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The research of the torsional vibrations of the screw in terms of impulsive force impacts

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Category: Geotechnical and mining mechanical engineering, machine building

Last Updated on 04 February 2016

Published on 04 February 2016

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Authors:

R.M. Rohatynskyi, Dr. Sci. (Tech.), Prof., Ternopil Ivan Pul’uy National Technical University, Vice Rector for Scientific Affairs, Ternopil, Ukraine.

Iv.B. Hevko, Dr. Sci. (Tech.), Assoc. Prof., Ternopil Ivan Pul’uy National Technical University, Professor of the Department of Technology of Machine Building, Ternopil, Ukraine.

A.Ye. Diachun, Cand. Sci. (Tech.), Ternopil Ivan Pul’uy National Technical University, Senior Lecturer of the Department of Technology of Machine Building, Ternopil, Ukraine.

Abstract:

Purpose. To analyze the impulsive force impact on nonlinear torsional vibrations of a screw.

Methodology. The methodology is based on the Bubnova-Galorcina’s and Van-der-Pol’s methods combination, which allowed receiving the equations in a standard form in terms of the impulsive force impacts.

Findings. The mathematical model of torsional vibrations of the screw in terms of the impulsive force impact was presented. The abrupt nature of changes in the amplitude-frequency characteristics of torsional vibrations of the screw was studied. The resonance torsional vibrations of the screw were considered under the impulsive force impacts. The torsional vibrations of the screw were explored on condition that the moment of forces of resistance is proportional to the relative angular velocity of the screw motion and the moment of impulsive forces is approximated by a nonlinear function. It has been determined, that in such a case the influence of impulsive forces becomes apparent only while changing the screw vibration frequency. The amplitude frequency characteristics of the torsional vibrations of the screw in different geometric parameters were presented.

Originality. The influence of impulsive forces on resonance and on non-resonance torsional vibrations of the screw was explored. The proper amplitude frequency characteristics were established.

Practical value. It has been established that in the non-resonance terms the impulsive nature of the screw loading results in the abrupt change of the screw amplitude and the phase of vibrations when the impulsive forces are performed. Its influence rises as the time of the screw machines exploration passes and it can result in considerable amplitudes of torsional vibrations of the screw. It has been established that the screw resonance falls as the vibration frequency raises.

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