Fatigue damage of structural joints accounting for nonlinear corrosion

Analysis of the influence of corrosion on the stress concentration factors of typical ship structural details is presented. While traditionally constant stress concentration factors are adopted, it is proposed here to use time-varying stress concentration factors, which result from the progress of corrosion in the structure. Three-dimensional finite-element models are adopted to obtain the detailed stress distribution at different times. Linear and nonlinear models of the effects of corrosion wastage on the plate thickness reduction are considered and stress concentration factors and fatigue damage are calculated as a function of time. It is concluded that the stress concentration factors have a nonlinear dependency with the time and this leads to a significant difference of the fatigue damage of structural components subjected to corrosion as compared with the traditional predictions.