Maintained ship hull xcgirxcder ultimate strength reliability considering corrosion and fatigue

摘要

The purpose of this paper is to propose a methodology to assess the time-variant ultimate strength of ship hull girder under the degradations of corrosion and fatigue. The effects of fatigue cracks on the tensile and compressive residual ultimate strength of stiffened panels and unstiffened plates are analyzed by an FE method. Based on FE analysis results, some empirical formulae are provided for effective calculation of the compressive or tensile ultimate strength of cracked or intact unstiffened plates or stiffened panels. A non-linear corrosion model is used to determine the corrosion rate of plates, webs and flanges, respectively. The effects of inspection and repair are taken into account. A minimum net thickness rule is used to determine repair policies. A procedure is proposed to determine the maximum allowable corrosion thicknesses of different parts of the hull cross section. The procedure developed is illustrated by application to a tanker. For a given set of inspection and repair criteria, the ultimate bending moment and reliability as a function of ship age is predicted.