Accelerated Vibration Durability Test Analysis of Aviation Equipment Based on Different Fatigue Damage Spectrum Calculation Methods

Aiming to simulate the actual level flight vibration environment of the aviation equipment during the whole life-cycle, the calculation methods of fatigue damage spectrum based on stationary broad-band hypothesis, stationary narrow-band hypothesis and rain flow counting method are studied separately, and the synthetic acceleration spectrum in frequency domain is carried out and the process of determining vibration endurance test conditions is proposed. The field measured data of three types of flight vibration environment of typical aviation equipment is selected to calculate different types of synthetic acceleration spectrum respectively, and the basic characteristics are compared and analyzed. Thirdly, the finite element model of a certain type of airborne equipment installation frame is established to verify the influence of vibration endurance acceleration test spectrum solved by different fatigue damage spectrum calculation methods on its life. The result shows that the RMS value of the acceleration spectrum calculated by the rain flow counting method is higher than others. Based on the RMS value of rain flow counting method, the relative error between Rayleigh distribution and its RMS is 0.011 while Dirlik and its RMS is 0.0347, and Wirsching's is 0.0373. Finally, the damage results show that the fatigue damage calculated by Dirlik distribution acceleration method is closest to that by rain flow counting acceleration method, and the vibration endurance test condition based on Dirlik distribution is closest to the flight vibration environment experienced in the whole life of aviation equipment.