Neuber’s theory of elastic and inelastic stress concentration factors are applied to the pit corrosion of plates. The finite element method is then employed to model the problem numerically and to calculate the stress concentration factors for semioblate spheroidal pits. Furthermore, corrosion development is a process with many random factors such as the geometry and the growth rate. A realistic reflection of corrosion effects on structural failure is to consider it within the framework of reliability analysis. By knowing the analytical formula of stress concentration factor, reliability analyses are conducted to calculate the reliability safety index of the panel based on a strain-based limit state. The structural failure can then be directly related to the reliability safety index. The reliability procedure is demonstrated in an example of a highly deformed bottom shell panel during ship grounding. Partial safety factors of two random variables which describe pit corrosion geometry and the effective nominal strain level are also calculated. Recommendations for using partial safety factors are provided.
Issue Section:
Materials Technology
Keywords:
corrosion,
elasticity,
finite element analysis,
plates (structures),
reliability,
safety,
ships
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