• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.223-224
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• 2014

• The Journal of the Acoustical Society of Korea
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• v.35 no.3
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• pp.183-191
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• 2016

A systematic development process for the low noise FEAD (Front End Accessory Drive) system is presented by combining CAE (Computer Aided Engineering) and the experimental rig test. In the estimation of the belt drive noise, two main difficulties arise from the high non-linearity due to the stick-slip contacts on the interfaces of the belt and pulleys, and the interaction of the belt drive system with the powertrain rotational parts. In this work, a recently developed analysis method of the belt drive has been employed considering powertrain rotational dynamics. As results, it shows good correlation with the vehicle tests in various operational modes. The established model has been employed to validate the new design improving the stick-slip noise of the problematic FEAD system. Furthermore, the best proposal of FEAD system in terms of functionality [NVH (Noise, Vibration and Harshness), fuel economy, cost. etc.] has been suggested in the concept design stage of new engine through this presented methodology.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.103-106
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• 2005

This paper reviews the dynamic load phenomenon referred to as 'silo quaking', caused shock vibration and loud noise, during gravity discharge in coal silos. Quaking in tall silo is examined using experimental data obtained from a Coal Power Plant and several experimental and numerical investigations available in the published literature. In the experiment, the acceleration was measured at various height on the silo column and floor and by doing so, not only could the variation of the amplitude of the quaking be observed, but also the propagation of waves could clearly be seen. Through an overview of recent research on this subject, it is shown that the current silo quaking is produced by slip-stick friction between the internal wall of silo and the granular material, i.e. coal.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.2
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• pp.116-125
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• 2003

Four models for stick-slip friction are presented and are adopted for a numerical simulation study for a manual transmission clutch damper in idle mode. Meaning of parameters for friction models are explained and proper values are suggested. Also explained ate the reason why those specific values for the parameters are chosen. Preferable model for the clutch damper In Idle mode is discussed in terms of calculation efficiency and fidelity of the model based on real measured data. For clutch damper idle mode simulation studies, all four models perform equally well.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.376-377
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• 2008

• Journal of KSNVE
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• v.11 no.3
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• pp.461-470
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• 2001

A friction-type clutch system sometimes generates spick-slip vibration during engagement, which disturbs smooth start of a car and makes a passenger uncomfortable. In this study, the spick-slip vibration in four types of friction couples was investigated at two different engagement conditions respectively of which the amount of slip time and clutch travel was varied. Results are found as follows. First, the vibration increased at the condition of small engine torque and large torque fluctuations due to higher harmonics of engine speed. Second, the friction couple without a pre-damper has advantages of reducing the vibration. This study also suggested an evaluation method of vehicle vibration in the view point of human perception by using the frequency weighting of ISO2631-1.

• Tribology and Lubricants
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• v.23 no.6
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• pp.266-271
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• 2007

The brake performance of sintered friction materials for the high speed train was studied. In this study, newly developed sintered materials based on copper were compared with the commercial products for high speed trains. They were tested on a 1/5 scale dynamometer using low carbon steel disks. Effectiveness, fade, and recovery tests were carried out to examine friction performance and the change of disk thickness variation (DTV) during brake applications and noise propensity were also evaluated. Results showed that the two sintered friction materials exhibit similar friction coefficients and braking performance, whereas the newly developed friction material was superior in terms of DTV generation and noise propensity to the commercial friction material. The improvement of the newly developed friction material was attributed to the high graphite content which reduced the stick-slip phenomena and prevented uneven disk wear by producing friction films on the counter disk.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.772-779
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• 2000

The friction and wear behavior of short carbon fiber reinforced polyetheretherketone was studied experimentally under dry sliding conditions against SCM440(AISI 4140) disks with a different surface roughness and hardness at the low sliding speeds and the high pressures on a pin-on-disk apparatus. Under the low disk surface roughness value the earsplitting noise and stick-slip were occurred. The increased adhesion friction and wear factor with stick-slip made the friction and wear behavior worse. Under the high disk surface hardness the break and falling-off of carbon fibers were accelerated. The carbon fibers fallen off from the matrix were ground into powder between two wear surfaces and this phenomenon caused a abrasive friction and wear factor to increase. So the friction and wear behavior became worse. With the transfer film made of wear particles formed on a disk, the carbon powder film formed on a pin lowered a friction coefficient.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.10
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• pp.555-562
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• 2000

We propose an adaptive nonlinear control algorithm for compensation of the stick-slip friction in a dynamic system. The friction force and mass of the system are estimated and compensated by adaptive control law. Especially, as the nonlinear control input in a small tracking error zone is enlarged by the nonlinear function, the steady state error is significantly reduced. The proposed algorithm is a direct adaptive control method based on the Laypunov stability theory, and its convergence is guaranteed under the bounded noise or torque disturbance. We verified the performance of the proposed algorithm by computer simulation on one-DOF mechanical system with friction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.255-261
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• 2002

A four-degree of freedom model is suggested to understand the basic dynamical behaviors of the normal interaction between two masses of the friction induced normal vibration system. The two masses may be considered as the pad and the disk of the brake. The phase space analysis is performed to understand complicated in-plane dynamics of the non-linear model. Attractors in the phase space are examined for various conditions of the parameters. In certain conditions, the attractor becomes a limit cycle showing the stick-slip phenomena. In this paper, on the basis of the in-plane motion not only the existence of the limit cycle but also the size of the limit cycle is examined o demonstrate the non-linear dynamics that leads the unstable state and then the normal vibration is investigated as the state of the in-plane motion For only one case of the system frequency(two masses with same natural frequencies), the propensity of the normal vibration is discussed in detail. The results show an important fact that it may be not effective when too much damping is present in the only one part of the masses.