• 한국자동차공학회논문집
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• 제24권5호
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• pp.520-526
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• 2016

Squeal noise is a typical brake noise that is annoying to both passengers and pedestrians. Its frequency range is fairly wide from 1 kHz to 18 kHz, which can be distressful to people. The brake squeal noise occurs due to various mechanisms, such as the mode coupling of the brake system, self-excited vibration, unstable wear, and others. In this study, several parameters involved in the generation of a squeal noise are investigated experimentally by using a brake noise dynamometer. The speed, caliper pressure, torque, and friction coefficient are measured as functions of time on the dynamometer. The contact pressure and temperature distributions of the disc and the pad are also measured by using a thermal imaging camera and a pressure mapping system. As a result of the simultaneous measurement of the friction coefficient and squeal amplitude as functions of the velocity, it is found that the onset of the squeal may be predicted from the ${\mu}-v$ curve. It is also found that a non-uniform contact pressure causes instability and, in turn, a squeal. Based on the analysis results, design modifications of the pad are suggested for improved noise characteristics.

• 한국자동차공학회논문집
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• 제12권5호
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• pp.118-124
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• 2004

To investigate the mechanics of brake squeal noise, the sound and vibration of an actual brake system was measured using a brake dynamometer. The experimental results show that disk run-out due to the misalignment of brake disk varies with brake line pressure and becomes the important factor of brake squeal noise generation. Also, it was confirmed that the frequency of the squeal noise equals to the natural frequency of the disk bending mode.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.320-325
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• 2006

The phenomenon of squeal in disc brakes has been, and stin is, a problem for the automotive industry. Extensive research has been done in an attempt to understand the mechanisms that cause it and in developing design procedures to reduce it to make vehicles more comfortable. In this paper, the study on squeal noise of disc brake is performed using complex eigen-value analysis, The first part describes the chassis-dynamometer and the testing procedure, and second part explains how the analysis is performed and shows some of the results from typical squeal tests. Finally, to reduce squeal nose of disc brake is investigated by the effects of brake design parameter.

• 한국산학기술학회논문지
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• 제14권7호
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• pp.3158-3163
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• 2013

본 연구에서는 회전속도, 브레이크 압력 제어가 가능한 브레이크 다이나모메타를 제작하여 스퀼 소음 실험을 실시하였다. 브레이크 패드는 각각 $34^{\circ}$, $30^{\circ}$, $26^{\circ}$로 가공하여 패드 각도에 따른 스퀼 발생 조건과 음의 기울기 발생에 따른 스퀼 연관성을 연구 하였다. 각도에 따라 특정한 회전속도와 브레이크 압력에서 스퀼이 발생하였으며, 각도에 상관없이 하모닉 성분을 가지는 특정 주파수 소음을 발견하였다. 햄머링 테스트 및 유한요소해석을 통해서 특정 주파수는 In-plane모드 성격을 갖고 있으며, 패드 각도에 둔감한 모드임을 밝혀냈다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.170-175
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• 2005

In this study, experimental and theoretical methods were applied to understand brake squeal noise VVVF rolling stock on tracks. Trailer cars needed to payed a particular attention, because they were the major source of brake noise. VVVF rolling stocks for lines no 1 of the subway system in Seoul were used for experimental analyses. In order to study brake squeal noise, a dynamometer test at the S&T Brake, Co., which was a manufacturer of brake pads had performed. For measuring vibration and noise, vibration tests of brake parts (brake lining, brake lining head, back plates, etc.) at the SNUT were executed. Also, vibration tests of disc assembly and lining block at the heavy maintenance shop of the Gunja depot were performed. The modal analyses by using an ANSYS which was one of the CAE commercial program were simulated to know the relationship to the mechanism of brake noise. On the based of the tests and the simulations it was found that specific frequencies of the brake parts affected squeal noise, and improvements for reducing squeal noise were proposed.

• 한국소음진동공학회논문집
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• 제16권8호
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• pp.830-839
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• 2006

The phenomenon of squeal noise in the disk brake system has been, and still is, a. problem for the automotive industry. Extensive research has been carried out in an attempt to understand the mechanism that causes squeal noise and In developing design procedures to reduce squeal noise to make vehicles more comfortable. In this paper, the study on the analysis of squeal noise is performed by using computer aided engineering to design the anti-squeal noise disk brake system. The first part describes the chassis dynamometer and the testing procedure, and second part explains the finite element model and the complex eigenvalue analysis. Finally, it is shown that the proposed squeal noise analysis could be useful to investigate the design parameters that affect the squeal noise characteristics.

• 한국철도학회논문집
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• 제20권1호
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• pp.1-10
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• 2017

제동 스킬소음은 승객과 선로 주변의 주민에게 불편을 끼쳐 시급히 해결해야 할 문제의 하나이지만 해결책을 찾는 것은 쉽지 않다. 제동 스킬소음을 저감하기 위한 해결책은 크게 제동 마찰재의 소재를 개량하거나 제동패드의 구조를 개선하는 것으로 구분할 수 있다. 본 연구에서는 현재 KTX 차량에 사용되고 있는 제동패드를 기준으로 마찰재의 소재만을 바꾼 패드와, 동일한 마찰재 소재를 사용하지만 구조를 유연형으로 바꾼 제동패드를 제작하여 제동 다이나모미터에서 다양한 조건으로 마찰특성과 소음특성을 평가하고 영업차량이 역에 정차할 때 측정한 스킬소음과 비교 및 분석하였다. 제동 다이나모미터 시험이 실차 시험을 어느 정도 재현하는 것이 가능한다는 것을 발견하였고, 영업열차에서 최고 스킬소음이 발생한 4,500Hz 대역의 스킬소음은 다이나모미터 시험에서도 정확히 일치하고, 이 주파수는 제동디스크의 고유진동수와 일치하는 것을 규명하였다. 제동 스킬소음이 발생하는 주파수는 캘리퍼에 작용하는 압력, 시험온도, 그리고 제동 초속도에 따라 달라지지만 일정한 경향을 보여주지는 않았다. 개발된 제동패드의 평균 마찰계수는 0.35~0.45의 범위에 있고 마찰재 소재만을 바꾼 경우는 21.6dB(A), 구조를 변경한 경우는 17.3dB(A) 만큼 최대 소음을 줄일 수 있었다.

• Steel and Composite Structures
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• 제19권4호
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• pp.939-952
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• 2015

In this paper, brake pad performance of two organic matrix composites namely, Sample 1 (contains no brass filler) and Sample 2 (contains 1.5% brass filler), is studied based on tribological and squeal noise behavior. In the first stage, a pin-on-disc tribometer is used to evaluate the frictional behavior of the two pads. On the following stage, these pads are tested on squeal noise occurrence using a drag-type brake dynamometer. From the two type of tests, the results show that; (i) brass fillers play a dual role; firstly as reinforcing element of the brake pad providing primary contact sites, and secondly as solid lubricant by contributing to the formation of a layer of granular material providing velocity accommodation between the pad and the disc; (ii) brass fillers contribute to friction force stabilization and smooth sliding behavior; (iii) the presence of small weight quantity of brass filler strongly contributes to squeal occurrences; (iv) there is close correlation between pin-on-disc tribometer and brake dynamometer tests in terms of tribological aspect.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1690-1695
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• 2003

In order to investigate the mechanism of brake squeal noise, the sound and vibration of an actua1 brake system were measured using a brake dynamometer. The experimental results show that disc run-out varies with brake line pressure and the factor of squeal generation is the run-out due to the misalignment of brake disk. A three degrees of freedom friction model is developed for the disk brake system where the run-out effect and nonlinear friction characteristic are considered. The results of numerical analysis of the model agree well with the experimental results. Also, the stability analysis of the model was performed to predict the generation of brake squeal due to the design parameter modification of brake systems. The results show that the squeal generation depends on the nm-out rather than the friction characteristic between the pad and the disk of brake.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.630-634
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• 2001

Predicting brake squeal noise in design stage can be beneficial to reducing the expense of development. In this paper, the possibility of pre-estimating squeal phenomena of a disc brake system was investigated. To preestimate squeal phenomena, complex eigenvalue analysis was performed for brake system. The evaluation of noise dynamometer test verified the prediction and it corresponded with the result of complex eigenvalue analysis.