Design and Analysis of Disc Brake Rotors

DESIGN AND ANALYSIS OF DISC BRAKE ROTORS

A Major Project Report Submitted in partial fulfillment of the requirements for the

Award of the degree of

BACHELOR OF TECHNOLOGYIN

MECHANICAL ENGINEERING

Submitted by

ROHAN KARTHIK- 11311A0367

Under the guidance of

M.RaviKanth Dr.A.Purushotham

STO, (CAD/CAM) Prof. of Mech.Engg

CIPET, Cherlapally, SNIST, Yamnampet,

Hyderabad. Hyderabad.

(External Guide) (Internal Guide)

Department of Mechanical Engineering

Sreenidhi Institute of Science and Technology

(An Autonomous Institution under

Jawaharlal Nehru Technology University Hyderabad)

Yamnampet, Ghatkesar, R.R. District, Hyderabad – 501 301

1

Central Institute of Plastics Engineering & Technology

Certificate

This is to certify that Mr. Rohan Karthik bearing Roll No. 11311A0367 a bona fide student of Sreenidhi Institute of Science and Technology, Ghatkesar, Hyderabad - Telangana has undergone a project for a period of 2 months from 21st January, 2015 to 21st March, 2015 in fulfillment of his B.Tech-Mechanical Engineering successfully. During the project period, he was found to be regular, hardworking and diligent.

The report submitted by him is found relevant.

We wish him all the very best for his future endeavors.

With best regards

M.RaviKanth STO,

(CAD/CAM) CIPET,

Cherlapally,

Hyderabad. (External Guide)

CIDA Phase-II, Post Bag No. 3, Cherlapally, HCL Post, Hyderabad – 500 051.

2

SREE NIDHI INSTITUTE OF SCIENCE AND TECHNOLOGYDEPARTMENT OF MECHANICAL ENGINEERING

CERTIFICATE

This is to certify that the project report on “DESIGN AND ANALYSIS OF DISC BRAKE ROTORS”, submitted By Rohan Karthik (11311A0367), is a bona fide work that has been carried out by them as part of their Project during B.Tech (Mechanical) Fourth Year Second Semester, under our guidance. This report has not been submitted to any other institute or university for the award of any degree.

INTERNAL GUIDE: Dr. T. CH. SIVA

REDDY

Professor & Head of the Department,

Dept. of Mechanical Engineering

SNIST

EXTERNAL EXAMINER:

3

ACKNOWLEDGEMENT

This project report is the outcome of the efforts of many people, who have

driven our passion to explore into Concept and Design regarding our project. We have

received great guidance, encouragement and support from them and have learned a lot

because of their willingness to share their knowledge and experience.

Primarily, we should express our deepest sense of gratitude to our external

guide Mr. Sri M.Ravikanth (S.T.O, CAD/CAM). His guidance has been of immense

help in surmounting various hurdles along the path of our goal.

We are deeply indebted to Dr.T.Ch.Shiva Reddy, Professor & Head of

Department of Mech. Engg, and Dr. A. Purushotham, Professor , Internal guide who

spared his most valuable time without any hesitation whenever we wanted.

We record with a great feeling of gratitude, the contributions of all the faculty

members, Principal and management who encouraged us during this project by

rendering their help when needed.

Finally we thank our parents and adore Almighty God who has made us come

in contact with such worthy people at the right time, provided us with all the

necessary resources and made us accomplish this task.

ROHAN KARTHIK- 11311A0367

4

ABSTRACT

The main objective of the project is to design of bike’s disc rotors and

analyze the structural performance by using finite element method (ANSYS

Software).

Disc brake technology used for bikes has improved significantly as high

performance is most desirable now days.

Rotor design is varies from company to company. Some companies still use

the same initial rotor designs that were introduced over a decade ago. With the finite

element analysis and optimization process, it is possible to understand the difficulties

of designing disc brake rotors. With CAD technology the validity of new design tends

is pursued quickly.

More specifically, the project deals with analysis of three different disc rotors that is

available on commercial two wheelers. The FEA analysis determines, the stresses

developed in three different disc rotors. Then the structural performance of all three

selected rotors is compared in terms stresses developed.

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CONTENTS

Titles Page. No

Acknowledgement 3

Abstract 4

List of figures 7

List of tables 9

Nomenclature 10

Chapter 1:Introduction 11

1.1 Introduction 11

1.2 Braking Requirements 11

1.3 Classification of Brakes 12

1.4 Disc Brake 12

1.5 Principle 12

1.6 Main Components 13

1.7 Applications Of Disc Brake 14

1.8 Assumptions 14

Chapter 2:Problem Statement & Methodology 15

2.1 Problem Statement 15

2.2 Methodology 16

Chapter 3:Design Parameters of Disc Brake 17

3.1 Steel 17

3.2 Specifications of Steel 17

3.3 Dimensions of Disc Brake 17

3.4 Engine Specifications 18

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3.5 Force Calculation 18

Chapter 4: 3D Modeling of Rotor Disc in Pro-E 21

4.1 Introduction 21

4.2 History 21

4.3 Key Features & Benefits 22

4.4 Main modules 22

4.5 Flow process in Pro-E 23

4.6 Sequential steps followed for building rotor disc in pro-e

24

Chapter 5:Finite Element Analysis of Rotor Disc With ANSYS

30

5.1 Introduction 30

5.2 Engineering Applications of Finite Element Method(FEM)

30

5.3 Various Applications of FEM 31

5.4 Advantages of FEM 31

5.5 Disadvantages of FEM 31

5.6 Procedure for ANSYS Analysis 32

5.6.1 Build the model 32

5.6.2 Material Properties 32

5.6.3 Solution 32

I. Pre-Processor 33

II. Solution 35

III. Post Processing 36

5.7 Structural Analysis in ANSYS 36

Chapter 6: Results & Discussions 51

Chapter 7: Conclusions & Future scope of studies 52

References 53

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LIST OF FIGURES

Fig. No

Description Page. No

1.1 Disc Brake Rotor 11

1.2 Disc Brake Assembly 11

1.3 Various Parts of Disc Brake 13

2.1 Fig2.1: Disc Rotor 1 (old model) 15

2.2 Fig2.2: Disc Rotor 2 (proposed model) 15

2.3 Fig2.3: Disc Rotor 3 (proposed model) 15

4.1 Rotor Disc Flow Chart 23

4.2 Sequential steps followed for building rotor disc in Pro-E, step 1

24

4.3 Step 2 24

4.4 Step 3 25

4.5 Step 4 25

4.6 Step 5 26

4.7 Step 6 26

4.8 Step 7 27

4.9 Step 8 27

4.10 pro-e model of rotor disc 1 28



5.1 Importing model 37

5.2 Element selection 37

5.3 Material type selection 38

5.4 Meshing 38

8

5.5 Appling load 39

5.6 Deformed + un deformed 39

5.7 Displacement vector sum 40

5.8 Dof in X-direction 40

5.9 Dof in Y-direction 41

5.10 Stress in X-direction 41

5.11 Stress in Y-direction 42

5.12 Vector plot 42

5.13 Von Mises stress 43

5.14 DISC ROTOR-2:

Deformed + un deformed

43




5.18 Stress in Z-direction 45

5.19 Vector plot 46


5.21 DISC ROTOR-3:

Deformed + un deformed

47




5.25 Stress in Z-direction 49

5.26 Vector plot 49


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LIST OF TABLES

Table no

Description Page. No

5.1 Description of Steps followed in Each phase 33

6.1 Results 51

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NOMENCLATURE

Symbol DescriptionE Young’s modulus (N/mm²)

P load (N)

L Displacement (mm)

μ Coefficient of friction

ν Poisson’s ratio

ρ Density (Kg/m³)

ω Angular velocity (rad/sec)

Ɵ Angle (radians)

h Wheel height (m)

W Weight of the vehicle (kgs)

Wb Wheel base (m)

Mt Torque (N-m)

v Maximum velocity of vehicle (m/sec)

I Moment of inertia (kg- m2)

k Radius of gyration (m2)

m Mass of disc rotor (kg)

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CHAPTER 1

INTRODUCTION

1.1 INTRODUCTIONA brake is an instrument or equipment that makes use of artificial frictional

resistance to stop the motion of a moving member. While performing this function,

the brakes imbibe potential energy or kinetic energy of the moving member. The

energy that is absorbed by the brakes is dissipated in the form of heat. The dissipated

heat is in turn liberated into the surrounding atmosphere.

Fig 1.1 Disc Brake Rotor Fig 1.2 Disc Brake Assemblies

1.2 BRAKING REQUIREMENTS:

Brakes of a vehicle should be strong enough to stop the vehicle in a minimum

time & distance.

While braking the driver should have good control over the vehicle i.e. the

vehicle should not skid.

Brakes should be a good anti wear resistant.

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Brakes should have good anti fade characteristics.

1.3 CLASSIFICATION OF BRAKES: Based on mode of operation brakes are classified as follows:

Hydraulic Brakes.

Electrical Brakes.

Mechanical Brakes.

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

divided into the following two groups:

Radial Brakes

Axial Brakes.

Radial Brakes. In these brakes the force acting on brake drum is in radial

direction for Radial brakes. These brakes are of two types: Internal Brakes and

external brakes

Axial Brakes. In these brakes the force acting on the brake drum is in axial

direction for axial brakes.

1.4 DISC BRAKE:A disc brake is a device, composed of cast iron or ceramic composites that are

connected to the wheel hub or axle and a caliper. In order to stop the wheel hub,

friction material is automatically or hydraulically forced on both sides of the brake in

the form of brake pads. This friction in turn originates the wheel hub and the disc to

slow down and stop. Different views of Disc Brake Rotor are shown in the figure 1(a)

and 1(b).

1.5 PRINCIPLE:

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Disc brake is a very essential brake application device in a vehicle. This part of

the brake helps in the slowing and stopping the motion of the vehicle. The principle of

disc brake is to produce a braking force on the brake pads which in turn compresses

the rotating disc.

1.6 MAIN COMPONENTS OF A DISC BRAKE:-

Rotor

Brake Pads

Caliper

Fig1.3 various parts of disc brake

Rotor: The disc rotor is connected to the wheel and it rotates with respect to

the wheel. When brakes are applied, the brake pads come in contact with the rotor in

order to stop or slow down the vehicle.

Brake pads: Brake pads are present in the disc which scrapes against the

disc that rotates with the wheel hub and creates high friction.

Caliper: A caliper is a motionless housing which is clipped to the frame of a

vehicle containing a piston. This piston forces the pads onto the rotor in order to stop

or slow down the vehicle.

In order to bring the vehicle to a slow or stop position, the driver applies

pressure on the brake pedal which activates the caliper that in turn compresses the

brake pads against the disc rotor. The Rotor is then connected to the wheel which

14

halts the vehicle. When the brakes are applied the kinetic energy of the moving

vehicle is converted into heat and dissipated into the surrounding atmosphere.

1.7 APPLICATIONS OF DISC BRAKES Cars

Motorcycles

Bicycles

1.8 ASSUMPTIONS Brakes are applied on two wheels.

Thickness of 3.5mm is considered for all the models.

Only ambient cooling is considered for dissipation of heat.

This analysis does not determine the life of the disc brake

The disc brake model used is of solid type.

The thermal conductivity of the material is uniform throughout.

The specific heat of the material is constant throughout and does not change

with the temperature.

The kinetic energy of the vehicle is lost through disc brakes i.e. there is no

heat loss between the tire and the road side.

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CHAPTER 2

PROBLEM STATEMENT & METHODOLOGY

2.1 PROBLEM STATEMENT:This project deals with the development of three models by Pro-E software

and to analysation of disc brake rotors using ANSYS 10.0 software. The models are

shown in Figures 2.1, 2.2, & 2.3.

Fig2.1: Disc Rotor 1 (old model) Fig2.2: Disc Rotor 2 (proposed model)

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Fig2.3: Disc Rotor 3 (proposed model)

The objective of the problem is to adopt proposed models by proving

minimum Von Mises stress compared to old model.

2.2 M ETHODOLOGY : Using the standard dimensions of rotor discs, 3D model is developed using

Pro-E.

Exporting Pro-E model on to ANSYS, finite element model is developed.

Braking load is calculated with road conditions and speed of the vehicle.

Minimum Von Mises stress is extracted after applying boundary conditions

and braking load.

A table is drawn comparing stresses and deformations in each disc rotor.

Among the three discs, the Von Mises stresses found minimum is considered

structurally good performance.

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CHAPTER 3

DESIGN PARAMETERS OF DISC BRAKE

3.1 STEEL: Steel is an alloy of iron, with carbon, which may contribute up to 2.1% of

its weight. Carbon, other elements, and inclusions with in iron act as hardening agents

that prevents the movement of dislocations that naturally exist in the iron atom crystal

lattices. Varying the amount of alloying elements, their form in the steel either as

solute elements, or as precipitated phases, retards the movement of those dislocations

that make iron so ductile and so weak, and so it controls qualities such as the

hardness, ductility, and tensile strength of the resulting steel. Steel can be made

stronger than pure iron, but only by trading away ductility, of which iron has an

excess.

3.2 SPECIFICATIONS OF MATERIAL

Mechanical properties of structural steel that are important to the designer include:

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Modulus of elasticity, E = 210,000 N/mm²

Shear modulus, G = E/[2(1 + ν)] N/mm², often taken as 81,000 N/mm²

Poisson's ratio, ν = 0.3

Coefficient of thermal expansion, α = 12 x 10-6/°C (in the ambient temperature

range).

Density = 8.05g/cm3.

3.3 DIMENSIONS OF DISC BRAKEThe dimensions of brake disc used for static structural analysis are given bellow

Diameter of Disc brake 240mm

Thickness 3.5mm

3.4 ENGINE SPECIFICATION

Displacement (cc) 97

Cylinders 1

Max Power 7.4

Maximum Torque 8

Bore (mm) 50

Stroke (mm) 49

Valves per Cylinder 2

Fuel Delivery System Carburetor

Fuel Type Petrol

Ignition C.D.I

Spark Plugs (Per Cylinder) 1

19

Cooling System Air Cooled.

3.5 FORCE CALCULATIONS:Data Available:

d=0.24m,

t=0.0035m,

Time for deceleration td =1.5sec,

Maximum velocity of vehicle v =140km/hr.

Outer radius of disc pad Ro=100mm,

Inner radius of disc pad Ri =60mm,

Weight of the vehicle W=100kgs (Assume),

Wheel diameter D = 45702mm,

Width w = 40.64mm,

Wheel height h = 0.015mts,

Wheel Base Wb = 0.457/ð

= 0.1455 mts.

Stopping distance L = 10mts.

Co-efficient of friction of pads µ = 0.3.

Density of material ñ =8000 kg/m3

ù = v/R,

= 38.88/0.12,

=324 rad/sec.

ω = 2πn ̸ 60,

n = (60*ω) ̸ 2π,

= (60*324) ̸ (2*3.14),

= 3065.54 rpm.

Kinetic Energy, K.E = ½(I*ù2),

I = m*k2,

m= ðd2 ̸ 4*t*density of material,

= [(3.14*(.242)] ̸ 4*.0035*8000,

= 1.26kg.

k2=d2/8.

= 0.0576 ̸ 8

20

=7.2*10-3m2.

K.E = ½ *(1.26*7.2*10-3*(3242))

= 476.17 J.

Ɵ = (ù1/2)*td

= (324/2)*1.5

= 243 rad.

Mt = K.E/Ɵ = 476.17/243

= 1.95N-m.

Friction radius, Rf = 2*(R03-Ri

3)/3*( R02-Ri

2)

= 2*(1003-603)/3*(1002-602)

= 81.66mm.

Mt = 1.95/2

= 0.979 N-m (torque on one pad)

Mt= µ*P*Rf

µ = 0.3

P= (0.979*103)/(0.3*81.66)

= 39.9624 N

= (39.9624/9.81) kgs

= 4.07kgs.

Static weight on front wheel Wfs = [W/2*(Wb-h*L)]/L

= 100/2*(0.145-0.015*10)/10

= 6.525 kgs

Total weight acting on disc brake = 6.525+8

= 15.525 kgs.

= 155.25N.

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CHAPTER 4

3D MODELING OF DISC ROTOR IN PRO-E

SOFTWARE

4.1 INTRODUCTION Pro/ENGINEER Wildfire is the standard in 3D product design, featuring

industry-leading productivity tools that promote best practices in design while

ensuring compliance with your industry and company standards. Integrated

Pro/ENGINEER CAD/CAM/CAE solutions allow you to design faster than ever,

while maximizing innovation and quality to ultimately create exceptional products.

Customer requirements may change and time pressures may continue to

mount, but your product design needs remain the same - regardless of your project's

scope, you need the powerful, easy-to-use, affordable solution that Pro/ENGINEER

provides.

4.2 HISTORY

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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. Created by Dr. Samuel P. Ginsberg in the

mid-1980s, Pro/ENGINEER was the industry's first successful rule-based constraint

(sometimes called "parametric" or "vibration") 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. Cero 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.

Companies use Cero Elements/Pro to create a complete 3D digital model of

their products. 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 is 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 associatively functionality in Cero

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.

4.3 KEY FEATURES AND BENEFITS: Fully integrated applications allow you to develop everything from concept to

manufacturing within one application.

Powerful parametric design capabilities for superior product design.

Automatic propagation of design changes to all downstream deliverables.

23

http://en.wikipedia.org/wiki/Creo_Elements/Pro#cite_note-4

Complete virtual simulation capabilities.

Automated generation of associative tooling design and manufacturing

deliverables.

4.4 THE MAIN MODULES

Part Design

Assembly

Drawing

4.5 FLOW PROCESS IN PRO-E : NEW FILE

PART DESIGN

SKETCH

EXTRUDE

24

SAVE (IN IGES FORMAT)

EXPORT TO ANSYS

Fig 4.1 Rotor Disc Flow Chart

4.6 SEQUENTIAL STEPS FOLLOWED FOR BUILDING ROTOR

DISC IN PRO-E

Sequential steps followed for building rotor disc in Pro-E are shown from fig. no 4.2 to 4.9.

Proposed rotor models also developed in Pro-E with change of number of spokes and shown in fig no 4.11&4.123

25

Fig 4.2 step 1

Fig 4.3 step 2

Fig 4.4 step 3

26

Fig 4.5 step 4

Fig 4.6 step 5

27

Fig 4.7 step 6

Fig 4.8 step 7

28

Fig 4.9 step 8

PRO-E MODEL OF ROTOR DISC 1:

Fig 4.10 pro-e model of rotor disc 1

29




30


Chapter 5

FINITE ELEMENT ANALYSIS

5.1INTRODUCTION

Finite Element Method (FEM) is also called as Finite Element

Analysis (FEA). Finite Element Method is a basic analysis technique

for resolving and substi tuting complicated problems by simpler ones,

obtaining approximate solutions Finite element method being a flexible

tool is used in various industries to solve several practical engineering

problems. ANSYS is general purpose FEA software developed,

supported & marketed by ANSYS Inc. ANSYS are used by several

companies to produce a wide range of products , including aircrafts &

automobile engines . Generally there are three methods to solve any

engineering problems such as analytical method, Numerical method, &

31

Experimental method in which numerical method is most commonly

used. Because i t is the mathematical representation of physical

problems & it gives the approximate solution & also applicable even if

physical prototype is not available. Numerical methods like Finite

element analysis are based on discritization of integral form of

equation. Basic theme of all numerical method is to make calculations

at only limited numbers of points & then interpolate the results for

entire domain. It is now used to solve problems in the following areas-

structural strength design, thermal analysis, vibration, & crash

simulations etc.

5.2 ENGINEERING APPLICATIONS OF FINITE ELEMENT

METHOD:Initially FEM method was used for only structural mechanics problems but

over the years researches have successfully applied it to various engineering

problems. It has been validated that this method can be used for other numerical

solution of ordinary and partial differential equations.

The finite element method is applicable to three categories of boundary value

problems

Equilibrium or steady state or Time-Independent problems

Eigen value Problems

Propagation or transient problems.

5.3 VARIOUS APPLICATIONS OF FEM : Civil Engineering Structures

Aircraft Structures

Heat Conduction

Geo mechanics

Hydraulic and Water Resource Engineering

Nuclear engineering

Bio-Medical Engineering

Mechanical Engineering

32

Electrical Machines and Electromagnetic.

5.4 ADVANTAGES OF FEA/FEM: Non-linear problems are easily solved.

Several types of problems can be solved with easy

formulation.

Reduces the costs in the development of new products.

Improves the quality of the end product.

Life of the product is increased.

Rapid development of new products.

High product reliability.

Product fabrication process is enhanced.

5.5 DISADVANTAGES OF FEA/FEM : Extreme aspect ratios can cause problems.

Not well suited for open region problems.

5.6 PROCEDURE FOR ANSYS ANALYSISStatic analysis is used to determine the displacements stresses, stains 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 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 non linear. In our present work we

consider linear static analysis. The procedure for static analysis consists of these main

steps

Building the model

Obtaining the solution

Reviewing the results.

5.6.1 BUILD THE MODEL

33

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 type both linear and nonlinear structural elements are allowed. The ANSYS

elements library contains over 80 different element types. A unique number and

prefix identify each element type.

5.6.2 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).

5.6.3 SOLUTION In this step we define the analysis type and options, apply loads and initiate the

finite element solution. This involves three phases:

Pre-processor phase

Solution phase

Post-processor phase

I. PRE-PROCESSOR Pre processor 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. It involves

the preparation of finite element data such as nodal coordinates, element connectivity,

boundary

conditions & loading & material information.

Table No: 5.1

34

The following Table 5.1 shows the brief description of steps followed in each phase:

GEOMETRICAL DEFINITIONS: There are four different geometric entities in pre processor namely key points,

lines, area 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.

MODEL GENERATIONS: Two different methods are used to generate a model:

Direct generation.

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 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.

35

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.

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.

FINITE ELEMENT GENERATION: The maximum amount of time in a finite element analysis is spent on

generating elements and nodal data. Pre processor 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 pre processor 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 pre processor 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 on one can plot, delete, or search

nodes.

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 ID. This helps the user to keep track of load

cases.

MODEL DISPLAY:

36

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. Pre processor offers these capabilities. By

windowing feature pre processor allows the user to enlarge a specific area of the

model for clarity and details. Pre processor also provides features like smoothness,

scaling, regions, active set, etc for efficient model viewing and editing.

MATERIAL DEFECTIONS: 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

Shell: 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.

II. 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 are 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.

III. POST PROCESSINGThe post processing stage deals with the presentation of the results. Typically,

the deformed configuration, mode shapes, temperature & stress distribution are

computed & displayed at this stage. While solution data can be manipulated many

ways in post processing, the important objective is to apply sound engineering

judgment in determining whether the solution results are physically reasonable.

5.7 STRUCTURAL ANALYSIS IN ANSYS

37

Structural analysis is the commonly used application of the FEA. We can perform the

seven types of structural analysis in ANSYS such as

Static Analysis

Modal Analysis

Buckling Analysis

Spectrum Analysis

Harmonic Analysis

Transient dynamic Analysis

Explicit dynamic analysis

A static analysis is performed over a structure when the loads & boundary conditions

remain stationary & do not change over time it is assumed that the load or field

conditions are applied gradually, not suddenly. The system under analysis can be

linear or nonlinear.

Inertia and damping effects are ignored in structural analysis. Static analysis is used

to determine displacements, stresses & so on.

In structural analysis following matrices are solved [K][X]= [F],Where K is stiffness

matrix, X is displacement matrix, &F is the force matrix. The above equation is called

the force balance equation for the linear system. Nonlinear systems include large

deformation, plasticity, and creep and so on.

ROTOR DISC MODEL 1:- STRESS & NODAL DEFLECTIONSequential steps followed in modeling rotor disc in ANSYS are given from fig. no 5.1 to 5.13. Similarly ANSYS analysis carried out on proposed rotor disc models and the results are shown from fig no 5.14to 5.27.

38

Fig 5.1 Importing model

Fig 5.2 Element selection

39

Fig 5.3 Material type selection

Fig 5.4 Meshing

40

Fig 5.5 Applying Loads

Fig 5.6 Deformed + un deformed

41

Fig 5.7 Displacement Vector sum

Fig 5.8 Dof in-X direction

42

Fig 5.9 Dof in- Y direction

Fig 5.10 Stress in – X direction

43

Fig 5.11 Stress in-Y direction

Fig 5.12 Vector Plot

44

Fig 5.13 Von Mises stress

ROTOR DISC MODEL 2:- STRESS & NODAL DEFLECTION


45


Fig 5.16 Stress in – X direction

46


Fig 5.18 Stress in-Z direction

47



48

ROTOR DISC MODEL 3:- STRESS & NODAL DEFLECTION



49

Fig 5.23 Stress in-X direction


50

Fig 5.25 Stress in-Z direction


51


52

CHAPTER 6

RESULTS & DISCUSSIONS S

In chapter 6 simulation studies are made on three rotor discs, using ANSYS software.

The resultant displacements undergone by each disc and the resultant stresses

developed in each disc are determined and tabulated in table no 6.1

Table No:-6.1

Rotor Discs Models

DISPLACEMENT VECTOR SUM (mm)

STRESSES IN X-DIRECTION (MPa)

STRESSES IN Y- DIRECTION(MPa)

VON MISES STRESSES (MPa)

1 2.601 8.608 30.04 22.8352 18.376 8.14 7.971 8.6633 0.0235 0.414 0.2002 2.128

From the table no 6.1 it is observed that the displacement and Von Mises stresses are

very low for the rotor disc of model -3. Under the high speed of 140Kmph and

retardation time of 1.5 sec, the rotor disc shows good structural displacement and

stresses. It is observed from the simulation studies that the weight of disc-3 is less

than the weight of disc-2 &1, because of only 6 spokes, instead of 12 spokes in

model-2. The material used for model-3 is steel having compressive strength of

300Mpa. Therefore, the factor of safety for the design is 56.49.

The main advantage observed in rotor disc model-3 is that, it undergoes 0.0235mm

radial deformation, so that the bearing life of disc drastically increases.

53

CHAPTER 7

CONCLUSIONS & FUTURE SCOPE OF STUDY

CONCLUSIONSIn this project, three disc rotor models with same outer dimensions but with different

design parameters have been modeled using Pro-E and analyzed using ANSYS to

determine structural performance. Based on the results of the ANSYS simulation

which are tabulated above in table no 6.1, It is concluded that the Von Mises stresses

developed in disc model no-3 are minimum compared to other two models. So It is

suggested that the use of 3rd disc model instead of 1st and 2nd models enables good

structural static performance in terms of deflection and resultant stresses. It is further

concluding that the proposed disc model 3 ideally suitable for two wheelers up to a

speed of 140KMPH with brake time 1.5seconds.

SCOPE FOR THE FURTHER STUDY In the present investigation of structural analysis of disc rotor, a simplified disc brake

without considering any thermal stresses, is analyzed by FEM package ANSYS. As

future work, a model considering thermal factors can be undertaken in the analysis.

The analysis still becomes complicated by considering variable thermal conductivity,

variable specific heat and non uniform deceleration of vehicle. This can be considered

for the future work.

54

REFRENCES

1. Design of Machine Elements by R.S.Khurmi.

2. ENDERSON, A. E. AND KNAPP, R. A. Hot Spotting in Automotive Friction .

3. By browsing in Internet.

4. DOW, T. A. AND BURTON, R. A. Thermo elastic Instability of Sliding

Contact in the absence of Wear, Wear, vol. 19, page 315-328, (1972).

5. LEE, K. AND BARBER, J.R. Frictionally-Excited Thermo elastic Instability

in Automotive Disk Brakes, ASME J. Tribology, vol. 115, page 607-614, (1993)..

6. BURTON, R. A. Thermal Deformation in Frictionally Heated Contact, Wear,

vol. 59, page 1- 20, (1980). ANDERSON, A. E. AND KNAPP, R. A. Hot Spotting in

Automotive Friction System Wear, vol. 135, page 319-337, (1990).

7. COMNINOU, M. AND DUNDURS, J. On the Barber Boundary Conditions

for Thermo elastic Contact, ASME J, vol. 46, page 849-853, (1979). BARBER, J. R.

Contact Problems Involving a Cooled Punch, J. Elasticity, vol. 8, page 409- 423,

(1978).

8. BARBER, J. R. Stability of Thermo elastic Contact, Proc. International

Conference on Tribology, p Institute of Mechanical Engineers, page. 981-986, (1987).

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Documents

Design and Analysis of Disc Brake Rotors