Study on Fracture Strength Assessment of Structural Components

概要

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Japan Welding Engineering Society (JWES) standard WES2805 has been widely used to evaluate fracture safety of structures. A work to better revise the standard is now underway so that it can take into account the recent advances in fracture mechanics treatment. On the other hand, the FAD approach of U.K. CEGB R6 (and of the revised version of BSI PD6493) 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. In this study, the validity and accuracy of the fracture assessment of JWES and FAD are investigated for the situation where brittle fracture occurs from a defect at a structural stress concentration. These two approaches are applied to four types of structural model test which were carried out in Japan. Furthermore, wide plate tests with crack emanating from a hole are carried out and the fracture strength is evaluated by means of JWES and FAD approaches. The assessment results are almost the same between those two approaches. However, it is said that the JWES method is more practical, because this method is based on the relation between CTOD and local strain. In some practical cases, only the local strain near the region is available where defect is to be discovered. The FAD approach requires information of the global stress condition (plastic collapse load) for fracture evalution.
財団法人日本海事協会の論文