An isogeometric analysis approach to the stability of curved pipes conveying fluid

Stability analysis of curved pipes conveying fluid is of significant interest in many engineering aplications such as floating and moored system dynamics. The aim of this paper is to develop a new formulation based on the Isogeometric Analysis (IGA) for vibration and stability analyses of curved pipes conveying fluid. Both divergence and flutter instabilities of curved pipes are investigated. IGA uses B-Splines and Non-Uniform Rational B-Splines (NURBS) as basis functions. The main feature of IGA, as required in dynamic analysis of curved structures, is the ability of the NURBS functions to represent the exact geometry of the problem with fewer control points. This method provides several advantages including high-order continuity of the solution and better accuracy. The governing differential equations of the problem are obtained using the Hamiltonian's principle. The effects of rotary inertias of both pipe and fluid are also included in the mathematical formulation. It is shown that the present formulation can provide accurate results with small number of degrees of freedom. It is concluded that IGA can be used efficiently to predict the instability of curved pipes conveying fluid with the advantage of considering the exact curvature of the pipe.