船体ブロック溶接継手の拘束度ならびに収縮

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As for the degree of external constraint of welded joints in ship construction, various discussions have long been made in connection with the problems of shrinkage and residual stress, but the magnitude of the constraint has been left unknown. On the degree of external constraint we adopted in this paper the following definition ;Degree of external constraint=Average value of transverse stress along weld line necessary to produce average dislocation of 1mm along weld line. we obtained the magnitude quantitatively by applying two methods. The one is the method of measuring the change of root gap due to external load applied transversely to weld line before welding, and the other is the method of comparing average shrinkage along weld line due to welding with the shrinkage in free welded joint.The main results obtained in this paper are summarized as follows : (a) Degree of external constraint seems to be independent to thickness of plate and total weight of assembly.(b) Degree of external constraint is generally very small. About 60 per cent. of total butt joints measured showed the degree of external constraint less than 1kg/sq.mm/mm, and none of them showed more than 10kg/sq. mm/mm.(c) When the magnitude of degree of external constraint and welding conditions are definite, average locked-in stress increases a little with the increase of the thickness of plate.
社団法人日本船舶海洋工学会の論文