Flow-induced vibration attenuation of a viscoelastic pipe conveying fluid under sinusoidal flow using a nonlinear absorber
Qi-Xiang Huang, Te Lin, Mehran Safarpour
Abstract
In this paper, the dynamics of a viscoelastic pipe conveying fluid attached to a nonlinear energy sink (NES) subjected to a sinusoidal flow is studied, aiming at performance improvement of such fluid-interaction systems. The NES has an essentially nonlinear cubic stiffness and a nonlinear cubic damping. Complexification-averaging and fourth-order Runge-Kutta methods are applied to solve the equations of the motion. The conditions of flow-induced instability, the weak modulated response (WMR), and the strongly modulated response (SMR) are investigated. The influence of the internal fluid velocity, the external flow velocity, the viscoelastic damping coefficient, the NES stiffness, location, and damping on the system efficiency is elucidated. The Poincare-Bendixson theorem implies that there are no closed trajectories in the phase diagram of the system response. The results revealed that the occurrence probability of the SMR and jump phenomenon in the system response increases by ascending the internal fluid velocity. Besides, it is shown that at high external fluid velocities or low viscoelastic damping coefficients, the detached resonance curve (DRC) emerges in the frequency-response curves, and simultaneously the unstable regions expand. Furthermore, by approaching the NES installation location to the pipe supports, the occurrence probability of the SMR, DRC, and WMR descends, the divergence regions are enlarged and the transient response lasts longer.