Abstract:

The fluid-structure interaction vibration equation of a clamped-hinged pipeline under steady flow, liquid pressure and lateral stimulating force is derived based on the Hamilton principle. A new mode function suitable for the Galerkin method is used to solve the equation. Expressions of the first five orders of natural frequencies of the system are derived and validated. Next, deflection, bending moment, and transverse force exerted on the cross-section of the clamped-hinged pipeline are expressed with the first-order approximation of the mode function. The effects of liquid pressure, flow velocity, and stimulating frequency on the middle-point deflection, maximal bending moment throughout the clamped-hinged pipeline are discussed. The results show that the natural frequencies of the clamped-hinged pipeline are easy to calculate and with high accuracy using the method. Their values depend on the liquid pressure and flow velocity in the pipe. The phenomenon that resonance occurs when the natural frequency is close to the stimulating frequency also exists in fluid-structure interaction.

Key words:  clamped-hinged pipeline,  forced vibration ,  Galerkin method ,  natural frequency , fluid-structure interaction