Stability Improvement of Brake Disc to Mode Coupling at High Frequency Squeal

2020 ◽  
Author(s):  
Anutcharee Khuntiptong ◽  
Chak Chantalakhana
Keyword(s):  
Field Test ◽  
High Frequency ◽  
Element Model ◽  
Modal Testing ◽  
Brake Disc ◽  
Complex Eigenvalue ◽  
Brake Pads ◽  
Locking Mechanism ◽  
Out Of Plane ◽  
Complex Eigenvalue Analysis

In this research study, the high-frequency squeal noise of a brake disc was found to occurred at a frequency of about 15 kHz. The potential root cause has been studied where mode frequency coupling and shape locking mechanism of brake disc and brake pads components are the main investigated topic. From the vehicle field test and the Dynamometer test, the braking condition, friction coefficient and braking pressure, have been confirmed to be used in numerical experiments. The updated finite element model (FEM) with the modal testing data of the existing brake components are formulated for the Complex Eigenvalue Analysis (CEA). In this study, the modification is based on in-board and out-board cheek thickness of the brake disc. Two of nine modifications of the brake disc cheek thickness are proposed with the method of separation the brake disc out-of-plane and in-plane modes and the method of avoiding shape locking between the brake disc and the brake pads modes. The constructed prototypes are verified with the vehicle field test and well agreed with the CEA.

Complex Eigenvalue Analysis Applied to an Aircraft Brake Vibration Problem

1995 ◽  
Author(s):  
Denis J. Feld ◽  
Dana J. Fehr
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Friction Force ◽  
Mode Shape ◽  
Element Model ◽  
Eigenvalue Analysis ◽  
Complex Eigenvalue ◽  
Friction Forces ◽  
Model Complex ◽  
Complex Eigenvalue Analysis

Abstract A conventional finite element model of an aircraft wheel and brake is extended to include forces responsible for friction-induced noise. Responses of aircraft brake vibration modes change the normal force across the brake friction interfaces, and consequently the friction forces. The resulting friction force variations are assembled in the form of a supplemental stiffness matrix and added to the finite element model. Complex eigenvalue analysis that includes the friction force variations provides frequency and mode shape information, as well as an assessment of the predicted mode stability. A predicted unstable vibration mode compares very well to operating mode shape data determined from instrumented tests. Hardware modifications to reduce a brake noise in an aircraft cabin were based on beneficial trends found from exercising the model. Implementation of the hardware modifications on the aircraft successfully suppressed the noise.

scholarly journals Maximum temperature of the disc during repeated braking applications

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983782 ◽  
Author(s):  
Piotr Grzes
Keyword(s):  
Friction And Wear ◽  
Element Model ◽  
Maximum Temperature ◽  
Bulk Temperature ◽  
Brake Disc ◽  
Subsequent Stage ◽  
System Of Equations ◽  
Brake Pads ◽  
Brake Application ◽  
The Mean

A computational finite element model of a brake disc for determining transient axisymmetric (two-dimensional) temperature field during repeated brake application has been proposed. The presented research is a subsequent stage of a previous study on the coupling of velocity and maximum temperature for a single braking in accordance with the system of equations of heat dynamics of friction and wear. In the analysed case, changes in the mean, flash, maximum and bulk temperature of the disc were determined and discussed. The calculations were carried out at the temperature-dependent coefficient of friction, the thermophysical properties of cast-iron disc combined with cermet brake pads and the time-varying contact pressure. The obtained results were compared with the reference values from the braking simulation at constant operating parameters and independent of temperature properties of materials. It was shown that the maximum values of the mean temperature for both cases differed slightly during the entire process. The flash temperature determined from the heat dynamics of friction and wear system of equations was the highest at the beginning and gradually decreased with the number of brake applications.

Investigation of Discrete Out-of-Plane Waviness in Composite Wind Turbine Blades Using Ultrasonic Nondestructive Evaluation

2011 ◽  
Author(s):  
Sunil Kishore Chakrapani ◽  
Vinay Dayal ◽  
Daniel Barnard ◽  
David Hsu
Keyword(s):  
Aspect Ratio ◽  
Nondestructive Evaluation ◽  
Wind Turbine ◽  
High Frequency ◽  
Turbine Blades ◽  
Element Model ◽  
Wind Turbine Blades ◽  
Out Of Plane ◽  
Process Detection ◽  
Air Coupled Ultrasonics

With the need for larger and more efficient wind turbine blades, thicker composite sections are manufactured and waviness becomes difficult to control. Thus, there is a need for more effective and field implementable NDE. In this paper we propose a method of detection and quantification of waviness in composite wind turbine blades using ultrasonics. By employing air coupled ultrasonics to facilitate faster and easier scans, we formulated a two step process. Detection was performed with single sided air coupled ultrasonics, and characterization was performed with the help of high frequency contact probes. Severity of the wave was defined with the help of aspect ratio, and several samples with different aspect ratio waves were made. A finite element model for wave propagation in wavy composites was developed, and compared with the experimental results.

Parametric Study of Track Support Structure to Minimize the Occurrence Possibility of Rail Corrugation

2021 ◽  
pp. 036119812110581
Author(s):  
Xiaolu Cui ◽  
Tong Li ◽  
Bo Huang ◽  
Haohao Ding
Keyword(s):  
Element Model ◽  
Small Radius ◽  
Complex Eigenvalue ◽  
Support Structure ◽  
Vertical Stiffness ◽  
Rail Corrugation ◽  
Main Research ◽  
Multiple Parameters ◽  
Track System ◽  
Complex Eigenvalue Analysis

Changing the track support structure is an effective method to suppress or eliminate rail corrugation in practical engineering. Rail corrugation on small-radius curves with booted short sleepers is the main research object in the present paper. A relevant finite element model of the wheelset-track system supported by booted short sleepers is built combined with the dynamic analysis of the vehicle-track system. The effects of various parameters of booted short sleeper structure on the wheel–rail friction-induced vibration are investigated by complex eigenvalue analysis. Considering the interaction of multiple parameters in the booted short sleeper structure, the multi-parameter fitting equation forecasting the possibility of rail corrugation is obtained using the least squares algorithm. Results show that wheel–rail friction-induced oscillation is a contributing factor in the formation of rail corrugation. Controlling wheel–rail friction-induced oscillation with a frequency of about 300 Hz is beneficial to suppress the possibility of rail corrugation in sections with booted short sleepers. Lower fastener stiffness or greater vertical fastener damping make it less likely that rail corrugation will occur. Rail corrugation is not generated when the vertical stiffness of the fastener is controlled below 20 MN/m in the booted short sleeper.

Influence of In-Plane Modes of a Rotor to Brake Noise

2004 ◽  
Author(s):  
Heewook Lee
Keyword(s):  
Opposite Sign ◽  
Frequency Separation ◽  
Mode Shapes ◽  
Complex Eigenvalue ◽  
Root Cause ◽  
Disk Rotation ◽  
Out Of Plane ◽  
Complex Eigenvalue Analysis ◽  
The Relationship ◽  
Brake Noise

In the effort of improving brake noise, recent studies showed increasing encounters with in-plane modes of a rotor for a root cause of a brake noise. Although studies about in-plane modes of a rotor or a disc have been done a lot, a study about the influence of in-plane modes to brake noise has rarely been done. This paper explored the relationship between unstable eigenvalues and rotor mode shapes, focusing on explaining why unstable eigenvalue excited by in-plane modes behaved differently from one caused by out-of-plane modes. Complex eigenvalue analysis was used to assess the instability of a brake corner. This paper showed the way of analytically calculating the sensitivities of unstable eigenvalues about out-of-plane and inplane modes of a rotor. By using the results of sensitivity analysis, it was first discovered that one of the rotor in-plane doublet modes has the opposite sign to the other in the real parts of the sensitivity, and this precludes eliminating the unstable eigenvalues, which are dominated by rotor in-plane modes. However, it was also found that the corresponding unstable eigenvalues could be eliminated if we could separate the frequencies of these modes. Frequency separation of in-plane doublet modes due to disk rotation was examined.

A Finite Element Approach to the Transient Dynamics of Rolling Tires with Emphasis on Rolling Noise Simulation4

2007 ◽  
Vol 35 (3) ◽  
pp. 165-182 ◽  
Author(s):  
Maik Brinkmeier ◽  
Udo Nackenhorst ◽  
Heiner Volk
Keyword(s):  
Finite Element ◽  
Traffic Noise ◽  
Complex Eigenvalue ◽  
Arbitrary Lagrangian Eulerian ◽  
Finite Element Approach ◽  
Road Systems ◽  
Element Approach ◽  
Road Surface Roughness ◽  
Complex Eigenvalue Analysis ◽  
Rolling Noise

Abstract The sound radiating from rolling tires is the most important source of traffic noise in urban regions. In this contribution a detailed finite element approach for the dynamics of tire/road systems is presented with emphasis on rolling noise prediction. The analysis is split into sequential steps, namely, the nonlinear analysis of the stationary rolling problem within an arbitrary Lagrangian Eulerian framework, and a subsequent analysis of the transient dynamic response due to the excitation caused by road surface roughness. Here, a modal superposition approach is employed using complex eigenvalue analysis. Finally, the sound radiation analysis of the rolling tire/road system is performed.

Brake Wear Particle Size and Shape Analysis of Non-Asbestos Organic (NAO) and Semi Metallic Brake Pad

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Hussain, S. ◽  
M.K Abdul Hamid ◽  
A.R Mat Lazim ◽  
A.R. Abu Bakar
Keyword(s):  
Particle Size ◽  
Wear Particle ◽  
Brake Disc ◽  
Wear Particles ◽  
Brake Pad ◽  
Brake Pads ◽  
Size And Shape ◽  
Brake Wear Particles ◽  
Brake Wear ◽  
Particle Size And Shape

Brake wear particles resulting from friction between the brake pad and disc are common in brake system. In this work brake wear particles were analyzed based on the size and shape to investigate the effects of speed and load applied to the generation of brake wear particles. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) was used to identify the size, shape and element compositions of these particles. Two types of brake pads were studied which are non-asbestos organic and semi metallic brake pads. Results showed that the size and shape of the particles generatedvary significantly depending on the applied brake load, and less significantly on brake disc speed. The wear particle becomes bigger with increasing applied brake pressure. The wear particle size varies from 300 nm to 600 µm, and contained elements such as carbon, oxygen, magnesium, aluminum, sulfur and iron.

Tribological Performance of a Non Asbestos Organic Brake Pad Using Various Organic and Mineral Fibers

2012 ◽  
Vol 585 ◽  
pp. 559-563
Author(s):  
M.A. Sai Balaji ◽  
K. Kalaichelvan
Keyword(s):  
Wear Behavior ◽  
Testing Machine ◽  
Brake Disc ◽  
Brake Pads ◽  
Degradation Temperature ◽  
Industrial Standards ◽  
Worn Surface ◽  
Acrylic Fibers ◽  
Automotive Brake

Non-Asbestos organic composite friction materials are increasingly used in automotive brake disc pad applications. The present paper deals with the role of various organic fibers Kevlar, Acrylic fibers and the Rock fiber namely the Lapinus fiber on the fade and recovery behavior of friction composites. Three different friction composites were developed with same formulation varying only the percentage of Kevlar, Acrylic and lapinus fibers within the formulation. The formulations containing 13.5% of these fibers were developed as brake pads and designated as NA01, NA02 and NA03 respectively. The chemical and Mechanical properties are tested as per Indian Industrial standards.. The composites are then tested for the tribo-performance using Chase Testing Machine following SAE J661a standards. The fade µ, recovery µ and wear are significantly influenced by the amount and type of fiber combinations. Also the TGA reveals the degradation temperature of these fibers. Composite NA 03 containing Kevlar and lapinus combination is found to have good tribo performance. Worn surface analysis by SEM has proved to be useful in understanding the wear behavior of the composites.

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