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
M.E. Mechanical - Design Engineering
3
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
M.E. Mechanical - Design Engineering
4
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
M.E. Mechanical - Design Engineering5
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)
M.E. Mechanical - Design Engineering
6
�
7. M.E. Mechanical - Design Engineering
7
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
M.E. Mechanical - Design Engineering8
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.
M.E. Mechanical - Design Engineering
9
10. 2.1 Analysis of brake squeal noise using
the finite element method: A parametric
study.
M.E. Mechanical - Design Engineering10
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
M.E. Mechanical - Design Engineering11
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
M.E. Mechanical - Design Engineering12
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
M.E. Mechanical - Design Engineering13
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
M.E. Mechanical - Design Engineering14
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
M.E. Mechanical - Design Engineering
15
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
M.E. Mechanical - Design Engineering16
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
M.E. Mechanical - Design Engineering17
18. 4.3 FE Mesh generation
Elements Used For Meshing of Disc-Pad Model
i] SOLID186: Higher order 3-D 20-node solid element
M.E. Mechanical - Design Engineering18
21. iv] TARGE170: Used to represent various 3-D target surfaces for the
associated contact elements
M.E. Mechanical - Design Engineering21
22. 4.4 Meshing the disc-pad model:
Hexahedral dominant mesh with sweep method
Mesh contains 60351 nodes and 11473 elements
M.E. Mechanical - Design Engineering22
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.
M.E. Mechanical - Design Engineering23
24. Results of Modal Analysis of Disc-Pad Assembly
M.E. Mechanical - Design Engineering24
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
M.E. Mechanical - Design Engineering25
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.
M.E. Mechanical - Design Engineering26
27. Results
Complex eigenfrequencies for first 30 modes
M.E. Mechanical - Design Engineering27
Linear non-prestressed modal analysis predicts unstable mode at 6474.25
Hz
28. Mode shape plots for unstable modes
M.E. Mechanical - Design Engineering28
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
M.E. Mechanical - Design Engineering29
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%
M.E. Mechanical - Design Engineering
31
32. 2) When outer diameter is increased by 8%
M.E. Mechanical - Design Engineering32
3) When outer diameter is increased by 12%
33. 4) When outer diameter is increased by 16%
M.E. Mechanical - Design Engineering
33
5) When outer diameter is increased by 20%
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
M.E. Mechanical - Design Engineering35
36. 2) Coefficient of friction 0.05
M.E. Mechanical - Design Engineering
36
3) Coefficient of friction 0.1
37. 4) Coefficient of friction 0.15
M.E. Mechanical - Design Engineering37
5) Coefficient of friction 0.2
38. 6) Coefficient of friction 0.25
M.E. Mechanical - Design Engineering
38
7) Coefficient of friction 0.3
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%)
M.E. Mechanical - Design Engineering43
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.
M.E. Mechanical - Design Engineering44
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%
M.E. Mechanical - Design Engineering45
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
M.E. Mechanical - Design Engineering46
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.
M.E. Mechanical - Design Engineering
48
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.
M.E. Mechanical - Design Engineering49
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.
M.E. Mechanical - Design Engineering
50