Ultimate strength of hull structural plate with pitting corrosion damnification under combined loading

The ultimate strength of the hull structural plates is degraded due to pitting corrosion on the surface of the plates. This report aims at development of an assessing formula for ultimate strength of hull plate with pitting corrosion damage under combined loading. Firstly, the qualitative expression was deduced in theory. Secondly, the effects of a few factors (such as the shape, the distribution status and the depth of corrosion pits and the element type for finite element method analysis) on the ultimate strength with respect to the corroded volume loss were investigated. The influences of some parameters (such as the plate slenderness ratio, the plate aspect ratio, the linear load factors at the edges, the ratio between the transverse and longitudinal in-plane stresses, the ratio between the shear and longitudinal in-plane stresses and the maximum deflection of the initial geometric imperfection) on the ultimate strength reduction with respect to the corroded volume loss were also discussed. Lastly, the ultimate strength assessment formula based on the corroded volume loss was obtained from the data by non-linear FEM analyses for series of corroded plate models that were in accord with the actual hull plates with pitting corrosion damage.