Effect of sound waves on fatigue of structures in frequency domain: a case study

In this paper, the fatigue of an aluminum ۲۰۲۴ T۳ plate caused by sound waves is investigated. Sources of sonic waves are motors and streamline. Since the major contribution of these waves is motor noise, in particular, this source has been highlighted. Due to the complexities of the behavior of the motor's output sonic waves in terms of time, the frequency method has been used to analyze the fatigue. For this purpose, first, the frequency spectrum of motor noise is identified from reliable references, and then sound pressure levels in the area near the jet noise are estimated and evaluated. In the next step, the stress at all the plate is obtained by FE modeling in ANSYS parametric design language (APDL) and applying the estimated sound pressure levels on the plate, and the points with maximum acoustic wave stress are identified. Because static stress is also imposed on the structure, in addition to the dynamic stress, the fatigue life is calculated as the sum of these stresses. Finally, the fatigue life of the plate is calculated using Miner's law.