

SS STAINLESS STEEL

CI CAST IRON

M METER

W WATT

K KELVIN

Q HEAT FLUX

A SURFACE AREA

T TEMPERATURE

H ENTHALPY

FEA FINITE ELEMENT ANALYSIS

Ψ PSI

[K] STIFFNESS MATRIX

INC. INCORPORATED

U INITIAL VELOCITY

G ACCERLATION DUE TO GRAVITY

1-D ONE DIMENSIONAL

µ COEFFICIENT OF FRICTION

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ABSTRACT

Braking is a process which converts the kinetic energy of the vehicle into mechanical

energy which must be dissipated in the form of heat. The disc brake is a device for de-

accelerating or stopping the rotation of a wheel. A brake disc (or rotor) usually made of cast iron

or ceramic composites, is connected to the wheel and/or the axle. Friction material in the form of

brake pads (mounted on a device called a brake calliper) is forced mechanically, hydraulically,

pneumatically or electromagnetically against both sides of the disc to stop the wheel. The present

research is basically deals with the modelling and analysis of solid and ventilated disc brake

using Pro-E and ANSYS. Finite element (FE) models of the brake-disc are created using Pro-E

and simulated using ANSYS which is based on the finite element method (FEM). In this research

Coupled Analysis (Structural & Thermal analysis) is performed in order to find the strength of

the disc brake. In structural analysis displacement, ultimate stress limit for the design is found

and in thermal analysis thermal gradients, heat flow rates, and heat fluxes to be calculates by

varying the different cross sections, materials of the disc. Comparison can be done for

displacement, stresses, nodal temperatures, etc. for the three materials to suggest the best

material for FSAE car.

The disc brake is a device used for slowing or stopping the rotation of the vehicle.

Number of times using the brake for vehicle leads to heat generation during braking event, such

that disc brake undergoes breakage due to high Temperature. Disc brake model is done by

CATIA/PROE and analysis is done by using ANSYS workbench. The main purpose of this

project is to study the Thermal analysis of the Materials for the Cast Iron, and HSS M2. A

comparison between the four materials for the Thermal values and material properties obtained

from the Thermal analysis low thermal gradient material is preferred. Hence best suitable design,

low thermal gradient material Grey cast iron is preferred for the Disc Brakes for better

performance.

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1. INTRODUCTION

In today’s growing automotive market the competition for better performance vehicle is

growing enormously. The disc brake is a device used for slowing or stopping the rotation of the

wheel. A brake is usually made of cast iron or ceramic composites include carbon, aluminum,

Kevlar and silica which is connected to the wheel and axle, to stop the vehicle. A friction

material produced in the form of brake pads is forced mechanically, hydraulically, pneumatically

and electromagnetically against the both side of the disc. This friction causes the disc and

attached wheel to slow or to stop the vehicle. The methods used in the vehicle are regenerative

braking system and friction braking system. A friction brake generates the frictional force in two

or more surfaces rub against to each other, to reduce the movement. Based on the design

configurations vehicle friction brakes are grouped into disc brakes and drum brakes. Our project

is about disc brakes modeling and analysis.

Repetitive braking of a vehicle generates large amount of heat. This heat has to be

dissipated for better performance of brake. Braking performance largely affected by the

temperature rise in the brake components. High temperature may cause thermal cracks, brake

fade, wear and reduction in coefficient of friction.

During braking, the kinetic and potential energies of a moving vehicle get converted into

thermal energy through friction in the brakes. The heat generated between the brake pad & disc

has to be dissipated by passing air over them. This heat transfer takes place by conduction,

convection and somewhat by radiation. To achieve proper cooling of the disc and the pad by

convection, study of the heat transport phenomenon between disc, pad and the air medium is

necessary. Then it is important to analyze the thermal performance of the disc brake system to

predict the increase in temperature during braking. Convective heat transfer model has been

developed to analyze the cooling performance. Brake discs are provided with cuts to increase the

area coming in contact with air and improve heat transfer from disc.

In this paper two different cut patterns of brake disc are studied for heat transfer rate.

Heat transfer rate increases with number of cuts in the disc. This is because large area is exposed

to air which makes more heat transfer through conduction and convection. But increase in

number and size of cuts decreases the strength of disc.

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2. LITERATURE REVIEW

Gao and Lin (2002) presented Transient temperature field analysis of a brake in a non-

axisymmetric three-dimensional model [1]. The disk-pad brake used in an automobile is divided

into two parts: the disk, geometrically axisymmetric; and the pad, of which the geometry is

three-dimensional. Using a two-dimensional model for thermal analysis implies that the contact

conditions and frictional heat flux transfer are independent of y. This may lead to false thermal

elastic distortions and unrealistic contact conditions. An analytical model is presented in this

paper for the determination of the contact temperature distribution on the working surface of a

brake. To consider the effects of the moving heat source (the pad) with relative sliding speed

variation, a transient finite element technique is used to characterize the temperature fields of the

solid rotor with appropriate thermal boundary conditions. Numerical results shows that the

operating characteristics of the brake exert an essentially influence on the surface temperature

distribution and the maximal contact temperature.

Voller, et al.(2003) perform an Analysis of automotive disc brake cooling characteristics

[2]. The aim of this investigation was to study automotive disc brake cooling characteristics

experimentally using a specially developed spin rig and Singh and Shergill 85 numerically using

finite element (FE) and computational fluid dynamics (CFD) methods. All three modes of heat

transfer (conduction, convection and radiation) have been analyzed along with the design

features of the brake assembly and their interfaces. The influence of brake cooling parameters on

the disc temperature has been investigated by FE modelling of a long drag brake application. The

thermal power dissipated during the drag brake application has been analyzed to reveal the

contribution of each mode of heat transfer.

Choi and Lee, (2004) presented a paper on Finite element analysis of transient

thermoelastic behaviors in disk brakes [3]. A transient analysis for thermoelastic contact problem

of disk brakes with frictional heat generation is performed using the finite element method. To

analyze the thermoelastic phenomenon occurring in disk brakes, the coupled heat conduction and

elastic equations are solved with contact problems. The numerical simulation for the

thermoelastic behavior of disk brake is obtained in the repeated brake condition. The

computational results are presented for the distributions of pressure and temperature on each

friction surface between the contacting bodies.

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Qi and Day (2007) discussed that using a designed experiment approach, the factors

affecting the interface temperature, including the number of braking applications, sliding speed,

braking load and type of friction material were studied [4]. It was found that the number of

braking applications had the strongest effect on the friction interface temperature. The real

contact area between the disc and pad, i.e. pad regions where the bulk of the kinetic energy is

dissipated via friction, had a significant effect on the braking interface temperature. For

understanding the effect of real contact area on local interface temperatures and friction

coefficient, finite element analysis (FEA) was conducted, and it was found that the maximum

temperature at the friction interface does not increase linearly with decreasing contact area ratio.

This finding is potentially significant in optimizing the design and formulation of friction

materials for stable friction and wear performance.

Eltoukhy and Asfour (2008) present a paper on Braking Process in Automobiles:

Investigation of the Thermoelastic Instability Phenomenon. In this chapter a case study regarding

a transient analysis of the thermoelastic contact problem for disk brakes with frictional heat

generation, performed using the finite element analysis (FEA) method is described in details.

The computational results are presented for the distribution of the temperature on the friction

surface between the contacting bodies (the disk and the pad) [5]. Also, the influence of the

material properties on the thermoelastic behavior, represented by the maximum temperature on

the contact surface is compared among different types of brake disk materials found in the

literature, such as grey cast iron (grey iron grade 250, high-carbon grade iron, titanium alloyed

grey iron, and compact graphite iron (CGI)), Aluminum metal matrix composites (AlMMC's),

namely Al2O3 Al-MMC \and SiC Al-MMC (Ceramic brakes).

Zaid, et al. (2009) presented a paper on an investigation of disc brake rotor by Finite

element analysis. In this paper, the author has conducted a study on ventilated disc brake rotor of

normal passenger vehicle with full load of capacity [6]. The study is more likely concern of heat

and temperature distribution on disc brake rotor. In this study, finite element analysis approached

has been conducted in order to identify the temperature distributions and behaviors of disc brake

rotor in transient response. ABAQUS/CAE has been used as finite elements software to perform

the thermal analysis on transient response. Thus, this study provide better understanding on the

thermal characteristic of disc brake rotor and assist the automotive industry in developing

optimum and effective disc brake rotor.

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3. BACKGROUND THEORY

3.1. Braking system

A brake is a device by means of which artificial frictional resistance is applied to moving

machine member, in order to stop the motion of a machine. In the process of performing this

function, the brakes absorb either kinetic energy of the moving member or the potential energy

given up by objects being lowered by hoists, elevators etc. The energy absorbed by brakes is

dissipated in the form of heat. This heat is dissipated in to the surrounding atmosphere to stop the

vehicle, so the brake system should have the following requirements:

i. The brakes must be strong enough to stop the vehicle with in a minimum Distance in an

emergency.

ii. The driver must have proper control over the vehicle during braking and the vehicle must

not skid.

iii. The brakes must have good ant fade characteristics i.e. their effectiveness should not

decrease with constant prolonged application

iv. The brakes should have good anti-wear properties.

Based on mode of operation brakes are classified as follows:

1. Hydraulic brakes.

2. Electric brakes.

3. Mechanical brakes.

The mechanical brakes according to the direction of acting force may be sub divided into

the following two groups:

i. Radial brakes:

In these brakes the force acting on the brake drum is in radial direction. The radial brake

may be subdivided into external brakes and internal brakes.

ii. Axial brakes:

In these brakes the force acting on the brake drum is only in the axial direction. E.g. Disc

brakes, Cone brakes.

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3.1.1 Disc brakes:

A disc brake consists of a cast iron disc bolted to the wheel hub and a stationary housing

called caliper. The caliper is connected to some stationary part of the vehicle, like the axle casing

or the stub axle and is cast in two parts, each part containing a piston. In between each piston and

the disc, there is a friction pad held in position by retaining pins, spring plates etc. passages are

drilled in the caliper for the fluid to enter or leave each housing.

These passages are also connected to another one for bleeding. Each cylinder contains

rubber-sealing ring between the cylinder and piston. A schematic diagram is shown in the figure

(1).

. The disc brake is a wheel brake which slows rotation of the wheel by the friction caused

by pushing brake pads against a brake disc with a set of calipers. The brake disc (or rotor in

American English) is usually made of cast iron, but may in some cases be made of composites

such as reinforced carbon–carbon or ceramic matrix composites. This is connected to the wheel

and/or the axle. To stop the wheel, friction material in the form of brake pads, mounted on a

device called a brake caliper, is forced mechanically, hydraulically, pneumatically or

electromagnetically against both sides of the disc. Friction causes the disc and attached wheel to

slow or stop. Brakes convert motion to heat, and if the brakes get too hot, they become less

effective, a phenomenon known as brake fade. Disc-style brakes development and use began in

England in the 1890s. The first caliper-type automobile disc brake was patented by Frederick

William Lanchester in his Birmingham, UK factory in 1902 and used successfully on Lanchester

cars. Compared to drum brakes, disc brakes offer better stopping performance, because the disc

is more readily cooled. As a consequence discs are less prone to the “brake fade”; and disc

brakes recover more quickly from immersion (wet brakes are less effective). Most drum brake

designs have at least one leading shoe, which gives a servo effect. By contrast, a disc brake has

no self-servo effect and its braking force is always proportional to the pressure placed on the

brake pad by the braking system via any brake servo, braking pedal or lever, this tends to give

the driver better “feel” to avoid impending lockup. Drums are also prone to “bell mouthing”, and

trap worn lining material within the assembly, both causes of various braking problems.

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Figure (1) Disk Braking System of Two Wheeler

3.1.2 Break Pads

Brake pads convert the kinetic energy of the car to thermal energy by friction. Two brake

pads are contained in the brake caliper with their friction surfaces facing the rotor. When the

brakes are hydraulically applied, the caliper clamps or squeezes the two pads together into the

spinning rotor to slow/stop the vehicle. When a brake pad is heated by contact with a rotor, it

transfers small amounts of friction material to the disc, turning it dull gray. The brake pad and

disc (both now with friction material), then "stick" to each other, providing the friction that stops

the vehicle.

In disc brake applications, there are usually two brake pads per disc rotor, held in place

and actuated by a caliper affixed to a wheel hub or suspension upright. Although almost all road-

going vehicles have only two brake pads per caliper, racing calipers utilize up to six pads, with

varying frictional properties in a staggered pattern for optimum performance. Depending on the

properties of the material, disc wear rates may vary. The brake pads must usually be replaced

regularly (depending on pad material), and most are equipped with a method of alerting the

driver when this needs to take place. Some are manufactured with a small central groove whose

eventual disappearance through wear indicates that the pad is nearing the end of its service life.

Others are made with a thin strip of soft metal in a similar position that when exposed through

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wear causes the brakes to squeal audibly. Still others have a soft metal tab embedded in the pad

material that closes an electric circuit and lights a dashboard warning light when the brake pad

gets thin.

The different types of brake pads that are most commonly used can be found below.

1. Metallic pads – metallic pads are undoubtedly the most common variety of brake pads and are

found on many of today’s vehicles. A unique blend of different metals creates metallic brake

pads and they’re affordable, durable and offer good performance. They’re best installed on

small vehicles that don’t witness very aggressive driving.

2. Organic pads – organic pads are made up of organic materials like rubber, glass and resin

which as the binding agent. Asbestos was the material of choice in earlier years as it dissipated

heat well. However, the dust created was dangerous to health and the environment so it was

replaced by more natural materials. Unlike metallic pads, organic pads are lightweight and

produce very little noise. They’re ideal for small vehicles and vehicles that don’t see a lot of

aggressive driving. However, their softness means they wear out faster so more dust is

produced.

3. Ceramic pads – ceramic brake pads are recommended for high performance vehicles that

witness sharp turns, high speeds and frequent stops. Ceramic pads are the most expensive of

the brake pads that are available as a consequence of its high performance and this means that

they are usually found on performance or racing cars as their distinctive advantages are best

suited to these performance models.

3.3.1 Material used in brake pad

The five most important characteristics that are considered when selecting a break pad

material are as follows:

a) The materials ability to resist brake fade at increased temperatures

b) The effects of water on brake fade (all brakes are designed to withstand at least temporary

exposure to water)

c) The ability to recover quickly from either increased temperature or moisture

d) Service life as traded off vs. wear to the rotor

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e) The ability of the material to provide smooth, even contact with the rotor or drum (rather than

a material that breaks off in chunks or causes pits or dents)

Today, brake pad materials are classified as belonging to one of four principal categories,

as follows

a) Non-metallic materials - these are made from a combination of various synthetic substances

bonded into a composite, principally in the form of cellulose, aramid, PAN, and sintered glass.

They are gentle on rotors, but produce a fair amount of dust and have a short service life.

b) Semi-metallic materials - synthetics mixed with some proportion of flaked metals. These are

harder than non-metallic pads, and are more fade-resistant and longer lasting, but at the cost of

increased wear to the rotor/ drum which then must be replaced sooner. They also require more

force than non-metallic pads in order to generate braking torque.

c) Fully metallic materials - these pads are used only in racing vehicles, and are composed of

sintered steel without any synthetic additives. They are very long-lasting, but require even

more force to slow a vehicle and are extremely wearing on rotors. They also tend to be very

loud.

d) Ceramic materials - Composed of clay and porcelain bonded to copper flakes and filaments,

these are a good compromise between the durability of the metal pads and the grip and fade

resistance of the synthetic variety. Their principal drawback, however, is that unlike the

previous three types and despite the presence of the copper (which has a high thermal

conductivity), ceramic pads generally do not dissipate heat well, which can eventually cause

the pads or other components of the braking system to warp. However, because the ceramic

materials causes the braking sound to be elevated beyond that of human hearing, they are

exceptionally quiet.

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3.2. Heat transference:

When a system is at a different temperature than its surroundings, the Nature tries to

reach thermal equilibrium. To do so, as the second law of thermodynamics explains, the thermal

energy always moves from the system of higher temperature to the system of lower temperature.

This transfer of thermal energy occurs due to one or a combination of the three basic heat

transport mechanisms: Conduction, Convection and Radiation.

3.2.1. Conduction:

Is the transference of heat through direct molecular communication, i.e. by physical contact

of the particles within a medium or between mediums. It takes place in gases, liquids and solids.

In conduction, there is no flow of any of the material mediums.

The governing equation for conduction is called the Fourier’s law of heat conduction and it

express that the heat flow per unit area is proportional to the normal temperature gradient, where

the proportionality constant is the thermal conductivity:

Where q is the heat flux perpendicular to a surface of area A, [W]; A is the surface area through

which the heat flow occurs, [m2] ; k is the thermal conductivity, [W/(mK)]; T is the temperature,

[K] or [°C]; and x is the perpendicular distance to the surface traveled by the heat flux.

3.2.2. Convection :

Convection is the heat transfer by mass motion of a fluid, when the heated fluid moves

away from the heat source. It combines conduction with the effect of a current of fluid that

moves its heated particles to cooler areas and replace them by cooler ones. The flow can be

either due to buoyancy forces (natural convection) or due to artificially induced currents (forced

convection).

The equation that represents convection comes from the Newton’s law of cooling and is of the

form:

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Where h is the convective heat transfer coefficient [W/ (m2K)]; T∞ is the temperature of the

cooling fluid; and Ts is the temperature of the surface of the body.

3.2.3. Radiation :

In general, radiation is energy in the form of waves or moving subatomic particles.

Among the radiation types, we are specifically interested in the Thermal radiation. Thermal

radiation is heat transfer by the emission of electromagnetic waves from the surface of an object

due to temperature differences which carry energy away from the emitting object.

The basic relationship governing radiation from hot objects is called the Stefan-Boltzmann law:

Where ε is the coefficient of emissivity (=1 for ideal radiator); σ is the Stefan-Boltzmann

constant of proportionality (5.669E-8 [W/(m2K4)]); A is the radiating surface area; T1 is the

temperature of the radiator; and T2 is the temperature of the surroundings.

3.3. Material used for disc brake manufacturing

Properties to be considered

1. Coefficient of friction.

2. Wear rate.

3. Heat resistance.

4. Withstanding pressure.

5. Heat dissipation.

6. Thermal expansion.

7. Mechanical strength.

8. Moisture.

There have been two principal materials used for their production in recent years. Cast

Iron and Stainless Steel.

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3.3.1 Cast Iron:

Cast iron is very cheap to produce and produces very good friction coefficients but it is also

fragile, it is not compatible with many modern pad materials, particularly sintered pads, it is

heavy and of course it rusts. Grey cast iron discs can shatter and ductile cast iron is fragile, very

fickle with pads and in our experience can warp very easily. We distributed a range of discs

made from ductile cast iron for several years and had to return far too many that were warped.

The answer usually came back that the problem had occurred due to the use of inappropriate

pads but the truth is it happened far too often! Some companies still believe it is the right

material to use but there are just too many negatives and not enough positives.

3.3.2 Stainless Steel:

Stainless steel on the other hand, although a little more expensive has a lot more

positives. It doesn’t rust, or at least not to any great extent. It is very robust, it is tolerant to

almost all brake pads and particularly to sintered brake pads. It is highly resistant to wear, it

doesn’t shatter and it resists heat very well. When it was first used the friction coefficients were

not as good as cast iron and this convinces some that cast iron is still the right material. But I

asked a Brembo executive about it some years ago and he said, that was true 30 years ago but the

friction coefficients of stainless steel discs and sintered pads went past cast iron around 20 years

ago! As usual, for proof he pointed to the race results and pointed out that with the exception of

carbon discs in GP, every race bike fitted with Brembo brakes for the last 20 years or so had

used stainless steel discs not cast iron. Since they are the winning brakes in almost every major

championship year in year out it is difficult to argue. The exact specification they use has never

been released but it is made especially for them.

Graph 2.1: Material analysis

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3.4. Manufacturing process of disc brake

In modern days, the use of metal is vast and there are various methods of manufacturing a

product from only use of pure molten metal or from any other state of metal as well. When

considering the different methods of manufacturing, most popular methods used in large

industries are as follows:

i. Metal Casting

ii. Metal Cutting

iii. Metal Forming and shaping

iv. Fabrication and welding

The above mentioned are few that are used by industries to produce different products

that could make up a machine such as a vehicle, electronic components or other day to day

tools.

3.4.1. Different brake disc designs

Figure2.2: Inclined row drilled disc

Figure 2.3: Curved row of drilled disc

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Figure2.4: Crossed row of drilled disc

Figure2.5: Slot disc

Figure2.6: Slot and drilled disc

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Figure2.7: Inclined row of slotted disc

Figure 2.8: Minimum ligment length for various pattern

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4. FINITE ELEMENT METHOD

4.1 Introduction to finite element method:

The finite element method is a powerful tool to obtain the numerical solution of wide

range of engineering problem. The method is general enough to handle any complex shape or

geometry, for any material under different boundary and loading conditions. The generality of

the finite element method fits the analysis requirement of today’s complex engineering systems

and designs where closed form solutions of governing equilibrium equations are usually not

available. In addition, it is an efficient design tool by which designers can perform parametric

design studies by considering various design cases, (different shapes, materials, loads, etc.) and

analyze them to choose the optimum design.

The method originated in the aerospace industry as a tool to study stress in a complex

airframe structures. It grows out of what was called the matrix analysis method used in aircraft

design. The method has gained increased popularity among both researchers and practitioners.

The basic concept of finite element method is that a body or structure may be divided into small

elements of finite dimensions called “finite elements”. The original body or the structure is then

considered, as an assemblage of these elements connected at a finite number of joints called

nodes or nodal points.

4.2.General procedure of finite element method:

The finite element method is a method of piecewise approximation in which the

structure or body is divided into small elements of finite dimensions called finite elements and

then the original body or the structure is considered as an assemblage of these elements

connected at finite number of joints called nodal points or nodes. Since the actual variation of

field variables like displacement, stress, temperature, pressure or velocity inside the continuum

are not known, the variation of the field variable inside a finite element can be approximated by a

simple function. These approximation functions called interpolation models are defined in terms

of the values of the field variables of the nodes. The nodal values of the field variable are

obtained by solving the field equations, which are generally in the form of matrix equations.

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Once the nodal values are known, the approximating functions define the field variable

throughout the assemblage of elements.

The solutions of general continuum problems by the finite element method always follow

an orderly step-by-step process.

The step-by-step procedure for static structural problem can be stated as follows:

Step 1:- Description of Structure (Domain). The first step in the finite element method is to

divide the structure of solution region in to sub divisions or elements.

Step 2:- Selection of proper interpolation model. Since the displacement (field variable) solution

of a complex structure under any specified load conditions cannot be predicted exactly, we

assume some suitable solution, within an element to approximate the unknown solution. The

assumed solution must be simple and it should satisfy certain convergence requirements.

Step 3:- Derivation of element stiffness matrices (characteristic matrices) and load vectors. From

the assumed displacement model the stiffness matrix [K(e)] and the load vector P(e) of element

‘e’ are to be derived by using either equilibrium conditions or a suitable Variation principle.

Step 4:- Assemblage of element equations to obtain the equilibrium equations.

Since the structure is composed of several finite elements, the individual element

stiffness matrices and load vectors are to be assembled in a suitable manner and the overall

equilibrium equation has to be formulated as

[K]φ = P

Where [K] is called assembled stiffness matrix, Φ is called the vector of nodal

displacement and P is the vector or nodal force for the complete structure.

Step 5:- Solution of system equation to find nodal values of displacement (field variable). The

overall equilibrium equations have to be modified to account for the boundary conditions of the

problem. After the incorporation of the boundary conditions, the equilibrium equations can be

expressed as,

[K]φ = P

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For linear problems, the vector ‘φ’ can be solved very easily. But for non-linear

problems, the solution has to be obtained in a sequence of steps, each step involving the

modification of the stiffness matrix [K] and ‘φ’ or the load vector P.

Step 6:- Computation of element strains and stresses. From the known nodal displacements, if

required, the element strains and stresses can be computed by using the necessary equations of

solid or structural mechanics. In the above steps, the words indicated in brackets implement the

general FEM step-by-step procedure.

4.3. Convergence requirement:

The finite element method provides a numerical solution to a complex problem. It

may therefore be expected that the solution must converge to the exact formulation of the

structure. Hence as the mesh is made finer the solution should converge to the correct result and

this would be achieved if the following three conditions were satisfied by the assumed

displacement function.

1. The displacement function must be continuous within the element. Choosing polynomials for

the displacement model can easily satisfy this condition.

2. The displacement function must be capable of representing rigid body displacement of the

element. This is when the nodes are given such displacement corresponding to a rigid body

motion; the element should not experience and hence leads to zero nodal forces. The constant

terms in the polynomials used for displacement models would usually ensure this condition.

3. The displacement function must be capable of representing constant strain states within the

element. The reason for the requirement can be understood if we imagine the condition when

the body or structure is divided in to smaller and smaller elements. As these elements

approach infinitesimal size the strain in each element also approach constant strain states. For

one, two and three-dimensional elasticity problems the linear terms present in the polynomials

satisfy the requirement. However, in constant curvature instead of constant strains.

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4.4. Advantages of FEM:

The properties of each element are evaluated separately, so an obvious advantage is that

we can incorporate different material properties for each element. Thus almost any degree of

non-homogeneity can be included. There is no restriction on to the shape of medium; hence

arbitrary and irregular shapes cause no difficulty like all numerical approximations FEM is based

on the concept of description. Nevertheless as either the variations or residual approach, the

technology recognizes the multidimensional continuous but also requires no separate

interpolation process to extend the approximate solution to every point with the continuum.

One of the important advantages of FEM is that it makes use of boundary conditions in

the form of assembled equations. This is relatively an easy process and requires no special

technology. Rather than requiring every trial solution to satisfy boundary conditions, one

prescribes the conditions after obtaining the algebraic equations for individual’s finite elements.

4.5.Limitations in FEM:

FEM reached high level of development as solution technology; however the method

yields realistic results only if coefficient or material parameters that describe basic phenomena

are available.

The most tedious aspects of use of FEM are basic process of sub-dividing the continuum

of generating error free input data for computer.

4.6. Applications of FEM:

The finite element method was developed originally for the analysis of aircraft structures.

However, the general nature of its theory makes it applicable to wide variety of boundary value

problem in engineering. A boundary value problem is one in which a solution is sought in

domain or region of a body subject to the satisfaction of prescribed boundary conditions.

Finite element method is the best tool in investigation of aircraft structures involving static

analysis of wings, structures of rockets and missiles, dynamic analysis, response to random loads

and periodic loads. In mechanical design, stress concentration problems, stress analysis of

pressure vessels, dynamic analysis of mechanical linkages can be effectively dealt using finite

element method.

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The specific application of the finite element method in the three major categories of

boundary value problems, namely equilibrium of steady state or time independent problems,

Eigen value problems, and propagation or transient problems. In the equilibrium problems steady

state displacement or stress distribution is found for a solid mechanics problem, temperature or

heat flux distribution in the case of heat transfer problem. Referring to Eigen value problems in

solid mechanics or structural problem, natural frequencies, buckling loads and mode shapes are

found, stability of laminar flows is found if it is a fluid mechanics problem and resonance

characteristics are obtained if it is an electrical circuit problem, while for the propagation or

transient problem, the response of the body under time varying force is found in the area of solid

mechanics.

Finite element method finds its application in the field of civil engineering in carrying out

the static analysis of trusses, frames and bridges. The dynamic analysis of the structure is to

obtain natural frequencies, modes and response of the structures to periodic loads. Nuclear

engineering also uses finite element method concept in the static and dynamic characterization of

its systems such as nuclear pressure vessels, containment structure and dynamic response of

reactor component containment structures. Even the Biomedical engineering applies finite

element method, for impact analysis of skulls. Finite element method can be applied to analysis

of excavation, underground openings and dynamic analysis of dam reservoir systems, which

come under Geomechanics.

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5. FEA SOFTWARE – ANSYS

5.1. Introduction to ANSYS Program:

Dr. John Swanson founded ANSYS. Inc. in 1970 with a vision to commercialize the

concept of computer simulated engineering, establishing himself as one of the pioneers of Finite

Element Analysis (FEA). ANSYS Inc. supports the ongoing development of innovative

technology and delivers flexible, enterprise wide engineering systems that enable companies to

solve the full range of analysis problem, maximizing their existing investments in software and

hardware. ANSYS Inc. continues its role as a technical innovator. It also supports a process-

centric approach to design and manufacturing, allowing the users to avoid expensive and time-

consuming “built and break” cycles. ANSYS analysis and simulation tools give customers ease-

of use, data compatibility, multi-platform support and coupled field multi-physics capabilities.

5.2. Evolution of ANSYS Program:

ANSYS has evolved into multipurpose design analysis software program, recognized

around the world for its many capabilities. Today the program is extremely powerful and easy to

use. Each release hosts new and enhanced capabilities that make the program more flexible,

more usable and faster. In this way ANSYS helps engineers meet the pressures and demands

modern product development environment.

5.3. Overview of the program:

The ANSYS program is flexible, robust design analysis and optimization package. The

software operates on major computers and operating systems, from PCs to workstations and to

super computers. ANSYS features file compatibility throughout the family of products and

across all platforms. ANSYS design data access enables user to import computer aided design

models in to ANSYS, eliminating repeated work. This ensures enterprise wide, flexible

engineering solution for all ANSYS user.

User Interface: Although the ANSYS program has extensive and complex capabilities, its

organization and user-friendly graphical user interface makes it easy to learn and use.

There are four graphical methods to instruct the ANSYS program:

1. Menus

2. Dialog Boxes

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3. Tool bar

4. Direct input of commands.

Menus: Menus are groupings of related functions or operating the analysis program located in

individual windows. These include:

1. Utility menu

2. Main menu

3. Input window

4. Graphics window

5. Tool bar

6. Dialog boxes

Dialog boxes: Windows that present the users with choices for completing the operations or

specifying settings. These boxes prompt the user to input data or make decisions for a particular

function.

Tool bar: The tool bar represents a very efficient means for executing commands for the

ANSYS program because of its wide range of configurability. Regardless of how they are

specified, commands are ultimately used to supply all the data and control all program functions.

Output window: Records the ANSYS response to commands and functions

Graphics window: Represents the area for graphic displays such as model or graphically

represented results of an analysis. The user can adjust the size of the graphics window, reducing

or enlarging it to fit to personal preferences.

Input window: Provides an input area for typing ANSYS commands and displays program

prompt messages.

Main menu: Comprise the primary ANSYS functions, which are organized in pop-up side

menus, based on the progression of the program.

Utility menu: Contains ANSYS utility functions that are mapped here for access at any time

during an ANSYS session. These functions are executed through smooth, cascading pull down

menus that lead directly to an action or dialog box.

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Processors: ANSYS functions are organized into two groups called processors. The ANSYS

program has one pre-processor, one solution processor; two post processors and several auxiliary

processors such as the design optimizer. The ANSYS preprocessor allows the user to create a

finite element model to specify options needed for a subsequent solution. The solution processor

is used to apply the loads and the boundary conditions and then determine the response of the

model to them. With the ANSYS post processors, the user retrieves and examines the solutions

results to evaluate how the model responded and to perform additional calculations of interest.

Database: The ANSYS program uses a single, centralized database for all model data and

solution results. Model data (including solid model and finite element model geometry,

materials etc.) are written to the database using the processor. Loads and solution results data are

written using the solutions processor. Post processing results data are written using the post

processors. Data written to the database while using one processor are therefore available as

necessary in the other processors.

File format: Files are used, when necessary, to pass the data from part of the program to another,

to store the program to the database, and to store the program output. These files include

database files, the results file, and the graphics file and so on.

5.4. Reducing the design and manufacturing costs using ANSYS (FEA):

The ANSYS program allows engineers to construct computer models or transfer CAD

models of structures, products, components, or systems, apply loads or other design performance

conditions and study physical responses such as stress levels, temperature distribution or the

impact of vector magnetic fields. In some environments, prototype testing is undesirable or

impossible. The ANSYS program has been used in several cases of this type including

biomechanical applications such as hi replacement intraocular lenses. Other representative

applications range from heavy equipment components, to an integrated circuit chip, to the bit-

holding system of a continuous coal-mining machine. ANSYS design optimization enables the

engineers to reduce the number of costly prototypes, tailor rigidity and flexibility to meet

objectives and find the proper balancing geometric modifications. Competitive companies look

for ways to produce the highest quality product at the lowest cost. ANSYS (FEA) can help

significantly by reducing the design and manufacturing costs and by giving engineers added

confidence in the products they design. FEA is most effective when used at the conceptual

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design stage. It is also useful when used later in manufacturing process to verify the final design

before prototyping.

Program availability:

The ANSYS program operates on Pentium based PCs running on Wndows95 or

Windows NT and workstations and super computers primarily running on UNIX operating

system. ANSYS Inc. continually works with new hardware platforms and operating systems.

Analysis types available:

1. Structural static analysis.

2. Structural dynamic analysis.

3. Structural buckling analysis.

a) Linear buckling

b) Nonlinear buckling

4. Structural non linearity’s.

5. Static and dynamic kinematics analysis.

6. Thermal analysis.

7. Electromagnetic field analysis.

8. Electric field analysis

9. Fluid flow analysis

a) Computational fluid dynamics

b) Pipe flow

10. Coupled-field analysis

11. Piezoelectric analysis.

5.5. Procedure for ANSYS analysis:

Static analysis is used to determine the displacements, stresses, strains and forces in

structures or components due to loads that do not induce significant inertia and damping effects.

Steady loading in response conditions are assumed. The kinds of loading that can be applied in a

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static analysis include externally applied forces and pressures, steady state inertial forces such as

gravity or rotational velocity imposed (non-zero) displacements, temperatures (for thermal

strain). A static analysis can be either linear or nonlinear. In our present work we consider linear

static analysis.

The procedure for static analysis consists of these main steps:

1. Building the model.

2. Obtaining the solution.

3. Reviewing the results.

5.6. Build the model:

Figure 5.1 Schematic Diagram of a Disc brake

In this step we specify the job name and analysis title use PREP7 to define the element

types, element real constants, material properties and model geometry element types both linear

and non-linear structural elements are allowed. The ANSYS element library contains over 80

different element types. A unique number and prefix identify each element type. E.g. BEAM 3,

PLANE 55, SOLID 45 and PIPE 16

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5.7. Material properties:

Young’s modulus(EX) must be defined for a static analysis .If we plan to apply inertia

loads(such as gravity) we define mass properties such as density(DENS).Similarly if we plan to

apply thermal loads (temperatures) we define coefficient of thermal expansion(ALPX).

5.8 Obtain the solution:

In this step we define the analysis type and options, apply loads and initiate the finite element

solution. This involves three phases:

a) Pre – processor phase

b) Solution phase

c) Post-processor phase

5.8.1. Pre – Processor:

Preprocessor has been developed so that the same program is available on micro, mini,

super-mini and mainframe computer system. This slows easy transfer of models one system to

other. Preprocessor is an interactive model builder to prepare the FE (finite element) model and

input data. The solution phase utilizes the input data developed by the preprocessor, and

prepares the solution according to the problem definition. It creates input files to the temperature

etc., on the screen in the form of contours.

5.8.1.1. Geometrical definitions:

There are four different geometric entities in preprocessor namely key points, lines, areas

and volumes. These entities can be used to obtain the geometric representation of the structure.

All the entities are independent of other and have unique identification labels.

5.8.1.2. Model generations:

Two different methods are used to generate a model:

a) Direct generation.

b) Solid modeling

With solid modeling we can describe the geometric boundaries of the model, establish

controls over the size and desired shape of the elements and then instruct ANSYS program to

generate all the nodes and elements automatically. By contrast, with the direct generation

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method, we determine the location of every node and size, shape and connectivity of every

element prior to defining these entities in the ANSYS model. Although, some automatic data

generation is possible (by using commands such as FILL, NGEN, EGEN etc.) the direct

generation method essentially a hands on numerical method that requires us to keep track of all

the node numbers as we develop the finite element mesh. This detailed book keeping can

become difficult for large models, giving scope for modeling errors. Solid modeling is usually

more powerful and versatile than direct generation and is commonly preferred method of

generating a model.

5.8.1.3. Mesh generation:

In the finite element analysis the basic concept is to analyze the structure, which is an

assemblage of discrete pieces called elements, which are connected, together at a finite number

of points called Nodes. Loading boundary conditions are then applied to these elements and

nodes. A network of these elements is known as Mesh.

5.8.1.4. Finite element generation:

The maximum amount of time in a finite element analysis is spent on generating elements

and nodal data. Preprocessor allows the user to generate nodes and elements automatically at the

same time allowing control over size and number of elements. There are various types of

elements that can be mapped or generated on various geometric entities.

The elements developed by various automatic element generation capabilities of

preprocessor can be checked element characteristics that may need to be verified before the finite

element analysis for connectivity, distortion-index, etc. Generally, automatic mesh generating

capabilities of preprocessor are used rather than defining the nodes individually. If required,

nodes can be defined easily by defining the allocations or by translating the existing nodes. Also

one can plot, delete, or search nodes.

5.8.1.5. Boundary conditions and loading:

After completion of the finite element model it has to constrain and load has to be

applied to the model. User can define constraints and loads in various ways. All constraints and

loads are assigned set 1D. This helps the user to keep track of load cases.

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5.8.1.6. Model display:

During the construction and verification stages of the model it may be necessary to view

it from different angles. It is useful to rotate the model with respect to the global system and

view it from different angles. Preprocessor offers this capability. By windowing feature

preprocessor allows the user to enlarge a specific area of the model for clarity and details.

Preprocessor also provides features like smoothness, scaling, regions, active set, etc. for efficient

model viewing and editing.

5.8.1.7. Material definitions:

All elements are defined by nodes, which have only their location defined. In the case of

plate and shell elements there is no indication of thickness. This thickness can be given as

element property. Property tables for a particular property set 1-D have to be input. Different

types of elements have different properties for e.g. Beams: Cross sectional area, moment of

inertia etc. Shells: Thickness Springs: Stiffness Solids: None

The user also needs to define material properties of the elements. For linear static analysis,

modules of elasticity and Poisson’s ratio need to be provided. For heat transfer, coefficient of

thermal expansion, densities etc. are required. They can be given to the elements by the material

property set to 1-D.

5.8.2. Solution:

The solution phase deals with the solution of the problem according to the problem

definitions. All the tedious work of formulating and assembling of matrices are done by the

computer and finally displacements and stress values are given as output. Some of the

capabilities of the ANSYS are linear static analysis, non-linear static analysis, transient dynamic

analysis, etc.

5.8.3. Post – Processor:

It is a powerful user-friendly post-processing program using interactive colour graphics.

It has extensive plotting features for displaying the results obtained from the finite element

analysis. One picture of the analysis results (i.e. the results in a visual form) can often reveal in

seconds what would take an engineer hour to asses from a numerical output, say in tabular form.

The engineer may also see the important aspects of the results that could be easily missed in a

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stack of numerical data. Employing state of art image enhancement techniques, facilities viewing

of:

a) Contours of stresses, displacements, temperatures, etc.

b) Deform geometric plots

c) Animated deformed shapes

d) Time-history plots

e) Solid sectioning

f) Hidden line plot

g) Light source shaded plot

h) Boundary line plot etc.

The entire range of post processing options of different types of analysis can be accessed through

the command/ menu mode there by giving the user added flexibility and convenience.

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6. DISC BRAKE CALCULATIONS:

6.1. Assumptions:

1. The analysis is done taking the distribution of the braking torque between the front wheel and

rear wheel is 32:68

2. Brakes is applied on all the front wheel only.

3. The analysis is based on pure thermal loading. The analysis does not determine the life of the

disc brake.

4. Only ambient air-cooling is taken in to account and no forced convection is taken.

5. The kinetic energy of the vehicle is lost through the brake discs i.e. no heat loss between the

tyres and the road surface and the deceleration is uniform.

6. The disc brake model used is of homogenous material.

7. The thermal conductivity of the material used for the analysis is uniform throughout.

8. The specific heat of the material used is constant throughout and does not change with the

temperature. 9. Heat flux on each front wheel is applied on one side of the disc only.

6.2. CALCULATION FOR INPUT PARAMETERS:

In the aspect of the car accident prevention, the braking performance of vehicles has been

a critical issue. The rotor model heat flux is calculated for the car moving with a velocity 27.77

m/s (100kmph) and the following is the calculation

Procedure: Data:

1) Mass of the vehicle = 300 kg

2) Initial velocity (u) = 22.22 m/s (80 kmph)

3) Vehicle speed at the end of the braking application (v) = 0 m/s

4) Brake rotor diameter = 0.262 m

5) staic front axle load

total motor cycle load=(γ)=0.3

6) Percentage of kinetic energy that disc absorbs (90%) k=0.9

7) Acceleration due to gravity g =9.81m/s2

8) Coefficient of friction for dry pavement μ=0.45.

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(a) Energy generated during braking:

K.E. =γkm(u−v)2

2

(b) To calculate deceleration time:

v = u + at

Deceleration time = Braking time = 5s

(c) Braking Power: Braking power during continued braking is obtained by differentiating

energy with respect to time

Pb=K.E.

t

(d) Calculate the Heat Flux (Q): Heat Flux is defined as the amount of heat transferred per unit

area per unit time

Q =Pb

A

Table6.1: Calculation for Input Parameters

Formulae Disc design Stainless

steel Cast iron

Kinetic energy K.E. =γkm(u−v)2

2 For all models 20958.021 J 20958.021 J

Deceleration

time v = u + at For all models 5 sec 6 sec

Braking Power Pb=K.E.

t For all models 4191.60 W 3493 W

Calculate the

Heat Flux Q =

Pb

A

Model 1 𝐴1=0.01473𝑚2 142281.20

W/𝑚2

118567.67

W/𝑚2

Model 2 𝐴2=0.014145𝑚2 148165.58

W/𝑚2

123471.32

W/𝑚2

Model 3 𝐴3=0.014939𝑚2 140290.66

W/𝑚2

116908.88

W/𝑚2

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6.3. ANALYTICAL TEMPERATURE RISE CALCULATIONS:

The contact area between the pads and disc of brake components, heat is generated due to

friction. For calculation of heat generation at the interface of these two sliding bodies, two

methods are suggested on the basis of “law of conservation of energy which states that the

kinetic energy of the vehicle during motion is equal to the dissipated heat after vehicle stop”. The

material properties and parameters adopted in the calculations are as shown in table.

Table.6.2: Material Properties for Stainless Steel and Cast Iron

Material Properties Stainless Steel (Model I) Cast Iron (Model II)

Thermal conductivity(w/m k) 36 50

Density , ρ (kg/m3) 7100 6600

Specific heat , c (J/Kg ϲ ) 320 380

Thermal expansion , α (10-6 /

k )

0.12 0.16

Elastic modulus, E (GPa) 210 110

Coefficient of friction, μ 0.5 0.5

Film co-efficient h(w/km2 ) 240 280

Operation conditions

Angular velocity,( rad /s) 50 50

Braking Time Sec 5 6

Hydraulic pressure, P (M pa) 1 1

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7. FEM MODELS OF BRAKE DISC WITH MESHING

Model 1:

Figure 7.1: Meshing of Model 1

Sizing

Relevance Center Fine

Element Size Default

Initial Size Seed Active Assembly

Smoothing Medium

Transition Fast

Span Angle Center Coarse

Minimum Edge Length 2.5e-004 m

Statistics

Nodes 53771

Elements 29243

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Model 2:

Figure 7.2: Meshing of Model 2

Sizing

Relevance Center Fine

Element Size Default

Initial Size Seed Active Assembly

Smoothing Medium

Transition Fast

Span Angle Center Coarse

Minimum Edge Length 8.5106e-005 m

Statistics

Nodes 52632

Elements 28833

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Model 3:

Figure7.3: Meshing of Model 3

Sizing

Relevance Center Fine

Element Size Default

Initial Size Seed Active Assembly

Smoothing Medium

Transition Fast

Span Angle Center Coarse

Minimum Edge Length 8.5106e-005 m

Statistics

Nodes 54667

Elements 30092

Mesh Metric None

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8. RESULTS

8.1. Stainless Steel: Model No. 1

Figure8.1: Temperature distribution plot for SS Model No. 1

Figure8.2: Heat flux plot SS Model No. 1

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Model No. 2:

Figure8.3: Temperature distribution plot SS Model No. 2

Figure8.4: Heat flux plot SS Model No. 2

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Model No. 3:

Figure8.5: Temperature distribution plot SS Model No. 3

Figure8.6: Heat flux plot SS Model No. 3

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8.2. Cast iron: Model No. 1

Figure8.7: Temperature distribution plot CI Model No. 1

Figure8.8: Heat flux plot CI Model No. 1

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Model No. 2

Figure8.9: Temperature distribution plot CI Model No. 2

Figure8.10: Heat flux plot CI Model No. 2

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Model No. 3

Figure8.11: Temperature distribution plot CI Model No. 3

Figure8.12: Heat flux plot CI Model No. 3

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9. DISCUSSION

From the figures, given above, we can summarize the results in the following manner: -

Table no. 9.1 Maximum and minimum Temperature Distribution

Results Temperature Distribution

( o C )

Material Stainless Steel Cast Iron

Min Max Min Max

Model No.1 72.11 225.32 86.425 181.74

Model No.2 48.399 261.21 75.615 173.25

Model no.3 49.09 246.66 75.645 165.03

Table no. 9.2 Maximum and minimum Total Heat Flux

Results Total Heat Flux

(W/m2)

Material Stainless Steel Cast Iron

Min Max Min Max

Model No.1 503.14 2.61×105 671.23 2.55×105

Model No.2 449.5 2.99×105 1239.2 3.51×105

Model no.3 489.94 3.05×105 1263.3 3.05×105

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10. CONCLUSION

From our study of various design patterns for different materials we have observed that

the maximum temperature rise for cast iron is much less as compared to stainless steel and thus

on the basic of thermal analysis, cast iron is the best preferable material for manufacturing disc

brake. However cast iron disc brake suffers a drawback of getting corroded when it comes in

contact with moisture and hence it cannot be used in two wheeler and thus we prefer stainless

steel.

Heat dissipation from disc brake also depends on the type of design pattern used. The

different design patterns studied are:-

A) Model No. 1- With more no. of circular holes

B) Model No. 2- With kidney shaped holes

C) Model No. 3- With less no. of circular holes

Among the above models best heat dissipation is observed for model 1 consisting large

number of holes and made of stainless steel.

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REFERENCE

1. “Brakes and Dynamometer”-Theory of Machine by R.S. Khurmi & J.K. Gupta-732.

2. “Heat Transfer”- D.S. Pavaskar & S.H. Chaudhari.

3. “Thermal analysis guide”-

http://orange.engr.ucdavis.edu/Documentation12.0/120/ans_the.pdf

4. “Disc Brake” - http://en.wikipedia.org/wiki/Disc_brake

5. “Structural and Thermal Analysis of rotor disc brake”-

http://core.ac.uk/download/pdf/9554608.pdf

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ACKNOWLEDGEMENTS:

It gives me immense pleasure to convey my sincere thanks to all those who have

contributed their efforts in completion of this seminar. Specific thanks to my guide Dr. R. K.

Shrivastava, for getting the work started and putting me on the methodical line of thinking. Her

technical guidance and timely suggestions have helped me a lot throughout. This report has been

an ambitious work from start and would never have been completed without the co-operation of

the concerned teachers.

We shall be failing in my duty if I do not express my gratefulness to our Mechanical staff

members for their never ending help in the form of advice right through the execution of the

report. Lastly, I pay my special appreciation to all my dear friends and colleagues for their time

to time encouragement.

PENGKAM K. LUNGCHANG (BE06F02F065)

PARAG DESHATTIWAR (BE10F02F068)

TOSHIF RUIKAR (BE11F02F046)

KAHANI MENJO (BE11F02F064)

SANJEET KUMAR (BE11F02F065)

B.E. MECHANICAL