On natural oscillations of shells under irradiation (Q2754722)

A problem of natural vibrations of shell constructions used in nuclear power plants as carcasses of nuclear reactors and elements of ``dry'' biological protection is studied. The consequence of radiation effects is change in physical and mechanical properties and expanding of material. These effects are described by empirical formulae used in the paper. For derivation of equations of equilibrium and vibrations of shells, thicknesses of zones of change in Young modulus and radiation expansion are determined. As a result of influence of radiation, shells become inhomogeneous. It is suggested to reduce mechanical problems to those for a homogeneous shell. For that, methods of reducing two-layered plates and shells to single-layered ones with effective stiffnesses are used. Derivation of reduced equations in the framework of Kirchhoff-Love hypotheses is performed.