• Title/Summary/Keyword: Hot Judder

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A Prediction of the Relation between the Disc Brake Temperature and the Hot Judder Critical Speed (주행 중 디스크 온도 변화와 열간 저더 임계속도와의 관계 예측)

  • Kim, Jaemin;Lee, Mingyu;Kim, Bumjin;Cho, Chongdu
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.1
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    • pp.61-67
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    • 2013
  • In this paper, it was studied how the critical speed which could occur hot judder due to disk temperature. Through the dynamometer experiment, we measured the critical velocity and surface temperature when the hot judder occur on the disk break. Also with the critical velocity theory equation and the temperature change graph of factors which used in the equation, we was induced experiment equation including theory equation and experiment values. And it has compared with the method which approach as linea. From this, we predicted the change of critical speed which could occur hot judder due to disk temperature. In addition, critical speed graph has compared with actual driving speed and disc temperature at a vehicle test. Therefore it was estimate to possibility of arising hot judder.

System Mode and Sensitivity Analysis for Brake Judder Reduction (브레이크 저더 개선을 위한 시스템 모드분석 및 민감도해석)

  • Hwang In-Jin;Park Gyung-Jin
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.6
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    • pp.142-153
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    • 2005
  • The brake judder is a phenomenon that the steering wheel is abnormally vibrating when the car is braked at a high speed. It is classified by the cold and the hot judder. The former is generated due to the initial uneven disk surface and the latter is resulted from the uneven heat spots on disc surface by repeatedly braking. There are two ways to reduce the judder. One is to control vibration by modification of the disk shapes and pad ingredients. The other is to improve modal characteristics of the suspension system. The latter approach is used in this research. In this paper, the real vehicle test and computer simulation are considered to systematically understand the judder phenomenon of the vehicle. The Macpherson strut suspension is employed. Especially, the judder sensitivity is calculated based on design sensitivity analysis. A bush stiffness was reworked and braking test was done to verify the sensitivity result. The judder reduction by the mode control was verified.

The Origin and Effect of Hot Spot Phenomena on Judder Vibration in Automotive Disk Brake (디스크 브레이크에서 열섬 현상이 발생되는 원인과 저더 진동에 미치는 영향)

  • Cho, Ho-Joon;Cho, Chong-Du;Kim, Myoung-Gu;Maeng, Ju-Won;Lee, Jae-Han
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.213-218
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    • 2006
  • Hot spot phenomenon is caused by non-uniform contact area between brake pad and disk frequent braking. Brake disk deformed by locally concentrated heat increases magnitude of frictional vibration. And this deformation can highly influence the judder vibration. In this experimental study, vibration and hot spot was measured in accordance with rotation of disk and pressure of master cylinder for finding the factors that causes hot spot phenomena. For comparing hot spot aspects with mode shapes of disk, mode shapes were measured by conducting modal test, and analyzed by using finite element analysis. Relation between hot spot phenomenon, and mode shape, pressure of master cylinder and rotation speed of disk respectively, was achieved by hot spot measurement and frequency analysis.

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The Origin and Effect of Hot Spot Phenomena on Judder Vibration in Automotive Disk Brake (디스코 브레이크에서 열섬 현상이 발생되는 원인과 저더진동에 미치는 영향)

  • Cho, Chong-Du;Kim, Myoung-Gu;Cho, Ho-Joon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.8 s.113
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    • pp.886-892
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    • 2006
  • Hot spot phenomenon is caused by non-uniform contact area between brake pad and disk frequent braking. Brake disk deformed by locally concentrated heat increases magnitude of frictional vibration. And this deformation can highly influence the judder vibration. In this experimental study, vibration and hot spot was measured in accordance with rotation of disk and pressure of master cylinder for finding the factors that causes hot spot phenomena. For comparing hot spot aspects with mode shapes of disk, mode shapes were measured by conducting modal test, and analyzed by using finite element analysis. Relation between hot spot phenomenon, and mode shape, pressure of master cylinder and rotation speed of disk respectively, was achieved by hot spot measurement and frequency analysis.

A Study of Frictional Contact Vibration Influence on Hot Spot in Automotive Disk Brake (디스크 브레이크에서 접촉 마찰 진동이 열섬에 미치는 영향 연구)

  • Cho, Ho-Joon;Kim, Myoung-Gu;Cho, Chong-Du
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.1
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    • pp.154-161
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    • 2007
  • Hot spot phenomenon that occurs, during judder vibration, is locally concentrated heat due to friction between brake disk and pad. It is important to understand the reason behind hot spot phenomenon, for reduction of judder vibration. In this experimental study, experiments were performed in accordance with rotation speed of brake disk, pressure of master cylinder and pad length for achieving different aspects of hot spot phenomenon. Temperature distribution of hot spot was obtained by using the infrared camera. As the hot spot occurred, vibration was measured and frequency analysis was performed. Finite element analysis of thermal deformation of disk was performed by using temperature distribution that was achieved by experimental results. And mode shapes of disk was analyzed by finite element analysis and compared with experimental results. It was observed that the excitation frequency band of frictional contact and frictional force mainly affects the hot spot phenomenon.

Analysis of Hot Judder of Disc Brakes for Automotives by Using Finite Element Method (유한 요소법을 이용한 자동차용 디스크 브레이크의 열간 저더 해석)

  • Jung, Sung-Pil;Park, Tae-Won;Chung, Won-Sun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.4
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    • pp.425-431
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    • 2011
  • Thermal energy generated because of the friction between the disc and pad is transferred to both sides and causes thermal expansion of the material, which affects the contact pressure distribution. This phenomenon, which is called thermoelastic instability (TEI), is affected by the natural mode of a disc. TEI results in the formation of a hot spot and causes hot judder vibrations. In this study, three-dimensional analysis of the hot judder of a ventilated disc for automotives was performed by using the commercial finite element analysis program, SAMCEF. The intermediate processor based on a staggered approach was used to exchange the result data of the mechanical and thermal model. The hot spot was formed on the surface of the disc, and the number of hot spots was compared with the natural mode of the disc.

A Study on Thermal Analysis in Ventilated Disk Brake by FEM (FEM을 이용한 벤틸레이티드 디스크 브레이크 열응력 해석에 관한 연구)

  • Kim, Sung-Mo
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.18 no.5
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    • pp.544-549
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    • 2009
  • Thermal brake judder caused by the high friction heat of the brake disk. Hot thermal judder makes serious problems such as to be unstability to drivers or to decrease braking force of automobile. Because thermal judder vibration makes high vibration occurrence and thermal deformation of brake disk. Therefore it Is necessary to reduce or eleminate thermal Judder phenomenon by understanding and investigation. This paper introduces the thermal deformation arising from friction heat generation in braking and proposes the FEM analysis to predict the distribution of temperature and thermal deformation. the results of the FEM analysis show the deformed shape and temperature distribution of the disk brake. The optimization is performed to minimize the thermal judder of ventilated disc brake that is induced by the thermal deformation of the disk brake.

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Optimal Design of Brake System considering Vehicle Vibration and Durability of Rotor (차량진동 및 Rotor 내구특성을 고려한 Brake System 의 최적설계)

  • Kim, B.S.;Kim, H.Y.;Kim, K.W.;Son, Y.K.;Lee, D.G.;Park, K.H.
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.764-769
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    • 2001
  • Brake-induced vibrations of a vehicle such as brake judder are determined by the excitation of brake torque variations and by their transfer to the driver's contact points via suspension, body and steering system. The formation of brake torque variation is mainly determined by static and dynamic disk thickness variations. The vibration transfer from the excitation by brake torque variation to the perception by the driver depends on the kinematic and dynamic behaviour of the components in the transfer path. Optimization of the judder performance can be achieved either by minimizing the excitation or by reduction of the judder sensitivity of the vehicle. In this paper, the optimization process of a front rotor is suggested to reduce brake judder considering the cooling performance of the rotor, the judder sensitivity of the vehicle and durability of the rotor.

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Thermoelastic Instability of the Layer Sliding between Two Non-conducting Half-planes (비전도 반평판 사이에서 미끄럼 운동하는 평판 층의 열탄성 불안정성)

  • 하태원;조용구;김흥섭;이정윤;오재응
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.483-488
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    • 2003
  • Frictional heating in brakes causes thermoelastic distortion of the contacting bodies and hence affects the contact pressure distribution. The resulting thermo-mechanical coupling can cause thermoelastic instability (TEI) if the sliding speed is sufficiently high, leading to non-uniform heating called hot spots and low frequency vibration known as hot judder. The vibration of brakes to the known phenomenon of frictionally-excited thermoelastic instability is estimated studying the interface temperature and pressure evolution with time. A simple model has been considered where a layer with half-thickness ${\alpha}$ slides with speed V between two half-planes which are rigid and non-conducting. The advantage of this properly simple model permits us to deduce analytically the critical conditions for the onset of instability, which is the relation between the critical speed and the growth rate of the interface temperature and pressure. Symmetrical component of pressure and temperature distribution at the layer interfaces can be more unstable than antisymmetrical component. As the thickness ${\alpha}$ reduces, the system becomes more apt to thermoelastic instability. Moreover, the evolution of the system beyond the critical conditions has shown that even if low frequency perturbations are associated with low critical speed, it might be less critical than high frequency perturbations if the working sliding speed is much larger than the actual critical speed of the system.

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