Extended fatigue response spectrum method for vibration fatigue assessment of aerospace components under multi-support excitation

Classical uniform excitation models are insufficient to reflect the complex vibration environments of aerospace components. To address this limitation, this paper focuses on the fatigue life assessment of aerospace components subjected to complex excitations, proposes an efficient extended fatigue response spectrum method (E-FRSM), and investigates the effects of multi-support excitation on vibration fatigue. The E-FRSM, an efficient strategy, consists of a novel calculation format and a broadened fatigue damage response spectrum (FDRS), addressing the multi-support excitation and mode truncation error through quasi-static responses. The calculation format is constructed by employing the analogy to the Projection by Projection criterion twice, converting the total damage into a weighted summation of the modal and quasi-static damage contributions. Further, the damage response, which quantifies the contribution of modal and quasi-static responses, is condensed from the damage contribution and used to establish the broadened FDRS. A problem-independent training model is then developed using a radial basis function neural network. In the numerical examples, the reliability and efficiency of the E-FRSM are discussed, as well as the effect of multi‑support excitation on the accuracy of frequency-domain methods. The dramatic impact of multi‑support excitation on vibration fatigue is investigated, with the underlying mechanism revealed from the perspective of PSD.