Fluid-structure Coupling Dynamic Model of Complex Spatial Fluid-conveying Pipe System and Its Verification

For the vibration analysis of complex aircraft pipe systems,a spatial fluid-structure coupling dynamic model is proposed.In this model the finite element method is adopted,the pipe is modeled using the beam element,and a node has 6 degrees of freedom,which includes the movements along and around the x,y and z directions.The fluid-structure coupling effect is considered,and the effect of fluid flow speed on the structure vibration is analyzed.The connections between the pipe and the base,and the connections between two pipes are considered in order to model the coupling vibration for a multi-pipe.The dynamic responses are obtained through direct numerical integration by using the Newmark-β method.The pipe vibrations due to base excitations,pressure fluctuation,and the fluid-structure coupling effect are also analyzed.The spatial pipe system of a practical hydraulic test stand is used to verify the new model.An experimental modal analysis is carried out by the hammering method.The spatial pipe model is modeled by the new method proposed in this paper,and the computation results are compared with the experimental results and those of the commercial finite software ANSYS Workbench.The results show the validity and the effectiveness of the new model.Finally,the effect of the fluid speed on the pipe system natural frequencies is simulated.