Load Uncertainties Effects on the Fatigue Life Evaluation by the Common Structural Rules

This study evaluated the fatigue life of various hot spots located amidship a handy size oil tanker and a capesize bulk carrier. Specifically, the fatigue was evaluated accordingly to the harmonized common structural rules for bulk carriers and oil tankers recently released by the international association of classification societies. This study examined the stillwater and wave loads uncertainties effect on the fatigue life assessment. Hydro-structure coupling analyses were thus carried out enabling direct hydrodynamic load computations and accurate structural response assessment by finite element analyses. The comparison between direct and rules assessment allowed to identify the load uncertainties effect on the fatigue evaluation. As a result, the fatigue life evaluated by both approaches was significantly different, as expected with regard to the stillwater and dominant wave loads deviations. In addition, the study showed that the influence of the subjected loads was underestimated by the rules, leading to overestimated hot spot stress.