2024 , Volume 29, № 6, p.16-34

The paper presents the results of numerical investigation of vertical circular cylindrical shells with a defect on their outer or inner surface. The inner cavity of the thin-walled shell is completely or partially filled with an ideal compressible fluid. The dynamic behavior of the examined fluid solid system does not account for the effects of sloshing on the free surface of the fluid. The defect in the form of a ring with rectangular cross-section is modeled using its own set of physical and mechanical parameters. The behavior of the fluid medium and multilayered elastic structure subjected to a combined action of axial forces and hydrostatic pressure is described in the framework of both potential theory and classical shell theory. To determine the hydrodynamic pressure exerted by the fluid on the inner surface of the shell (defect), the Bernoulli equation is used. A mathematical formulation of the dynamic problem for the elastic body is developed using the variational principle of virtual displacements, and the system of equations for the fluid medium is constructed using the Bubnov-Galerkin method. For the numerical implementation of the algorithm, a semi-analytical version of the finite element method is employed. The stability of the system is estimated using the calculation and analysis of complex eigenvalues for the coupled system of equations. The validity of the obtained results is confirmed by comparison with known numerical solutions. The dependences of the lowest vibration frequencies and critical loads, provoking the loss of the system stability are analyzed in detail as functions of the defect parameters and the level of fluid in the shell under different types of boundary conditions.