Block finite-element model of layer-by-layer analysis of three-layer stress–strain state in general irregular shells of rotation of double curvature

This study proposes a finite-element block approach to building a new, refined model for layer-by-layer analysis of the stress–strain state of generally irregular sandwich shells of revolution with double curvature. A core material model is developed for the first time for such shells, based on more precise statements compared to those of similar common models; it allows the avoidance of the discontinuity of generalized displacements on the surfaces of an interface with base layers and switching to simpler models depending on the problem statement. Using the proposed model, it is possible to create an allowance for the changes in the properties and parameters of the stress–strain state in all the three coordinates, to which the shell is assigned, and to obtain a solution within the specified statement for different shell shapes and boundary conditions of layers, including in the case of discontinuity.