Research On The Comprehensive Reliability About Vibration Of Compressor Blade

The compressor blades are one of the key components of aircraft engines. Its reliability has adirectly effect on the operational status and lifetime of the entire engine. The failure mode caused byvibration is the main mode of the blade failure. An analysis model of compressor blade vibrationreliability is established by considering the effects of material properties, dimensional tolerances andexcited force factors. The model can offer reference and basis for modification of compressor blades.The main research content is as follows:(1) From the vibration mode of blades and the mechanism of forced vibration, a dynamic modelis presented based on the finite element method. Then, the modal analysis and response analysis ofblade vibration can be carried out. Based on the finite element dynamic model and considering thedispersibility of material properties, structure dimension and working condition, a analysis model andmethod with response surface method and Monte Carlo method is presented to study the probabilityanalysis of the natural frequency, maximum amplitude and maximum vibration stress.(2) Based on the stress-strength interference theory, the structure reliability analysis models ofanti-resonance are established respectively for single frequency excitation-single degree of freedom,single frequency excitation-multiple degrees of freedom and multiple frequency excitation-multipledegrees of freedom. Combined with the probability analysis method, the structure reliability analysismodel of anti-resonance is established for the compressor blade. The model is then verified byanalyzing the anti-resonance reliability for a blade.(3) The stiffness overload failure and strength overload failure are unified as the amplitudeoverload failure. Based on the stress-strength interference theory, the anti-amplitude reliability modelis presented. The model consists of single frequency excitation-single degree of freedom, singlefrequency excitation-multiple degrees of freedom and multiple frequency excitation-multiple degreesof freedom. Combined with the probability analysis method, the structure reliability analysis model ofanti-amplitude is established for the compressor blade. The model is then verified by analyzing theanti-amplitude reliability for a blade.(4) Based on the anti-resonance reliability model and the anti-amplitude model, and according tothe probability analysis theory for independent events, the comprehensive reliability model is deduced.Combined with the dynamic probability analysis method for compressor blade, the comprehensive reliability model of compressor blade vibration is established and the comprehensive reliabilityanalysis for a blade is carried out.(5) Based on the dynamic probability analysis method for compressor blade, the sensitivityanalysis for the effect of material properties, structure dimension and working condition on the naturalfrequency and amplitude is studied. It can be concluded that, for a constant cross-section straightblade, the natural frequency is most sensitive to the length dimension; the amplitude response has asensitivity descending order as follow, amplitude of excited force, material density, frequency ofexcited force, width of blade, material elastic modulus, length of blade.