破壊強度評価法に関する最近の研究動向
2クライテリアアプローチを中心として
1993 年 31 巻 2 号 p. 83-98
詳細
1993 年 31 巻 2 号 p. 83-98
In order to evaluate safety of the structures, establishment of the method of fracture strength assessment with high accuracy is needed. In England, two widely applied methods for fracture assessment have been developed, namely, BSI PD6493 and CEGB R6 approach. The BSI procedure is now under revision, so that it can take into account the benefit of CEGB R6 approach and the recent advancement of fracture mechanics. The CEGB R6 approach has lately attracted considerable attention. The notable feature of it is that the approach interpolates between two criteria, that is, LEFM failure and plastic collapse.
On the other hand, the fracture assessment method based on the CTOD design curve approach has been developed in Japan, that is, WES standard 2805. This standard adopted an elastic-plastic fracture parameter CTOD as a judgement criterion, because brittle fracture may occur from defects at structural stress concentration where plastic size generally seems to be greater than defect size.
This paper describes the main points of the above three fracture assessment methods. Although these three methods alike are based on the elastic-plastic fracture mechanics, it seems that the methods of BSI and R6 are quite different from WES approach in appearance. The purpose of this paper, therefore, is to clarify the relation of these methods. Recent numerical and experimental studies on fracture strength assessment are also presented.
