| Acoustic fatigue problem is often encountered in the flight task of an aircraft, the structural vibration caused by the engine jet noise and the aerodynamic noise brings about serious impact on airframe. Therefore the research on the fatigue life prediction in aircraft noise environment is of vital importance to ensure flight safety. In this paper, prediction of fatigue life of empennage based on finite element method, the acoustic simulation method and vibration fatigue theory in noise environment is carried out, on this basis, the factors influencing the fatigue life is studied. The core content of this paper is:A finite element analysis model is established in FEM software, then the modal analysis is carried out for empennage, finally get the natural frequency and vibration mode.The random vibration theory, the basic acoustic theory and the random acoustic theory are described, according to the modal analysis the dynamic analysis software is used to finish the vibro-acoustic coupling calculation. Modal participation factor, modal displacement and the power spectral density of the stress response on the coupled surface are acquired,provide necessary data for fatigue calculation.Based on the theory of vibration fatigue, identified the material S-N curve and the linear cumulative damage theory, using the Dirlik model in the frequency domain method for vibration fatigue to predict fatigue life of empennage. According to the characteristics of the acoustic load, several factors affecting the vibration fatigue are studied, especially studied the effects of load characteristics and damping ratio on the fatigue life In comparison with the results of several different conditions, the design of the anti-fatigue design is put forward. |
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