Spindle Critical Speed Analysis Of Aero-Engine Intershaft Bearing Test Bench

The aero-engine intershaft bearing is one of the key components of aircraft engine; its performance and reliability are important guarantee of aircraft performance and flight safety. It is difficult to predictive the lifetime of the aero engine key component. There are many reasons cause this problem, such as complexity structure, variety loading forms, poor working conditions and faintly early fault characteristics. The existing intershaft bearing test bench fails to consider the influence of the rotor system while underemphasizing the actual working condition of bearing. In this paper, an intershaft bearing test bench is designed based on the actual support of rotor system. It could simulate rotor system faults, bearing defect, oil cut-off etc, which helps to effectively response the working characteristics of the ’bearing-rotor’ system. The performance test bench supply aero engine failure data under typical working conditions and provide data basis for modeling the aero engine lifetime model. Therefore, it is meaningful to design and develop the aircraft engine rolling bearing performance test bench.In this paper, the spindle critical speed analysis of the intershaft bearing test bench are our mainly work as it is our research object. The structure parameters of intershaft bearing are firstly introduced to analysis the function of the bearing in practical work based on the actual support structure of aircraft engine. The experiments are obtained by discussing the typical failure mechanism of the intershaft bearing. Several methods of bearing lubrication are discussed and compared, after which the oil-air lubrication is finally determined for the test bench.In the second place, two coupling models in the intershaft bearing are established:spring coupling and contact coupling. Then the critical speeds of dual rotor system are analyzed using the ANSYS finite element method (FEM). In order to satisfy the requirement of flexible shaft system, several commonly used methods are compared with each other. According to the structure and space of the test bench, we decided to install the squirrel cage elastic support to reduce the critical speeds.In the third place, the design stiffness of squirrel cage elastic support is obtained by trial test, and then it is optimized by genetic algorithm (GA) to select the appropriate dimensions in case of insufficient stiffness and stress. The FE model is established to observe the stress performance, the simulation results tallies with the numerical calculation which means that the optimization design has obtained the good effect. The system critical speed decreased significantly after install the squirrel-cage that can meet the requirements of the flexible.Finally, the data acquisition system is designed. The development environment and overall structure of the test bench is introduced; on this condition, the data acquisition system consists of appropriate sensors and acquisition modules based on the test scheme is built. After which, we test the motor of the rotor system and the result shows the effectiveness of the acquisition system.