VIBRATIONAL DISPLACEMENT OF NESTED STRUCTURES

The article investigates the mechanism of vibration movement of nested structures in closed volumes (pipes). Nested structures are structures whose constituent elements are located inside each other and are connected to each other by at least two opposite surfaces by dry friction forces. Such structures are often found in modern technology: transportation of long loads, fastening of pipelines with clamps, braking devices of lifting machines, etc. The peculiarities of the movement of nested structures in closed volumes (pipes) are considered in the case when a harmonic force acts on the internal element, which is directed perpendicular to its longitudinal axis. The conditions for the beginning of the movement of the internal element of the nested structure relative to the external (pipe) element are analyzed. Based on the method of mathematical modeling, a system of equations is proposed that describes the motion of the internal element of a nested structure relative to the external element under the action of forced vibrations. A new dependence is obtained for determining the friction moment between the supports of the internal element and the external cylinder under the action of a harmonic external force. The conducted experimental studies confirmed the possibility of vibrational movement of the internal element of the nested structure (cantilevered fixation of the rod in a cylindrical base) along the external element of the nested structure (cylinder) when applying an external force only to the internal element of the structure. In addition, experimental studies to identify the quantitative dependence of the magnitude of the vibration force that occurs when the internal element of the nested structure moves relative to the external element (cylinder) when vibration acts on the internal element, on the magnitude of the dry friction force between the internal and external elements allowed us to assess the influence of friction forces between elements by the magnitude of the vibration force that occurs when the internal element of the nested structure moves relative to the external one. The results obtained can be used in the creation of vibration systems for moving loads over distances that exceed the capabilities of modern vibration systems.