• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.569-579
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• 2001

This study investigates the effects of operating conditions on the chattering of an automotive disk brake by experimental and computational methods. Design factors, which cause chattering in automobiles, have attracted great attentions for long time; but they are not well understood yet. For this study, we construct a brake dynamometer for measuring the disk surface temperature during chattering, and propose an efficient hybrid algorithm (combining FFT-FEA and traditional FEA program) for analyzing the thermo-elastic behavior of three-dimensional brake system. We successfully measure the judder in a brake system via the dynamometer and efficiently simulate the contact pressure variation by the hybrid algorithm. The three-dimensional simulation of thermo-mechanical interactions on the automotive brake, showing the transient thermo-elastic instability phenomenon, is presented for the first time in this academic community. We also find from the experimental study that the disk bulk temperature strongly influences the brake chattering in the automotive disk brakes.

• 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.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.432-439
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• 2020

Brake judder has been identified in some operating military units of Korean Light Tactical Vehicles(KLTV) with In-board brake systems to improve braking performance. Severe vibration generated while driving the vehicle may reduce the KLTV's driving stability and further lead to accidents. For the prevention of this, this study analyzes the root cause through the failure analysis on the vehicles with the brake judder identified. Furthermore, the improvement factor was derived by identifying a vibration transmission path by analyzing the vibration transmission mechanism. The study analysis confirmed that the vibration of the frame during braking in the tactical vehicle is a cold judder phenomenon, which is caused by an increase in disk thickness variation due to rust and foreign substances under excessive brake disc's run-out. In addition, it was confirmed that such vibration can be reduced by improving the mounting structure. So, an improvement method for each factor was suggested and its effectiveness was verified by comparison test. Finally, it is expected that the improvement plans derived through this study can be used in the development of a next military vehicle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.6 s.249
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• pp.587-593
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• 2006

A ventilated disc brake having semi-cylindrical grooves has been proposed to improve the thermal judder by way of heat transfer enhancement. The local heat transfer coefficients were measured in the flow passage of disc brake. These measured local heat transfer data were utilized to do the finite element numerical analysis which predicts the maximum temperatures on the disc brake. The results show that the maximum temperatures on the disc surface with semi-cylindrical grooves are approximately 35.2% lower than those without them.

• Journal of Auto-vehicle Safety Association
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• v.12 no.2
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• pp.7-13
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• 2020

Recently, there is a big issue of downsizing on brake system according to fuel efficiency and regenerative braking cooperation control. Especially, small cars have improved in a variety ways such as electric vehicle and smart car compared to previous small cars. So, small brake system is strongly required in the car industry. A new small brake system for light compact vehicles was proposed in this paper. For this system, the solid type disc and caliper were newly developed. And the important design factors were considered to reduce brake size. First, we calculated the temperature rise of disc through heat capacity formula and CAE analysis. Second, we analyzed the housing and carrier stiffness of caliper to select the reasonable condition. Finally, the superiorities of the developed brake system were verified by heat capacity, consumption liquid level, braking feeling, judder, wear test and regenerative braking cooperation control analysis. A developed brake system is expected to be useful for brake system of light compact platform.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.3
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• pp.259-265
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• 2014

When the brakes of a vehicle are applied, large amounts of heat are generated on the surfaces of the brake discs owing to friction between the discs and the brake pads. A high temperature gradient on the disc surfaces leads to thermal deformation and severe disc abrasion. Ultimately, the thermal deformation and disc wear give rise to a thermal judder phenomenon, which has a major effect on the stability of the vehicle. To investigate and propose a solution to these problems, thermoelastic instabilities under applied thermal and mechanical loads were analyzed using the commercial finite element package ANSYS by considering the contact surfaces between the discs and pads. Direct-contact three-dimensional finite elements between the discs and pads were applied to investigate the disc friction temperature, thermal deformation, and contact stress so that the thermal judder phenomenon on the surface of the disc could be predicted.

• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.104-111
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• 2006

A ventilated disc brake having spirally fluted surface has been proposed to improve the thermal judder by way of heat transfer enhancement. The local heat transfer coefficients were measured in the flow passage of disc brake. These measured local heat transfer data were utilized to do the finite element numerical analysis which predicts the maximum temperatures on the disc brake. The results show that the maximum temperatures on the disc surface with spirally fluted surface are approximately 26.6% lower than those without them.

• 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.