溶接部Pop-inの完全性評価法の提案
1987 年 5 巻 1 号 p. 131-137
詳細
1987 年 5 巻 1 号 p. 131-137
The occurrence of a short-arrested brittle crack (Pop-in) in the COD test for welds is usually regarded as a critical event because significance of Pop-in has not yet been made clear. It is, however, considered to be possible to accept the occurrence of Pop-in which doesn't make significant influence on the safety of actual structures. Based on this conception, authors have investigated the dynamic behaviours of Pop-in in order to establish the assessment method for its significance from the viewpoint of brittle fracture and the followings are considered to be the key points on predicting the behaviours of Pop-in occurred in an actual structures from the results of 3-point bending COD test.
1) Influence of applied load drop on the behaviours of Pop-in crack initiated in a small sized specimen as a 3-point bending one.
2) Influence of applied loading type on propagation and arrest of the small crack in Pop-in
About the latter, it was shown by numerical analyses performed in the previous report that 3-point bending loading was able to be severer than tensile one for the small crack propagation and arrest under some limited conditions. In this report, more detailed investigations are carried out experimentally and analytically in order to clarify the conditions under which the crack arrested as a Pop-in in a 3-point bending specimen is sure to be arrested even in an infinite body under tensile one.
About the former, the existence of Pop-in of which crack was arrested without the influence of applied load drop was already shown together with the verification by dynamic FEM code. The results are discussed again with some additional investigations because they have much importance to show the theoretical background of the assessment method proposed in this report.
Finally, assessment procedure for the significance of Pop-in is proposed from the results of these investigations.
