PSI - Issue 48

Nikola Momčilović et al. / Procedia Structural Integrity 48 (2023) 12 – 18 N. Mom č ilovi ć et al / Structural Integrity Procedia 00 (2023) 000 – 000

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4. Results Results are calculated using PCA method for new and a corroded ship according to the procedure elaborated in Methodology section. Two cases of corrosion are analysed: one in which all structural members experience either pitting or uniform corrosion, and one in which double bottom and top side tank experience either pitting or uniform corrosion. In both cases, we assumed that the severity of the corrosion is relatively high. Bending moment-curvature diagrams are plotted in Fig. 3 and Fig. 4. Pitting equivalent thickness reduction is taken to be 16%. It is derived based on presumed values of DOP and DOC (DOP = 40%, DOC = 40%), considered as such in order to investigate the effect of the severe pitting incidence. Uniform corrosion is assumed to produce as-built thickness diminution by 25%, as this is the most used limit for the plate removal, according to the rules of the classification societies. In addition, an actual ultimate strength values are evaluated for new ship, pitting corrosion affected ship (for both cases and various combinations of DOP and DOC) and uniform corrosion affected ship (for both cases, and for 10% and 25% thickness diminution), see Fig. 5 and Fig. 6. Results are given for both sagging and hogging condition.

Fig. 3. Bending moment-curvature diagram for new and pitting corrosion affected ship.

Fig. 4. Bending moment-curvature diagram for new and uniform corrosion affected ship.