コンテナ船の実船計測に基づくホイッピングの統計モデルの構築

抄録

　In order to properly evaluate the fatigue strength of hull structures, it is necessary to consider the effects of whipping on fatigue crack propagation in more detail. However, so far, the relationship between the frequency of whipping and sea conditions has not been well studied, making it difficult to predict the frequency of whipping under different sea conditions and to evaluate its effects. In particular, it is difficult to reproduce whipping wave equivalent to those that actually occur from the probabilistic models reported to date on the occurrence of whipping. Therefore, it is difficult to investigate the effects of variable wave with whipping on fatigue using fatigue tests or fatigue crack propagation analysis.

　In this study, longitudinal bending stresses in the center of the hull of an 8600 TEU container ship were measured in headwaters, and the waveforms that could be considered as whipping were extracted. The probability of whipping occurring and the magnitude of whipping were defined, and a statistical model was constructed to determine the probability of whipping occurrence and its magnitude based on the sea conditions using the MCMC method. This enables the generation of wave including whipping under arbitrary sea conditions at the time of sailing in head-waves, and enables fatigue tests and various studies to be conducted using the wave that more closely resembles actual phenomena.