Nonlinear energy sinks with nonlinear control strategies in fluid-structure simulations framework for passive and active FIV control of sprung cylinders

Abstract

This article investigates the vortex-induced vibration reduction of a circular cylinder as well as the flow-induced vibration suppression of an elastically-mounted square cylinder freely oscillating in the transverse and streamwise directions with the aid of passive and active nonlinear energy sinks that benefit from nonlinear intelligent control strategies. To this end, firstly, the optimized parameters of the passive nonlinear energy sink including mass, damping and stiffness ratios are tuned. Next, the passive control method is turned into an active nonlinear energy sink by employing an adaptive fuzzy sliding-mode controller. Owing to the computational complexity of the employed controller, the obtained results are used to design a fuzzy controller based on the adaptive neuro-fuzzy inference system. The results of collaborative fluid-structure interaction (FSI) simulations indicate that the nonlinear energy sink equipped with the fuzzy controller based on the active fuzzy sliding-mode controller successfully decreases the maximum transverse and streamwise displacements of circular cylinder by, respectively, 95.56% and 98.53% at Re = 85, 96.26% and 97.64% at Re = 90, 95.80% and 97.64% at Re = 95, and 93.82% and 97.05% at Re = 100. Also, for the square cylinder, the maximum transverse and streamwise displacements decrease by 95.06% and 90.9% at Re =87.5, 99.94% and 86.66% at Re = 90, 95.80% and 96.33% at Re = 220, and 72.41% and 99.21% at Re = 250 compared to the uncontrolled case. All these cases demonstrate the superiority of active nonlinear energy sink over its passive counterpart.