A dynamic modeling approach for vibration analysis of hydraulic pipeline system with pipe fitting

Abstract

The hydraulic pipeline system with pipe fitting in the aircraft is subjected to both hydraulic pump fluid and engine-induced excitation. It is essential to investigate the vibration characteristics of pipeline systems with fittings. This paper proposed a dynamic modeling approach for vibration analysis of hydraulic pipeline system with fitting. Firstly, the relationship between the tightening torque and the pipe fitting stiffness is obtained. Then, the dynamic modeling of the hydraulic pipeline system with fitting is established via the finite element method. A pipeline with fitting is investigated as a numerical example to validate the present approach. The effects of the fitting friction coefficient, pipeline diameter and length on the modal frequencies of pipeline system are further analyzed. The results show that the natural frequencies of the pipeline increase non-linearly with the increasing of tightening torque and friction coefficient. When the tightening torque is greater than 8 N·m, the natural frequencies of the pipeline system tend to be stable. Moreover, the natural frequencies of the pipeline system increase significantly with the increasing of pipe fitting diameter. However, the increasing of pipeline length decreases the natural frequencies of the pipeline system. The results indicate that the current modeling approach can serve as an efficient guidance for the design of hydraulic pipeline systems.