Development of Brittle Crack Arrest Toughness Kca Test Method: Brittle Crack Arrest Design for Large Container Ships -2

摘要

Brittle fracture of hull structure causes serious structural, fatal andrnenvironmental damage once it happens. Therefore, ships are basicallyrndesigned and constructed in such a way to prevent brittle cracks fromrnoccurring. Further, if by chance a brittle crack occurs, it is essentiallyrnand extremely important that a backup brittle crack arresting function isrnprovided to arrest its propagation and to ensure structural reliability.rnAs an evaluation method of arrest toughness, several test methods havernbeen developed: Robertson test (1953), ESSO test (1955), Doublerntension test (1958) and others. At the moment temperature gradientrntype ESSO test is the most popular method for the determination ofrnarrest toughness of material used because of its convenience. However,rnthere is no code or standard ESSO test despite its long history. In thisrnreport, with the goal of developing a standard of ESSO test, effects ofrntesting conditions - that is, thickness of tab plate, width of tab plate,rndistance between pins, temperature gradient and crack length - on thernevaluated Kca values are investigated. Investigation is based on manyrnlarge scale crack arrest tests with 16, 50 and 80mm thick low carbonrnsteel plate conducted in four research groups in Japan.rnThis research has been conducted by the research committee of NipponrnKaiji Kyokai (ClassNK) and the results have been summarized andrnincorporated in their “Guidelines on Brittle Crack Arrest Design”.