19 バットシフト継手における脆性き裂の伝播挙動 : 溶接継手脆性き裂伝播のシミュレーション(第3報)

概要

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Recently, plate thickness in mega container ships has reached the very heavy thickness range, exceeding 70mm, not common in shipbuilding. The most important requirement for ensuring structural reliability of such ships is the prevention of brittle fracture. In the previous papers, influence of applied stress, residual stress, toughness of welded joint, weld heat input and texture of base metal on brittle crack propagation was analyzed based on a fracture mechanics model developed by the authors. And influence of these factors was almost clarified. Based on the above results, brittle crack propagation behavior at Butt Shifted Welded Joint is analyzed using the improved numerical model. For mega container ships, brittle crack propagating in the hatch side coaming must not break into the upper deck side welded joint. Numerical simulations are carried out for various conditions, and it can be said that distance between weld of the hatch side coaming and that of the upper deck must be larger than 300mm for prevention of continuing brittle crack propagation.