Sensibility of shells to buckling disturbances in connection with parameters of critical loading spectrum

This paper considers the critical loading density in the vicinity of the first eigenvalue for the stability problems of both a structurally orthotropic longitudinally-compressed cylindrical shell and a spherical panel. For structurally orthotropic shells it is shown that the critical loading spectrum in the above-mentioned problems can begin with the condensation point only when definite relations between structurally orthotropic parameters take place. In connection with the presence of eigenvalue condensation points in the stability problems it becomes expedient to obtain approximate solutions for nonhomogeneous problems where the right-hand part of the equation describes disturbances. The linear systems of such a type show a strong selectivity as regards to initial deflections and to small external disturbances. The experimental results were treated. The process of the additional shell deflection development was analyzed. It was established by experiment that the shells with more rigid longitudinal stiffeners are less sensitive to initial imperfections and disturbances that explains a good agreement of critical loadings of these imperfect shells with Euler loadings. The number of equivalent forms for the shells with longitudinally stiffened, transversely stiffened and non-stiffened shells has the following order, respectively: 0(1), 0(10), 0(100).