Flow-induced Vibration And Instability Analysis Of Functionally Graded Pipes

Fluid-conveying pipe structure is a logistic transfer method wildly used in modern industry and agriculture and daily life, and acts as an important role in the production and living of the people. The fluid-structure interaction problem is considered as a typical dynamic problem, for its simple physical model, concise mathematical description, and easy design and manufacture. However, the vibration and instability problem is one key factor affecting the performance of the fluid-conveying pipes. In order to improve the vibration characteristics, functionally graded materials (FGMs) are employed in the fluid-conveying pipe structures. Functionally graded materials is a new non-uniform composite materials whose composing and structural constitution element is continuous gradient from one side to another, leading to the continuous gradient of the material properties and function. This continuous gradient of material component volume fraction will results in the continuous gradient of structural performance, thus eliminating the mutation of the material properties, and avoiding the stress concentration.In this paper, the Euler-Bernoulli beam theory and Timoshenko beam theory will be used in the analysis of FGM fluid-conveying pipe. The influence of gradient index on the vibration and instability properties will be mainly discussed with different boundary conditions. Furthermore, the main contents of this paper can be divided into the following two parts:(1) An FGM pipe without any fluid conveying within it will be discussed, and be modeled as a hollow round-section beam. Under conditions of hinged at both ends and clamped at both ends, the influence of the gradient index on the bending, buckling, vibration and dynamic instability properties of the FGM pipe is discussed with hinged-hinged and fixed-fixed boundary conditions.(2) Assume that the fluid is incompressible ideal fluid. The influence of the gradient index on the vibration and instability of the FGM pipe is discussed with hinged-hinged and fixed-fixed boundary conditions.In the theoretical analysis and mathematical derivation, the Hamilton principle is used in deriving the governing equations and the corresponding boundary conditions. The differential quadrature method (DQM) is used to discretize the governing equations, which are then solved numerically. Furthermore, the homogeneous multi-layered model is used in calculating the stiffness coefficient and the inertia coefficient of the FGM pipe.