Numerical and Experimental Study on Trimaran Cross-Deck Structure's Fatigue Characteristics Based on the Spectral Fatigue Method

Spectral fatigue analysis is performed on the trimaran cross-deck structural detail. A global finite element (FE) model with local fine meshes at hot spot locations is built for the calculation of structural response. Three-dimensional linear potential flow theory and global FE analysis are used for wave load and stress transfer function calculations. Then, the hot spots' fatigue damage is calculated, considering various factors influencing spectral analysis, which includes cycle counting correction factors, wave scatter diagram, and the distribution coefficient of wave headings. A full-scale model fatigue test is used to investigate the fatigue behavior of the cross-deck structural detail. Using the fatigue test data, the S-N curve characteristic of the cross-deck structural detail is produced. Finally, the trimaran cross-deck structural detail's fatigue characteristics are summarized and the effects of the factors influencing spectral fatigue analysis are reported.