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CHAPTER 3 DISK BRAKE AND DRUM BRAKE

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CHAPTER 3 DISK BRAKE AND DRUM BRAKE Powered By Docstoc
					ABSTRACT

This B.Sc. project is about the composition, performance, finite element analysis and poss-
ible faults of the car brake system .The outline of the system units is presented and the
function of each unit is discussed. The performance characteristics of the system (e.g.
chemical composition, microstructure, wear rate, and friction coefficient) are presented and
discussed. The solid model for some components of the brake system is done using solid-
works Software. The finite element analysis is conducted, presented and discussed for the
displacement and stress distribution on both the friction pad and the brake disk. The ex-
pected temperature distribution on the disk is presented and discussed. The drum brake
forces were analysis to evaluate the friction force moment, normal force moment and the
total torque applied in the drum brake. The maximum pressure on the shoe and its location
is presented. A virtual prototype for Rotor, Caliper and splash was produced in project.




                                              I
                                                              Contents

ABSTRACT ..................................................................................................................................... I



CHAPTER 1: INTRODUCTION .............................................................................................. 1

                   1.1 Project objectives ......................................................................................... 2

                   1.2 Methodology ................................................................................................ 2



CHAPTER 2 BRAKE SYSTEM AND ITS UNITS ............................................................... 3

                   2.1 Brake System Definitions ............................................................................ 3

                   2.2 Types of Brakes ........................................................................................... 4

                   2.3 Brake Materials ............................................................................................ 4



CHAPTER 3: DISK BRAKE AND DRUM BRAKE ............................................................ 6

                   3.1 Description of Brake System Components .................................................. 6

                   3.2 Master Cylinder, Brake Fluid and Lines ...................................................... 8

                   3.3 Proportioning, Pressure Differential and Combination Valves ................... 9

                   3.4 Disk Brakes ................................................................................................ 10

                   3.5 Caliper & Support ...................................................................................... 12

                   3.6 Drum Brakes .............................................................................................. 13

                   3.7 Power Brake Booster ................................................................................. 16

                   3.8 Performance Characteristics ...................................................................... 17
                                                                       II
                3.9 Faults in brake system ................................................................................ 20



CHAPTER 4 SOLID MODEL ................................................................................................. 22

                4.1 Exploded view for disk brake .................................................................... 22

                4.2 Engineering drawing for the disk brake ..................................................... 23

                           4.2.1 Rotor .......................................................................................... 24

                           4.2.2 Brake pad ................................................................................... 25

                           4.2.3 Caliper ....................................................................................... 25

                           4.2.4 Hex bolt ..................................................................................... 26

                           4.2.5 Splash......................................................................................... 26

                           4.2.6 Other parts ................................................................................. 27

CHAPTER 5: FINITE ELEMENT ANALYSIS .................................................................. 28

                5.1 Stress Analysis for the Brake Pad .............................................................. 28

                5.2 Stress analysis for the disk brake (pad, Rotor, holder) .............................. 31

                5.3 Temperature Distribution at Rotor ............................................................. 35

                5.4 Optimum Design of Rotor Using Solidworks Software ............................ 36

CHAPTER 6: ANALYSIS OF A DRUM BRAKE FORCE .............................................. 38

                6.1 Analysis Details for Self-Energizing Shoe ................................................ 40

                6.2 Deenergizing Shoe Analysis ...................................................................... 41

CHAPTER 7: VIRTUAL PROTOTYPE .............................................................................. 42

                                                               III
                   7.1 Disk Brake Virtual Prototypes before Painting.......................................... 42

                   7.2              Disk Brake Virtual Prototypes after Painting .................................. 43



Results discussion ........................................................................................................................ 44


Conclusion ..................................................................................................................................... 45


Recommendation ......................................................................................................................... 45


References ..................................................................................................................................... 46




                                                         LIST OF TABLES

Table 1: Friction Pad Material ............................................................................................... 5

Table 2: Showing The Possible Fault In Brake System And Its Remedy ........................... 21
                                                                        IV
Tables 3: Material Property ................................................................................................. 28

Tables 4 : Loads And Constrain ......................................................................................... 28

Table 5: Mesh Property ...................................................................................................... 29

Table 6: Property And Units For Disk Brake ...................................................................... 31

Table 7: Rotor Material Property......................................................................................... 31

Table 8: Holder Material Property....................................................................................... 31

Table 9: Restraint................................................................................................................. 32

Table 10: Contact Information ............................................................................................ 32

Table 11: Disk Brake Mesh Information ............................................................................ 33

Table 12:Drum Dimension .................................................................................................. 40




                                                   LIST OF FIGURES

Figure 1: Disk Brake Components ........................................................................................ 1

Figure 2: Brake System ......................................................................................................... 3

                                                                  V
Figure 3: Microstructure of Friction Material A) Nf1 B) NF2 C) NF5 D) CMA And CMB 5

Figure 4: Brake System ......................................................................................................... 6

Figure5: Drum Brake ............................................................................................................. 7

Figure 6: Disk Brake.............................................................................................................. 7

Figure 7: Master Cylinder...................................................................................................... 8

Figure 8: Disk Brake............................................................................................................ 10

Figure 9: Pad ...................................................................................................................... 11

Figure10:Rotor…………………………………………………………………………… 11

Figure 11: Caliper ................................................................................................................ 12

Figure 12: Drum Brake ........................................................................................................ 13

Figure 13: Brake Shoes........................................................................................................ 14

Figure 14: Drum Brake ........................................................................................................ 15

Figure 15: Brake Booster ..................................................................................................... 17

Figure 16: Relation between Master Pressure and Pedal Position ...................................... 19

Figure 17: Relation between Master Pressure and Force exert ........................................... 19

Figure 18: Crack in Rotor .................................................................................................... 20

Figures 19: Exploded View for Disk Brake (1) ................................................................... 22

Figure 20: Exploded View for Disk Brake (2) .................................................................... 23

Figure 21: Rotor Dimensions in (mm). ............................................................................... 24


                                                                  VI
Figure 22: Rotor Section Views .......................................................................................... 24

Figure 23: Pad Dimensions in (mm).................................................................................... 25

Figure 24: Caliper Dimensions in (mm) .............................................................................. 25

Figure 25: Bolt Dimensions in (mm) ................................................................................... 26

Figure 26: Splash Dimensions in (mm) ............................................................................... 26

Figure 27: Part 1 Dimensions in (mm) ................................................................................ 27

Figure 28: Part 2 Dimensions in (mm) ................................................................................ 27

Figure 29: Load and Restraints ............................................................................................ 29

Figure 30 : Pad Mesh ........................................................................................................... 29

Figure 31: Displacement ...................................................................................................... 30

Figure 32: Stress .................................................................................................................. 30

Figure 33: Disk Brake Restraint .......................................................................................... 32

Figure 34: Disk Brake Mesh ................................................................................................ 33

Figure 35: Disk Brake Displacement................................................................................... 34

Figure 36: Stress Von Mises ................................................................................................ 34

Figure 37: Contact / friction force at µ=0.2 and µ=0.3 ....................................................... 35

Figure 38: Temperature Distribution at the End of Action Brake ....................................... 35

Figure 39: Temperature (C0) At Different Time (S)............................................................ 36

Figure 40: The Dimension (Mm) Selected Before Optimize ............................................. 36


                                                                 VII
Figure 41: The New Dimension .......................................................................................... 37

Figure 42: New Design Weight ........................................................................................... 37

Figure 43: Drum dimensions ............................................................................................... 38

Figure 44: Drum Force ........................................................................................................ 39

Figure 45: Drum Angels ...................................................................................................... 39

Figure 46: Rotor Outside and Vehicle Side ......................................................................... 42

Figure 47: Disk Brake Caliper and Splash .......................................................................... 42

Figure 48: Rotor Prototypes ................................................................................................ 43

Figure 49: Caliper And Splash Prototypes .......................................................................... 43




                                                              VIII
                         CHAPTER 1: INTRODUCTION

The worldwide automobile brake system market is flooded with advanced, modern and
cost effective brake system technologies. Canada (21.73%), Mexico (19.22%), Japan
(16.33%), China (13.56%) and Brazil (6.54%) are the largest manufacturing countries of
automobile brake systems in the world. The braking system constitutes an integral part of
an automobile. Failure of the automobile brake system at the time of emergency can lead to
accidents, property damage or even death of an individual. In recent years, braking systems
have undergone tremendous changes in terms of performance, technology, design and safe-
ty. Today, the brake system market is bombarded with so many new and innovative tech-
nologies such as electronic brakes, anti lock brakes, cooling brakes, disc brakes, drum
brakes, hand brakes, power brakes, servo brakes and brake by wire. Anti lock brake sys-
tems are the most sought after these days, which are now used in almost all the vehicles the
(Figure 1) show the componets of disk brake




                            Figure 1: Disk Brake Components
                                              1
1.1 Project objectives

We can summarize the project objectives in following points:

   1. Identifying function of disk brake and its parts.
   2. Discussing the performance of the disk brake and the microstructure of the friction
       pad.
   3. Developing a solid model for the disk brake using solidworks® along with its de-
       tailed drawings.
   4. Developing a finite element model in order to study the mechanism of rotor and
       pad at different situations.
   5. Developing an optimum design for the rotor using solidworks® software.
   6. Conducting force analysis on the drum to evaluate:
       a. The total braking torque.
       b. The maximum pressure on the shoe and its location.
   7. Making virtual prototypes for main components of brake system.




1.2 Methodology

The steps need to achieve the goals of project

1-disassemble the brake system components by suitable Screwdrivers.

2- Take the Dimensions of disk brake by using Vernier caliper.

3- Drawing the parts by using solidworks software.

4- Run finite elements analysis using cosmos software.

5- Take the dimensions of drum brake using Vernier caliper.

6- Performing the virtual prototypes using turning machine and glue



                                             2
              CHAPTER 2 BRAKE SYSTEM AND ITS UNITS

2.1 Brake System Definitions

The braking system (Figure 2) used in automobiles is mainly used for helping the driver
control the deceleration of the vehicle. It is one of the crucial systems, which is especially
designed for decreasing the speed of the fast moving vehicle. A typical automobile braking
system comprises of a braking device having different components, which are used for
slowing or stopping down a vehicle. More precisely, these devices decrease or stop the
speed of a moving or rotating body by absorbing kinetic energy mechanically or electrical-
ly. These systems automatically control wheel slips and prevent the wheels from spinning.
They are widely used in motor vehicles, buses, trucks, trains, airplanes, passenger coaches,
trailers, and other types of automobiles. Brake systems used in automobiles has come a
long way in recent years. The adoption of anti lock brake systems along with the introduc-
tion of different brake components made of carbon fiber; steel, aluminum etc have really
provided better stopping performance in comparison with traditional braking systems. The
major manufacturers of brake systems in the world are Bendix, Bosch, Delco, Continental
Teves, Kelsey-Hayes, Nippondenso, Sumitomo, and Toyota.




                                 Figure 2: Brake System


                                              3
2.2 Types of Brakes

Automobiles use either drum brakes, disc brakes or a combination of the two. In drum
brakes, two semicircular brake pads (also called brake shoes) are located inside a drum.
When the brakes are applied, the brake shoes are forced outward and press against the
drum. The drum, shaped like a covered cylinder," Catches" much of the brake pad dust that
is worn during braking. Disc brakes consist of two brake pads located on either side of a
rotor. When the brakes are applied, the two pads squeeze against the rotor. Disc brakes are
more exposed to the environment than drum brakes. Dust generated by disc brakes that
does not temporarily affix to the car falls to the road or becomes suspended in the air Disc
brakes tend to have better braking performance than drum brakes. Most cars today use disc
front -drum rear braking systems. Some vehicles use disc brakes on all four wheels while
few, if any, use only drums brakes.



2.3 Brake Materials

Brake materials generally fall into the category of organics or semi-metallic. Other catego-
ries have also been cited such as metallic and low-metallic but these may be variations on
the semi-metallic pad.1 However, all auto repair shops and parts stores contacted offered
only organic or semi-metallic brake pads. The different formulations have varying wear
rates, braking properties, and noise levels. Semi-metallic brake pads are visibly different
from organics. Semi-metallic pads are a darker color with visible metallic fibers and have a
rough texture. Organic pads are a lighter shade of gray and have a smoother texture. Organ-
ic formulations often contain polymers such as Kevlar, resins, and sometimes asbestos fi-
bers. Organic brake pads may also contain copper. In the past, asbestos was used extensive-
ly in organic formulations before it was discovered that breathing dust containing asbestos
fibers can cause serious bodily harm. Today, although use of asbestos is still legal, manu-
facturers are generally moving towards non-asbestos organic formulations for safety rea-
sons. Semimetallic generally refers to the presence of iron and steel in the formulation.
Semi metallic brake pads are composed of finely powdered iron or copper, graphite, and
lesser amounts of inorganic fillers and friction modifiers. Manufacturers have voluntarily
phased out lead in brake pad formulations to protect human health.
                                             4
In the (Table 1)and (Figure 3) we see the chemical composition of friction pad material
(EL-Tayeb, N. and Liew, K. (2009)

                              Table 1: Friction Pad Material




Figure 3: Microstructure of Friction Material A) Nf1 B) NF2 C) NF5 D) CMA And CMB




The Researches on brake pad materials stated that commercial composition of the pad can-
not be concluded whether is preferable to contain organic or semi metallic brake pads con-
tain more copper. Both organic and semi-metallic may contain copper although specific
amounts will depend on the manufacturer.


                                            5
             CHAPTER 3: DISK BRAKE AND DRUM BRAKE

3.1 Description of Brake System Components




                                  Figure 4: Brake System




The modern automotive brake system (Figure 4) has been refined for over 100 years and
has become extremely dependable and efficient. The typical brake system consists of disk
brakes in front and either disk or drum brakes in the rear connected by a system of tubes
and hoses that link the brake at each wheel to the master cylinder. Other systems that are
connected with the brake system include the parking brakes, power brake booster and the
anti-lock system when you step on the brake pedal; you are actually pushing against a
plunger in the master cylinder which forces hydraulic oil (brake fluid) through a series of
tubes and hoses to the braking unit at each wheel. Since hydraulic fluid (or any fluid for
that matter) cannot be compressed, pushing fluid through a pipe is just like pushing a steel

                                             6
bar through a pipe. Unlike a steel bar, however, fluid can be directed through many twists
and turns on its way to its destination, arriving with the exact same motion and pressure
that it started with. It is very important that the fluid is pure liquid and that there is no air
bubbles in it. Air can compress which causes sponginess to the pedal and severely reduced
braking efficiency. If air is suspected, then the system must be bled to remove the air. There are
“bleeder screws” at each wheel cylinder and caliper for this purpose on a disk brake, the fluid
from the master cylinder is forced into a caliper where it presses against a piston. The pis-
ton, in-turn, squeezes two brake pads against the disk (rotor) which is attached to the
wheel, forcing it to slow down or stop This process is similar to a bicycle brake where two
rubber pads rub against the wheel rim creating friction With drum brakes, fluid is forced
into the wheel cylinder which pushes the brake shoes out so that the friction linings are
pressed against the drum which is attached to the wheel, causing the wheel to stop In either
case, the friction surfaces of the pads on a disk brake system (Figure 6), or the shoes on a
drum brake ( Figure 5) convert the forward motion of the vehicle into heat. Heat is what
causes the friction surfaces (linings) of the pads and shoes to eventually wear out and re-
quire replacement




             Figure 6: Disk Brake                             Figure5: Drum Brake




Let’s take a closer look at each of the components in a brake system.



                                                7
3.2 Master Cylinder, Brake Fluid and Lines

Master Cylinder The master cylinder (Figure 7) is located in the engine compartment on
the firewall, directly in front of the driver’s seat. A typical master cylinder is actually two
completely separate master cylinders in one housing, each handling two wheels. This way
if one side fails, you will still be able to stop the car. The brake warning light on the dash
will light if either side fails, alerting you to the problem. Master cylinders have become
very reliable and rarely malfunction; however, the most common problem that they expe-
rience is an internal leak. This will cause the brake pedal to slowly sink to the floor when
your foot applies steady pressure. Letting go of the pedal and immediately stepping on it
again brings the pedal back to normal height




                                Figure 7: Master Cylinder

Brake Fluid: Brake fluid is special oil that has specific properties. It is designed to with-
stand cold temperatures without thickening as well as very high temperatures without boil-
ing. (If the brake fluid should boil, it will cause you to have a spongy pedal and the car will
be hard to stop.) Brake fluid must meet standards that are set by the Department of Trans-
portation (DOT). The current standard is DOT-3 which has a boiling point of 460º F. But
check your owner’s manual to see what your vehicle manufacturer recommends. The brake
fluid reservoir is on top of the master cylinder. Most cars today have a transparent reservoir
so that you can see the level without opening the cover. The brake fluid level will drop
slightly as the brake pads wear. This is a normal condition and no cause for concern. If the
level drops noticeably over a short period of time or goes down to about two thirds full,
have your brakes checked as soon as possible. Keep the reservoir covered except for the
                                               8
amount of time you need to fill it and never leave a can of brake fluid uncovered. Brake
fluid must maintain a very high boiling point .Exposure to air will cause the fluid to absorb
moisture which will lower that boiling point.

Brake Lines: The brake fluid travels from the master cylinder to the wheels through a se-
ries of steel tubes and reinforced rubber hoses. Rubber hoses are only used in places that
require flexibility, such as at the front wheels, which move up and down as well as steer.
The rest of the system uses non-corrosive seamless steel tubing with special fittings at all
attachment points. If a steel line requires a repair, the best procedure is to replace the com-
plete line. If this is not practical, a line can be repaired using special splice fittings that are
made for brake system repair. You must never use brass “compression” fittings or copper
tubing to repair a brake system. They are dangerous and illegal.




3.3 Proportioning, Pressure Differential and Combination Valves

Proportional Valve: These valves are mounted between the master cylinder and the rear
wheels. They are designed to adjust the pressure between the fronts and rear brakes de-
pending on how hard you are stopping. The shorter you stop, the more of the vehicle's
weight is transferred to the front wheels, in some cases, causing the rear to lift and the front
to dive. These valves are designed to direct more pressure to the front and less pressure to
the rear the harder you stop. This minimizes the chance of premature lockup at the rear
wheels

Pressure Differential Valve: This valve is usually mounted just below the master cylinder
and is responsible for turning the brake warning light on when it detects a malfunction. It
measures the pressure from the two sections of the master cylinder and compares them.
Since it is mounted ahead of the proportioning or equalizer valve, the two pressures it de-
tects should be equal. If it detects a difference, it means that there is probably a brake fluid
leak somewhere in the system.

Combination valve: It is simply a proportioning valve and a pressure differential valve that
is combined into one unit.

                                                9
3.4 Disk Brakes

The disk brake is the best brake we have found so far. Disk brakes (Figure 8) are used to
stop everything from cars to locomotives and jumbo jets. Disk brakes wear longer, are less
affected by water, are self adjusting, self cleaning, less prone to grabbing or pulling and
stop better than any other system around. The main components of a disk brake are the
Brake Pads, Rotor, Caliper and Caliper Support




                                   Figure 8: Disk Brake



Brake Pads: There are two brake pads on each caliper. They are constructed of a metal "shoe"
with the lining riveted or bonded to it. The pads are mounted in the caliper, one on each side
of the rotor (Figure 9). Brake linings used to be made primarily of asbestos because of its heat
absorbing properties and quiet operation; however, due to health risks, asbestos has been out-
lawed, so new materials are now being used. Brake pads wear out with use and must be re-
placed periodically. There are many types and qualities of pads available. The differences have
to do with brake life (how long the new pads will last) and noise (how quiet they are when you
step on the brake). Harder linings tend to last longer and stop better under heavy use but they
may produce an irritating squeal when they are applied. Technicians that work on brakes
usually have a favorite pad that gives a good compromise that their customers can live with
Brake pads should be checked for wear periodically. If the lining wears down to the metal
brake shoe, then you will have a "Metal-to-Metal" condition where the shoe rubs directly
                                             10
against the rotor causing severe damage and loss of braking efficiency. Some brake pads come
with a "brake warning sensor" that will emit a squealing noise when the pads are worn to a
point where they should be changed. This noise will usually be heard when your foot is off
the brake and disappear when you step on the brake. If you hear this noise, have your brakes
checked as soon as possible.




                      Figure 9: Pad                  Figure 10: Rotor




Rotor: The disk rotor (Figure 10) is made of iron with highly machined surfaces where the
brake pads contact it. Just as the brake pads wear out over time, the rotor also undergoes
some wear, usually in the form of ridges and groves where the brake pad rubs against
it. This wear pattern exactly matches the wear pattern of the pads as they seat themselves
to the rotor. When the pads are replaced, the rotor must be machined smooth to allow the
new pads to have an even contact surface to work with. Only a small amount of material
can be machined off of a rotor before it becomes unusable and must be replaced. A mini-
mum thickness measurement is stamped on every rotor and the technician doing the brake
job will measure the rotor before and after machining it to make sure it doesn't go below
the legal minimum. If a rotor is cut below w the minimum, it will not be able to handle the
high heat that brakes normally generate. This will cause the brakes to "fade," greatly re-
ducing their effectiveness to a point where you may not be able to stop!




                                            11
3.5 Caliper & Support

There are two main types of calipers: Floating calipers and fixed calipers. There are other
configurations but these are the most popular. Calipers must be rebuilt or replaced if they
show signs of leaking brake fluid.


Single Piston Floating Calipers (Figure 11) are the most popular and also least costly to
manufacture and service. A floating caliper "floats" or moves in a track in its support so
that it can center itself over the rotor. As you apply brake pressure, the hydraulic fluid
pushes in two directions. It forces the piston against the inner pad which in turn pushes
against the rotor. It also pushes the caliper in the opposite direction against the outer pad,
pressing it against the other side of the rotor. Floating calipers are also available on some
vehicles with two pistons mounted on the same side. Two piston floating calipers are found
on more expensive cars and can provide an improved braking "feel"


Four Piston Fixed Calipers are mounted rigidly to the support and are not allowed to move.
Instead, there are two pistons on each side that press the pads against the rotor. Four piston
calipers have a better feel and are more efficient, but are more expensive to produce and
cost more to service. This type of caliper is usually found on more expensive luxury and
high performance cars




                                     Figure 11: Caliper




                                             12
3.6 Drum Brakes

So if disk brakes are so great, how come we still have cars with drum brakes? The reason
is cost. While all vehicles produced for many years have disk brakes on the front, drum
brakes are cheaper to produce for the rear wheels. The main reason is the parking brake
system. On drum brakes, adding a parking brake is the simple addition of a lever, while on
disk brakes, we need a complete mechanism, in some cases, a complete mechanical drum
brake assembly inside the disk brake rotor! Parking brakes must be a separate system that
does not use hydraulics. It must be totally mechanical, but more on parking brakes later
Drum brakes (Figure 12) consist of a backing plate, brake shoes, brake drum, wheel cylind-
er, return springs and an automatic or self-adjusting system. When you apply the brakes,
brake fluid is forced, under pressure, into the wheel cylinder which, in turn, pushes the
brake shoes into contact with the machined surface on the inside of the Drum. When the
pressure is released, return springs pull the shoes back to their rest position. As the brake
linings wear, the shoes must travel a greater distance to reach the drum. When the distance
reaches a certain point, a self-adjusting mechanism automatically reacts by adjusting the
rest position of the shoes so that they are closer to the drum




                                   Figure 12: Drum Brake


                                              13
Brake Shoes: Like the disk pads, brake shoes (Figure 13) consist of a steel shoe with the
friction material or lining riveted or bonded to it. Also like disk pads, the linings eventual-
ly wear out and must be replaced. If the linings are allowed to wear through to the bare
metal shoe, they will cause severe damage to the brake drum




                                   Figure 13: Brake Shoes



Backing Plating: is what holds everything together. It attaches to the axle and forms a solid
surface for the wheel cylinder, brake shoes and assorted hardware. It rarely causes any
problems


Brake Drum: Brake drums (Figure 14) are made of iron and have a machined surface on
the inside where the shoes make contact. Just as with disk rotors, brake drums will show
signs of wear as the brake linings seat themselves against the machined surface of the
drum. When new shoes are installed, the brake drum should be machined smooth. Brake
drums have a maximum diameter specification that is stamped on the outside of the drum.
When a drum is machined, it must never exceed that measurement. If the surface cannot
be machined within that limit, the drum must be replaced.


Wheel Cylinder: The wheel cylinder consists of a cylinder that has two pistons, one on
each side. Each piston has a rubber seal and a shaft that connects the piston with a brake
shoe. When brake pressure is applied, the pistons are forced out pushing the shoes into con-


                                              14
tact with the drum. Wheel cylinders must be rebuilt or replaced if they show signs of leak-
ing.


Return Springs: Return springs pull the brake shoes back to their rest position after the pres-
sure is released from the wheel cylinder. If the springs are weak and do not return the shoes
all the way, it will cause premature lining wear because the linings will remain in contact with
the drum. A good technician will examine the springs during a brake job and recommend their
replacement if they show signs of fatigue. On certain vehicles, the technician may recommend
replacing them even if they look good as inexpensive insurance




                                   Figure 14: Drum Brake



Self Adjusting System: The parts of a self adjusting system should be clean and move freely to
insure that the brakes maintain their adjustment over the life of the linings. If the self adjusters
stop working, you will notice that you will have to step down further and further on the brake
pedal before you feel the brakes begin to engage. Disk brakes are self adjusting by nature and
do not require any type of mechanism. When a technician performs a brake job, aside from
checking the return springs, he will also clean and lubricates the self adjusting parts where ne-
cessary


Parking Brakes: system controls the rear brakes through a series of steel cables that are
connected to either a hand lever or a foot pedal The idea is that the system is fully mechan-
                                              15
ical and completely bypasses the hydraulic system so that the vehicle can be brought to a
stop even if there is a total brake failure. On drum brakes, the cable pulls on a lever
mounted in the rear brake and is directly connected to the brake shoes. This has the effect
of bypassing the wheel cylinder and controlling the brakes directly. Disk brakes on the rear
wheels add additional complication for parking brake systems. There are two main designs
for adding a mechanical parking brake to rear disk brakes. The first type uses the existing
rear wheel caliper and adds a lever attached to a mechanical corkscrew device inside the
caliper piston. When the parking brake cable pulls on the lever, this corkscrew device
pushes the piston against the pads, thereby bypassing the hydraulic system, to stop the ve-
hicle. This type of system is primarily used with single piston floating calipers, if the cali-
per is of the four piston fixed type, then that type of system can't be used. The other system
uses a complete mechanical drum brake unit mounted inside the rear rotor. The brake shoes
on this system are connected to a lever that is pulled by the parking brake cable to activate
the brakes. The brake "drum" is actually the inside part of the rear brake rotor on cars with
automatic transmissions, the parking brake is rarely used. This can cause a couple of prob-
lems. The biggest problem is that the brake cables tend to get corroded and eventually se-
ize up causing the parking brake to become inoperative. By using the parking brake from
time to time, the cables stay clean and functional. Another problem comes from the fact
that the self adjusting mechanism on certain brake systems uses the parking brake actuation
to adjust the brakes. If the parking brake is never used, then the brakes never get adjusted.




3.7 Power Brake Booster
The power brake booster (Figure 15) is mounted on the firewall directly behind the master
cylinder and, along with the master cylinder, is directly connected with the brake pedal. Its
purpose is to amplify the available foot pressure applied to the brake pedal so that the
amount of foot pressure required to stop even the largest vehicle is minimal. Power for the
booster comes from engine vacuum. The automobile engine produces vacuum as a by-
product of normal operation and is freely available for use in powering accessories such as
the power brake booster. Vacuum enters the booster through a check valve on the booster.
The check valve is connected to the engine with a rubber hose and acts as a one-way valve
that allows vacuum to enter the booster but does not let it escape. The booster is an empty
                                              16
shell that is divided into two chambers by a rubber diaphragm. There is a valve in the di-
aphragm that remains open while your foot is off the brake pedal so that vacuum is allowed
to fill both chambers. When you step on the brake pedal, the valve in the diaphragm
closes, separating the two chambers and another valve opens to allow air in the chamber on
the brake pedal side. This is what provides the power assist. Power boosters are very reli-
able and cause few problems of their own; however, other things can contribute to a loss of
power assist. In order to have power assist, the engine must be running. If the engine stalls
or shuts off while you are driving, you will have a small reserve of power assist for two or
three pedal applications but, after that, the brakes will be extremely hard to apply and you
must put as much pressure as you can to bring the vehicle to a stop




                                 Figure 15: Brake Booster




3.8 Performance Characteristics

Brake pads are designed for friction stability, durability, and minimization of noise and vi-
bration. 'Friction stability' means that the brake pad's friction coefficient remains high un-
der hot, cold, wet and dry conditions at various braking speeds. Automotive engineers use a
variety of materials to maximize performance in all areas, often combining five to twenty
different   material   ingredients   to   form    complex   composite    friction   materials.
                                             17
Metals, such as copper, tend to be good friction materials because they are good at dissipat-
ing heat generated .During braking. Metallic formulations generally have high "hot" fric-
tion coefficients making them perform well under extreme braking conditions. Larger cars
and cars that need to stop quickly generally require semi-metallic pads while organic pads
are fine for light and medium weight vehicles. Asbestos is a highly versatile friction ma-
terial, providing consistent braking performance at a variety of speeds and weather condi-
tions. Researchers are constantly testing new materials for braking performance, often in
response potential upcoming regulations. The technical literature suggests that polymer
friction materials have been developed as alternatives to asbestos and metals in organic
brake pad (Amaguchi, Y. and Ahondas, J., 1991) .The effect of metals on durability and
noise characteristics is unclear at this point. Some automobile technicians indicated that
semi-metallic pads are more durable than organics allowing longer replacement intervals.
However, it was also noted that driving style is generally more important than brake pad
formulation in determining the frequency of replacement. Some varieties of organic pads
may tend to squeal more than semi-metallic pads.

The Santa Clara Valley study found that copper is used less, if used at all, in the brake pads
used in domestic cars than in Japanese and European vehicles. Copper is used more exten-
sively in brake pads in European and Japanese vehicles. There are many possible explana-
tions for the lower copper content in domestic vehicles including cost and driving condi-
tions. The use of copper in domestic brake pad formulations is limited by cost since copper
is more expensive than organic materials. Another possible explanation is driving style;
lower metal formulations may be more appropriate

For American drivers who brake slowly and steadily rather than European drivers who tend
to brake more quickly.

The results of study also indicate that zero or low-copper formulations are used in many in
light and medium weight vehicles. The study did not indicate whether the brake pads tested
were semi-metallic or organic formulations since either type may contain copper. Since
their study did not focus on performance characteristics of the brake pads, it is not possible
to draw conclusions on the durability or noise characteristics of the different models tested.


                                              18
Figure 16 and 17 showing the relationships between the pedal position, master cylinder
pressure and force exert ( Fouvry, S., Paulin, C. and Deyber, S. ,2009).




             Figure 16: Relation between Master Pressure and Pedal Position




               Figure 17: Relation between Master Pressure and Force exert




                                             19
3.9 Faults in brake system

Reason for rotor crack

They are two reasons for rotor crack the first one Braking in very small distance results in
heating of over part of the rotor, while the real of the rotor is cold .this a very high tem-
perature causing crake and the second The Cooling slots in the rotor cause not uniform
stress distribution this create crack see Figure 18 (Bagnoli, F., Dolce, F. and Bernabei, M.
, 2009)




                           Figure 18: Crack in Rotor in both side




                                             20
           Table 2: showing the possible fault in brake system and its remedy




   Condition               Cause                             Remedy

                          Low fluid level in
                           master
                          Air in system                Fill master cylinder
 Excessive pedal          Excessive brake              Bleed hydraulic system
     travel                shoe to drum clear-          Adjust brake shoes
                           ance


                                                        Fill master cylinder and look
Fading brake ped-         Leak in hydraulic             for leaks in the lines, wheel cy-
  al (pedal falls          system                        linder or master cylinder repair
away under steady         Defective master cy-          as required
    pressure )             linder primary cup           Repair or replace as necessary

  Spongy brake
  pedal (soft or
                      Air in hydraulic system                  Bleed brakes
springy when ap-
      plied)
                          Grease , brake fluid
                           or water on brake
                                                        Replace or allow to dry as ne-
                           lining
                                                         cessary
                          Incorrect or loose
                                                        Replace as necessary
Grabbing brakes            lining on brake
                           shoes                        Remove restriction or replace
                                                         line
                          Wheel cylinder
                           sticking or frozen
                          Restricted brake line
                          Drum out of round
                                                        Machine or replace drums
                          Rotor bent or un-
 Pulsating brake                                        Repair or replace rotor
                           even
      pedal                                             Adjust wheel bearing
                          Front wheel bearing
                           loose
                          Lining worn out
                          Broken or weak re-           Replace brake lining
                           turn or hold-down
                                                        Replace spring
                           spring
  Noise brakes                                          Clean or replace as necessary
                          Foreign material in
                                                        Return or turn as necessary
                           brake drum
                          Grooved or scored
                           drum or rotor
                                          21
                        CHAPTER 4 SOLID MODEL

4.1 Exploded view for disk brake




                    Figures 19: Exploded View for Disk Brake (1)

                                        22
                      Figure 20: Exploded View for Disk Brake (2)




4.2 Engineering drawing for the disk brake

Actual brake system (DIHATSU CAR) has been disassembled and the dimension of the
components were taken using Vernier Caliper the following figures illustrates the dimen-
sion and configurations of the DIHATSU disk brake.


                                          23
4.2.1 Rotor




              Figure 21: Rotor Dimensions in (mm).




                 Figure 22: Rotor Section Views

                              24
4.2.2 Brake pad




                   Figure 23: Pad Dimensions in (mm)

4.2.3 Caliper




                  Figure 24: Caliper Dimensions in (mm)

                                   25
4.2.4 Hex bolt




                  Figure 25: Bolt Dimensions in (mm)

4.2.5 Splash




                 Figure 26: Splash Dimensions in (mm)

                                 26
4.2.6 Other parts




                    Figure 27: Part 1 Dimensions in (mm)




                    Figure 28: Part 2 Dimensions in (mm)
                                    27
                  CHAPTER 5: FINITE ELEMENT ANALYSIS

5.1 Stress Analysis for the Brake Pad

Tables 3: Material Property


                        Material                          Ceramic Porcelain
                    Property Name                        Value           Units
                    Elastic modulus                  2.2059e+011        N/m^2
                     Poisson's ratio                      0.22            NA
                     Shear modulus                   9.0407e+010        N/m^2
                      Mass density                        2300         kg/m^3
                    Tensile strength                 1.7234e+008        N/m^2
                  Compressive strength               5.5149e+008        N/m^2
              Thermal expansion coefficient            1.08e-005       /Kelvin
                  Thermal conductivity                   1.4949        W/(m.K)
                      Specific heat                      877.96        J/(kg.K)
                          Mass                         0.165072           kg
                        Volume                       7.17703e-005        m^3




Tables 4 : Loads And constrain see Figure 29


         Load                                                             Loading
                                     Selection set
         name                                                              type
                     on 2 Face(s) apply force 4000 N along plane
        Force-1
                    Dir 2 force 15000 N normal to reference plane        Sequential
        <Brake
                    with respect to selected reference Face< 1 > us-      Loading
         pad>
                                ing uniform distribution




                                           28
                                                     4000 N    15000 N



                            Figure 29: Load and Restraints

Table 5: Mesh Property see Figure 30


                           Mesh Type:             Solid Mesh
                          Mesher Used:             Standard
                      Automatic Transition:             Off
                        Smooth Surface:                 On
                         Jacobian Check:            4 Points
                          Element Size:           2.2864 mm
                            Tolerance:           0.11432 mm
                             Quality:                   High
                       Number of elements:          41923
                        Number of nodes:            62021




                                 Figure 30 : Pad Mesh
                                           29
Result

Figures (31-32) shows the displacement of each node of the brake pad

a- Displacement (mm)




                                Figure 31: Displacement

b- Stress von Mises (N/m2)




                                    Figure 32: Stress




                                           30
5.2 Stress analysis for the disk brake (pad, Rotor, holder)

Table 6: property and units for disk brake

                                Analysis type     Static
                                 Mesh Type:     Solid Mesh
                                 Solver type     FFEPlus
                               Inplane Effect:      Off
                                Soft Spring:        Off
                               Inertial Relief:     Off
                                Unit system:        SI
                            Length/Displacement    Mm
                              Angular velocity     rad/s
                              Stress/Pressure     N/m^2



Table 7: Rotor material property

                       Material name:               Gray Cast Iron
                       Property Name               Value      Units
                       Elastic modulus         6.6178e+010 N/m^2
                        Poisson's ratio            0.27       NA
                       Shear modulus              5e+010      N/m^2
                        Mass density               7200       kg/m^3
                       Tensile strength        1.5166e+008 N/m^2
                     Compressive strength      5.7217e+008 N/m^2
                 Thermal expansion coefficient   1.2e-005     /Kelvin
                     Thermal conductivity            45       W/(m.K)
                         Specific heat              510       J/(kg.K)
Table 8: Holder material property



                        Material name:               Cast Carbon Steel
                        Property Name                 Value       Units
                        Elastic modulus              2e+011      N/m^2
                         Poisson's ratio               0.32        NA
                        Shear modulus               7.6e+010     N/m^2
                         Mass density                 7800       kg/m^3
                        Tensile strength          4.8255e+008 N/m^2
                         Yield strength           2.4817e+008 N/m^2
                 Thermal expansion coefficient     1.2e-005     /Kelvin
                     Thermal conductivity              30      W/(m.K)
                         Specific heat                500      J/(kg.K)
                                             31
Table 9: Restraint

              Restraint name                               Selection set
        Restraint-1 <Brake Shoe-1,
                                           On 2 Face(s) immovable (no translation).
              Brake Shoe-2>
                                         on 1 Face(s) with displacement 0. mm along
                                          radial. Displacement 11.459200 mm along
        Restraint-2 <Brake Disk >
                                          circumferential. Displacement 0 mm along
                                                             axial.
         Restraint-3 <Brake Disk
                                                       On 3 Face(s) fixed.
         steel-1, shoe holder2-1>




Table 10: contact information

                                      No Penetration contact pair: Between selected
            Contact Set-1            entities of Brake Shoe-2 and Brake Disk steel-1
                                      Include friction with Friction Coefficient: 0.2




                     Ceramic Porcelain
                                              Cast
                                              carbon
                                              steel




                                               Gray
                                               Cast iron




                                Figure 33: Disk Brake Restraint


                                              32
Table 11: Disk brake mesh information see (Figure 34)

                             Mesh Type:          Solid Mesh
                            Mesher Used:          Standard
                         Automatic Transition:       Off
                           Smooth Surface:            On
                           Jacobian Check:         4 Points
                            Element Size:       0.0088212 m
                              Tolerance:       0.00044106 m
                               Quality:              High
                         Number of elements:        22605
                          Number of nodes:          41398




                              Figure 34: Disk Brake Mesh



                                          33
Results

Figures 35-36 shows the displacement and stress in assemble disk brake

A-displacement (mm)




                            Figure 35: Disk Brake Displacement

B-Stress von Mises (N/m2)




                               Figure 36: Stress Von Mises
                                           34
                  Figure 37: Contact / friction force at µ=0.2 and µ=0.3


                      16
                      14
                      12
                      10
                       8
                       6
                       4
                       2
                       0
                                  µ=0.2                µ=.3




5.3 Temperature Distribution at Rotor

Figure 38 show the temperature distribution at different location in the rotor

Figure 39 show the relation between the time and Temperature degree




             Figure 38: Temperature Distribution at the End of Action Brake


                                             35
                    Figure 39: Temperature (C0) At Different Time (S)




5.4 Optimum Design of Rotor Using Solidworks Software

Constrains, forces, material and the actual dimension of the rotor (Figure: 40)




                                                                                  15000 N



                                                                                   Material
                                                                                   is IRON


                                                                                  Restraint
                                                                                  in face is
                                                                                  fixed


                Figure 40: The Dimension (Mm) Selected Before Optimize




                                             36
After running the program given new dimension (Figure: 41)




                            Figure 41: The New Dimension




This change reduces the weight 8.15% (Figure: 42)




                            Figure 42: New Design Weight




                                          37
          CHAPTER 6: ANALYSIS OF A DRUM BRAKE FORCE

The illustration depicts a side view of a brake drum (Figure 43) that is typical of automo-
tive applications. Using W=300lbs, θ1=5°, θ2=120°, r=5 in (12.7 cm), d7=4.25 in (10.7 cm).
The shoe width is 3 in (7.62 cm). Assume that the shoes are centered in the drum. Esti-
mated the coefficient of friction is µ=0.20




                                 Figure 43: Drum dimensions




The self energizing shoe is the one where the moment due to the friction stress acts in the
same direction as the applied load’s moment about the hinge pin. Because of the indicated
rotation direction, the shoe on the right is the self energizing shoe.




                                               38
                                                               Location of
                                                               maximum
                                                               pressure
        Deenergizing
        shoe                                                 Self-energizing shoe




                                Figure 44: Drum Force




The 30° angles are known because of symmetry. d6 is then given by

                            d6=2d7cos30°=7.3612 in (19cm)




                               Figure 45: Drum Angels




                                          39
6.1 Analysis Details for Self-Energizing Shoe

Table 12 show the Parameters for car



                                       Table 12:Drum Dimension

          W              θ1             θ2          R           d7         B            µ         d6
         300lb           5             120         5in        4.25 in     3 in         0.2      7.36 in




The normal force moment is:

                     brd 7 p max                                         
           MP                     2 2  1  180  sin 2 2  sin 21   80.547in p max
                                                                                       3

                      4sin  a                                            




The friction force moment is:


          p maxbr                                                    
   MF 
           sin  a
                                                   d7
                                                                              
                        r cos  2  cos  1   2 sin  2  sin  1   17.7101in p max
                                                        2
                                                                 2                 3

                                                                      




Equation for pmax:

                              M P  M F 80.547 p max  17.71 p max
           W  300lbs                                            ; p max  35.13psi
                                 d6              7.36in




The torque:


                       p maxbr 2 cos1  cos 2 
                 T                                  788.4in  lb  88.32298 Nm
                                  sin  a

                                                     40
6.2 Deenergizing Shoe Analysis

The normal force moment and friction force moments are the same as for the self-
energizing shoe.



Equation for pmax:

                          M P  M F 80.547 p max  17.71 p max
           W  300lbs                                        ; p max  22.47psi
                             d6              7.36in



The torque:

                     p maxbr 2 cos 1  cos 2 
                T                                  504.29in  lb  56.523 Nm
                                sin  a



The clear difference in the behavior was demonstrated by analyzing the self-energizing and
deenergizing shoes separately. This important think we must be used when determine de-
sign performance of shoe.




                                              41
                     CHAPTER 7: VIRTUAL PROTOTYPE

The Meaning of prototype

A prototype is an original type, form, or instance of something serving as a typical exam-
ple, basis, or standard for other things of the same category.




7.1 Disk Brake Virtual Prototypes before Painting

Rotor made from wood and performing by turning machine (Figure 46)




                         Figure 46: Rotor Outside and Vehicle Side

Caliper and Splash made from wood (Figure 47)




                         Figure 47: Disk Brake Caliper and Splash
                                              42
   7.2 Disk Brake Virtual Prototypes after Painting

Figure 48 and 49 show the virtual prototypes of rotor, Caliper and Splash after painting




                                Figure 48: Rotor Prototypes




                         Figure 49: Caliper and Splash Prototypes
                                             43
Results discussion

This project presents the outline of brake system. It is concluded that hydraulic brake sys-
tem in all car are same with little different in components structure like pad materials and
rotor material. The Researches on brake pad materials stated that commercial composition
of the pad cannot be concluded whether is preferable to contain organic or semi metallic
brake pads contain more copper. Both organic and semi-metallic may contain copper al-
though specific amounts will depend on the manufacturer. Found that contact areas also
increase as wear develops. This corresponds to the reduction of roughness values of the
pad surface. The finite element analysis simulated the present stress and displacement dis-
tribution in the pad and in the rotor .the friction force at different friction coefficient dis-
played .the temperatures distribution at different time are displayed .for the dimensions of
brake system components can optimize any dimension if we give appropriate studies in our
project .Reduce rotor width achieve reduce in weight equal 8.15% This save can increase
the profit of producing in mass production .in the drum .We concluded the lining material
in the maximum pressure side must be more reliable to resist the applied forces. The virtual
prototypes give us good imagine for the disk brake in the components side and the dimen-
sions side.




                                              44
Conclusion

This project represents an application of reverse engineering in the car brake system. The
engineering design supported by CAD (Computer-Aided-Design)/CAE (Computer-Aided-
Engineering) techniques allows optimizing the product concept before manufacturing with
assistance of CAM (Computer-Aided-Manufacturing), in management for rapid product
development and rapid set-up production in advance. On one side permanent software ap-
plication improvement imply in production line constant shortening of time intended for
new product development - (re) design. Solid models, finite analysis; virtual prototypes are
all used throughout the reverse engineering stage. The present work shows that a lot of de-
velopment and improvement could be achieved in the brake system through the models
developed.




Recommendation

We can summarize the recommendation in following points:

   1- When disassemble the brake system parts for take the dimension we preferred to
       use digital measurement equipments because that allow to take more precise di-
       mension in less time
   2- use catia software instead solidworks software when need to drawing because ca-
       tia give more options to perform the work
   3- optimize dimensions for brake system components should be studied at different
       conditions and constrains to get more accurate results
   4- simulate the forces and torque in the drum brake using software to get more accu-
       rate results
   5- Use 3D printer to perform the visual prototypes instead the wood because the prin-
       ter give the same results in less time




                                                45
References

Amaguchi, Y. and Ahondas, J. (1991). “Non-Asbestos, Non-Metallic, Non-Glass Brake
Pad Composite”.Automotive Engineering, 99, pp 12.

Bagnoli, F., Dolce, F. and Bernabei, M. (2009).”Thermal Fatigue Cracks Of Fire Fighting
Vehicles Gray Iron Brake Discs”, Engineering Failure Analysis, 16, pp 152-163

EL-Tayeb, N. and Liew, K. (2009).”On The Dry and Wet Sliding Performance Of Poten-
tially New Friction Brake Pad Materials For Automotive Industry”. Wear, 266, pp 275-287

Fouvry, S., Paulin, C. and Deyber, S. (2009). “Impact of contact size and complex gross-
partial slip conditiond on Ti-6Al-4V/Ti-6Al-4V fretting wear”, Tribology International,
42, pp 461-474.




                                          46

				
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