• Title/Summary/Keyword: Squeal

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Reduction of Wet Brake Squeal in a Forklift (지게차용 습식 브레이크의 소음저감)

  • 장한기;이성호;김태일
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.10a
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    • pp.98-103
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    • 1996
  • Elimination of squeal noise generated during brake application is an important task for the improvement of comforts in vehicles. In this paper, the structure of the wet brake and its operation are described first, and the cause of the noise is analyzed by identifying how the factors such as torque, speed, oil pressure, lubricant, and friction material affect the noise. To verify the mechanism of generation of the noise, several experiments of brake applications are executed, Based upon the review on the technical papers and the results from the experiments, several solutions to reduce the noise, available in real applications, are suggested, and the feasibilities of them are confirmed through the applications to the current system.

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A Study on Dry Friction-Induced Sound (乾性摩찰音 에 관한 硏究)

  • 김재호;김석삼
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.8 no.6
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    • pp.591-598
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    • 1984
  • The results of measurements showing normal vibrations and rubbing noise generated during unlubricated smooth sliding between metal surfaces are presented. The measurements were made on pin-on-disc type apparatus instrumented with piezoelectric acceleration transducers and microphones. Spectral analysis of the both signals up to frequency of 10kHz indicates that they are closely correlated. The major components of both signals in this frequency range are primarily associated with the normal contact vibrations which are excited by surface irregularities being swept through the contact region during sliding. As an approximation to the seismic input of surface irregularities, an effective surface wavenumber spectrum was assumed in the form of an inverse vibration and noise measurements for a number of surface finishes and mean loads. The predominant frequency component of which levels of the normal vibration and noise are close to overall levels of the both signals is induced by contact resonance between the two bodies and its frequency can be calculated from the Hertzian theory.

Finite Element Analysis for Friction Noise with Respect to the Friction Curve of Several Materials (재질 별 마찰곡선을 반영한 마찰소음 유한요소 해석 연구)

  • Baek, Jongsu;Nam, Jaehyeon;Do, Hyuncheol;Kang, Jaeyoung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.5
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    • pp.449-455
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    • 2016
  • This study provides the finite-element (FE) squeal-model predicting friction-induced noise with respect to several friction materials that have different friction characteristics. The friction curve and the corresponding friction noise were measured for four friction materials (Cu, Ni, Al, Mg) using the pin-on-disk and reciprocating friction system. The slope of the friction curve linearized at the sliding velocity was applied to the FE model. The unstable modes in the complex eigenvalue analysis were shown to correspond to the squeal frequencies that existed in the experiment.

The Effect of Damping of a Two-degree-of-freedom Model for the Disc Brake Squeal Noise (2자유도계 모델을 이용한 디스크 브레이크 스퀼 소음에 대한 댐핑의 영향에 관한 연구)

  • Shin, Ki-Hong;Joe, Yong-Goo;Oh, Jae-Eung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.12
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    • pp.903-910
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    • 2003
  • A two-degree-of-freedom model is suggested to describe basic dynamical behaviors of the interaction between the pad and the disc of a disc brake system. Although a pad (and a disc) has many modes of vibration in practice, only one mode of each component Is considered. In this paper, a linear analysis is performed by means of the stability analysis to show various conditions for the system to become unstable, and is based on the assumption that the existence of limit cycle (this corresponds to an unstable equilibrium point inside the limit cycle) represents the squeal state of the disc brake system. The results of the stability analysis show that the damping of the disc is as much Important as that of the pad, whereas the damping of the pad only is considered In most practical situations.

Investigation on Friction Noise in Beam Structure Under Mode-Coupling by Using Analytical Finite-Element Squeal Model (스퀼 융합모델을 이용한 모드연성에 의한 빔 구조 마찰 소음 연구)

  • Kang, Jaeyoung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.5
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    • pp.545-550
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    • 2014
  • This study provided the analytical finite element method estimating the friction-induced noise on the complex beam structure. The frictional contact model was theoretically constructed and applied to the analytical finite element squeal model. The numerical results showed that the beam structure was excited by the mode-coupling instability of the specific system modes. Also, the direction of friction was shown to influence on the dynamic instability of the modes. Besides, the unstable modal frequencies estimated from the numerical calculation were validated by the experiment of the actual beam structure.