VIBRATIONS OF A SPHERICAL SHELL WITH A DISCRETELY ATTACHED VERTICAL ROD.

In aircraft structures, auxiliary equipment in the form of antennas, sensors, observation devices, etc. are often attached to its lifting elements. These devices change the dynamic behaviour of the entire structure and they can bring it into a resonant state, since some additional partial spectra from the attached dynamic subsystems are superimposed on the spectrum of natural frequencies of oscillations of the carrier system. This increases the likelihood of resonant modes of motion. Therefore, the study of vibrations of composite structures is relevant and it is of significant practical interest. In the proposed paper, we consider a structure consisting of a shallow spherical shell (lifting system) and an additionally attached vertically standing rod. In addition to purely practical applications, the problem is also of purely scientific interest, since the individual components of the structure experience different types of oscillatory movements. The shell performs transverse (radial) vibrations, and the rod -- longitudinal. To solve the problem, two mechanical design models based on different variants of the structure idealisation are proposed. The first one of them is reduced to a one-stage oscillatory model (linear oscillator), which takes into account only the inertial properties of the rod, and the second one, in addition, also its elastic properties. In both versions of the solution, the shell itself retains only elastic properties, neglecting its mass characteristics. The stiffness of the equivalent springs that simulate the local compliance of the shell at the rod attachment point is determined on the basis of the classical theory of shells. The last problem itself is extremely time consuming, therefore its corresponding solution is taken from previously published scientific sources. [ABSTRACT FROM AUTHOR]