Study On Vibration Fault Diagnosis Of An Aeroengine Accessory Gearbox

The accessory gearbox,as an important part of the aeroengine,has an important impact on the operating state of the engine.Therefore,it is very significant to carry out reliable vibration monitoring and vibration identification on the aeroengine accessory gearbox,which has great promotion and guidance for the improvement of the comprehensive level of the aeroengine in China.Based on the structural characteristics of the aeroengine gearbox,the paper analyzes the phenomenon that the amplitude of the aeroengine gearbox is too large,sums up the causes and characteristics of the various faults of the aeroengine gearbox,and designs a set of vibration signal extraction and analysis system based on the sensor and data acquisition system,aims at the time domain and frequency domain characteristics of different measuring points of a kind of aeroengine accessory,analyzes the fault point and fault type,puts forward the vibration reduction method and treatment measures according to the signal characteristics of each fault.And the validity of the study in this paper is verified by the data before and after the improvement.The main contents of this paper include the following aspects:(1)The main structural features of the various components in the aeroengine gearbox were studied.Then the problems such as the failure of the aeroengine gearbox in the long running time were summarized.The time domain and the frequency domain signal were used to determine the different fault or vibration anomaly state.(2)A set of vibration signal test system based on acceleration sensor was designed.And the principle and composition of the equipment were analyzed.A kind of aeroengine casing test bed was arranged in the laboratory.Then the vibration signals under different working conditions were collected.(3)Analyze its signal characteristics in the time domain according to the acceleration signal under different working conditions.Transform it into frequency domain by FFT(Fourier transform).Then identify its main frequency,point and type of fault.(4)In view of the non-stationary characteristics of the fault signals and the low signal to noise ratio(SNR)of the bevel gear in the casing,it is difficult to extract the fault characteristics.The dual tree complex wavelet transform is used to decompose the gear fault signals,and several component signals of different frequency bands are obtained.But the gear fault signals are often submerged by mechanical system,multiple interference sources and noise.It is difficult to extract useful fault feature information from the decomposed dual tree complex wavelet.Based on this,this paper proposes dual tree complex wavelet transform andminimum entropy deconvolution for fault diagnosis.By analyzing the experimental data of gear faults,it can be found that the method can accurately and effectively extract the weak fault feature information of gears,and provides a new method for practical engineering applications.Through the research of the subject,the structure and characteristics of the aeroengine accessory case are studied,the potential vibration fault shape is studied,and the operation state of the engine accessory is monitored by the perfect test system;Analysis and treatment of test results,diagnosis of vibration fault source,and then guide the commissioning process,improve the efficiency of engine test,to ensure the safety and stability of the operation of the accessory casing.