• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1422-1427
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• 2007

MR fluid is a suspension of micrometer-sized magnetizable particles in silicon oil and a functional fluid whose apparent viscosity can be controlled by the applied magnetic field strength. In this paper, a rotary brake using MR fluid called MR brake for tension control of precision machinery such as roll-to-roll printing machinery is presented. First, to obtain the higher performance than conventional powder brake, a MR brake with a modified rotor shape is newly designed and analyzed using FEM. Second, the prototype of MR brake is fabricated with the optimized structural parameters and an experimental apparatus is constructed. Then, basic characteristics of the MR brake are investigated with the different MR fluids. Finally, the validity of the developed MR brake is verified through the comparison with the conventional powder brake.

• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.236-240
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• 2005

This paper deals with friction-induced vibration of disc brake system under constact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model, The comparison of experimental and analytical results shows a good agreement and the analysis indicates that mode coupling due to friction force and geometric instability is responsible fur disc brake squeal. And the Front brake system reduced the squeal noise using design of experiment method(DOE). This helped to validate the FEM model and establish confidence in the simulation results. Also they may be useful during real disk brake model.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.240-246
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• 1999

The effect of microstructure of gray cast iron disk was investigated by using a pad-on-disk type friction tester. Three different rotors with different microstructures were studied in this work. They showed a pearlitic matrix, a ferritic matrix, and a martensitic structure, respectively. All of them have graphite flakes in common. Drag tests at different pressure and speed conditions were carried out to study friction stability, temperature rise during drags. The rotor containing pearlitic matrix showed lower values of friction coefficient, small amount of temperature rise, and less fading. The results showed that gray cast iron disk containing pearlitic matrix has good friction characteristics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.820-825
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• 2004

This paper deals with friction-induced vibration of disc brake system under constant friction coefficient. A linear, finite element parameter model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model, the experimental modal test and the dynamometer test are performed. The comparison of experimental and simulation results shows a good agreement and the analysis indicates that mode coupling due to friction force is responsible for disc brake squeal. And squeal type instability is investigated by using the parametric rotor simulation. This indicates parameters which have influence on the propensity of brake squeal. This helped to validate the FEM model and establish confidence in the simulation results. Also they may be useful during real disk brake model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.3
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• pp.325-331
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• 2013

In this study, a complex eigenvalue analysis is implemented to verify the unstable mode of a brake system using ABAQUS software. The component participation factors and component modal participation factors are used to analyze the total contributions from each component and each component mode to a particular unstable system mode. This study shows that the 1.4-kHz unstable system mode comes from mode coupling between the 2nd nodal diametric mode and 3rd lateral axial mode (LAM) in the baseline model. A sensitivity analysis with a linking index is performed to prevent the mode coupling of the component modes. This linking index analysis shows the optimum mass loading position to move away the natural frequency of the 3rd LAM, which contributes to the unstable mode. Finally, a complex eigenvalue analysis is implemented with mass loading in the tie bar position, and no unstable system mode is generated in the low-frequency range (below 2 kHz).