Effective Three-Dimensional Shell Model for Layer-by-Layer Study of Stress–Strain State of Three-Layer Irregular Cylindrical Shells

An approach to obtaining approximations and constructing a three-dimensional shell model of a filler layer based on the use of effective approximating functions used in two-dimensional models of bearing layers in the general case of irregular three-layer cylindrical shells, including those weakened by rectangular cutouts, is presented. The effective approximating functions of the displacements of the bearing layers are based on the initial approximation of deformations. As an example, studies of the influence of the angular dimension of rectangular cutouts on the stress and strain state of sandwich cylindrical shells are carried out for the first time.