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Friction force reduction efficiency in sliding motion under tangential vibrations of elastic support

Leus Mariusz, Gutowski Paweł

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 1

101--109

EN

The efficiency of reducing the friction force in sliding motion under the influence of forced vibrations of an elastic substrate significantly depends on the direction of these vibrations in relation to the sliding direction. This article presents a comparison of computational models developed by the authors to estimate the friction force in sliding motion under longitudinal and transverse tangential vibrations of the substrate. Fundamental differences between these models are discussed, and the results of comparative analyses of the impact of tangential vibrations on the friction force depending on their direction are presented. In the developed models describing the friction force, dynamic friction models of Dahl and Dupont and the so-called LuGre model were utilised. The analyses were performed as a function of the sliding velocity and two basic parameters of vibration, which are frequency f and amplitude u0. It has been shown that under longitudinal vibrations, the key parameter, which determines the occurrence of friction force reduction at a given driving velocity vd, is the amplitude va of vibration velocity. However, the level of this reduction cannot be determined unequivocally based on the value of this parameter alone since the identical value va can be obtained at different magnitudes of the frequency and amplitude of vibrations, and the reduction level is a nonlinear function of these parameters. The results of simulation analyses were verified experimentally.

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Effectiveness of friction force reduction in sliding motion depending on the frequency of longitudinal tangential vibrations, sliding velocity and normal pressure

Leus Mariusz, Gutowski Paweł, Rybkiewicz Marta

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 4

490--498

EN

The article presents the results of experimental research and simulation analyses of the influence of slip velocity, normal pressures and vibration frequency on the effectiveness of friction force reduction carried out in sliding motion in the presence of forced tangential vibrations. In experimental studies, changes in the driving force were measured during the slip of the upper body over the vibrating lower body. The direction of these vibrations was parallel both to the contact plane and to the direction of movement of the shifted body. The simulation tests were carried out in the Matlab/Simulink environment through the use of numerical procedures that were specially created for this purpose. Dynamic friction models considering the tangential compliance of contact and the phenomenon of pre-sliding displacement were used for calculations. The paper presents the designated values of the so-called coefficient of average friction force reduction in sliding motion for the following friction pairs: steel C45–steel C45, steel C45–cast iron GGG40 and steel C45–polytetrafluoroethy-lene PTFE (Teflon). The results of numerical analyses were in good agreement with those of experimental tests. A significant dependence of the level of average friction force reduction on the frequency of forced vibrations, sliding velocity as well as the kind of sliding pair material, and normal pressures was shown.

3

Selection of the Friction Model for Numerical Analyses of the Impact of Longitudinal Vibration on Stick-Slip Movement

Rybkiewicz Marta, Leus Mariusz

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no 3

277--287

EN

The purpose of the experimental and numerical tests presented in this paper was to indicate a friction model suitable for simulation analyses of the impact of longitudinal tangential vibrations on stick-slip movement in sliding motion. The vibration parallel to the shift direction are forced in the contact zone of a shifted body and the base. They can cause partial or total reduction of the stick-slip phenomenon or even reduce the value of necessary drive force. The time characteristics of drive force were determined experimentally and in simulation for two cases, i.e. at a motionless or vibrating base. Simulation analyses were carried out in accordance with the described computational procedures implemented in Matlab-Simulink environment. Four models of friction were tested in the presented studies: Dahl, Karnopp, Reset Integrator and LuGre. Experimental tests were carried out on a specially designed tests stand. The Root Mean Square Error (RMSE) was used to compare the results of numerical calculations with results of experimental tests. The performed qualitative assessment and the determined RMSE values indicated that the LuGre and the Reset Integrator models ensure he best consistency of model and experimental time characteristics of the driving force.

4

Experimental and numerical analysis of stick-slip suppression with the use of longitudinal tangential vibration

Rybkiewicz Marta, Gutowski Paweł, Leus Mariusz

Journal of Theoretical and Applied Mechanics

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2020

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Vol. 58 nr 3

637--648

EN

The results of experimental tests and numerical simulation analyses of the possibility of partial reduction or entire elimination the stick-slip phenomenon in sliding motion through introduction of longitudinal tangential vibrations to the contact zone of a shifted body and the substrate are shown in the paper. The experimental tests were carried out on a specially designed stand. In the computational model, the dynamic equation of motion of the shifted body was used, and for the friction force description the LuGre model was adopted. A excellent consistency of the experimentally determined results with those calculated with the use of the developed model is obtained.

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Experimental investigations of elimination the stick-slip phenomenon in the presence of longitudinal tangential vibration

Leus Mariusz, Abrahamowicz Marta

Acta Mechanica et Automatica

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2019

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Vol. 13, no. 1

45--50

EN

The article presents a scheme and description of the test stand as well as selected experimental results of the influence of longitudinal tangential vibrations on the stick-slip phenomenon. The tests were carried out at a constant forced vibration frequency f = 2000 Hz, as a function of the amplitude of the vibration velocity va. The position of the sliding body and the drive force necessary to make the body slip and maintain this motion were measured. The measurements were made in two successive stages. In the first stage, when the substrate on which the sliding occurred was stationary. In the second one, the substrate is in a vibrating motion in the direction parallel to the slip. The conducted experimental analyses have shown that longitudinal tangential vibrations can contribute to the reduction or even complete elimination of the stick-slip phenomenon.