Non-axisymmetric buckling of stiffened supercavitating shells: static and dynamic analysis

Supercavitating vehicles undergo high longitudinal forces as a result of their high underwater velocity. The drag force compresses axially the body and may cause its buckling. In addition, the time-dependent properties of the cavity generate time-varying longitudinal loads, which are sources of parametric resonances. Static and dynamic buckling need to be considered as limiting factors for the operating speed of this class of vehicles. The stability of supercavitating underwater vehicles is here investigated through a finite element model that predicts the behavior of plain and stiffened shells and is used to obtain stability maps for varying vehicle’s velocity, as well as frequency and amplitude of the force oscillations. Periodically placed circumferential stiffeners are proposed as means to enhance the stability of the considered class of shells. The results indicate the effectiveness of the stiffening rings in extending the range of stable operating conditions, by increasing the critical static buckling loads, and more importantly by reducing the extension of the regions corresponding to dynamic instability.