On the Dynamic Response of Flow-Induced Vibration of Nonlinear Structures

摘要

Fundamentals of Fluid-Structure Interaction (FSI) of a nonlinear structure placed in the wake of a prismatic bluff body is studied, experimentally. Elastically mounted prismatic structures placed in flow can undergo Flow-Induced Vibration (FIV). Flow forces acting on these structures consist of a main frequency, close to the natural frequency of the system, as well as its higher harmonic components. Mostly in FIV studies, the structural stiffness is provided through linear springs. The linearity of the structure limits occurrence of potential large amplitude oscillations at higher harmonics of the main frequency. In this study, an inherently nonlinear structure is implemented in FIV study of a prismatic structure. The results show that large amplitude, low frequency galloping type oscillation is accompanied by large contributions from the higher harmonics in the frequency content of the oscillations. Numerical simulation using Differential Quadrature Method was conducted to identify the optimum structural configurations for coupling between the higher harmonics and natural frequencies of the system.