Stochastic modeling of friction force and vibration analysis of a mechanical system using the model

강원석,최찬규,유홍희 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.9

The squeal noise generated from a disk brake or chatter occurred in a machine tool primarily results from friction-induced vibration. Since friction-induced vibration is usually accompanied by abrasion and lifespan reduction of mechanical parts, it is necessary to developa reliable analysis model by which friction-induced vibration phenomena can be accurately analyzed. The original Coulomb’s frictionmodel or the modified Coulomb friction model employed in most commercial programs employs deterministic friction coefficients. However, observing friction phenomena between two contact surfaces, one may observe that friction coefficients keep changing due tothe unevenness of contact surface, temperature, lubrication and humidity. Therefore, in this study, friction coefficients are modeled asrandom parameters that keep changing during the motion of a mechanical system undergoing friction force. The integrity of the proposedstochastic friction model was validated by comparing the analysis results obtained by the proposed model with experimental results.

마찰기인진동에서의 수직항력 변화 효과

최연선,손현배 成均館大學校 科學技術硏究所 1999 論文集 Vol.50 No.2

The effects of normal force variation due to disk inclination in friction-induced vibration are investigated. The investigations on friction-induced vibration should be done on the basis of experiment since complicate phenomena occur depending on experimental conditions. In this study, a friction experiment is performed using an experimental apparatus of pin-on-disk type. The experimental results show that friction coefficient is a function of relative velocity, not of normal force, and also show that squeal of severe vibration occurs due to the normal force variation which is resulted from the inclination of the disk. For the justification of the experimental results, a two-degree of freedom model of friction-induced vibration is suggested and calculated the response numerically.

Friction-induced vibration of marine propeller shaft based on the LuGre friction model

Qianwen Huang,Jing Xia,Huaiguang Liu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8

The friction-induced vibration with stick-slip behavior is caused by the contact of the shaft-bearing system. A LuGre friction model is thus applied in the investigation of frictioninduced vibration of the marine propeller shaft. The model parameters contain Coulomb friction, stiction force, Stribeck velocity and viscous coefficient are obtained through fitting curves of friction with experimental data in published papers. The dynamical response of a marine propulsion system is measured with an experiment and calculated with the Stribeck model to verify the adaptation of the LuGre friction model in the friction-induced vibration. To capture the nature of the LuGre friction model, the velocity-dependent function, friction coefficient, pre-sliding displacement, hysteresis, break-away force and dynamical response are numerically calculated. The impact factors include relative velocity, tangential force, and rotational speed are discussed with specific comparison. Therefore a suitable model focusing on the friction-induced vibration is proposed for the marine propeller shaft.

Noise and vibration on the bogie of a mass rapid train

Hsiu-Ying Hwang,Jia-Shiun Chen 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.10

This paper investigated a noise and vibration concern on a metro train while the train made turns. The study was conducted to identify the root causes of the vibration and noise through hardware experimental testing as well as dynamic computer simulation. The initial investigation indicated the noise came from the bogie of the train. It was between the slewing ring bearing and the friction sets. A lab test was established to duplicate the reported problem and to root out the causes. One-factor-at-a-time method was used to screen the main key factors. Under certain contact conditions, unsmooth turning would occur and cause the noise and vibration. Dynamic simulation was proposed in the study to predict the potential issue. A multibody dynamic model was built with train body, underbody, slewing ring bearing and friction set to simulate the train turning motion. The results showed unsmooth/discontinuous dynamic motions and torque oscillation behaviors. The stop-and-go and stick-and-slip motion led to the vibration. The analysis confirmed the unsmooth friction forces and adhesion could cause the noise and vibration. The computer simulation showed good correlation with the hardware testing. It demonstrated the computer dynamic simulation could be used to predict the potential friction induced vibration issues. In the study, a different substitute material was also investigated through the computer simulation. The results showed the vibration could be effectively reduced if ceramic compound friction material was used.

Influence of different parameters on nonlinear friction-induced vibration characteristics of water lubricated stern bearings

Lin Chang-Gang,Zou Ming-Song,Zhang Hai-Cheng,Qi Li-Bo,Liu Shu-Xiao 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

To investigate the mechanism of friction-induced vibration and noise of ship water lubricated stern bearings, a two-degree-of-freedom (2-DOF) nonlinear self-excited vibration model is established. The novelty of this work lies in the detailed analysis of influence of different parameters on the stability and nonlinear vibration characteristics of the system, which provides a theoretical basis for the various friction vibration and noise phenomenon and has a very important directive meaning for low noise design of water lubricated stern bearings. The results reveal that the change of any parameter, such as rotating speed of shaft, contact pressure, friction coefficient, system damping and stiffness, has an important influence on the stability and nonlinear response of the system. The vibration amplitudes of the system increase as (a) rotating speed of shaft, contact pressure, and the ratio of static friction coefficient to dynamic friction coefficient increase and (b) the transmission damping between motor and shaft decreases. The frequency spectrum of the system is modulated by the first mode natural frequency, which is continuous multi-harmonics of the first mode natural frequency. The response of the system presents a quasi-periodic motion.

Application of impulse damper in control of a chaotic friction-induced vibration

Mansour Ataei,Ali Asghar Atai,Sajjad Mirjavadi,Mohammad Sahebnasagh,Mansour Nikkhah-Bahrami 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.2

Friction-induced vibration is an important phenomenon with adverse effects on many dynamic systems involving friction. In this study,a very simple and well-known one-dimensional friction-induced dynamic system is considered in which the novel PZT stack impulse damper is incorporated into the system. It has been shown that by appropriately tuning the damping parameters, the chaotic behavior is removed quickly and efficiently. It has also been demonstrated that the system is sensitive to parameter change, and minimal modification of these parameters can revert the chaotic or periodic motion.

경사안내면 상에서 이송되는 볼나사-슬라이드 이송계의 마찰기인 진동해석

최영휴(Young Hyu Choi) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.6

A moving mass on a skewed linear guideway model to analyze the friction-induced stick-slip behavior of ball-screw-driven slides is proposed. To describe the friction force, a friction coefficient function is modelled as a third-order polynomial of the relative velocity between the slide mass and a guideway. A nonlinear differential equation of motion is derived and an approximate solution is obtained using a perturbation method for the amplitudes and base frequencies of both pure-slip and stick-slip oscillations. The results are presented with time responses, phase plots, and amplitude plots, which are compared adequately with those obtained by Runge Kutta 4th-order numerical integration, as long as the difference between the static and kinematic friction coefficients is small. However, errors in the results by the approximate solution increase and are not negligible if the difference between the friction coefficients exceeds approximately 40% of the static friction coefficient.

Lyapunov exponent of friction-induced vibration under smooth friction curve

강재영 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.8

This paper studies the nonlinear behavior of the friction-induced vibration by using spring-mass model subject to the smooth frictionvelocity curve. The nonlinearity and instability of the friction may produce the chaotic vibration depending on the friction curve. In order to show this, the Lyapunov exponents are calculated for a variety of the slope and magnitude in the smooth friction curve. In turn, the dependency of the friction curve on the chaotic attractor is illustrated.

해수윤활 선미관 베어링에서 발생되는 비선형 Stick-slip 마찰진동 발생 조건 및 주요인자 분석

한형석,이경현,박성호,전수홍 한국소음진동공학회 2018 한국소음진동공학회 논문집 Vol.28 No.6

Seawater-lubricated bearings applied to stern tubes are widely used to support ship propeller shafts. Generally, the material of these seawater-lubricated bearings is rubber or polymer. Because the lubricating fluid for this kind of bearing is sea water, its coefficient of friction is somewhat higher than that of an oil-lubricated bearing. In particular, in the case of a low-speed regime where the slope of the speed-friction coefficient curve is negative, the shaft system becomes unstable because of the friction force, and self-excited vibration can be generated. This phenomenon is called nonlinear friction-induced vibration by stick-slip motion. In this paper, a simplified model of the propeller shaft and bearing system with two degrees of freedom is suggested to define the mechanism of the stick-slip motion; the stability of the shaft-bearing system according to the change in vertical force, damping coefficient, and friction coefficient on the bearing surface was investigated with the virtual shaft model. In addition, an actual improvement case for the stick-slip non-linear vibration problem occurring in the propulsion shaft of a typical naval vessel is introduced by applying the result from the investigation of the virtual shaft model described in this research.

Sound Radiation Property of Tribe-System

B. L. STOIMENOV,K. KATO,K. ADACHI 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.2002 No.10

Frictional sound is observed in great many practical systems, but its generation mechanism is still unknown. Model systems are best suited for research on the fundamental mechanisms, but results cannot be easily applied to real systems, because each system has different sound radiation properties. At present, there is no easy method for evaluation of these properties. We propose to describe the sound radiation property of a tribo-system by the relationship between friction-induced sound power and the friction-induced vibration velocity of the contact element. It was found that the sound power of a tribo-system is linearly proportional to the mean-square velocity of the sliding element by a constant coefficient having the dimension of mass flow rate (㎏/s).