擾乱のある従動荷重を受ける薄肉シェルの非周期運動と不安定移行

概要

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The deformation and dynamic behavior mechanism of submerged thin shell structures are in principle of a non-conservative nature, because the working load is the follower type as hydrostatic pressure that works vertically to its deformed surface at all times. Also, disturbance forces of various types, existing in a marine environment, lead the structure to exhibit dynamic instabilities at a much earlier stage than that could be predicted by a static stability criterion. The dynamic behavior of a thin shell should be clarified to be the complicated phenomenon undergoing large deflections with small disturbances. This paper deals with a characteristic analysis on non-oscillatory behavior and unstable state of a thin shell subjected to follower forces with small disturbances. For that purpose, the governing equations for finite deformation and dynamic behavior of the thin shell are defined in a mono-clinically particle coordinates description. Then, the stability region chart of the disturbed equilibrium in an excitation field is calculated numerically. Moreover, the chaotic behaviors of a partial spherical shell are investigated by analyzing the power spectra, phase plane portraits and Poincare sections. By the results of these studies, it is clarified that the dynamic behaviors of a thin shell have two scenarios, as "Self-organization type" and Self-assembly type", getting to unstable state through non-periodic motion.