Investication Of Accelerated Life Testing Of Random Vibration

Acoustic fatigue damage phenomenon exists in the flight of the aircraft. Acoustic loading loads on the surface of the structure with random strength. The structures used in the fatigue test, testing methods and testing equipments should be simulated as the actual boundary conditions and load conditions. When the distribution of the band coupled with the dynamics of the structure, the distribution of the stress response on the surface will obviously appear. It could lead to the acoustic fatigue damage of aircraft structure. The regulations for the Administration of the Airworthiness of Civil Aircraft rules the acoustic fatigue strength. But because of the limitation of the long experiment cycle, we don’t do the practical fatigue life test under the actual load, in order to shorten the fatigue life test and simplify the loading process. Determine whether the structure meets the design requirements according to the test life.This paper intends to establish a set of methods of the aircraft typical structure on acoustic accelerated testing analysis that is suitable for the engineering use. On the basis of the acoustic response analysis, use the frequency domain analysis method to estimate acoustic fatigue life of the typical structure of the aircraft. Through the research of the S-N curve testing of7075-T6aluminum alloy material under random loads, Estimate the linear range of the fatigue life curve of the structure, verify the fatigue curve exist linear response in105-106interval. Get the slope of the curve2.14. Use the narrow-band approximation method and Dirlik method to predict fatigue life, Get the slope of the two curves,4.83and4.82. Through the finite element simulation analysis, using the above two methods to predict fatigue life of the structure under the power spectral density of different levels, then compare the two groups of data. Finally, discuss the acoustic fatigue accelerated testing methods of the civil aircraft typical structure and formulate the corresponding technical specification, obtain the results of fatigue accelerated testing analysis and research by verification tests, compare the FEM data with the test data establish preliminary test techniques and analysis methods of the acoustic fatigue damage.