Summary
Many theoretical studies on post-critical non-planar motions of a cantilevered pipe conveying fluid have been studied for more than forty years. This system belongs to non-self-adjoint system and reveals self-excited oscillation. Therefore, depending on system parameters, a certain mode can reveal dynamical instabilities. It is well known that an end mass is a key parameter to generate non-planar motions and make the dynamics of systems very rich. In this presentation, we experimentally investigate the effects of the end mass on the post-critical non-planar motions. In particular, we focus on the complex non-planar motions which are caused by nonlinear interactions between dynamically unstable modes. The experiments were extensively conducted by changing the end mass and the flow velocity as control parameters. Three-dimensional non-contacting measurements system consists of two high speed video cameras and image processing system which enabled us to capture the non-planar motions caused by nonlinear interactions between unstable modes. Due to mode exchanges and double Hopf bifurcations, in wide range of parameters, we observed complex non-planar motions.
