• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1555-1556
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• 2011

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.606-607
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• 2008

Nowadays, noise and vibration phenomena of a disc brake system have been given various names that provide some definitions of sound and vibration emitted such as grind, grunt, moan, squeak, squeal, judder and wire brush. The most common and annoying noise of a disc brake system is squeal noise. It is defined as noise whose frequency content is 1 kHz and higher with excessively high and irrigating sound pressure levels. In this paper, the noise and vibration characteristics of a disc brake system have been investigated to develop the fusion-type friction material, which overcomes the low steel and non-asbestos organic friction materials. For the purpose, both experimental evaluation and complex eigenvalue analysis have been carried out.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.964-968
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• 2008

Infrared thermography using high-speed infrared camera has been recognized as a powerful method for various potential applications, such as nondestructive inspection, failure analysis, stress analysis, and medical fields, due to non-contact, high-speed, and high spatial resolution at various temperature ranges. In this investigation, damage evolution due to generation of hot spots on railway brake disc was investigated using the infrared thermography method. A high-speed infrared camera was used to measure the surface temperature of brake disc as well as for in-situ monitoring of hot spot evolution. From the thermographic images, the observed hot spots and thermal damage of railway brake disc during braking operation were qualitatively analyzed. Moreover, in this investigation, the previous experimental and theoretical studies on hot spots phenomenon were reviewed, and the current experimental results were introduced and compared with theoretical prediction.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.697-698
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• 2008

• 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.

• Smart Structures and Systems
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• 제17권2호
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• pp.275-296
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• 2016

This paper focuses on developing a new configuration on magnetorheological (MR) brake damper as prosthetic knee. Prosthetic knee uses magnetic fields to vary the viscosity of the MR fluid, and thereby its flexion resistance. Exerted transmissibility torque of the knee greatly depends on the magnetic field intensity in the MR fluid. In this study a rotary damper using MR fluid is addressed in which a single rotary disc will act as a brake while MR fluid is activated by magnetic field in different walking gait. The main objective of this study is to investigate a prosthetic knee with one activating rotary disc to accomplish necessary braking torque in walking gait via T-shaped drum with arc surface boundary and implementing of Newton's equation of motion to derive generated torque at the inner surface of the rotary drum. For this purpose a novel configuration of a T-shaped drum based on the effects of a material deformation process is proposed. In this new design, the T-shaped disc will increase the effective areas of influences in between drum and MR fluid together and the arc wall crushes the particles chains (fibrils) of the MR fluid together instead of breaking them via strain in a conventional MR brake. To verify the proposed MR brake, results of the proposed and conventional MR brakes are compared together and demonstrated that the resisting torque of the proposed MR brake is almost two times greater than that of the conventional brake.

• 한국철도학회논문집
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• 제16권4호
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• pp.253-261
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• 2013

KTX 열차가 정거장에서 정차 시 측정한 제동 스퀼소음은 저주파에서부터 18,000Hz의 고주파 영역에 걸쳐 관찰되었다. 제동 스퀼소음이 제동디스크/패드의 상호작용에 의한 불안정 진동모드에 의해 발생한다는 가정 하에 유한요소법을 적용하여 하나의 제동디스크와 4개의 제동패드로 구성된 제동 유니트에 대해 유한요소 모델링을 하고 마찰계수, 마찰면에 작용하는 압력, 마찰재와 백플레이트의 탄성계수 등 여러 파라미터의 특성값을 변경해 가면서 제동 유니트의 불안정 진동모드에 미치는 영향을 해석하고 각 파라미터의 영향을 분석하였다. 해석결과에 의하면 불안정 진동모드는 이러한 변수들과 밀접한 관련이 있음을 알 수 있었다.

• 한국가스학회지
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• 제20권1호
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• pp.40-45
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• 2016

이 연구의 목적은 브레이크 저더가 자동차 브레이크 시스템에서 나타나는 많은 문제중에 하나 이며,연구자들이나 엔지니어가 브레이크 저더를 최소화하기 위하여 원인과 메카니즘에 대해 연구하고 있음에도 불구하고 나타나는 현상이다.운전자들이 느끼는 것은 핸들이나 브레이크 페달 또는 차체 바닥에서 오는 높은 주파수의 진동으로 느낄수 있으며 소음도 같이 동반하게 된다.따라서 고장사례를 통하여 운전자가 디스크 브레이크의 길들이기를 하거나 디스크의 열변형 부분을 제거하여 브레이크 저더를 저감 할수 있도록 조치방법에 대해서 고장사례 연구를 하였다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.429-430
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• 2002

In this study, three kinds of brake: discs including two coated brake discs and one steel disc were tested under the same experimental conditions on a reduced scale braking test bench. Plasma spray coating technique was used to coat ceramic powder on the discs. In the test, four commercial sintered brake pads were coupled with discs. Ceramic coated discs have shown good stability in friction coefficient at high speed and high energy braking conditions. However, ceramic coated discs caused more wear loss of pad mass than the steel disc. It was shown that thermal barrier effect in ceramic coated discs adjusted the thermal partition between pad and disc. Steel disc showed fluctuating friction coefficient at high speed but less wear loss of pad mass than ceramic coated discs.

• 한국생산제조학회지
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• 제18권5호
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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.