The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Shuji Aihara - One of the best experts on this subject based on the ideXlab platform.
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an experimental study on k ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2020Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness Kca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the Kca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate Kca of 6000 N/mm3/2, nevertheless the Kca value of 8000 N/mm3/2 was needed in the test plate simulating hatch side coaming. The different Kca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.
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Effects of residual stress by EB welds on assessment of Crack arrest temperature (CAT)
Welding in the World, 2020Co-Authors: Chiyomi Iwatake, Kazuyuki Matsumoto, Shuji Aihara, Masahito Kaneko, Tsutomu Fukui, Tomoya KawabataAbstract:The concept of Brittle Crack arrest has recently become an internationally focused issue for container ships. The International Association of Classification Society (IACS) also prescribed the unified requirement (UR) for Brittle Crack arrest design, and Brittle Crack arrest design has been internationally authorized. As one of the methods to evaluate Brittle Crack arrestability, the Crack arrest temperature (CAT) concept, by isothermal Crack arrest test, has been proposed since the 1990s. The concept has been applied mainly for tank design. However, no standard has been specified to describe the detailed evaluation procedure. This means that only limited organizations can evaluate CAT and it is considered to be a problem when arrest evaluation is mandated as an international standard. In the background of such circumstances, Japanese research groups including the Japan Welding Engineering Society (JWES) and Nippon Kaiji Kyokai (ClassNK) started the standardization for CAT test in 2016. In the research programme, various aspects of control factors have been investigated based on the test results from many experiments and numerical calculations. The CAT test shall include the emBrittled zone to initiate a Brittle Crack. Either electron beam (EB) line remelting or a local temperature gradient (LTG) can be applied to the emBrittled zone. Even if we focus on EB welding only, welding defects in the emBrittled zone can be an influencing factor. In this report, we investigate the effects of residual stress by EB welding on the Crack driving force, which is quantified as the K value using a 3D finite element method (FEM). As a result, we confirmed the existence of the residual stress which cannot be ignored that is formed on the surface of the EB-welded portion; however, the influence of that on the K value is considered to be small if the CAT test conditions can sufficiently secure the arrest Crack length. This result shows that the driving force at the arrested point in the CAT test can be simply evaluated by the LEFM formula without consideration of the residual stress of the EB weld for emBrittlement.
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historical review of research on Brittle Crack propagation arresting technology for large welded steel structures developed in japan with the application of kca parameters
Marine Structures, 2020Co-Authors: Tomoya Kawabata, Kazuki Shibanuma, Tetsuya Tagawa, Takehiro Inoue, Tsutomu Fukui, Yasuhito Takashima, Shuji AiharaAbstract:Abstract In response to the concern of increased risk of Brittle fracture accompanying the recent enlargement of container ships, experimental research is being conducted to investigate Brittle Crack propagation arrest properties in Japan. The objective is to obtain the required toughness of the material to arrest Brittle Crack propagation in a 100-mm thick plate, which is considered to be the maximum thickness used in such applications. The use of Kca as a method for determining arrest toughness is a main difference with respect to methodologies employed in Europe and the United States. In this review, we compare the approaches for determining Brittle Crack propagation arrest properties that are used in Japan with those used in Europe and the United States. Moreover, we review recent research trends, particularly with respect to the background and development of Kca parameters. With regard to the industrial application techniques concerning arrestability of Brittle Crack propagation in steel plates, studies in the ship and storage tank research fields date back to after World War II, while some attention is also seen for nuclear power and line pipes. These research procedures were initially established in Europe and the United States, but was first adopted by Japan. However, soon after, Japan and the time when the research fell downward due to progress of steel manufacturing technology and defect management technology. Since then, research has actively resumed, and original contributions are being realised. The background of this work in Japan, and the creation of the Kca concept will be explained herein. Further, the background of research on Brittle Crack propagation arrest properties in very large container ships, determination philosophy for deriving demand values, and ultrawide Brittle Crack propagation tests in the study of 75-mm thick material and their results are described. In both of the scenarios considered, i.e. one in which Cracks are generated from the top of the hatch side coaming and arrested on the upper deck, and the other wherein Brittle Cracks occur at the upper deck end and are arrested in the hatch side coaming, the required Kca was found to be 6000 N/mm3/2.
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An experimental study on K_ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2019Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness K _ca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the K _ca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate K _ca of 6000 N/mm^3/2, nevertheless the K _ca value of 8000 N/mm^3/2 was needed in the test plate simulating hatch side coaming. The different K _ca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.
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a simplified method for evaluation of Brittle Crack arrest toughness of steels in scaled down bending tests
Engineering Fracture Mechanics, 2019Co-Authors: Yuki Nishizono, Shuji Aihara, Tomoya Kawabata, Teppei OkawaAbstract:Abstract The wide-plate Crack arrest test under tensile load for characterizing the Brittle Crack arrest toughness of high strength shipbuilding steel requires high economical cost and long lead-time, so there is still a substantial industry need for the simplified evaluation using the scaled-down specimen. The alternative method using a single edge-notched bending specimen, which assumes the complete load redistribution during the Crack propagation, was recently proposed. However, it was confirmed that the results obtained using this method exhibited a low correlation with the arrest toughness obtained using the wide-plate tests. A new scaled-down version of the Crack arrest test under bending load and a series of simplified evaluation based on the dynamic elasto-plastic FEA were introduced to characterize the Crack arrest performance of the two types of steel plates in this investigation. The specimen is a single edge-notched tapered plate subjected to a three-point bending load in an isothermal environment. The geometry was selected so that the dynamic Crack driving force calculated using FEA decreases monotonically with the Crack propagation. For adopting a simplistic analytical approach considering the dynamic effect, the dynamic FEA simulation assumed the constant Crack velocity and flat Crack front and output the opening stress distributed ahead of the growing Crack. The experimentally obtained values of the arrested Crack length and the analytically obtained transition curves of the dynamic SIF were employed to characterize the Crack arrest performance of the two steels. The results obtained using the simplified method developed in this investigation exhibited a high correlation with the arrest toughness obtained using the wide-plate Crack arrest test.
Tomoya Kawabata - One of the best experts on this subject based on the ideXlab platform.
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an experimental study on k ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2020Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness Kca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the Kca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate Kca of 6000 N/mm3/2, nevertheless the Kca value of 8000 N/mm3/2 was needed in the test plate simulating hatch side coaming. The different Kca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.
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Effects of residual stress by EB welds on assessment of Crack arrest temperature (CAT)
Welding in the World, 2020Co-Authors: Chiyomi Iwatake, Kazuyuki Matsumoto, Shuji Aihara, Masahito Kaneko, Tsutomu Fukui, Tomoya KawabataAbstract:The concept of Brittle Crack arrest has recently become an internationally focused issue for container ships. The International Association of Classification Society (IACS) also prescribed the unified requirement (UR) for Brittle Crack arrest design, and Brittle Crack arrest design has been internationally authorized. As one of the methods to evaluate Brittle Crack arrestability, the Crack arrest temperature (CAT) concept, by isothermal Crack arrest test, has been proposed since the 1990s. The concept has been applied mainly for tank design. However, no standard has been specified to describe the detailed evaluation procedure. This means that only limited organizations can evaluate CAT and it is considered to be a problem when arrest evaluation is mandated as an international standard. In the background of such circumstances, Japanese research groups including the Japan Welding Engineering Society (JWES) and Nippon Kaiji Kyokai (ClassNK) started the standardization for CAT test in 2016. In the research programme, various aspects of control factors have been investigated based on the test results from many experiments and numerical calculations. The CAT test shall include the emBrittled zone to initiate a Brittle Crack. Either electron beam (EB) line remelting or a local temperature gradient (LTG) can be applied to the emBrittled zone. Even if we focus on EB welding only, welding defects in the emBrittled zone can be an influencing factor. In this report, we investigate the effects of residual stress by EB welding on the Crack driving force, which is quantified as the K value using a 3D finite element method (FEM). As a result, we confirmed the existence of the residual stress which cannot be ignored that is formed on the surface of the EB-welded portion; however, the influence of that on the K value is considered to be small if the CAT test conditions can sufficiently secure the arrest Crack length. This result shows that the driving force at the arrested point in the CAT test can be simply evaluated by the LEFM formula without consideration of the residual stress of the EB weld for emBrittlement.
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historical review of research on Brittle Crack propagation arresting technology for large welded steel structures developed in japan with the application of kca parameters
Marine Structures, 2020Co-Authors: Tomoya Kawabata, Kazuki Shibanuma, Tetsuya Tagawa, Takehiro Inoue, Tsutomu Fukui, Yasuhito Takashima, Shuji AiharaAbstract:Abstract In response to the concern of increased risk of Brittle fracture accompanying the recent enlargement of container ships, experimental research is being conducted to investigate Brittle Crack propagation arrest properties in Japan. The objective is to obtain the required toughness of the material to arrest Brittle Crack propagation in a 100-mm thick plate, which is considered to be the maximum thickness used in such applications. The use of Kca as a method for determining arrest toughness is a main difference with respect to methodologies employed in Europe and the United States. In this review, we compare the approaches for determining Brittle Crack propagation arrest properties that are used in Japan with those used in Europe and the United States. Moreover, we review recent research trends, particularly with respect to the background and development of Kca parameters. With regard to the industrial application techniques concerning arrestability of Brittle Crack propagation in steel plates, studies in the ship and storage tank research fields date back to after World War II, while some attention is also seen for nuclear power and line pipes. These research procedures were initially established in Europe and the United States, but was first adopted by Japan. However, soon after, Japan and the time when the research fell downward due to progress of steel manufacturing technology and defect management technology. Since then, research has actively resumed, and original contributions are being realised. The background of this work in Japan, and the creation of the Kca concept will be explained herein. Further, the background of research on Brittle Crack propagation arrest properties in very large container ships, determination philosophy for deriving demand values, and ultrawide Brittle Crack propagation tests in the study of 75-mm thick material and their results are described. In both of the scenarios considered, i.e. one in which Cracks are generated from the top of the hatch side coaming and arrested on the upper deck, and the other wherein Brittle Cracks occur at the upper deck end and are arrested in the hatch side coaming, the required Kca was found to be 6000 N/mm3/2.
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Brittle Crack arrest behavior and its interpretation in an isothermal Crack arrest test
Engineering Fracture Mechanics, 2020Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Shota Nanno, Kazuyuki Matsumoto, Tomoya KawabataAbstract:Abstract Brittle Crack arrest behavior in steel plates and its evaluation test technique were investigated exhaustively from the1950s to the 1980s. Nevertheless, similar discussions have been revived recently by issues related to Brittle Crack arrest design applicable to mega-container ships. For example, the issue of whether the Brittle Crack arrest properties of steel plates evaluated under isothermal conditions and gradient temperature conditions are equivalent or not, which was also an issue in earlier studies, has been discussed again since 2010. This discussion is the results of ongoing debate in the International Association of Classification Societies (IACS) concerning provisions for heavy-gauge Brittle Crack arrest (BCA) steel plates for mega-container ships. In the present work, the Crack arrest temperature, abbreviated as CAT, was evaluated by an isothermal Crack arrest test in a specimen with a Crack runway emBrittled by electron beam weld (EBW) re-melting. The dependence of CAT and the arrested Crack length on the Crack runway length were discussed. Crack arrest toughness Kca was also evaluated based on test that resulted in Crack arrest in the isothermal condition, and the results were compared with those of the gradient temperature Crack arrest test. An unexpected variation was observed in the Kca values in the isothermal test, but it was suggested that this represents the R-curve behavior of a running Brittle Crack. The R-curve concept can qualitatively explain the Crack arrest behaviors with different Crack runway lengths. The analogical difference in Crack arrest behaviors between the isothermal condition and gradient temperature condition were also discussed.
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An experimental study on K_ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2019Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness K _ca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the K _ca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate K _ca of 6000 N/mm^3/2, nevertheless the K _ca value of 8000 N/mm^3/2 was needed in the test plate simulating hatch side coaming. The different K _ca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.
Tsunehisa Handa - One of the best experts on this subject based on the ideXlab platform.
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an experimental study on k ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2020Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness Kca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the Kca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate Kca of 6000 N/mm3/2, nevertheless the Kca value of 8000 N/mm3/2 was needed in the test plate simulating hatch side coaming. The different Kca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.
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Brittle Crack arrest behavior and its interpretation in an isothermal Crack arrest test
Engineering Fracture Mechanics, 2020Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Shota Nanno, Kazuyuki Matsumoto, Tomoya KawabataAbstract:Abstract Brittle Crack arrest behavior in steel plates and its evaluation test technique were investigated exhaustively from the1950s to the 1980s. Nevertheless, similar discussions have been revived recently by issues related to Brittle Crack arrest design applicable to mega-container ships. For example, the issue of whether the Brittle Crack arrest properties of steel plates evaluated under isothermal conditions and gradient temperature conditions are equivalent or not, which was also an issue in earlier studies, has been discussed again since 2010. This discussion is the results of ongoing debate in the International Association of Classification Societies (IACS) concerning provisions for heavy-gauge Brittle Crack arrest (BCA) steel plates for mega-container ships. In the present work, the Crack arrest temperature, abbreviated as CAT, was evaluated by an isothermal Crack arrest test in a specimen with a Crack runway emBrittled by electron beam weld (EBW) re-melting. The dependence of CAT and the arrested Crack length on the Crack runway length were discussed. Crack arrest toughness Kca was also evaluated based on test that resulted in Crack arrest in the isothermal condition, and the results were compared with those of the gradient temperature Crack arrest test. An unexpected variation was observed in the Kca values in the isothermal test, but it was suggested that this represents the R-curve behavior of a running Brittle Crack. The R-curve concept can qualitatively explain the Crack arrest behaviors with different Crack runway lengths. The analogical difference in Crack arrest behaviors between the isothermal condition and gradient temperature condition were also discussed.
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An experimental study on K_ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2019Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness K _ca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the K _ca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate K _ca of 6000 N/mm^3/2, nevertheless the K _ca value of 8000 N/mm^3/2 was needed in the test plate simulating hatch side coaming. The different K _ca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.
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Effect of toughness distribution in the thickness direction on long Brittle Crack propagation/arrest behaviour of heavy gauge shipbuilding steel
Welding International, 2018Co-Authors: Tsunehisa Handa, Kimihiro Nishimura, Tetsuya Tagawa, Hisakazu Tajika, Satoshi Igi, S TsuyamaAbstract:ABSTRACTBrittle Crack arrestability of the heavy gauge steel plates for shipbuilding is now an important issue for the recent mega container ships. In the present work, the Brittle Crack arrestability of the steel plate with different toughness distributions in thickness is examined in ultra-wide duplex ESSO tests. It is examined whether a running long Brittle Crack arrests or not in flat temperature condition in ultra-wide duplex ESSO test that are harder mechanical conditions similar to an actual ship hull condition. Test temperatures are selected at which arrest toughness, Kca, evaluated by temperature gradient type standard ESSO test is the same for two test plates. The steel plate with higher toughness in mid-thickness (t/2) than that in quarter thickness (t/4) could arrest a running long Brittle Crack although the plate with lower toughness in mid-thickness than that in quarter thickness could not arrest it. The typical split-nail shape appeared at the arrested Crack front in the plate with higher t...
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Brittle Crack propagation/arrest behavior in T-joint structure of heavy gauge steel plate
Welding in the World, 2015Co-Authors: Tsunehisa Handa, Kenji Oi, Tetsuya Tagawa, Fumiyoshi MinamiAbstract:Brittle Crack arrestability is extremely important in welded joints of heavy gauge steel plates used in large container ships. Recently, much attention has been focused on potential Crack propagation along welds fabricated by large heat input welding. This paper examines the application of a T-joint to the strength deck structure of container ships to enhance Crack arrestability. The unwelded face and the Crack arrest toughness, K _ca, for Crack arrest were varied. In the case of a T-joint with an unwelded face, the ESSO test of the T-joint components showed that a Brittle Crack arrested at the T-joint embedding the unwelded face. In the case of a full penetration T-joint, the Brittle Crack was arrested if the steel plate used for the flange had a high K _ca value in the range from 4900 to 7300 N/mm^3/2. FEM analysis of the stress intensity factor K indicated that Brittle Crack propagation was arrested under the condition that the K value at the running Crack tip was less than the K _ca of the material. In the T-joint, it was noted that the K value around the deepest point of the Crack decreased and was finally less than the K _ca of the flange plate when the Brittle Crack penetrated into the flange plate. This phenomenon shows the advantage of using a T-joint for Brittle Crack arrest in the flange plates of strength deck structures. In order to verify the long Brittle Crack arrestability of the T-joint structure, ultra-large-scale tests were carried out under the recommended conditions obtained from a dynamic FEM analysis. The test results showed that long Brittle Cracks could arrest at the aforementioned T-joint structures.
Takehiro Inoue - One of the best experts on this subject based on the ideXlab platform.
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an experimental study on k ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2020Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness Kca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the Kca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate Kca of 6000 N/mm3/2, nevertheless the Kca value of 8000 N/mm3/2 was needed in the test plate simulating hatch side coaming. The different Kca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.
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historical review of research on Brittle Crack propagation arresting technology for large welded steel structures developed in japan with the application of kca parameters
Marine Structures, 2020Co-Authors: Tomoya Kawabata, Kazuki Shibanuma, Tetsuya Tagawa, Takehiro Inoue, Tsutomu Fukui, Yasuhito Takashima, Shuji AiharaAbstract:Abstract In response to the concern of increased risk of Brittle fracture accompanying the recent enlargement of container ships, experimental research is being conducted to investigate Brittle Crack propagation arrest properties in Japan. The objective is to obtain the required toughness of the material to arrest Brittle Crack propagation in a 100-mm thick plate, which is considered to be the maximum thickness used in such applications. The use of Kca as a method for determining arrest toughness is a main difference with respect to methodologies employed in Europe and the United States. In this review, we compare the approaches for determining Brittle Crack propagation arrest properties that are used in Japan with those used in Europe and the United States. Moreover, we review recent research trends, particularly with respect to the background and development of Kca parameters. With regard to the industrial application techniques concerning arrestability of Brittle Crack propagation in steel plates, studies in the ship and storage tank research fields date back to after World War II, while some attention is also seen for nuclear power and line pipes. These research procedures were initially established in Europe and the United States, but was first adopted by Japan. However, soon after, Japan and the time when the research fell downward due to progress of steel manufacturing technology and defect management technology. Since then, research has actively resumed, and original contributions are being realised. The background of this work in Japan, and the creation of the Kca concept will be explained herein. Further, the background of research on Brittle Crack propagation arrest properties in very large container ships, determination philosophy for deriving demand values, and ultrawide Brittle Crack propagation tests in the study of 75-mm thick material and their results are described. In both of the scenarios considered, i.e. one in which Cracks are generated from the top of the hatch side coaming and arrested on the upper deck, and the other wherein Brittle Cracks occur at the upper deck end and are arrested in the hatch side coaming, the required Kca was found to be 6000 N/mm3/2.
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An experimental study on K_ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2019Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness K _ca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the K _ca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate K _ca of 6000 N/mm^3/2, nevertheless the K _ca value of 8000 N/mm^3/2 was needed in the test plate simulating hatch side coaming. The different K _ca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.
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Inverse Fracture in DWTT and Brittle Crack Behavior in Large-Scale Brittle Crack Arrest Test
Journal of Pressure Vessel Technology, 2018Co-Authors: Tetsuya Tagawa, Takehiro Inoue, Takahiro Sakimoto, Toshihiko Amano, Takashi Hiraide, Satoshi Igi, Taishi Fujishiro, Takuya Hara, Shuji AiharaAbstract:The drop weight tear test (DWTT) has been widely used to evaluate the resistance of linepipe steels against Brittle fracture propagation. Although there is an ambiguity in the evaluation of DWTT results if inverse fracture appears on the fracture surfaces, the cause of inverse fracture is not yet fully understood. In the present work, DWTTs were performed with X65, X70, and X80 steel linepipes. In addition to the conventional DWTT specimen with a pressed notch (PN), PN specimens with a back slot (BS) and specimens with a chevron notch (CN) or static preCrack (SPC) were also examined, and the fracture appearances in different strengths and different initial notch types were compared. Although the frequency of inverse fracture in these DWTTs was different with each material and each specimen type, there was no material or specimen type that was entirely free from inverse fracture. The purpose of the DWTT is to evaluate the Brittle Crack arrestability of the material in a pressurized linepipe. Therefore, the DWTT results should be examined with a running Brittle Crack arrest (BCA) test. A large-scale BCA test with temperature gradient was also performed with the X65 mother plate, and the shear area fraction measured in the DWTT fracture surface was compared with the local shear lip thickness fraction in the BCA test. Based on the results, the count of inverse fracture in the DWTT was discussed in comparison with the long BCA behavior in the BCA test.
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effect of specimen size applied stress and temperature gradient on Brittle Crack arrest toughness test
International Journal of Fracture, 2017Co-Authors: Yusuke Shimada, Takehiro Inoue, Tomoya Kawabata, Shuji AiharaAbstract:Temperature gradient type ESSO test is one of the most popular test methods for evaluating the Brittle Crack arrest toughness, \(K_{ca}\). However, test conditions which are specimen shape, tab plate shape, applied stress and temperature gradient affect \(K_{ca}\). This document reports effects of specimen geometries that are specimen width, tab plate length, tab plate thickness and tab plate width on \(K_{ca}\) evaluation. In addition, effects of applied stress and temperature gradient have also been investigated. Temperature gradient type ESSO tests are conducted at three different steel mills in Japan. Then, test conditions were varied and test results were compared. In the result, influence range of effect specimen width, tab plate thickness, applied stress and temperature gradient were demonstrated. The applicable range of specimen geometry, applied stress and temperature gradient were clarified and implemented to the Brittle Crack arrest standard.
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Brittle Crack Arrestability and Inverse Fracture in DWTT
Journal of Pressure Vessel Technology, 2020Co-Authors: Takahiro Sakimoto, Tetsuya Tagawa, Toshihiko Amano, Takashi Hiraide, Satoshi Igi, Yasuhiro ShinoharaAbstract:Abstract The drop-weight tear test (DWTT) has been widely used to evaluate the resistance of linepipe steels against Brittle Crack propagation, and the shear area fraction SA% in the DWTT has been adopted in the requirement for the linepipe steels. However, recent studies have pointed out the issue of ambiguity in evaluation of the DWTT when a ductile Crack initiates from the notch and then transits to a Brittle Crack during ductile Crack propagation. This fracture behavior is termed “inverse fracture.” According to the API Recommended Practice 5L3 (API RP 5L3), a test is considered invalid when a DWTT specimen shows inverse fracture. In this case, it is difficult to examine the acceptance criterion (85% shear area transition temperature) for linepipe steels. Because the purpose of the DWTT is to evaluate the Brittle Crack arrestability of the steels in a pressurized linepipe, the DWTT results should be examined with a propagating Brittle Crack arrest test. A large-scale Brittle Crack arrest test called the West Jefferson test is generally conducted to reproduce the Crack propagation and arrest behavior in actual linepipes. However, it is somewhat difficult to control the lower test temperature and to initiate Brittle Crack in recent high-toughness steels in this burst test. Although the test stress conditions of the uniaxial tension in the plate tension Brittle Crack arrest test and the biaxial tension in a pressurized pipe are different, the plate tension Brittle Crack arrest test has the advantages of accurate control of the test temperature, test stress, and Brittle Crack initiation in comparison with the actual pipe burst test. Therefore, in this study, the Brittle Crack arrestability of linepipe steel which showed inverse fracture in the DWTT was investigated by conducting plate tension Brittle Crack arrest tests under an isothermal condition (Crack arrest temperature test (CAT test)), which simulates the condition of the actual pipelines in service. This study also investigated the local shear lip thickness fraction in the CAT tests together with the shear area fraction SA% measured in DWTTs. Based on the results, the effect of Brittle Crack arrestability on inverse fracture appearance in the DWTTs was discussed in comparison with the Brittle Crack arrest behavior in the CAT tests.
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an experimental study on k ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2020Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness Kca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the Kca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate Kca of 6000 N/mm3/2, nevertheless the Kca value of 8000 N/mm3/2 was needed in the test plate simulating hatch side coaming. The different Kca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.
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historical review of research on Brittle Crack propagation arresting technology for large welded steel structures developed in japan with the application of kca parameters
Marine Structures, 2020Co-Authors: Tomoya Kawabata, Kazuki Shibanuma, Tetsuya Tagawa, Takehiro Inoue, Tsutomu Fukui, Yasuhito Takashima, Shuji AiharaAbstract:Abstract In response to the concern of increased risk of Brittle fracture accompanying the recent enlargement of container ships, experimental research is being conducted to investigate Brittle Crack propagation arrest properties in Japan. The objective is to obtain the required toughness of the material to arrest Brittle Crack propagation in a 100-mm thick plate, which is considered to be the maximum thickness used in such applications. The use of Kca as a method for determining arrest toughness is a main difference with respect to methodologies employed in Europe and the United States. In this review, we compare the approaches for determining Brittle Crack propagation arrest properties that are used in Japan with those used in Europe and the United States. Moreover, we review recent research trends, particularly with respect to the background and development of Kca parameters. With regard to the industrial application techniques concerning arrestability of Brittle Crack propagation in steel plates, studies in the ship and storage tank research fields date back to after World War II, while some attention is also seen for nuclear power and line pipes. These research procedures were initially established in Europe and the United States, but was first adopted by Japan. However, soon after, Japan and the time when the research fell downward due to progress of steel manufacturing technology and defect management technology. Since then, research has actively resumed, and original contributions are being realised. The background of this work in Japan, and the creation of the Kca concept will be explained herein. Further, the background of research on Brittle Crack propagation arrest properties in very large container ships, determination philosophy for deriving demand values, and ultrawide Brittle Crack propagation tests in the study of 75-mm thick material and their results are described. In both of the scenarios considered, i.e. one in which Cracks are generated from the top of the hatch side coaming and arrested on the upper deck, and the other wherein Brittle Cracks occur at the upper deck end and are arrested in the hatch side coaming, the required Kca was found to be 6000 N/mm3/2.
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Brittle Crack arrest behavior and its interpretation in an isothermal Crack arrest test
Engineering Fracture Mechanics, 2020Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Shota Nanno, Kazuyuki Matsumoto, Tomoya KawabataAbstract:Abstract Brittle Crack arrest behavior in steel plates and its evaluation test technique were investigated exhaustively from the1950s to the 1980s. Nevertheless, similar discussions have been revived recently by issues related to Brittle Crack arrest design applicable to mega-container ships. For example, the issue of whether the Brittle Crack arrest properties of steel plates evaluated under isothermal conditions and gradient temperature conditions are equivalent or not, which was also an issue in earlier studies, has been discussed again since 2010. This discussion is the results of ongoing debate in the International Association of Classification Societies (IACS) concerning provisions for heavy-gauge Brittle Crack arrest (BCA) steel plates for mega-container ships. In the present work, the Crack arrest temperature, abbreviated as CAT, was evaluated by an isothermal Crack arrest test in a specimen with a Crack runway emBrittled by electron beam weld (EBW) re-melting. The dependence of CAT and the arrested Crack length on the Crack runway length were discussed. Crack arrest toughness Kca was also evaluated based on test that resulted in Crack arrest in the isothermal condition, and the results were compared with those of the gradient temperature Crack arrest test. An unexpected variation was observed in the Kca values in the isothermal test, but it was suggested that this represents the R-curve behavior of a running Brittle Crack. The R-curve concept can qualitatively explain the Crack arrest behaviors with different Crack runway lengths. The analogical difference in Crack arrest behaviors between the isothermal condition and gradient temperature condition were also discussed.
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An experimental study on K_ca value to arrest a running Brittle Crack in structural model specimens with steel plate of 100 mm thickness for container ships
Journal of Marine Science and Technology, 2019Co-Authors: Tetsuya Tagawa, Hisakazu Tajika, Tsunehisa Handa, Teppei Okawa, Yusuke Shimada, Takehiro Inoue, Shota Nanno, Kazuyuki Matsumoto, Tomoya Kawabata, Shuji AiharaAbstract:With demand for ultra-large container ships, high-strength steel plates with extremely large thicknesses are applied to the structural elements around hatch side structures. The two longitudinal plates of the upper deck and hatch side coaming are the main structural elements that support bending stress during hogging of the ship structure, and Brittle Crack arrest toughness as well as Crack initiation toughness are required in these steel plates to avoid the catastrophic ship damage. Although the International Association of Classification Societies prescribes a unified requirement for Brittle Crack arrest steel plates providing the value of Brittle Crack arrest toughness K _ca at − 10 °C for plate thicknesses of 80 mm or less, ultra-large container ships using steel plates with thicknesses exceeding 80 mm are continuously required and built. In the present work, Brittle Crack arrest tests with large scale structural model specimens which simulate the structural element of the hatch side structure were performed to investigate the K _ca value required to arrest a running Brittle Crack for steel plates with the thickness of 100 mm. The present investigation suggested that the test plate simulating upper deck could arrest a running Brittle Crack at the plate K _ca of 6000 N/mm^3/2, nevertheless the K _ca value of 8000 N/mm^3/2 was needed in the test plate simulating hatch side coaming. The different K _ca values required to arrest a running Crack between the test plates simulating the upper deck and the hatch side coaming are also discussed from the viewpoint of the arrested Crack size and shape.