欠陥を有する裏当金付溶接継手の疲労強度に対する破壊力学的検討

抄録

Since a weld defect may occur at the root of butt welded joint with backing strip, its fatigue strength is lower than conventional butt welded joint. In order to investigate the effect of weld defect on the fatigue strength, it was carried out a series of fatigue tests of welded joint with backing strip containing artificial defect and natural defect. The data of fatigue tests were compared with the calculated fatigue life using fracture mechanics.
As a result, it is confirmed that fracture mechanics is effective method of assessing the fatigue life in the welded joint with backing strip, because the calculated fatigue life is shown to be consistent with the experimental results. The change of propagated crack shape were made clear for the welded joint with backing strip. The S-N diagram of welded joint with backing strip have been proposed and the S-N diagram also offer that this joint is possible to allow up to 1 mm defect.