Brittle fracture of hull structure causes serious structural, fatal and environmental damage once it happens. Therefore, ships are basically designed and constructed in such a way to prevent brittle cracks from occurring. Further, if by chance a brittle crack occurs, it is essentially and extremely important that a backup brittle crack arresting function is provided to arrest its propagation and to ensure structural reliability. As an evaluation method of arrest toughness, several test methods have been developed: Robertson test (1953), ESSO test (1955), Double tension test (1958) and others. At the moment temperature gradient type ESSO test is the most popular method for the determination of arrest toughness of material used because of its convenience. However, there is no code or standard ESSO test despite its long history. In this report, with the goal of developing a standard of ESSO test, effects of testing conditions - that is, thickness of tab plate, width of tab plate, distance between pins, temperature gradient and crack length - on the evaluated Kca values are investigated. Investigation is based on many large scale crack arrest tests with 16, 50 and 80mm thick low carbon steel plate conducted in four research groups in Japan. This research has been conducted by the research committee of Nippon Kaiji Kyokai (ClassNK) and the results have been summarized and incorporated in their "Guidelines on Brittle Crack Arrest Design".
Review of Wide Plate Test Method for Arrest Toughness Determination The two principal philosophies for the avoidance of brittle fracture are (i) to prevent the initiation of cracks and (ii) to select materials which will arrest brittle running cracks following crack initiation. The brittle crack arrest concept in addition to brittle crack initiation control makes it possible to achieve "double integrity" by preventing both brittle crack initiation and propagation.