EFFECT OF GEOMETRIC IMPERFECTIONS ON NONLINEAR STABILITY OF CYLINDRICAL SHELLS CONVEYING FLUID

Circular cylindrical shells conveying subsonic flow are addressed in this study; they lose stability by divergence when the flow speed reaches a critical value. The divergence is strongly subcritical, becoming supercritical for larger amplitudes. Therefore the shell, if perturbed from the initial configuration, undergoes severe deformations causin g failure much before the critical velocity predicted by the linear threshold. Both Donnell’s nonlinear theo ry retaining in-plane displacements and the nonlinear Sanders-Koiter theory are used for the shell. The f luid is modelled by potential flow theory. Geometric imperfections are introduced and fully studied. Non classical boundary conditions are used to exactly simulate the conditions of the experiments performe d. Comparison of numerical and experimental results is performed.