Influence of Initial Deflection Imperfections on Critical Flutter Aerodynamic Pressures of Shallow Cylindrical Shells

To study the effect of initial deflection imperfection on the flutter critical dynamic pressure of a cylindrical shallow shell aeroelastic system, an initial deflection was introduced into the aeroelastic equation of cylindrical shallow shells. The differential quadrature method was used to discretize the system, and the flutter critical dynamic pressure of a linear system in supersonic axial flow was analysed using the eigenvalue method. The results showed that the initial deflection imperfection can significantly affect the flutter critical dynamic pressure. Herein, when the circumferential half wave number of the initial deflection equals 1, the critical dynamic pressure parameter of flutter is proportional to the initial deflection imperfection factor. When the circumferential half wave number is less than 4, with the increase in the initial deflection imperfection factor, the critical dynamic pressure of the system tends to decrease. For the small curvature condition, when the circumferential half wave number is greater than 4, the flutter critical dynamic pressure change caused by the increase in the initial deflection imperfection factor is not significant. For the large curvature condition, when the circumferential half wave number is greater than 4, the flutter critical dynamic pressure decreases significantly with the increase in the initial deflection imperfection factor. It was also found that the geometric form of the initial deflection affected the circumferential half wave number of the flutter coupling modes.