Fracture Mechanics-Based Fatigue Analyses of Aging Tankers

摘要

This paper focuses on the application of fracture mechanics in naval engineering. Fracture mechanics-based fatigue analysis has been conducted to predict the remaining life of cracks in aging tankers. In this analysis, three types of cracks including through-thickness crack, surface crack, and embedded crack are considered in the safety assessment of defected ships. Following the IACS Common Structure Rules (CSR), the stress range histogram at a specific location in a tanker can be determined with fitting Weibull distribution. In fracture mechanics-based fatigue analysis, Paris' law is employed to predict the crack growth and the remaining life under time-varying loads. Based on this theoretical background, ABS has developed a useful tool for fracture mechanics-based fatigue analysis of aging tankers. As a benchmark, an example damaged tanker is investigated for parametric study using this approach. The analysis results indicate that: 1) the simplified method can provide a reasonable prediction of the remaining life of cracks; 2) the corrosion is one of major reasons causing the fracture of defected tanker; 3) the initial length of crack, the ratio of depth to half length of a crack, the sectional modulus of hull girder are three important parameters affecting the remaining life; 4) the reduction of sectional modulus due to corrosion might lead to a significant decrease of the remaining life.