Vibration mitigation of a pipe conveying fluid with a passive geometrically nonlinear absorber: a tuning optimal design

Abstract

The objective of the presented article is to investigate the nonlinear dynamics and vibration of a simply supported fluid conveying pipe coupled with a geometrically nonlinear absorber, as well as the occurrence of the targeted energy transfer phenomena in the system. In addition, given the sensitivity of passive nonlinear absorbers performance to uncertainties in design (e.g., damping coefficient) and aleatory parameters such as the initial excitation of the primary system, the optimal design of the absorber in presence of uncertainties is also examined in this paper. The absorber consists of two linear springs, a lightweight mass, and one linear damping configured in a particular formation and is coupled to the pipe in grounded and ungrounded configurations. It was indicated that the absorber can perform as a tuned mass damper (TMD), nonlinear energy sink (NES), or a modified NES based on the bifurcation parameter value, and finding the optimal type of the absorber is left to the optimization solver without any preceding knowledge of the physics of the system. It is illustrated that the stability of the pipe and the absorber effectiveness is reduced by increasing the inside flow velocity. Moreover, the efficiency of the absorber slightly dependents on the density of the inside fluid. The results show that the stochastic optimally designed absorber can nonlinearly resonate with the pipe over extensive frequency ranges which leads to a synchronized motion of the pipe and absorber. In this situation a significant irreversible energy pumping from the pipe to the absorber may occur that make the motion localizes to the absorber and reduce the amplitude of the pipe for a wide range of initial excitation and fluid velocity. Also, comparing the present work to other similar works yields a great result.