No abstract

Functionally graded carbon nanotubes reinforced composite joined spherical-cylindrical-spherical thin-walled structure under the actions of axial and lateral distributed loads is considered. The static buckling of this structure is analyzed numerically. The Ritz method is used to derive the governing equations of the joined thin-walled structure buckling. Higher-order shear deformation theory is applied to describe the structure stress-strain state. The continuity conditions of the spherical-cylinder junction are derived. The displacements projections are chosen in the special form to satisfy these continuity conditions. The dependences of the buckling axial load on the CNTs distributions, CNTs volume fractions are analyzed numerically.

In this paper, dynamic instability of functionally graded carbon nanotubes (CNTs)-reinforced composite joined conical-cylindrical shell in supersonic flow is analyzed numerically. The higher-order shear deformation theory is applied to describe the stress–strain state of thin-walled structure. The assumed-mode method is used to derive the finite degrees-of-freedom dynamical system, which describes the structure motions. The structure motions are expanded by using the eigenmodes, which are obtained by the Rayleigh–Ritz method. The trial functions, which satisfy the continuity conditions at the cylindrical-cone junction, are used to obtain the eigenmodes. The properties of free vibrations of thin-walled structure are analyzed numerically. The dynamic instability of the joined conical-cylindrical shell in supersonic flow is analyzed using the characteristic exponents. As follows from the numerical study, the dynamic instability is arisen due to the Hopf bifurcation. The dependences of the supersonic flow critical pressure on the Mach number and the type of CNTs distribution are analyzed numerically.

An analytical solution of the non-stationary axisymmetric thermoelasticity problem of the pressurized thermal shock event for unbounded two-layered elastic cylinder has been proposed. The physical and mechanical properties of the cylinder materials were assumed to be temperature independent. The thermal boundary conditions correspond to the stepwise medium temperature drop at the inner cylinder surface. The outer cylinder surface has been considered as heat-insulated. Given solution has been applied to the development of analytical basis for the generation of nuclear power plant emergency operation limiting pressure-temperature curves. The comparison of the results of analytical approach with the results of finite-element analysis performed for real, temperature-dependent material properties has been carried out. The accuracy of the analytical results is shown to be sufficient for the application of the given analytical approach for the generation of the limiting curves.