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# Final Seminar

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### Final Seminar

1. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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
19. 19. ii] SOLID187: Higher order 3-D, 10-node tetrahedral structural solid M.E. Mechanical - Design Engineering19
20. 20. iii] CONTA174: 3-D 8-Node Surface-to-Surface Contact element M.E. Mechanical - Design Engineering20
21. 21. iv] TARGE170: Used to represent various 3-D target surfaces for the associated contact elements M.E. Mechanical - Design Engineering21
22. 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. 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. 24. Results of Modal Analysis of Disc-Pad Assembly M.E. Mechanical - Design Engineering24
25. 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. 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. 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. 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. 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. 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. 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. 32. 2) When outer diameter is increased by 8% M.E. Mechanical - Design Engineering32 3) When outer diameter is increased by 12%
33. 33. 4) When outer diameter is increased by 16% M.E. Mechanical - Design Engineering 33 5) When outer diameter is increased by 20%
34. 34. Results M.E. Mechanical - Design Engineering34
35. 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. 36. 2) Coefficient of friction 0.05 M.E. Mechanical - Design Engineering 36 3) Coefficient of friction 0.1
37. 37. 4) Coefficient of friction 0.15 M.E. Mechanical - Design Engineering37 5) Coefficient of friction 0.2
38. 38. 6) Coefficient of friction 0.25 M.E. Mechanical - Design Engineering 38 7) Coefficient of friction 0.3
39. 39. M.E. Mechanical - Design Engineering39 • Results
40. 40. 6. Experimental Validation M.E. Mechanical - Design Engineering40 6.1 Test setup NVH brake testing machine • Single-ended inertia dynamometer • Semi-anechoic chamber • Auto spectrum microphone •Accelerometer
41. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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
51. 51. Thank you M.E. Mechanical - Design Engineering51