• Tribology and Lubricants
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• v.38 no.2
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• pp.63-69
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• 2022

In this research, the rotordynamic characteristics of the labyrinth seal with and without swirl brake were predicted using the computational fluid dynamic (CFD) model. Based on previous studies, a simple swirl brake consisting of square vanes without stagger angle is designed and placed in front of the seal inlet. The rotating frame of reference is utilized to consider the whirling motion of the rotor in the steady-state analysis since the whirling motion is transient behavior in nature. CFD analysis was performed in the range of -1 to 1 pre-swirl ratio for a given seal and swirl brake design and operating conditions. The CFD analysis result shows that the swirl brake effectively reduces the pre-swirl since the circumferential fluid velocity of labyrinth seal with swirl brake was lower than that without swirl brake. The cross-coupled stiffness coefficient, which is greatly affected by the circumferential fluid velocity, increased with an increasing pre-swirl ratio in a seal without a swirl brake but showed a low value in a seal with a swirl brake. The change in the damping coefficient was relatively small. The effective damping coefficient of the labyrinth seal with swirl brake was generally constant and showed a higher value than the labyrinth seal without swirl brake.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.26-31
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• 2000

There are various noises generated by friction. Among the rest, eliminating squeal noise generated during braking is an important task for the improvement of vehicle passengers' comfort. The parameters affecting brake squeal noise are the material properties of the braking pad, the dynamic properties of the brake parts and the dimensions of the brake assembly etc. Also, the squeal noise changes its inherent form with the normal load and sliding speed. In this study, the characteristics of brake squeal noise generated by friction is analyzed experimentally. The experiment focused on the analysis of friction self-excited vibration and squeal noise level. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding speeds. And Friction self-excited vibration is raised the brake squeal noise.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.9
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• pp.1385-1390
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• 2015

This paper is analysis of multiple factor that should be considered in the design of an eddy current brake used as auxiliary brake system. The eddy current brake is a brake that generates a braking torque in a rotational direction opposite to the direction of the rotor by using a time-varying magnetic flux. The eddy current brake has the advantage of being able to take high current densities because this is used for a short period of time. Also, the eddy current brake is influenced by multiple factor such as number of slots, teeth width, coating thickness, air-gap length and so on. Therefore the eddy current brake was designed for use in railway application in consideration of the operation region and critical parameters.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.1
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• pp.34-41
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• 2009

In this paper, a novel MR brake with permanent magnet is developed. This system consists of rotary disk, permanent magnet, spring and MR fluid. Permanent magnets are attached to the rotary disk and moves in the direction of radius. The magnets are linked to rotor axis by spring. As rotation speed increases, the magnets move outward from the center of the system by centrifugal force in the MR fluid. A proper design of stator or case makes the system have unique torque characteristics. The research is performed like following procedures. First, the electromagnetic characteristic of the system is analyzed using Maxwell. Next, torque is calculated using the results of the electromagnetic analysis. Finally, the performance of various types of the brake systems are investigated and compared with each other.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.90-96
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• 1998

There are various noises generated by friction. Among the rest, eliminating squeal noise generated during braking is an important task for the improvement of vehicle passengers' comfort. The parameters affecting brake squeal noise are the material properties of the braking pad, the dynamic properties of the brake parts and the dimensions of the brake assemble etc. Also, the squeal noise changes its inherent form(i.e. its sound pressure level and its frequency) with the normal load and sliding speed. In this study, the characteristics of brake squeal noise generated by friction is analyzed experimentally. The experiment focused on the analysis of friction self-excited vibrationand squeal noise level. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding speeds. And Friction self-excited vibration is raised the brake squeal noise.

• 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 KIEE Conference
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• 2002.11d
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• pp.109-111
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• 2002

It requires to study on accurate control skill for the technical improvement of servo system require. It needs to study on brake that has constant-torque speed range as load. In this paper, braking torque of eddy current brake between electromagnet stator and rotating disk are analyzed. The torque-speed characteristics and proper disk construction are presented in here. From the computer simulation results, it was found that eddy current braking torque is linear or approximately constant over the desired speed range depending on the rotor material, disk construction, pole number and pole displacement of stator, these are confirmed by experimental results.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.46-48
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• 2002

It needs to study on proper brake performance used in servo system of industrial application. In this study, braking torque of eddy current brake between electromagnet stator and rotating disk are analyzed. The torque-speed characteristics and proper disk construction are presented in this paper. From the computer simulation results, it was found that eddy current braking torque is linear or approximately constant over the desired speed range depending on the rotor material, disk construction, pole number and pole displacement of stator.

• Tribology and Lubricants
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• v.18 no.3
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• pp.204-210
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• 2002

Automotive brake pads with four different sizes of zircon particles (average sizes of 1㎛, 6㎛, 75㎛, and 140㎛, respectively) were investigated to evaluate the size effect of abrasive particles on friction performance. Results showed that the brake pads with the larger size of zircon particles tend to show better frictional stability and low pad wear. However, the rotor surface was severely abraded in the case of using larger zircon particles. On the other hand, the small zircon particles in the pads showed the fast increase of the coefficient of friction with friction force oscillation and the tendency was pronounced at low sliding speeds. The brake pads with small particle sizes also exhibited strong fade phenomena at elevated temperatures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.325-328
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• 2001

Disc brake squeal is caused by mechanical vibrations generated from friction force excitations exerted by the pad on the rotor. In order to understand the origin of these vibrations and to speed up the design, the characterization of the individual brake system components is desirable. In this paper, the results of modal analysis are presented in terms of several slot-type with free-free boundary conditions. Special attention is paid to variations of the natural frequency at each vibration mode as the result of modifying slot pattern.