FEATURES OF THE CALCULATION OF RUBBER-METAL VIBRATION ISOLATORS WITHHOLES IN THE RUBBER LAYERS

Abstract

The article describes the features of the static and dynamic behavior of rubber-metal vibration
isolators planned for use for vibration isolation of buildings in a modern building complex. The results of finite
element modeling of vibration isolators are presented in order to determine the static and dynamic
characteristics. Both single-layer vibration isolators and vibration isolators, including three rubber layers, are
considered. As the calculation results showed, the presence of perforations significantly affects the bearing
capacity of vibration isolators, significantly reducing it, however, the efficiency of such vibration isolators
significantly increases compared to completely monolithic vibration isolators without holes. This is due to a
number of reasons, one of which is the practical incompressibility of the rubber layers. In fact, rubber bodies
can be subjected to compression only due to the deformation of the side surface, thus, by developing the side
surface of the rubber layers, it is possible to achieve acceptable rigidity of the vibration isolator as a structural
element, which will reduce the rigidity of the vibration isolation system. The spatial arrangement of the holes is
also essential, since the placement of the holes close to the side surface of the rubber layer gives a significantly
smaller effect compared to the placement of the holes in the center. In the process of calculation in the
compressed rubber layers, the effect of the formation of pronounced zones of all-round compression was
observed. The presence of central holes leads to the destruction of such zones in most samples, which makes it
possible to reduce the first natural frequency of the vibration-isolated system to a greater extent, thereby
contributing to an increase in the effectiveness of vibration protection measures. The choice of hole
configuration is an optimization problem, where, on the one hand, it is necessary to ensure the bearing capacity
of vibration isolators acceptable from the point of view of vibration isolation practice for given dimensions of
the vibration isolator in plan, and, on the other hand, to minimize the rigidity of the system, thus increasing the
effectiveness of vibration protection events.