Buckling and Free Vibrations of Cylindrical Stiffened Composite Shells with Internal Liquid

Abstract

The free vibration and buckling of cylindrical composite shell with internal liquid is studied in this study. The shell composed of several composite layers and stiffeners which are rings and stringers. The first order shear theory was used for shell and stiffeners. Stiffeners were used in equations as discrete elements. The effects of axial force, internal pressure and shell rotation about cylinder axis, were calculated. The Reily-Ritz method was used for solving the problem. The potential and kinetic energy of shell and each stiffeners and kinetic energy of liquid are substituted in the functional of energy. The natural frequencies and the critical axial forces in each mode is obtained. The section shape of each stiffener is rectangle. The stringers can have variable height in their length (a parabolic shape for example) and its effect is studied for shell with and without liquid. Also Stiffened composite shell with different internal pressure, different axial forces and different rotation speeds is studied. The liquid is ideal and sloshing was neglected.