DYNAMICS OF AN INTERNAL VIBRATOR CONSIDERING THE TRANSLATIONAL AND ANGULAR MOTION OF THE WORKING BODY

Abstract

The article considers the dynamics of an internal vibrator for compacting concrete mixtures, taking into account the translational and angular motion of its working body. A calculation scheme of the internal vibrator is developed as a spatial oscillatory system in which the housing is assumed to be a rigid body with six degrees of freedom, while the action of the concrete mixture is considered through the added mass, elastic resistance, and inelastic resistance of the medium. The operation of an unbalanced vibration exciter with two unbalanced masses mounted on the shaft with corresponding eccentricities and a mutual phase angle is considered. Analytical dependencies are obtained for determining centrifugal forces, the resulting moment, the reduced mass of the system, the amplitude of translational oscillations of the center of mass, and the amplitude of angular oscillations of the housing. It is shown that the motion of the internal vibrator cannot be reduced only to horizontal oscillations, since the action of the unbalanced masses forms a rotating resultant force and a resulting moment, which cause complex spatial motion of the working body. It is established that the trajectory of an arbitrary point of the housing depends on its distance from the center of mass, the phase angle of the unbalanced masses, the moment of inertia, the shaft rotation frequency, and the added mass of the concrete mixture. It is proved that changing the phase angle of the unbalanced masses makes it possible to regulate the ratio between the translational and angular components of motion and, consequently, to influence the nature of vibration energy transmission into the concrete mixture. The obtained results can be used to substantiate the parameters of internal vibrators, select rational compaction modes, reduce the risk of mixture segregation, and further optimize the shape of the working body.