Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Passive Control of Vortex-Induced Vibrations with a rotational Nonlinear Energy Sink
Submission Author:
Gabriel Placeres Araujo , SP
Co-Authors:
Gabriel Placeres Araujo, José Augusto Ignacio da Silva, Flavio D. Marques
Presenter: Gabriel Placeres Araujo
doi://10.26678/ABCM.COBEM2021.COB2021-0294
Abstract
Fluid flow can be responsible for vibration phenomena in structures, such as the Vortex-Induced Vibrations (VIV) and galloping in fluid-immersed bluff bodies. These fluid-structure interaction vibrations are a relevant topic in several engineering fields since they can lead to structural fatigue and catastrophic failures, and their control is of major concern. This work investigates the effects of a rotational Nonlinear Energy Sink (rotational NES) on the VIV passive control. The Nonlinear Energy Sink concept has been chosen since, when properly calibrated, they can robustly suppress vibration in a wide range of excitation frequencies. The model consists of an elastically mounted cylinder subjected to transversal fluid flow. The rotational NES is attached to the cylinder as a rigid arm horizontal pendulum that can freely oscillate, thereby absorbing the cylinder vibration and passively dissipating it. The VIV fluid modeling is based on a shedding wake model, which consists of an adapted van der Pol oscillator differential equation. The study is carried through simultaneous computational simulations of the system equations of motion. Here, the absorber’s parameters and its effects on the system response are carried out. In particular, it is expected to identify the rotational NES parameter values in which a constant angular speed steady-state oscillatory regime of the NES mass is observed. Besides, the rotational NES design is based on an optimization scheme to find its optimal vibration suppression features. The optimization scheme is performed through the Particle Swarm Optimization method (PSO) based on minimizing a cost function of the accumulated mechanical energy in the cylinder. The range of the complete vibration suppression and the subsequent limit cycles oscillations range is calculated. An energy transfer path during VIV is also analyzed. With the numerical simulations, the search for strongly modulated responses is performed for a broad range of the system and rotational NES parameters.
Keywords
VIV, NES, rotational NES, vortex induced vibrations, nonlinear energy-sink
