船体強度の信頼性解析 : 第5報 : 疲労における損傷確率と許容応力

概要

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This paper presents a probabilistic method of prediction of occurrence of fatigue failure in ship's structural members under external load during ship's life. The considered kinds of load are irregular wave load during ship's life and quasi-constant load such as exciting force due to propeller. For occurrence of fatigue crack, a lognormal distribution function is adopted. Three stochastic variables are considered for fatigue crack in ship structure ; scatter of S-N curve, misalignment due to workmanship and distribution of applied stress level in a group of structural members such as in a row of bottom transverses in tanker. The obtained distributions of number of failure against age of ship show good agreement with the observation in actual ship obtained on occasion of hull survey. An approximate method on estimation of allowable hot spot stress including effect of welding bead is proposed.
社団法人日本船舶海洋工学会の論文