Ultimate strength assessment of ship hull plates under non-uniform and non-stationary corrosion

An advanced methodology has been developed to evaluate the ultimate strength of ship hull plates, accounting for the non-uniform and non-stationary behaviour of the corrosion process. A stochastic Gamma process combined with random field theory is used to model the spatiotemporal variability of corrosion degradation. A large sample of spatiotemporal random plates with different levels of corrosion is generated and analysed using a non-linear finite element method. Moreover, several sensitivity analyses are performed to examine the effects of factors such as corrosion degradation heterogeneity, correlation length, plate configuration, and potential disturbances in corrosion progression on the estimation of ultimate strength. The proposed methodology provides a more realistic assessment of the ultimate strength of ship plates than current state-of-the-art approaches. This approach accounts for the temporal non-stationarity and spatial correlation and heterogeneity of corrosion, as well as the influence of initial imperfections, possible disturbances in corrosion progression, and variations in plate configuration and boundary conditions on the ultimate strength evaluation. Additionally, the framework maintains the cumulative and monotonic nature of the corrosion process, ensuring physically consistent degradation over time, and provides a robust framework for time-dependent reliability analysis and maintenance planning of ship components, facilitating more informed decision-making throughout the service life