The Fatigue Life Calculation And Vibration Characteristic Analysis On Fan Blades Of Aircraft Engine

Fan blades are the key components of aircraft engine and play the role of transporting air to the bypass. In the flight state of high speed and high pressure, fan blades mainly bear the aerodynamic load, centrifugal load and temperature load. So, the possibility of fan blades caused by the fatigue failure is relatively high, once the fracture occur, they will directly endanger the normally running of the other components. In order to ensure the stable and reliable running of the engine during the flight, there is an urgent need to calculate fatigue life and analysis vibration characteristics of fan blades.This paper focus on the first stage fan blades of the engine and make the following researches:At the base of the establishment of a three-dimensional model of the fan blade, this paper make analysis on the finite element stress and strain of three flight states(climbing, cruising and the maximum speed) in the 900 hours load spectrum. And the results of stress and strain under aerodynamic load, centrifugal load and temperature load can be obtained. Through comparative analysis, the stress-strain state of the key positions, which are likely in fatigue failure, can be determined.Then, combining the practical 900 hours load spectrum with the results of the stress-strain at fatigue failure key positions, this paper uses nominal stress method and linear cumulative damage theory to calculate the fatigue life of fan blades’ body part. Based on this, this paper gets the flight time of the fan blades under the 900 hours load spectrum.Finally, for different pre-stress generated by different flight states, this paper make analysis on the vibration characteristics of fan blades and get the results of the vibration frequency, vibration mode of fan blade, and they offer some reference on preventing resonance of fan blades.Through the analysis on the fatigue life and vibration characteristics of fan blades under the 900 hours flight load spectrum, this paper provides some references for the fatigue life and vibration characteristics analysis of the whole engine.