船体強度の信頼性解析(第3報) : 疲労モデルによる実船損傷統計解析

概要

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The statistics of hull failures of ships chassed with Nippon Kaiji Kyokai obtained from annual survey reports were analysed. From their databank, an approximate method to predict number of annual failures has been proposed for ships of several ages and types, mainly in case of corrosive damages in previous reports^<l,2)>. This report presents a more exact theory to predict the expected number of fatigue failures by using a fatigue model which is characterized by uncertainties of crack initiations and applied stress levels of Gamma distribution type as well as Paris' law of propagation. An expected theoretical distribution of crack length which would be detected at annual survey is discussed in a group of transverse hull members. Two examples by the present method are shown ; one is the case of fatigue cracks in bottom transverses of cargo ships due to vibration under load of approximately constant amplitude and the other is the case of fatigue cracks in transverse bulkheads of vehicle carriers under irregular wave loads.
社団法人日本船舶海洋工学会の論文