Chaotic Vibration and Wear Characteristics of a Circular Loosely Supported Tube Subjected to a Fluid Flow

When a circular, loosely supported tube is subjected to fluid forces and vibrates with a large amplitude, the tube may continually collide with support structures and show wear. As a result, the tube is considered to reveal non-linearities such as chaotic behaviors, that depend on the support conditions and the fluid flow conditions. In the present study, a cantilever tube having a loose support at the free end is mathematically modeled based on the FEM. The nonlinear vibration analysis is performed by using the DAE (Differential Algebraic Equation) for the three kinds of excitation forces: (a) harmonic exciting forces, (b) nonlinear fluid forces, such as the Iwan & Blevins wake oscillator model etc., and (c) random fluid forces. The chaotic behavior and the wear damage are investigated for these fluid forces by taking the structural damping ratio and the gap size, for example, as parameters. Moreover, the influences of the chaotic phenomena on the deviation from the deterministically predicted wear volume at the tube support location are discussed.