brake analysis

8/10/2019 brake analysis

http://slidepdf.com/reader/full/brake-analysis 1/7

Babu, et al, International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974

Int. J. Adv. Engg. Res. Studies/III/I/Oct.-Dec.,2013/45-51

Research Paper

STRUCTURAL DESIGN AND THERMAL ANALYSIS OF CAR

DISC BRAKE ROTORK. Naresh Babu

1, T.Siva Krishna

2

Address for Correspondence1M. Tech Student,

2Assistant Professor, Department of Mechanical Engineering, QIS College of Engineering &

Technology, Ongole – 523272, Andhra Pradesh, India

ABSTRACTThe motive of undertaking this project of “Structural Design and Thermal Analysis of Car Disc Brake Rotor” is to study and

evaluate the performance under severe braking conditions and there by assist in disc rotor design and analysis. This study isof disc brake used for cars.

ANSYS is a finite element package used for determining the temperature distributions, variation of stresses anddeformations across the disc brake profile.In this present work, an attempt has been made to investigate the effect of stiffness, strength and variations in disc brake

rotor design on the predicted stress and temperature distributions. By identifying the true design features, the extended

service life and long term stability is assured. This paper studies about the model of a disc brake used in Toyota Rav4. Atransient thermal analysis has been carried out to investigate the temperature variation across the disc using axis-symmetricelements. Further structural analysis is also carried out by coupling thermal analysis.An attempt is also made to suggest a best combination of materials (like Cast iron, stainless steel, High strength S-glass fiber

and Aluminum metal matrix composite), flange width and wall thickness used for disc brake rotor, which yields a low

temperature variation across the rotor, less deformation, and minimum von-misses stress possible.

1.0 INTRODUCTIONA disc brake consists of a disc component bolted to

the wheel hub and a stationary housing called caliper.

The caliper is connected to some stationary part of

the vehicle like the axle casing or the stub axle as iscast in two parts each part containing a piston. In

between each piston and the disc there is a friction

pad held in position by retaining pins, spring plates

Etc. passages are drilled in the caliper for hydraulic

fluid to enter or leave each housing. The passages arealso connected to another one for bleeding. Each

cylinder contains rubber-sealing ring between the

cylinder and piston. A schematic diagram is shown in

the following figure.

Figure 1: Disc Brake full assemble view

1.1 Working Principle

When the brakes are applied, hydraulically actuated

pistons move the friction pads in to contact with the

disc, applying equal and opposite forces on the later.

On releasing the brakes the brakes the rubber-sealing

ring acts as a return spring and retract the pistons and

the friction pads away from the disc (see fig).

Figure .2: Working principle of Disc brakes

Figure .3: Location of Disc Brakes in a car

2.0 DISC BRAKE ROTOR MODEL DESIGN

Figure .4: Solid Disc Brake Rotor isometric view

3.0 THERMAL STRUCTURAL ANALYSISTemperature distributions in different materials

In transient thermal analysis a time varying thermal

load (temperature load) is applied and its behavior is

analyzed. Both convection and heat flux parameters

are considered for evaluation of results. Although the

convection coefficient varies with velocity and

surface a general convection coefficient of 5

W/(m2.°C) is taken for both internal and external

convection. In this case study, a time varying

temperature load is calculated for a car of mass

1400Kg travelling at 31.11 m/s brought to a complete

stop (one complete stop).

Thermal Loads:Heat flux (q) = 881141.3283 W/ m

2 (for 4 seconds of

braking)

Heat flux (q) =704913.0626 W/m2

(for 5 seconds of

braking)





Heat flux (q) =587427.5522 W/m2

(for 6 seconds of

braking)

Convection film co-efficient (h) = 5.0 W/ m2 k

Temperature fixed at the hub bore grinds = 35°C

Case 1: At flange thickness of 10 mm

Figure .5: Temperature distribution in steel Disc at 6 sec of breaking time (for 10 mm thick flange)

Figure .6: Temperature distribution in AMMC Disc at 6 sec of breaking time (for 10 mm thick flange)


Figure .7: Temperature distribution in S2-glass Disc at 6 sec of breaking time (for 12 mm thick flange)







Figure .9: Temperature distribution in cast iron Disc at 6 sec of breaking time (for 15 mm thick flange)


4.0 Comparison of Temperature distributions in Disc materials

Figure .11: Formation of vonmises stresses in S2-glass at 6sec of breaking time (for 10 mm thick flange)







Figure .14: Formation of Vonmises stresses in Cast iron disc at 6sec of breaking (for 10 mm thick flange)

Figure .15: Formation of Vonmises stresses in Castiron disc at 6sec of breaking (for 12 mm thick flange)





Figure .16: Formation of Vonmises stresses in Castiron disc at 6sec of breaking (for 15 mm thick flange)

Figure .17: Formation of Vonmises stresses in Steel disc at 6sec of breaking (for 10 mm thick flange)







Figure .20: Formation of Vonmises stresses in AMMC disc at 6sec of breaking (for 10 mm thick flange)

Figure .21: Formation of Principal stresses1 in AMMC disc at 6sec of breaking (for 12 mm thick flange)

Figure .22: Formation of Vonmises stresses in AMMC disc at 6sec of breaking (for 15 mm thick flange)

5.0 Comparison of Thermal stresses in Disc BrakeRotor

Now for establishing a best material for the car disc brake rotor for the present application, four different

materials which are commonly used for the disc

brakes namely Cast Iron (CI), stainless steel 302

annealed (S.S), Aluminium metal matrix composite

(AMMC), high strength S2-glass fiber were takenand analysis is done using their properties on the disc

brake rotor with 6.5mm wall thickness with differentflange widths at 4, 5 and 6 seconds of breaking time.

Case1: The following table illustrates the Thermal

stresses distribution in Disc Brake Rotor for 10 mm

thick flange at 4, 5 and 6 seconds of braking time

Table .1: Comparison of Thermal stresses distribution in disc rotor for 10 mm thick flange

Case2: The following table illustrates the thermal stresses distribution in Disc Brake Rotor for 12 mm thickflange at 4, 5 and 6 seconds of braking time.




Int J Adv Engg Res Studies/III/I/Oct -Dec 2013/45-51

Table .2: Comparison of Thermal stresses distribution in disc rotor for 12 mm thick flange

Case3: The following table illustrates the thermal stresses distribution in Disc Brake Rotor for 15 mm thickflange at 4, 5 and 6 seconds of braking time.Table .3: Comparison of Thermal stresses distribution in disc rotor for 15 mm thick flange

6.0 CONCLUSIONS

The following conclusions are drawn from the

present work.• An Axis-symmetric analysis of disc brake

has been carried out using elements Plane

55 and Plane 42 through ANSYS 12.0

(F.E.A) software.

• A transient thermal analysis is carried out

using the direct time integration technique

for the application of braking force due to

friction for time duration of 4, 5 and 6

seconds.

• The maximum temperature obtained in S2-

Glass brake disc at the contact surface is

observed to be 125.3 °C.

•

Static structural analysis is carried out bycoupling the Thermal solution to the

structural analysis and the maximum

Vonmises stress in S2-Glass brake disc is

observed to be 60.3 M Pa.

• The Brake disc design is safe based on the

Strength and Rigidity Criteria.

• To arrive at a best combination of

parameters of the Disc Brake like Flange

width, wall thickness and Material Transient

Thermal and Structural Analysis for three

different combinations in each of the four

different materials were carried outseparately and the results were compared.

• Comparing the different results obtained

from the analysis, it is concluded that disc

brake with 12 mm flange width, 6.5 mm

Wall Thickness and of material high

strength S2-Glass is the Best possible

combination for the present application.

REFERENCES1. Introduction to Finite Elements in Engineering by

Chandrupatla &Belegundu2. A.C.Delco Disc Rotors Catalogue book

3. User Guide for ANSYS 12.0

4.

Internet web site WWW. How Stuff works.com5.

A Text book of Machine Design by Pandya & Shaw.

6.

A Text book of Machine Design by R.S. Khurmi &J.K.Gupta

7. Machine Design Data hand Book by PSG college of

technology

8. Heat and Mass Transfer Data Book by C PKothandaraman, S Subramanyan

Documents

brake analysis