Analysis Of Low-frequency And Large-amplitude Waves In Rectangular Liquid-elastic Shell Coupled System

As so many engineering structures are working or running in hydro-medium, various liquid-solid coupled question for discussion are emerged constantly. In addition, the action of the nonlinear factors in the liquid-solid coupled system are beyond ignoring,. it is of great value to study the nonlinear vibration of the liquid-solid coupled system.The paper is on the phenomenon of low-frequency and large-amplitude gravity waves of coupled liquid and elastic shell system. which were inspired with the exciting force .According to the appearance of the gravity waves and the data of the waves and the parameter of the system mode, the reasons and the features of the gravity waves as well as the influence of the exciting force to the gravity waves are researched by means of numerical and analytic methods.1.Based on the experimental phenomenon that the low-frequency and large-amplitude gravity waves may be generated by the high-frequency external excitation in the liquid-elastic shell coupled system, a set of nonlinear equations for the multi-degree of freedom system is constructed applying the correlative theory of hydrokinetics and elasticity.2.By means of the Runge-Kutta method ,the numerical solution to the nonlinear equations is carried out ,the time history curves and frequency spectrum curves are obtained, the relations between the changed amplitude of the gravity waves and altered frequency and amplitude of the exterior exciting force are found which could explain the precondition of the emergence of the waves well. the conclusions are constituent with what drawn from the experiment.3.Depending on the conclusions of the numerical solutions, a set of nonlinear differential equations for the two-degree of freedom system is solved. according to the analysis of the approximate stationary solution of the first order, we could find that the analytic results are good agreement with the numerical conclusions..4. The modes of rectangular shell and the liquid-elastic shell coupled system and the water were analysed with FEM method, the results which drawn from the analysis with FEM method are well constituent to the result of the experimentation.By means of numerical and analytic methods and FEM method the gravity waves generated by the high-frequency external excitation in the liquid-elastic shell coupled system were ulteriorly researched, the reasoning of the emergence of the waves were well explained.