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Acta Aeronautica et Astronautica Sinica

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Response spectrum method and its engineering application for random fatigue assessment

Guohao Sui1,   

  • Received:2024-10-31 Revised:2025-01-14 Online:2025-01-16 Published:2025-01-16

Abstract: To address efficient prediction of structural fatigue life under random excitation, the fatigue response spectrum method (FRSM), a high-efficiency algorithm, is established and organized. In the proposed method, a fatigue damage response spectrum (FDRS) is constructed to quantify the contribution of modal response to the total fatigue damage of the structure, and an explicit relationship is deduced to connect the fatigue life of the structure and structural characteristics, such as the natural frequency and the stress mode shape. Firstly, based on the theory of random vibration, the establishment of the FRSM is discussed in terms of the single moment method and the power spectral density (PSD) decomposition strategy of the fatigue life assessment in the frequency domain, and three calculation formats of the FRSM is provided. Then, the dimensionless FDRS is constructed, with the spatial characteristics of the structure (the stress mode and the modal participation coefficient) separated from the modal contribution to the total fatigue damage, and a feasible database establishment strategy is proposed. Finally, numerical examples are carried out based on the engineering application of the FRSM to vibration and acoustic fatigue problems, demonstrating its advancement in dealing with large-scale engineering problems. The result shows that the accuracy of the FRSM is consistent with that of classical methods such as the rainflow counting method, Dirlik method, and T-B method, and the efficiency can be improved by 2-3 orders of magnitude due to the avoidance of the PSD functions as well as the spectral moments.

Key words: High-cycle fatigue, Random vibration, Frequency domain method, Fatigue response spectrum method, Fatigue damage response spectrum

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