TRANSIENT ANALYSIS OF METAL – CERAMIC DISK BRAKE€¦ · TRANSIENT ANALYSIS OF METAL - CERAMIC DISK BRAKE S.Vivekanand 1, ... a numerical simulation is carried out in ANSYS to predict

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ICNSCET19- International Conference on New Scientific Creations in

Engineering and Technology

TRANSIENT ANALYSIS OF METAL - CERAMIC DISK BRAKE

S.Vivekanand1, V.Sukumar

2

1Department of Mechanical Engineering, Government College of Engineering, Bodinayakanur, 2Department of Mechanical Engineering, Government college of Engineering, Bodinayakanur,

Abstract— Disk brakes have been used for many years in automobiles and are still

undergoing further development in terms of the temperatures that they can reach and operate safely

at. Many new materials have been introduced for the disk brake rotor to withstand high temperature

produced during braking action. Apart from the high temperature property, the disc rotor materials

must also have high thermal conductivity property, as this property decides the amount of heat

dissipation to the air stream from the disk rotor. A brake material with good temperature and high

thermal conductivity property gives maximum efficiency by overcoming the problem of thermo-

mechanical instability [TEI] in the rotor which is more common in low thermal conductivity brake

rotor material. In the present work, a Grey cast iron and metal-ceramic material has been chosen for

the disk brake rotor. Many methods have been introduced in the past to simulate and predict the

temperature history of the different disk brake materials, To simulate and predict the temperature

history for the Grey cast iron material, and metal-ceramic, a numerical simulation is carried out in

ANSYS to predict temperature distribution as a function of time in the disk brake rotor. The results

from the transient analysis are compared. From the analysis, the best material for the brake Rotor

metal-ceramic as far as thermal and structural behavior is concerned in order to prevent “thermal

elastic instability”.

Keywords— ANSYS, cast iron, Disc brake, metal and ceramic.

I. INTRODUCTION

In the past 30 years the automotive industry has seen a transition from drum brakes to disc

brakes. This transition was made with the purpose of improving performance and reducing mass.

Concurrent with this transition has been an all out effort to improve perceived quality of

automobiles. The most important quality factor of brake systems can be considered thermal

mechanical instability (1). During the braking action, the kinetic energy produced at the wheel is

transformed into heat energy, which doesn’t dissipate fast enough into the air stream from the brake

to the brake disk, as a result, one of the disk brake material properties; the thermal conductivity plays

a critical role in handling such friction heat generated (2). Thermal judder occurs as a result of no

uniform contact cycles between the pad and the disk brake rotor, which is primarily an effect of the

localized Thermo-Elastic Instabilities (TEI) at the disk brake rotor surface. Localized TEI act at the

friction ring surface generating intermittent hot bands around the rubbing path which may in turn

leads to the development of so-called hot spots (3-4). The mechanism of the TEI phenomena taking

place during the braking process has been of interest to many researchers (5-6). However, in this

paper an assumption has been made that the thermo mechanical phenomenon of each disk are in

symmetry about the disk’s mid-plane. Also, the wear action taking place during the braking process,

resulting from the friction between the disk brake and the pad, is assumed to be so small and thus to

be neglected in the analysis (7-8). The suggested FEA model is simulating the braking action by

1st International Conference on New Scientific Creations in Engineering and Technology (ICNSCET-19)

International Journal of Recent Trends in Engineering & Research (IJRTER)

Special Issue; March - 2019 [ISSN: 2455-1457]


investigating both the thermal and elastic actions occur during the friction between the two sliding

surfaces, the pad and the disk made of metal-ceramic and grey cast iron (9 -10).

II. PROBLEM IDENTIFICATION

A disk brake consists of a cast iron disk 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 is cast in two parts each part containing a piston. In between each piston and the disk there is

a friction pad held in position by retaining pins, spring plates etc. passages are drilled in the caliper

for the fluid to enter or leave each housing. The passages are also connected to another one for

bleeding. Each cylinder contains rubber-sealing ring between the cylinder and piston.

Fig.1 Disk Brake

The main components of the disc brake are The Brake Pads the Caliper which contains the piston

The Rotor, which is mounted to the hub When the brakes are applied, hydraulically actuated pistons

move the friction pads in to contact with the rotating disk, applying equal and opposite forces on the

disk. Due to the friction in between disk and pad surfaces, the kinetic energy of the rotating wheel is

converted into heat, by which vehicle is to stop after a certain distance. On releasing the brakes the

brakes the rubber-sealing ring acts as return spring and retract the pistons and the friction pads away

from the disk.

2.1 PROBLEMS IN DISK BRAKE

In the course of brake operation, frictional heat is dissipated mostly into pads and a disk, and

an occasional uneven temperature distribution on the components could induce severe thermo elastic

distortion of the disk. The thermal distortion of a normally flat surface into a highly deformed state

called thermo elastic transition. It sometimes occurs in a sequence of stable continuously related

states s operating conditions change. At other times, however, the stable evolution behavior of the

sliding system crosses a threshold whereupon a sudden change of contact conditions occurs as the

result of instability.

This invokes a feedback loop that comprises the localized elevation of frictional heating, the

resultant localized bulging, a localized pressure increases as the result of bulging, and further

elevation of frictional heating as the result of the pressure increase. When this process leads to an

accelerated change of contact pressure distribution, the unexpected hot roughness of thermal





distortion may grow unstably under some conditions, resulting in local hot spots and leaving thermal

cracks on the disk. This is known as thermo elastic instability (TEI).

The thermo elastic instability phenomenon occurs more easily as the rotating speed of the

disk increases. This region where the contact load is concentrated reaches very high temperatures,

which cause deterioration in braking performance. Moreover, in the course of their presence on the

disk, the passage of thermally distorted hot spots moving under the brake pads causes low-frequency

brake vibration.

III. MODELING AND ANALYSIS

It is very difficult to exactly model the brake disk, in which there are still researches are

going on to find out transient thermo elastic behavior of disk brake during braking applications.

There is always a need of some assumptions to model any complex geometry. These assumptions are

made, keeping in mind the difficulties involved in the theoretical calculation and the importance of

the parameters that are taken and those which are ignored. In modeling we always ignore the things

that are of less importance and have little impact on the analysis. The assumptions are always made

depending upon the details and accuracy required in modeling.

The assumptions which are made while modeling the process are given below:-

1. The disk material is considered as homogeneous and isotropic.

2. The domain is considered as axis-symmetric.

3. Inertia and body force effects are negligible during the analysis.

4. The disk is stress free before the application of brake.

5. Brakes are applied on the entire four wheels.

6. The analysis is based on pure thermal loading and vibration and thus only stress level

due to the above said is done. The analysis does not determine the life of the disk brake.

7. Only ambient air-cooling is taken into account and no forced Convection is taken.

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

the tyre and the road surface and deceleration is uniform.

9. The disk brake model used is of solid type and not ventilated one.

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

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

temperature.

IV. DEFINITION OF PROBLEM DOMAIN

Due to the application of brakes on the car disk brake rotor, heat generation takes place due to

friction and this thermal flux has to be conducted and dispersed across the disk rotor cross section.

The condition of braking is very much severe and thus the thermal analysis has to be carried out. The

thermal loading as well as structure is axis-symmetric. Hence axis-symmetric analysis can be

performed. Thermal analysis is carried out and with the above load structural analysis is also

performed for analyzing the stability of the structure.

4.1 DIMENSIONS OF DISK BRAKE

The dimensions of brake disk used for transient thermal and static structural analysis are shown in

Fig.2





Fig 2 -DIMENSIONS OF DISC BRAKE ROTOR

V. CREATING A FINITE ELEMENT MODEL AND MESH

5.1 AXISYMMETRY MODEL

Fig 3. MODEL AND MESH DISC BRAKE

5.2 MATERIAL PROPERTIES FOR GREY CAST IRON

5.3 STRUCTURAL BOUNDARY CONDITIONS FOR GREY CAST IRON:

Fig 4. Boundary Conditions for Grey Cast Iron

Properties

Grey Cast Iron

Density

7.06 *10³-7.34 *10³ kg/m³

Modulus of elasticity

124 GPa

Thermal expansion

9.0*10-6

ºCˉ¹

Thermal conductivity

53.3 W/(m*K)

Specific heat capacity 840 J/(kg*K)





The boundary conditions for the structural analysis of the brake rotor are given into the model

as pressure 2 MPa acting from the pad to the surface and the inner edge of the brake rotor is arrested

in all the directions which shown in the figure.4 The very important load required for the structural

analysis in addition to the pressure load is thermal load from the previous thermal analysis which is

stored in the Ansys database as result thermal file with extension. The material properties required

for the structural analysis are young’s modulus and thermal expansion coefficient which are given as

input in the material properties under preprocessor.

5.4 MATERIAL PROPERTIES FOR ALUMINUM AND ZIRCONIA CERAMIC

VI. RESULT AND DISCUSSION

6.1 THERMAL ANALYSIS:

Transient analysis of the disc brake rotor for different materials such as grey cast iron and metal-

ceramic are carried out. The properties of different brake rotor materials such as thermal

conductivity, thermal expansion, density, specific heat, young’s modulus are given as input for the

transient analysis. The heat flux which has been calculated for the specified operating conditions is

given as the thermal load in to the FEA model. The results for the two different disc brake rotor

materials are given below. It has been concluded from the results that among the two materials

chosen for the transient analysis, the metal-ceramic material is best as far as heat dissipation is

concerned compared to the other material, grey cast iron.

6.2 GREY CAST IRON:





T = 1 sec T = 5 sec

T = 10 sec

Fig 5 – Grey Cast Iron - Thermal Analysis Result

6.3 METAL - CERAMIC





T= 1 sec T= 5 sec

T = 10sec

Fig 6– METAL AND CERAMIC - Thermal Analysis Result

6.4 METAL AND CERAMIC vs CAST IRON





Fig 7 – Temperature vs Time

The above graph clearly describes the salient features of the metal-ceramic i.e when t=10 sec,

the maximum temperature at the NODE NUMBER 25 which is located near the heat zone, is 324 k

but in grey cast iron, temperature is 347 k. From the temperature values, it’s been concluded that the

metal-ceramic is comparatively best material for the disc brake rotor as it dissipates heat rapidly to

the atmosphere which is very important phenomenon as far as thermo- mechanical instability factor

is concerned. In the next step of the project, structural analysis will be investigated for the disc brake

rotor material metal-ceramic.

6.5 STRUCTURAL ANALYSIS:

Static structural analysis of the disc brake rotor for different materials such as grey cast iron

and metal-ceramic are carried out. The properties of different brake rotor materials such as thermal

expansion, young’s modulus are given as input for the structural analysis. The pad pressure from the

literature study has been given as the mechanical load in to the FEA model. The results for the two

different disc brake rotor materials are given below. It has been concluded from the results that

among the three materials chosen for the structural analysis, the metal-ceramic is best as far as

stiffness is concerned compared to the other material, grey cast iron.

6.6 GREY CAST IRON:

Fig. 8 Displacement Fig. 9 Stress





6.5. METAL AND CERAMIC

Fig. 10 Displacement Fig 11 Stress

6.6 RESULT ANALYSIS

MATERIAL DISPLACEMENT [mm] STRESS [N/mm2 ]

Grey Cast Iron 0.36 670

Metal and Ceramic 0.0128 37.4

From the results shown above for all 2 brake materials, its been concluded that the displacements and

stress values for the Metal and Ceramic material is very less than the values of other material[Grey

CI] for the same thermal load and Structural loads. Its evident from the analysis, the best material

for the brake Rotor is metal and ceramic as far as thermal and structural behavior is concerned in

order to prevent “thermal elastic instability”.

VII. CONCLUSIONS

In this study, the transient thermal analysis of the disk brake rotor for the different materials

such grey cast iron and metal-ceramic has been performed. ANSYS software is applied to the

transient thermal analysis problem with frictional heat generation. To obtain the simulation of

thermal behavior appearing in different disk brake rotor material, the basic governing equation for

the heat conduction is solved with the initial boundary conditions and the thermal load such as heat

flux at the brake rotor and pad interface for the three materials. Through the axis symmetric disk

brake model, the thermal elastic instability [TEI] phenomenon on the disc brake rotor surfaces has

been investigated. It has been observed from the analysis; metal-ceramic is comparatively best

material for the disc brake rotor as it dissipates heat rapidly to the atmosphere which is very

important phenomenon as far as thermo- elastic instability factor is concerned.





The second part of the project i.e., structural analysis for the two materials produces excellent

result by treating the problem as coupled field analysis. From the structural analysis results for all

the 2 brake materials, its been concluded that the displacements and stress values for the Metal and

Ceramic material is very less than the values of other two material [Grey CI] for the same thermal

load and Structural loads. Its evident from the analysis, the best material for the brake Rotor is metal

and ceramic as far as thermal and structural behavior is concerned in order to prevent “thermal

elastic instability”.

REFERENCES [1] Sathishkumar.S, et.al, A Review on Heat Transfer and Thermal Analysis of Disc Brake System,

International Journal of Pure and Applied Mathematics (2017).

[2] Vikas Gupta et.al, Comparative Analysis of Disc Brake Model for Different Materials Investigated under

Tragic Situations, Asian Review of Mechanical Engineering (2016).

[3] M.-A. Zaid, et.al, An investigation of disc brake rotor by Finite element analysis, Journal of Advanced

Manufacturing and Technology, (2009).

[4] Subbarayudu.B et.al, Design and Analysis of Ventilated Disc Brake, IOSR Journal of Mechanical and Civil

Engineering (IOSR-JMCE) (2018).

[5] N Saran Kumar, N Kaleeswaran, B Radha Krishnan, “Review on optimization parametrs in Abrasive Jet

Machining process” , International Journal of Recent Trends in Engineering and Research, Volume 04,

Issue 10; October- 2018 [ISSN: 2455-1457]. DOI:10.23883/IJRTER.2018.4388.HTNOQ

[6] Dhiyaneswaran et.al, Comparative Study of Disc Brake Materials through Computer Aided Engineering,

International OPEN ACCESS Journal Of Modern Engineering Research. (2009).

[7] Swapnil R. et.al, Analysis And Optimization of Disc Brake Rotor, International Research Journal of

Engineering and Technology (IRJET) 2016.

[8] Ali Belhocine, Mostefa Bouchetara, Thermo-mechanical modelling of dry contacts in automotive disc

brake, International Journal of Thermal Sciences 60 (2012)

[9] G. Babukanth and M. Vimal Teja, Transient Analysis of Disk Brake By using Ansys Software,

International Journal of Mechanical and Industrial Engineering (2012).

[10] Oder, G. et.al, Thermal And Stress Analysis Of Brake Discs In Railway Vehicles, International Journal of

Advanced Engineering (2009).

[11] B. Radha Krishnan, et al. "Design and Analysis of Modified Idler in Drag Chain Conveyor." in

International Journal of Mechanical Engineering and Technology, Volume 9, Issue 1, pp. 378–387.

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of Latest Trends in Engineering and Technology (2013).

[13] M.A.Maleque, et.al, Material Selection Method in Design of Automotive Brake Disc, Proceedings of the

World Congress on Engineering (2010).

Documents

TRANSIENT ANALYSIS OF METAL – CERAMIC DISK BRAKE€¦ · TRANSIENT ANALYSIS OF METAL - CERAMIC DISK BRAKE S.Vivekanand 1, ... a numerical simulation is carried out in ANSYS to predict