PROBABILISTIC PREDICTION OF EXTREME STRESS AND FATIGUE DAMAGE FOR SHIPS IN SLAMMING CONDITIONS

Probabilistic models for the prediction of extreme stress and fatigue damage are developed for ships in slamming conditions. The wave-induced stress is considered as a stationary Gaussian process, while both the whipping and combined stress processes are considered as non-stationary. Two relationships between the wave-induced stress and whipping stress are investigated, namely, independence and with correlation. Numerical studies show that the model assuming independence overestimates the maximum combined stress when structural damping is large, but leads to underestimation when damping is small. The model accounting for correlation is thus generally recommended. For ships subjected to frequent and strong slamming impacts, the fatigue damage resulting from the combined stresses is found to be considerably larger than that resulting from the wave-induced stresses alone. The analytical models presented are readily applicable for practical design considerations.