Computer Simulation of Ultimate Strength Degradation of Ship Structures by Corrosion and Fatigue

Current ship structure strength assessment procedures used by ship classification societies are mostly experience-based. The degradation effects of damages including fatigue, corrosion, collision and grounding on ultimate strength are seldom taken into account. Cui and Wu [1] proposed a more rational ship structure strength assessment method, First-Principle-Based Strength Assessment System (FBP-SAS), which take all damages into account. The calculation results depend on the input data and the input data depend on the aim of assessment. For newly designed ships, statistical damage data and loading data can be used and the calculating results are reliability results. For inspecting the ship in service, the actual damage data based on measuring can be inputted and the calculating results are the ship structure’s actual residual ultimate strength. The purpose of this paper is to address how such a computer simulation system is developed and what problems need to be solved in order to realize practical application. Corrosion and fatigue are two main factors for strength degradation. Based on the recent research work carried out in authors group, the ultimate strength degradation of ship structures by corrosion and fatigue is studied in this paper and this result acts as a demonstration to the FPB-SAS method.