This document presents a dissertation on finite element modeling and analysis of brake squeal. It discusses modeling a disc-pad assembly in CATIA and developing a finite element model in ANSYS. Modal and brake squeal analyses are performed using linear non-prestressed and full nonlinear perturbed modal analysis methods. Parametric studies examine the effect of increasing the disc's outer diameter and friction coefficient on squeal frequencies. Experimental validation of results shows less than 1% error. Increasing the disc's diameter decreases squeal propensity while friction coefficient has minimal effect. Future work could vary additional parameters like pressure, temperature, and materials.

1. By
Mr. Savant Rushikesh Dadasaheb
Exam Seat No.: 1518
Guide
Dr. Shekhar Y. Gajjal
Head, PG Mechanical Design Engineering
NBN SSoE,Ambegaon (Bk), Pune-41.
Dissertation on
Finite Element Modelling and Analysis of
Brake Squeal
1
M.E. Mechanical - Design Engineering

2. Contents
M.E. Mechanical - Design Engineering2
Abstract
1. Introduction
2. Literature review
3. Methodology
4. Finite element modelling of disc-pad assembly
5. Finite element analysis of disc-pad assembly
6. Experimental Validation
7. Results and Discussion
Conclusion and Future Scope
References
Publications

3. Abstract
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Automobile brakes generates several kinds of noises
Squeal is prevalent, annoying and can be reduced by varying
parameters
Brake squeal occurs in the range of 1-16 kHz
ANSYS 14.5 has introduced an ability to perform brake squeal
analysis
Linear non-prestressed and full nonlinear perturbed modal analysis is
applied to predict squeal frequency
Full nonlinear perturbed modal analysis is performed with increasing
the coefficient of friction and the outer diameter of disc
Increasing friction coefficient has no desirable effect while increased
outer diameter decreases squeal propensity

4. 1. Introduction
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Brake is a device by means of which artificial frictional resistance is
applied to moving machine member to stop motion of machine
During this the undesirable noise is produced called as brake squeal
No precise definition of brake squeal has gained complete acceptance
Brake noise is generally related to comfort and refinement rather
than to safety or performance
It is high frequency (1 kHz-16kHz) vibration of brake system
components during a braking action resulting a noise audible to
vehicle occupants and passers-by

5. Substantial research has been conducted into predicting and
eliminating brake squeal
It is still difficult to predict its occurrence due to complexity of the
mechanisms that cause brake squeal
Physically, squeal noise occurs when the friction coupling between
the rotor and pad creates a dynamic instability
Frequency range of squeal is between 1 and 16 kHz
Low frequency squeal : 1 kHz to 5 kHz
High frequency squeal : 5 kHz and above
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6. Brake squeal generation mechanisms:
A] Mode coupling theory:
i. Self-excited vibration
ii. If two vibration modes are close to each other in the frequency
range may merge if the coefficient of friction increases
iii.When they merge at the same frequency called couple frequency,
one of them becomes unstable producing noise called Squeal.
iv.Variable friction forces are sources for brake squeal
f (Hz)
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�

7. M.E. Mechanical - Design Engineering
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B] Stick slip mechanism:
i. Motion made up of periods where the bodies hardly move, and
where there are sudden motions is called as Stick-slip motion
ii. Resistance against the beginning of the motion from the state of the
rest called stick mode
iii.Resistance against of an existing motion called slip mode
iv.Stick-slip motion can be introduced by the difference between the
coefficient of the kinetic and static friction
v. Variable friction coefficient provides the energy source for the brake
squeal

8. Objectives
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To determine unstable squealing modes and frequencies of the
braking system
 Analysis of effect of increased friction coefficient and increased
outer diameter of disc on the modes and squealing

9. Present Work
To study types and generation mechanisms of brake squeal.
To learn the basics of ANSYS software (Static Structural and Modal
analysis)
Modelling the disc-pad assembly by using CATIA V5 software.
Develop finite element model of disc-pad combination
Determine the effect of increase in outer diameter of the disc on the
squeal propensity of the disc-pad assembly.
Study the effect of coefficient of friction on the frequency of brake
squeal
Compare the results of analysis with experimental results.
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10. 2.1 Analysis of brake squeal noise using
the finite element method: A parametric
study.
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 Authors: Mario TrichesJu´nior, Samir N.Y. Gerges*, Roberto
 Application of complex eigenvalue analysis in a finite element model
of a commercial brake system
The effect of friction coefficient, braking pressure, brake
temperature and wear on the dynamic stability of the brake system is
examined
Changes in material properties and the application of brake noise
insulators and their effects discussed

11. 2.2 Complex Eigenvalue Analysis for
Reducing Low Frequency Brake Squeal
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 Authors: Shih-Wei Kung, K. Brent Dunlap and Robert S. Ballinger
Stiffness of the rotor is changed by a reduction in the Young’s
modulus of the rotor material
Parametric studies are also performed to find out the effects of
friction coefficient and rotor stiffness
Shifting rotor resonance frequencies may decouple the modal
interaction and eliminate dynamic instability

12. 2.3 An Investigative Overview of
Automotive Disc Brake Noise
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 Authors: K. Brent Dunlap, Michael A. Riehle and Richard E.
Longhouse
Three groups of brake noise are presented:
i) Low frequency noise: below 1 kHz
ii) Low frequency squeal: 1kHz to 5 kHz
iii)High frequency squeal: above 5 kHz

13. 2.4 Disc-Plate Squeal Investigation
Using Finite Element Software: Study
and Compare
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Ammar A. Yousif Mohammed, Inzarulfaisham Abd Rahim
The plate on disc as a new model is presented to study the instability
of the system
Matrix27 as a contact element is used to simulate the behaviour of
the system
Maximum degree of instability appeared as a result of changing the
contact stiffness effect rather than changing the friction coefficient
plate-disc system

14. 2.5 Review-Automotive disc brake squeal
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N. M. Kinkaid, O.M. O’Reilly and P. Papadopoulos
Background sections on vibrations, contact between disc and pad,
disc brake systems are included
Disc brake systems, Effect of contact, temperature and wear,
Experimental studies on brake squeal, Methods to eliminate brake
squeal, Central features of some theories for brake squeal, Models of
disc brake squeal and analyses are explained

15. 3. Methodology
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Procedure for a typical FEA can be divided into three distinct steps:
• build the model (Pre-processor)
• apply loads and obtain the solution (Solver)
• review the results (Post-processor)

16. 4. Finite Element Modelling of Disc-pad
Assembly
4.1 Solid modelling of disc-pad assembly:
Modelled using CATIA V5 R20 software
Inner diameter of disc: 250 mm
 Outer diameter of disc: 350 mm
Disc thickness:10 mm
Brake pad thickness: 15 mm
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17. 4.2 Material properties and boundary conditions
• Young’s Modulus (N/m2
): 2.0 E+11 Pa
• Density: 7850 Kg/m3
• Poisson’s Ratio: 0.3
• Inner diameter of the cylinder hub and bolt holes are constrained in
all directions
• Small pressure loading is applied on both ends of the pad to establish
contact include prestress effects
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18. 4.3 FE Mesh generation
Elements Used For Meshing of Disc-Pad Model
i] SOLID186: Higher order 3-D 20-node solid element
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19. ii] SOLID187: Higher order 3-D, 10-node tetrahedral structural solid
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20. iii] CONTA174: 3-D 8-Node Surface-to-Surface Contact element
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21. iv] TARGE170: Used to represent various 3-D target surfaces for the
associated contact elements
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22. 4.4 Meshing the disc-pad model:
Hexahedral dominant mesh with sweep method
Mesh contains 60351 nodes and 11473 elements
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23. 5. Finite element analysis of disc-pad
assembly
5.1 Modal analysis
Used to determine vibration characteristics (natural frequencies and
mode shapes) of a structure or a machine component while it is
being designed
The frequencies obtained from the modal solution have real and
imaginary parts due the presence of an unsymmetric stiffness matrix.
The imaginary frequency reflects the damped frequency while real
frequency indicates whether the mode is stable or not.
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24. Results of Modal Analysis of Disc-Pad Assembly
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25. 5.2. Brake squeal analysis
Concerned with the prediction of the natural frequencies at which
brake squeal occurs
Methods:
5.2.1 Linear Non-prestressed Modal Analysis
• Effective when large deflection or stress-stiffening effects are not
critical
• Accuracy is less and prestress effect is not included
• Less time consuming, as Newton-Raphson iterations are not
required
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26. Solution process
i) Perform a linear partial-element modal analysis with no prestress
effect.
ii) Generate the unsymmetric stiffness matrix.
iii)Generate sliding frictional force.
iv)Perform a complex modal analysis using the UNSYM eigensolver for
mode extraction.
v) Expand the modes and postprocess the results.
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27. Results
Complex eigenfrequencies for first 30 modes
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Linear non-prestressed modal analysis predicts unstable mode at 6474.25
Hz

28. Mode shape plots for unstable modes
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Mode Shape for Unstable Mode 21 Mode Shape for Unstable Mode 22

29. 5.3 Full Nonlinear Perturbed Modal Analysis
• Most accurate method for modelling the brake squeal problem than
linear non-prestressed modal analysis
• Uses nonlinear static solutions to both establish the initial contact
and compute the sliding contact
• Includes prestress effects
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30. M.E. Mechanical - Design Engineering30
Solution process
i) Perform a nonlinear, large-deflection static analysis. Use the
unsymmetric Newton-Raphson method. Specify the restart control
points needed for the linear perturbation analysis
ii) Perform a full second static analysis. Generate sliding contact to
form unsymmetric stiffness matrix
iii)After obtaining the second static solution, postprocess the contact
results
iv)Restart the previous static solution and perform the first phase of the
perturbation analysis
v) Obtain the linear perturbation modal solution using QRDAMP or
UNSYM eigensolver
vi)Expand the modes and postprocess the results

31. 5.3.1 Parametric study with increasing the outer
diameter of disc
Increasing the outer diameter of disc in the range of 4% upto 120%.
With increasing outer diameter of disc, the dimensions of pad also
varied accordingly
1) When outer diameter is increased by 4%
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32. 2) When outer diameter is increased by 8%
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3) When outer diameter is increased by 12%

33. 4) When outer diameter is increased by 16%
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5) When outer diameter is increased by 20%

34. Results
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35. 5.3.2 Parametric Study with Increasing Friction
Coefficient
Increasing coefficient of friction from 0 to 0.3 in the range of 0.05
Changes in the frequencies and mode shapes are observed
1) Coefficient of friction 0.0
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36. 2) Coefficient of friction 0.05
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3) Coefficient of friction 0.1

37. 4) Coefficient of friction 0.15
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5) Coefficient of friction 0.2

38. 6) Coefficient of friction 0.25
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7) Coefficient of friction 0.3

39. M.E. Mechanical - Design Engineering39
• Results

40. 6. Experimental Validation
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6.1 Test setup
NVH brake testing machine
• Single-ended inertia dynamometer
• Semi-anechoic chamber
• Auto spectrum microphone
•Accelerometer

41. M.E. Mechanical - Design Engineering41
SAE J2521 is commonly used to:
i) Determine the propensity of a given friction material and to generate
squeal noise on a given brake configuration
ii) Select and evaluate different brake configurations
ii) Development of noise reduction measures using prototype
materials or configurations
 Brake-in: 30 snubs; 70 km/h; 100 °C
 Warm Up: 20 stops; 55 km/h; 100 °C
 Friction characteristic: 6 snubs; 70 km/h; 100 °C
 Deceleration: 100 stops; 55 km/h; 25 bar; 50-250-50 °C
6.2 Test Specifications

42. M.E. Mechanical - Design Engineering42
6.3 Result of test
Both noise and accelerometer peaks standing out obviously above the
immediate frequency buckets, this is considered a true brake noise event
during the dynamometer test.
At the frequency 6440 Hz, there is distinctive peak i.e. squeal occurs

43. 7. Results and discussion
Squeal frequencies obtained for two methods shows full nonlinear
perturbed modal analysis is more accurate.
When FEA and experimental results are compared, error in FEA
solution is found to be 0.4674 % (less than 1%)
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Linear non-prestressed
modal analysis
Full nonlinear perturbed
modal analysis
6474.25 Hz 6470.24 Hz
Experimental frequency of
Brake Squeal
FEA frequency of Brake
Squeal by ANSYS
6440 Hz 6470.24 Hz

44. Conclusion
1. As the outer diameter of disc is increased, real eigenfrequency
decreases linearly for both modes 21 and 22
2. For Mode 21, imaginary eigenfrequency decreases and for Mode
22, imaginary eigenfrequency increases as the outer diameter of
disc is increased.
3. When coefficient of friction is increased from 0 to 0.1, the real
eigenfrequency decreases, further increase in coefficient of friction
real eigenfrequency increases again for both modes 21 and 22.
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45. 4. In this analysis, as the variation is minor, friction coefficient has no
desirable effect on brake squeal
5. For Mode 21, imaginary eigenfrequency increases and for Mode
22, imaginary eigenfrequency decreases linearly as the friction
coefficient increased
6. Finite Element Analysis result error is 0.4674% which is within
the acceptable limit of 1%
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46. Future scope
Further brake squeal analysis can be carried out by variations in
structural design
Squeal analysis can be performed by varying parameters such as
brake pressure, brake temperature, wear etc.
The materials of assembly can be optimized by composite materials
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47. 9. References
1) Mario Triches Junior, Samir N.Y. Gerges and Roberto Jordan,
“Analysis of brake squeal noise using the finite element method: A
parametric study”, Applied Acoustics 69 (2008), 147-162.
2) Shih-Wei Kung, K. Brent Dunlap and Robert S. Ballinger,
“Complex eigenvalue analysis for reducing low frequency brake
squeal”, SAE Technical Paper 2000-01-0444, 2000.
3) K. Brent Dunlap, Michael A. Riehle and Richard E. Longhouse, “An
Investigative overview of automotive disc brake noise”, SAE
Technical Paper 1999-01-0142, 1999.
4) Ammar A. Yousif Mohammed, Inzarulfaisham Abd Rahim, “Disc-
plate squeal investigation using finite element software: Study and
Compare”, International Journal of Scientific and Technology
Research, Vol.2, Issue 1, (January 2013), 143-154.
. M.E. Mechanical - Design Engineering47

48. 5) João Gustavo Pereira da Silva, Érico Romera Fulco, Paulo Emilio
Dias Varante, “Numerical and Experimental evaluation of brake
squeal”, SAE Technical Paper 2013-36-030, 2013.
6) N. M. Kinkaid, O.M. O’Reilly and P. Papadopoulos, “Review-
Automotive disc brake squeal”, Journal of Sound and Vibration, 267
(2003), 105-166.
7) Nouby M. Ghazaly, Sufyan Mohammed and Ali M. Abd-El-
Tawwab, “Understanding mode-coupling mechanism of brake squeal
using finite element analysis”, International Journal of Engineering
Research and Applications, Vol. 2, Issue 1 (Jan-Feb 2012), 241-
250,.
8) Dihua Guan, “Brake vibration and noise-A Review and discussion”,
Proceedings of 20th
International Congress on Acoustics, Australia
(August 2010), 23-27.
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49. 9) P. Liu, H. Zheng, C. Cai, Y. Y. Wang, C. Lu, K. H. Ang and G. R.
Liu, “Analysis of disc brake squeal using the complex eigenvalue
method”, Applied acoustics, Vol. 68 (2010), 603-615.
10) A. Akay, O. Giannini, F. Massi and A. Sestieri, “Disc brake squeal
characterization through simplified test rigs”, Mechanical systems
and signal processing, Vol. 23 (2009), 2590-2607.
11) M. Noubyand and K. Srinivasan, “Parametric studies of disc brake
squeal using finite element approach”, Journal Mechanical, No. 29
(Dec. 2009), 52-66.
12) Abd Rahim Abu-Bakar and Huajiang Ouyang, “Recent studies of
car disc brake squeal”, New Research on Acoustics (2008), 159-198.
13) N. S. Gokhale, S. S. Deshpande, S. V. Bedekar, A. N. Thite,
“Practical finite element analysis”, First Edition, Finite to Infinite
(2008), Pune.
14)ANSYS, ANSYS User’s Manual, Version 14.5, ANSYS Inc, 2011.
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50. 10. Paper Published
1. Rushikesh D. Savant[1]
, S. Y. Gajjal[2]
and V. G. Patil[3]
, “Review on
Disc Brake Squeal”, International Journal of Engineering Trends and
Technology (IJETT), ISSN: 2231-5381, Volume 9-Number 12,
March 2014, pp.605-608.
2. R. D. Savant[1]
, S. Y. Gajjal[2]
, “Finite Element Modelling and Analysis of
Disc-Pad Assembly”, International Conference on Multidisciplinary
Research and Practice, Gujarat.
3. A Research paper titled “Finite Element Modelling and Analysis of
Brake Squeal” is accepted for:
• International Journal of Research and Scientific Innovation
• International Journal of Latest Technology in Engineering,
Management and Applied Science.
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51. Thank you
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