Nonlinear and chaotic fluidelastic vibrations of a flexible pipe conveying fluid

Abstract

The dynamics of a cantilevered pipe conveying fluid have been investigated, both theoretically and experimentally, focusing on the nonlinear effects introduced by motion-limiting constraints. The experiments have indicated that, with increasing flow velocity, beyond the Hopf bifurcation (flutter) there are regions of period-doubling and chaos. Fractal dimension calculations of the recorded vibration signals showed that finite-dimensionalmodelling of the system is possible. Accordingly, a two-degree-of-freedom, four-dimensional analytical model was implemented, with the aim of investigating the existence of chaotic vibrations in the parameter space of this autonomous system. Chaotic regions were indeed found to exist, with the aid of modern numerical techniques, involving the construction of bifurcation diagrams and the determination of Lyapunov exponents and power spectra. The analytical results are in qualitative agreement with experimental observations.