NONLINEAR VIBRATION ANALYSIS OF A COMPOSITE PIPE CONVEYING FLUID WITH FRICTION INTERFACE

To solve the fluid-structure interaction dynamics of a composite pipe conveying fluid with friction interface, an axisymmetric semi-analytical finite element method is developed to construct a nonlinear dynamic model. The dynamic equations of fiber-reinforced composite pipe and fluid medium are established based on the Reissner’s thin shell theory and the convected wave equation. A macro-slip friction model is adopted to describe the distribution of nonlinear frictional forces on the friction interface. The effects of fluid load and friction interface on the nonlinear vibration response of the pipe conveying fluid are examined. The results show that the hysteresis loop of points on the friction interface of the composite pipe conveying fluid with friction interface consists of two symmetric stick regions and two symmetric slip regions. The stick-slip transition of the friction interface causes the vibration response of the pipe conveying fluid to contain not only the excitation frequency but also a series of odd-order super-harmonics. As the friction coefficient of the interface increases, the axial vibration amplitude of the pipe conveying fluid at the fundamental frequency decreases while the normal vibration amplitude increases, and both the axial and normal vibration amplitudes of the pipe conveying fluid at the third-order super-harmonic first increase and then decrease. As the friction stiffness of the interface increases, the axial vibration amplitude of the pipe conveying fluid at the fundamental frequency and the third-order super-harmonic first decreases and then increases. The flow velocity mainly affects the normal vibration of the pipe conveying fluid with friction interface and has little impact on the axial vibration of the pipe.