Emad T. The structural strength of fiberglass rotational shells with interlayer structural defects.

The thesis presents the solution of a number of important scientific and engineering tasks, containing validation of the models and calculation methods for strength and loading capacity of multilayer shells with interlayer structural defects. In the work there were developed the algorithms, programs, research methods and theoretical and experimental results, obtained on their basis, showed the presence of the new peculiarities in the solution of the set tasks. The new numerical solutions were proposed for geometrically linear and nonlinear problem of deformation of multilayer thin-walled elements with imperfect contact between layers under static loading. There were revealed the basic laws of change of the stress state and contact pressure in the area of local areas of non-adherences or delamination. It is shown that the stress state of multilayer elements, defined on the basis of discrete-structural theory of anisotropic shells, is qualitatively different, and strains have higher values than those obtained according to the structural and continuous theory. There was solved the task of unilateral contact between two conjugate layers of the shell, which may occur in the areas of non-adherences or delamination. The influence of the stiffness of the flanges on the stress-strain state of fiberglass pipes in the area of their junction was determined.