The effects of orthotropicity, boundary conditions, and eccentricity on the vibrations of cylindrical shells are examined. Theoretically, a useful approximate frequency equation is developed for eccentrically stiffened shells under four different boundary conditions. Experimentally, vibration tests were performed on an isotropic, an axially stiffened, and a circumferentially stiffened shell with both clamped-clamped and clamped-free edges, under axial shaking. Results show that adding circumferential stiffeners greatly increases most frequencies, while adding axial stiffeners has little effect. Reducing edge constraints decreases the minimum frequencies and the value of n for these minimums, but has little effect on the high n modes. Outside axial stiffeners give higher frequencies than inside ones, whereas inside circumferential stiffeners give high frequencies than outside ones. The axial shaking also caused various subharmonic resonances of the cylinders. (Author)
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