Nonlinear Ship Loads and Ship Fatigue Reliability

"Stochastic methods are described here to predict the effects of nonlinear ship loads on fatigue accumulation in random seas. These are found to be capable of predicting the net fatigue damage over many ship response cycles, at a fraction of the cost of direct time-domain analysis. It is also shown how these nonlinear ship load models can be used within a full reliability analysis of ship components. This uses first-order reliability methods to estimate not only the net effect of all uncertainty sources, but also the relative contribution of each (e.g., load vs. material property variability). In our ship load application, nonlinear effects are found to increase the relative impact of load (and wave) modelling and its uncertainty."--V.