Friction-induced oscillations of a slider: Parametric study of some system parameters (original) (raw)
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Friction-induced oscillations of a pin-on-disk slider: analytical and experimental studies
Wear, 1999
. The paper presents coordinated experimental and numerical studies of friction-induced oscillations of a Pin-On-Disk POD slider. The primary objective is to verify and expand the understanding of friction-induced vibrations, and to confirm validity of the analytical predictive technology. A special experimental apparatus was built, which possesses desirable qualities of mechanical simplicity and controllable dynamic characteristics. For this apparatus, an analytical model is devised, taking into consideration both the dynamics of the mechanical system and the strongly nonlinear constitutive properties of the contact interface. These properties are determined through asperity-based homogenization approach. By variation of selected details of the apparatus, both stable and unstable configurations of the system were set up and tested. The experimental observations correlate very well with analytical predictions of dynamic instability and of limit cycle oscillations. q 1999 Elsevier Science S.A. All rights reserved.
Self-excited vibrations induced by dry friction, part 1: Experimental study
Journal of Sound and Vibration, 1990
An experimental investigation was conducted in the laboratory with a pin-on-disk type sliding apparatus to study self-excited vibrations induced by dry friction. These vibrations are often encountered in practice, with detrimental effects such as excessive wear of components, surface damage, fatigue failure and noise generation. Four different friction regimes are obtained as the normal load is increased. Self-excited vibrations occur in the last regime when the normal load, or equivalently the kinetic coefficient of friction, reaches a certain critical value. The waveforms of the self-excited vibrations are analyzed. A mathematical model of the contact, including non-linear contact stiffness and damping, is obtained based on experimental data. This model of contact mechanics is necessary for stability analysis given in a companion paper.
Vibrations induced by friction forces in dynamic systems
2010
Vibrations induced by friction generated a series of major problems in functioning of mechanisms of industrial equipment. Dynamic systems, with parts in motion, function with friction due to direct contact between surfaces of its various components. The present paper shows a synthesis of negative effects caused by different types of friction that can be identified analyzing the vibration signal, thus avoiding the appearance of faults and shortcomings that can compromise the ongoing of an industrial process.
Self-excited vibrations induced by dry friction, part 2: Stability and limit-cycle analysis
Journal of Sound and Vibration, 1990
An experimental investigation was conducted in the laboratory with a pin-on-disk type sliding apparatus to study self-excited vibrations induced by dry friction. These vibrations are often encountered in practice, with detrimental effects such as excessive wear of components, surface damage, fatigue failure and noise generation. Four different friction regimes are obtained as the normal load is increased. Self-excited vibrations occur in the last regime when the normal load, or equivalently the kinetic coefficient of friction, reaches a certain critical value. The waveforms of the self-excited vibrations are analyzed. A mathematical model of the contact, including non-linear contact stiffness and damping, is obtained based on experimental data. This model of contact mechanics is necessary for stability analysis given in a companion paper.
Numerical Modeling of Friction-Induced Vibrations and Dynamic Instabilities
Applied Mechanics Reviews, 1994
A numerical study of dynamic instabilities and vibrations of mechanical systems with friction is presented. Of particular interest are friction-induced vibrations, self-excited oscillations and stick-slip motion. A typical pin-on-disk apparatus is modeled as the assembly of rigid bodies with elastic connections. An extended version of the Oden-Martins friction model is used to represent properties of the interface. The mechanical model of the frictional system is the basis for numerical analysis of dynamic instabilities caused by friction and of self-excited oscillations. Coupling between rotational and normal modes is the primary mechanism of resulting self-excited oscillations. These oscillations combine with high-frequency stick-slip motion to produce a significant reduction of the apparent kinetic coefficient of friction. As a particular study model, a pin-on-disk experimental setup has been selected. A good qualitative and quantitative correlation of numerical and experimental ...
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2019
Finite Element Method (FEM) is proposed to model the friction-induced vibration in the gear system with a lead screw and nut. In order to validate it, the experiment was conducted by using the lead screw test setup. In the frequency spectrogram, there were two distinctively different patterns of the unstable modes: a mode where the frequency significantly changed and another where the frequency remained almost unchanged. Under a constant friction coefficient, the complex eigenvalue analysis in the FE model demonstrated that the system frequencies altered with respect to the transfer distance of the nut. The unstable modes were found to occur due to mode-coupling between the paired bending modes of the screw. Meanwhile, an unstable mode in which the frequency showed little changes in relation to the translation distance of the nut, was found to be an unstable torsion mode, which was caused by the negative friction-velocity slope.
Analytical Approaches for Friction Induced Vibration and Stability Analysis
2011
The traditional mass on a moving belt model without external force excitation is considered. The displacement and velocity amplitudes and the period of the friction induced vibrations can be predicted using a friction force modelled by the mean of friction characteristics. A more precise look at the non-smooth transition points of the trajectories reveals that an extended friction model is looked-for. In present job, two so-called polynomial and exponential friction functions are investigated. Both of these friction laws describe a friction force that first drops off and then raises with relative interface velocity. An analytical approximation is applied in order to derive relations for the vibration amplitudes and base frequency and in parallel a stability analysis is performed. Moreover, results and phase plots are illustrated for both analytical and numerical approaches.
The effect of amplitude of vibration on the coefficient of friction for different materials
Tribology International, 2008
This work examines how friction coefficients are affected by amplitude of normal vibration at different frequencies. Variation of friction coefficient with the amplitude of normal vibration is investigated experimentally when mild steel pin slides on different types of material such as glass fiber reinforced plastic, cloth reinforced ebonite, polytetrafluoroethylene (PTFE), rubber and mild steel. For this, a pin-on-disc apparatus having facility of vibrating the test samples at different amplitudes and frequencies of vibration was designed and fabricated. During the experiments, the effects of sliding velocity, roughness, normal load and duration of rubbing were also investigated. Studies have shown that the friction coefficient decreases with the increase of amplitude of vibration within the observed range. The observed ranges of amplitude of vibration were 10-200 mm. In this study, it is also observed that the rate of reduction of friction coefficient has a particular relationship on the amplitude and frequency of vibration. The experimental results are compared with those available in the literature and simple physical explanations are provided.
A Non-Linear Friction Model for Self-Excited Vibrations
Journal of Sound and Vibration, 1997
The motivation behind this work is to develop a dynamical systems understanding of the phenomenon of squeal. Squeal is a form of self-excited vibration; vibrations are induced in a structure such as a wheel or violin string by the action of a frictional driving force. The nature of this force is rather difficult to define; however, a phenomenological model is proposed which combines the concepts of static and dynamic friction, which seems intuitively reasonable and for which there is documented evidence. In the case presented here, the vibrating structure is simplified to that of a block resting on a moving conveyor belt, restrained by a simple spring and dashpot to a rigid wall. The non-linear system dynamics predicted by using the new friction model are unusual in that the conditions giving rise to squeal include not only the belt speed, but also the initial conditions of the structure. It is thought that this information may be useful in the control of the onset of squeal.