For analysis of dynamic characteristics of aero-engine pipe system

a fluid-structure coupling dynamic model using the user-defined three-dimensional (3D) pipe element was proposed based on the finite element method. The flexural fluid-structure coupling

axial and torsional dynamic behavior of the pipe was considered in the user-defined pipe element. The support was modeled using the nonlinear spring element. The user-defined pipe element was verified through comparisons with the measured data and analytical results. The natural frequencies and responses of a pipe system were calculated. The results show that the natural frequencies and the critical velocity decrease as the fluid pressure increases. And the effects of the nonlinear stiffness coefficient and the excitation amplitude on the pipe system under harmonic base excitation can be obtained.