INTEGRATED PHYSICAL MODEL FOR CYLINDRICAL-SHELLS

An integrated physical model for closed thin-walled cylindrical shells under nonaxisymmetric pressure is proposed. The model, based on the interaction of the beam-plate bending, the membrane, and an equivalent ring foundation load-carrying mechanism, is capable of capturing the overall physical behavior of the shell under both lower (n = 0,1) and higher load (n > 1) harmonics. The model converges to the beam on elastic foundation model (n = 0), to the Bernoulli-Euler beam model (n = 1), and to the slice-beam on elastic foundation model (n > 1). It also accounts for the beam-plate bending behavior of the shell (even though only approximately for n > 1). The load-carrying mechanisms activated along the cylindrical shell are determined by the shell geometry and the load harmonic under consideration. For rather shallow and/or thin cylindrical shells and for the lower load harmonics (n = 2,3), membrane action is shown to represent the dominating load-carrying mechanism throughout the cylinder. The corresponding edge disturbances, absorbed by a rather weak ring foundation, have very long decay lengths. As the shell becomes thicker and/or taller, and especially for the higher load harmonics n = 6,7,8, the ring action progressively becomes active over a larger portion of the shell.