Rotor-pendulum self-synchronization of parametrical vibration generators on an isotropic elastic foundation

Significant improvement of dynamic characteristics of vibration machines on the basis of the use of resonant oscillatory systems with two or more degrees of freedom is proposed. It is shown that reasonable complication of models due to the increase in the number of degrees of freedom, taking account of nonlinearity makes it possible to increase reciprocal enhancement of vibrations of partial subsystems and to open additional opportunities in the development of new equipment and technologies. The involvement of objects of an oscillatory system in collective interaction is achieved on the basis of using compound resonances which occur in coupled systems only. Combination parametric resonance caused by pair-wise interaction of free modes of oscillations represents this kind of resonance. The results of theoretical and experimental studies of self-synchronization of parametric rotor-pendulum vibration generators installed on a common elastic isotropic foundation are presented in the paper. The dynamic model of a vibration machine is represented by a set of peer interacting nonlinear oscillators (pendulums) under resonant excitement of which the Huygens's effect, that is, pendulum clock-type self-synchronization (pendulum self-synchronization) occurs. One or several oscillators perform the functions of the working body of the vibration machine. Other oscillators of this system act as the inertial element of a rotor-pendulum vibration generator. It is shown that in the case of combined action of at least two rotors-pendulum vibration generators unbalanced rotor-type self-synchronization (rotor self-synchronization) takes place. Thus, the device under examination at the same time combines rotor and pendulum self-synchronization. The results of numerical modeling in the form of amplitude-frequency characteristics and dependences of generation frequencies on the frequency of parametric excitation are presented. It is established that the amplitude of the working body oscillations, due to resonant interactions with the generator pendulums, underreacts to an increase in damping. The sum of natural frequencies of pendulums and the working body meets the condition of combination parametric resonance over the whole range of the instability region.