Research On Signal Transmission Path Of Aero Engine Bearing Fault

The interval of refurbishment of aero engine is largely decided by the running condition of aero engine bears supporting the rotor system.The accident of engine off in flight will be caused once the bearing failure occurs.Therefore,it is necessary to establish the real-time state monitoring system for the main engine bearing.In this paper,the fault signal transmission mechanism of bearings is studied,the distribution of vibration measurement points is optimized and the fault signal transmission paths of bearings are analyzed taking the main bearing of a specific aero engine as research object based on the finite element analysis software.The main contents and conclusions are as follows:(1)The fault signal transmission mechanism of bearings is studied based on the explicit dynamic simulation.The finite element model of rolling bearing test rig is established and the explicit dynamic simulation is done to analyze the vibration response of preposition bearing fault test rig during operation.And then,the transmission mechanism of rolling bearing fault signal in the experimental platform is summarized.(2)The distribution of vibration measurement points is optimized to realize the purpose of accurate monitoring the vibration signals of the engine bearings.The time domain characteristics of impact force caused by the raceway damage of the engine bearing are determined by analyzing dynamic simulation results.The impact response analysis of aero engine model with simplifying domain load is carried out and the vibration response data of measuring points which can provide the condition of placing vibration sensor located in the external casing is extracted.Comparing the response of these measuring points,the more sensitive to the bearing fault are selected and the distribution of vibration sensors placed in the aero engine case is optimized.(3)The fault signal transmission paths of aero engine bearings are analyzed.The inherent characteristic of the finite element model of the engine is analyzed and the natural frequency of being easily inspired is also determined.The transmission path is analyzed by taking the excitable natural frequency as the center and the bearing characteristic frequency on both sides as the solution area.The main vibration transmission path of bearing fault signal is determined by solving the vibration energy transfer coefficient of multiple paths of bearing fault points to outer casing measurement points.It is significant to master the main transmission path of bearing fault signal for guiding and recommending the selection of demodulation bandwidth for bearing fault diagnosis.