Experimental Studies on Influence of Natural Frequencies of Oscillations of Mechanical System on Angular Velocity of Pendulum on Rotating Shaft

Abstract

The article describes the results of an experimental study of the natural frequencies of oscillations of a mechanical system influence on the angular velocity of a pendulum mounted with the possibility of free rotation on a rotating shaft of an electric motor. It is established that at a constant moment of friction in the pendulum support, providing for a change in its mass moment of inertia, a mode of motion takes place in which the motor shaft rotates at a working angular velocity, and the angular velocity of the pendulum coincides with one of the natural frequencies of the oscillations of the mechanical system. The studies have also shown that there are ranges of the values of moments of inertia of the pendulum mass. For these moments of inertia, one can observe the establishment of a stable or unstable angular velocity of the pendulum, which is equal to one of the natural frequencies of the oscillations of the mechanical system.

Studying the excitation of resonance oscillations in a rotor on isotropic supports by a pendulum, a ball, a roller

“…The use of a known device for the new purpose becomes possible due to the fact that a rotary machine with the specified auto-balancers can execute various steady motion modes that correspond to: -auto-balancing or a synchronous rotation of loads together with a rotor [2]; -loads' jamming at the resonance rotational speed of the rotor (caused by the Sommerfeld effect) [3][4][5][6][7][8][9][10][11][12];…”

Studying the load jam modes within the framework of a flat model of the rotor with an auto­balancer

“…Detecting, in papers [2,16], the three, rather than one, possible frequencies of load jams is due to that these speeds were determined from exact formulae [2] or in higher approximation [16]. In studies [5,[7][8][9][10][11][12][13][14][15] the frequencies of load jams were determined approximately, by different approximation methods. Therefore, in the lowest approximations, two smaller frequencies of load jams coincided with the resonance speed of rotor rotation, and the highest -with the speed of rotor rotation.…”

“…Studying only such a jam mode under which loads are assembled together can be explained as follows. Computational or field experiments [2,5,8,14] can only detect stable steady motion modes of the system. This is how the jam modes were found under which the loads are assembled together.…”

“…Passive auto-balancers, ball (roller), pendulum, etc. [1][2][3][4][5][6][7][8][9][10][11][12][13], are used for balancing high-rotational rotors at operation. The same devices with a single or more loads can be used in vibration machines in order to excite vibrations [14][15][16][17][18].…”

“…-load jams (caused by the Sommerfeld effect) [5][6][7][8][9][10][11][12][13][14][15][16]; -parametric and other oscillations of loads [17,18].…”