In recent years, the increasing size of container ships has led to more frequent occurrences of elastic vibrations such as whipping and springing, which superimpose on wave responses and reduce fatigue life. Therefore, the importance of fatigue assessment considering elastic vibration is increasing. In this study, fatigue assessment using several spectral methods was conducted on stress measurement data from two large container ships, and the effectiveness of each method was examined. The spectral methods employed included the narrow-band method, the Jiao method for bimodal processes, and the DK method for wide-band processes. Their results were compared with those from the rainflow counting method. The results showed that the narrow-band method and the Jiao method tended to evaluate fatigue damage on the conservative side, while the DK method tended to yield less conservative (riskier) evaluations. The narrow-band method did not accurately reflect actual phenomena, as it deviates from actual rainflow counting. On the other hand, the DK method was found to be a good model that captures the real physical behavior.
Sato et al. (Wed,) studied this question.