• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.365-370
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• 2003

The problem of brake judder is typically caused by quality defects in manufacturing. This quality problem, however, can't be controlled deterministically and requires analyses and designs considering uncertainties. This paper presents a method for dynamic analysis of a brake judder considering uncertainties. Firstly, quality defects, which come from the uncertainties, are determined by examination of symptoms of the brake judder quality problem. Effective quality defects are selected by investigation of process capability and comparison of sensitivity of each quality defects and noise levels of the effective quality defects are determined. Secondly, flexible multibody dynamic analysis and finite element analysis according to the proposed method are carried out. Finally, The analysis results are compared with the test results with noise levels of the effective quality defects.

• 한국자동차공학회논문집
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• 제21권1호
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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.

• 소음진동
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• 제9권3호
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• pp.613-620
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• 1999

디스크 두께 변화(DTV)에 의해 야기되는 져더현상은 일반적으로 차체진동, 브레이크 페달 떨림, 그리고 스티어링 휠의 떨림에 의해 감지된다. 이번 연구에서는, 차수분석 및 Operational Vibration Analysis(OVA)를 통해 차체진동이 DTV profile에 의해 어떻게 영향을 받는지를 중점적으로 조사하였다. 진동 측정위치는 knuckle, lower arm, lower arm 연결 차체부위이고, 져더 발생 DTV profile도 실측하였다. 시험 분석 결과, DTV는 져더현상에 차수별 상대적인 방향 기여도를 나타내며 특히 디스크 회전 2차 성분은 차량진행 방향으로의 lower arm 진동을 현저하게 야기시키는 것으로 나타났다. 이러한 시험 및 분석 기술은 져더 현상을 진단하고 문제를 개선하는데 유효하리라고 예측된다.

• 한국소음진동공학회논문집
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• 제23권6호
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• pp.485-494
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• 2013

This paper deals with experimental evaluation methods for high speed judder on the brake-caliper system. Firstly, two types of brake caliper systems due to the wheel vibration was evaluated. Secondly, the high-speed judder of the brake was also investigated using the subjective rating evaluation in the high-speed road test. These experimental evaluations were carried out by changing the materials of brake pad and the specifications of the brake-corner module. Based upon the test results, a new specification of the brake pad, $15{\times}5$ vertical chamfer, was proposed. The new brake pad showed 3 points, 60 %, improvement in the subjective-rating evaluation comparing with conventional one. Besides, we need to decide properly with judder characteristic of pad material and have to carefully take into consideration other design parameters; caliper, disc, and the braking performance, durability, squeal noise.

• International Journal of Precision Engineering and Manufacturing
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• 제2권2호
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• pp.31-37
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• 2001

In this paper, a method to improve judder by changing the front and rear wheel brake force distribution ratio was proposed. ADAMS, a commercial dynamic analysis software was used to model a small size bus and its modeling procedure was explained. By using the ADAMS vehicle model, the judder phenomena of the small bus were analyzed, and based on analysis results, the validity of the improvement method was proposed. Also in order to lessen the problem jubber sensitivity analysis and test results were proposed.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.489-494
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• 2000

In the high speed driving conditions, the vibrational phenomena with relation to chassis system are becoming more important factors in chassis design and development. In this paper Commercial Dynamic program is used to model middle size bus for brake judder phenomenon. To verify the effects of a body structure in brake judder, body structure is modeled in flexible. Also mode shapes and frequencies are obtained from Commercial FEA program in the same condition of experimental test. The simulation results are compared to the experimental results and summarized

• 한국정보통신학회논문지
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• 제12권3호
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• pp.569-574
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• 2008

자동차에서 디스크 편차 변이(Disk Thickness Variation : DTV)가 차체 진동 혹은 브레이크 페달 떨림 발생의 근원이 되므로 이를 운전자 보호차원에서 또는 생산 초기 출하시점에서 이를 검사할 수 있는 측정기기의 개발에 본 연구의 목적이 있다. 본 논문에서는 이런 DTV정보와 Labview 언어를 이용한 휴대용 Brake Judder측정 시스템을 개발하였다.

• 대한기계학회논문집A
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• 제31권12호
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• pp.1131-1138
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• 2007

This paper studies experimentally on the building-up process for the amplitude of a commercial truck vibration induced by brake judder. A front axle drum equipped with a drum brake system is utilized for this experiment. A brake dynamo test, a real vehicle ride test and a real vehicle braking test are performed for the analysis of brake judder. The brake dynamo test measures judder by applying brake chamber pressures of 1, 2 and 3 bar at initial brake pad temperatures of $100^{\circ}C$ and $150^{\circ}C$. In order to assess the vertical acceleration at the front axle, the real vehicle ride test on a straight test road with velocities of 20, 40, 60 and 80 km/h is performed. The real vehicle braking test is carried out at the deceleration rate of 0.2g from a velocity of 90km/h for evaluating the vertical, lateral and longitudinal accelerations both at the front axle and at the cab floor under the driver's seat. The magnitudes and frequencies of the measured peak accelerations from the brake dynamo test, the real vehicle ride test and the real vehicle braking test are comparatively analyzed. This paper shows that the vibration produced by brake judder is built up due to the brake system's peak acceleration frequency being close to the vehicle ride mode's frequency.

• 대한기계학회논문집A
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• 제24권3호
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• pp.593-602
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• 2000

The shape optimization is performed to minimize the judder of ventilated disc brake rotor that is induced by the thermal deformation of the disc. A three-dimensional finite element is developed to analyze the coupled system of temperature and displacement field, and the thermal conductivity and mechanical stiffness matrices are simultaneously taken into account. To reduce computing time, an equivalent heat transfer rate is introduced approximating the heat transfer rate on the disc surface. A deformation factor is introduced to describe the thermal deformation causing the judder. The deformation factor is chosen as an objective function in the optimization process. Consequently an optimum design is then performed minimizing the deformation factor with the design variables of the shape of the disc. The optimum design procedure presented in this study is proven to be an effective method of minimizing the judder, and it reduces the thermal deformation by 23% of the initial geometry.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.148-156
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• 2001

Brake judder, one of low Sequency vibrations in brake system is determined by the excitation of Brake Torque Variation (BTV). The largest contributor to BTV is disc thickness variation. In this study, the static loads of brake torque at Suspension Mounting Points (SW) are obtained by the quasi-static analysis using DADS. The dynamic loads with frequency of BTV at SW are derived from correlation between forced vibration analysis with static loads and brake test results. And the accelerations at steering wheel were analyzed by forced vibration analysis with dynamic loads using commercial finite element program MSC/NASTRAN so that vibration characteristics of vehicle due to brake judder were investigated. Reliability of analysis results was verified through comparing the brake test results. Also, a parametric study with natural frequencies of frame, such as the 1st torsional mode and 1st bending mode, was conducted to reduce vibration amplitudes. As a result we could detect frame natural frequency conditions to improve vibration characteristics and obtained the frame model to reduce vibration amplitude.