| 後藤 浩二（ごとう こうじ） | データ更新日：2024.04.24 |
教授 ／
工学研究院
海洋システム工学部門
船舶海洋構造工学
| 1. | Feng Yongyi, Gotoh Koji, Prediction of weld bead shape and defects by deep learning using welding conditions and acoustic features during welding as input variables, 3rd Hungary-Korea-Japan Joint Seminar on Design, Fabrication, and Maintenance of Welded Steel Structures, 2024, 2024.03. |
| 2. | 鬼塚 博之，日本貴 秀一，一二三 浩史，伊藤 一智，荒巻 翔平，後藤 浩二，村上 幸治，岩田 知明 , 構造用接着剤の船体建造での利用に関する基礎研究 －３点曲げ試験とそのシミュレーション－, 日本船舶海洋工学会 令和5年秋季講演会, 2023.11, [URL]. |
| 3. | 兵藤 義浩，柚賀 正雄，栗原 康行，ドアン ティーフィン，﨑本 隆洋，村上 善明，田川 哲哉，後藤 浩二, 疲労き裂進展下限界ΔKthが異なるSM490級鋼の微小き裂進展抵抗に関する考察, 溶接構造シンポジウム2023, 2023.11, [URL]. |
| 4. | 寺辻 和陸，内村 友哉，後藤 浩二 , 溶接止端部へのレーザ照射および局部浸炭処理による疲労強度改善効果に関する検討, 溶接構造シンポジウム2023, 2023.11, [URL], 溶接止端部近傍をレーザ照射して疲労亀裂発生領域の結晶粒を微細化させること，一部の継手に対してはレーザ照射により止端部近傍に局所的な浸炭処理を施すことで，疲労寿命の改善を試みた．これらレーザ照射処理では止端部形状の緩和も同時に達成できることもあり，溶接まま継手に比較して寿命の改善を達成した．. |
| 5. | Yoshihiro HYODO, Masao YUGA, Yasuyuki KURIHARA, Thi-Huyen Doan, Takahiro SAKIMOTO, Yoshiaki MURAKAMI, Koji GOTOH, Tetsuya TAGAWA, Consideration on short crack propagation resistance in SM490 steels with different ΔKth., Fatigue 2022+1 (13th International Fatigue Congress), 2023.11.  |
| 6. | 真所 最，後藤 浩二, 光造形方式3Dプリンタにおける材料選択の注意点と設計手法の考察, 1DCAE・MBDシンポジウム2023, 2023.11, [URL], 色が異なる以外は同一の材料特性を持つレジンを用いて光造形方式3Dプリンタにより引張試験を作製，引張試験を実施し，色違いによる特性差を調査し，材料選択の注意点と設計手法について考察した．. |
| 7. | 兵藤 義浩，柚賀 正雄，栗原 康行，ドアン ティーフィン，崎本 隆洋，村上 善明，田川 哲哉，後藤 浩二, 疲労き裂進展下限界ΔKthが異なるSM490級鋼の微小き裂進展抵抗に関する考察, 溶接構造シンポジウム2023, 2023.11. |
| 8. | 寺辻 和陸，内村 友哉，後藤 浩二, 溶接止端部へのレーザ照射および局部浸炭処理による疲労強度改善効果に関する検討, 溶接構造シンポジウム2023, 2023.11, 溶接構造物の疲労強度向上対策として，レーザ照射により疲労亀裂発生領域となる溶接止端部の結晶粒を微細化するとともに局所浸炭による硬化処理を試み，疲労強度の改善に資することを検討した．. |
| 9. | Tsukasa SHIMOOKA, Koji MURAKAMI, Kazuki MATSUDA, Koji GOTOH, Numerical simulation of fatigue crack growth with stress-strain relationship under cyclic loading, The 36th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2023), 2023.10, In numerical simulations of fatigue crack propagation, the true stress-true strain relationship under cyclic loading should be considered, but in simulations modelling crack opening behaviour, the stress-strain relationship of the material is regarded as rigid plastic or isotropically hardened elastic-plastic material from the point of view of model simplification. In this study, the true stress-true strain relationship under cyclic loading, estimated from the true stress-true strain relationship under monotonic tensile loading, is implemented in fatigue crack propagation simulations of work-hardened materials proposed by some of authors. Fatigue crack growth curves under the following three loadings, (1) constant cyclic loading under different stress ratios, (2) two-stage block loading cycles, (3) constant cyclic loading with a spike load, were estimated and compared with the measured results obtained in previous studies. The results show that the accuracy of the fatigue crack growth estimation is better than the conventional stress-strain relationship assuming elastic-perfectly plastic materials.. |
| 10. | Toshiki TSURUOKA, Tomoya NAKADA, Tomoya UCHIMURA, Kazuki MATSUDA, Koji GOTOH, Study on fabrication of butt welded joints of thick plates by laser-arc hybrid welding in horizontal position, The 36th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2023), 2023.10, Laser-arc hybrid welding (LAHW) is an advanced welding process that combines arc and laser welding as one molten pool. Compared with conventional arc welding, LAHW can be performed higher welding speeds with narrower grooves, and weld deformation can be significantly reduced. When LAHW is applied to construction of structural members, the welding is generally performed in a flat position because it is automatic welding system is applied from the viewpoint of safety in the work environment. Flat position (PA), it is expected to be applied to many welds of large steel structures by applying LAHW to horizontal position. However, the application of LAHW in the construction of large structures is expected by expanding the applicable welding position. In this study, butt joints with a plate thickness of 20 mm were fabricated in the horizontal position (PC) as a target of welding position in LAHW. By trial and error, referring to the welding conditions in the flat position, the welding conditions that produced a sound weld bead appearance were derived. However, molten metal was sagging at some of lower weld bead edge of the front bead. A sliding jig was designed to prevent the front bead sagging. As a result, the sagging was prevented and it was expected that the jig was effective in relaxing the shape of the weld toe for improving the fatigue strength of the joint. In the construction stages of large structures, it is difficult to maintain a constant root gap over the entire length of the weld line, so it is desirable to extend the allowable range of the initial gap. Therefore, we attempted to process with an initial root gap of 1.5 mm. However, we were unable to find welding conditions that would avoid undercutting and melting-in, and confirmed that the applicable limit of the initial root gap is 1.0 mm for the construction method studied in this study.. |
| 11. | Kazutaka TERATSUJI, Tomoya UCHIMURA, Kazuki MATSUDA, Koji GOTOH, Improvement of fatigue strength of welded joints by grain refinement using laser irradiation and locally carburized, The 36th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2023), 2023.10, The purpose of this paper is to confirm fatigue strength of welded joints can be improved by grain refinement using laser irradiation and localized carburization considering corrosion and abrasion. The measured temperature histories due to laser irradiation were compared with theoretical solutions for moving and instantaneous line heat sources, and it was confirmed that the temperature history could be estimated well using moving heat source. Maximum temperature and time required from 800 ℃ to 500 ℃ (Δt8/5) of the grain refinement region are obtained by applying moving heat source. Four-point bending fatigue tests were conducted on T-joint specimens as welded, laser irradiated, and locally carburized. As a result, number of cycles to failure of the specimens which locally carburized and laser irradiated were equivalent and they are longer than that of the specimens as-welded. The main reason is locally carburized and laser irradiated had more gentler toe shapes than as-welded. However, the porosity was observed in the carburized specimen. It can affect fatigue strength, further improvement of fatigue strength was expected by eliminating it.. |
| 12. | Sai Madokoro, Koji Gotoh, Effect of Water-soluble Cutting Fluid on Mechanical Properties of Nylon12 Manufactured by SLS 3D Printer, The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023 (ATEM-iDICs '23), 2023.10, [URL], Effect of cutting fluid on mechanical properties of Nylon12 parts fabricated by SLS 3D printer was investigated. There was a difference of approximately 30% in tensile strength between the "As build material immersed in cutting fluid (build direction: vertical)" and the "material with surface finishing by cutting processing (build direction: horizontal)". This result suggest that caution should be taken in strength calculations during the design phase when using Nylon12 parts fabricated by SLS 3D printer exposed to cutting fluid environments.. |
| 13. | 真所 最，後藤 浩二, Generative Designを活用した軽量化ロボットアーム部品の開発, Designシンポジウム2023, 2023.10, [URL], 産業用ロボットのアーム延長用部品を対象に，従来の切削加工製とGD（Generative Design）による構造最適化をしたAM製を比較し，その効果やデザインについて比較しつつAM製部品の有用性を検証した．. |
| 14. | 真所 最，後藤 浩二, Generative Designによる産業用ロボット向け軽量パーツの開発, 日本設計工学会2023年度秋季大会研究発表講演会, 2023.09, [URL], 産業用ロボットのアーム延長用部品を対象に，従来の切削加工製とGD による構造最適化をしたAM 製の比較を実施しその効果を検討した．. |
| 15. | 鶴岡 寿樹，内村 友哉，後藤 浩二, レーザ・アークハイブリッド溶接における横向水平溶接の施工法確立に向けた基礎検討, 溶接学会九州支部講演会, 2023.08, 横向姿勢によるレーザ・アークハイブリッド溶接に関する研究成果は，10 mm級の板厚であること，溶接パス数が2パス以上必要とするものが大半を占める． 著者らは先行研究として，板厚20 mm，溶接長300 mmの横向突合せ継手製作ならびに表ビードの垂れを報告した． 本研究ではレーザ・アークハイブリッド溶接による横向姿勢の溶接施工法確立を目的とし，表ビードの垂れ抑制および板厚20 mm，溶接長1,000 mmの突合せ継手製作を試みた．. |
| 16. | 小林 寛郎，鶴岡 寿樹，内村 友哉，後藤 浩二, レーザ・アークハイブリッド溶接を用いた裏当てレス1パス施工に向けた基礎検討, 溶接学会九州支部講演会, 2023.08, 厚板の突合せ溶接は裏当て材の使用や多層盛り溶接が主流であるものの，裏当て材の設置作業による生産効率の低下や過大入熱による溶接変形が懸念される． 局所的かつ深溶込みが可能なレーザ・アークハイブリッド溶接は，生産効率の向上やコストの削減，過大入熱の抑制が期待できるとして近年注目を浴びている． 本研究では，レーザ・アークハイブリッド溶接を用いた裏当てレス1パス施工の条件探索を実施した．. |
| 17. | B L Josefson, B-Q Chen, K Gotoh, F Fang, K Liu, S van Duin, P Dong, Benchmark Study of Welding Deformations in Stiffened Plate, ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2022), 2022.06, The fabrication of ship hulls involves welding operations, one typical operation is fillet welding of stiffeners to plates (panels) a so-called T-joint. The residual stresses from the welding process will influence the fatigue life of the structure, and residual deformations will increase the risk for buckling of the panel and give poor fabrication tolerances which may complicate the assembly of a built-up structure. Though this weld geometry has been frequently studied in the literature both experimentally and numerically, the focus has been on the residual stress field and if residual deformations are studied, the angular distortion and the typical V-shape seen in the welded plate (panel) are reported. This benchmark focusses on the residual shape after two-pass fillet welding of a stiffener to a plate (T-joint and the influence of the constraints used during welding. The information of the full welding residual deformations may be useful for the fabrication of larger complex welded structures. The benchmark study clearly shows that careful consideration is needed when defining a reference plane for comparison of resulting deformations from FE-simulations and from experiments as well as good documentation of the actual boundary conditions and steps carried after the completion of the welding and before measuring residual deformations. The FE-simulations have shown that it is difficult to obtain the full antisymmetric, twisted shape of the plate as measured in the experiments, although a trend similar to the experiments can be seen as the plate tends to move upwards at the end of each weld pass, i.e a slight influence of the weld pass direction.. |
| 18. | 下岡 司，村上 幸治，松田 和貴，後藤 浩二, 繰返し負荷を受ける鋼材の応力～ひずみ関係に関する実験的検討, 溶接学会九州支部研究発表会, 2022.09, 繰返し負荷時の応力～ひずみ関係については種々の報告があるが，疲労亀裂伝播解析に必要とされる真応力～真ひずみ関係は測定が困難であったこともあり，殆ど報告されていない．しかし，近年では計測機器の進歩によって繰返し負荷時の真応力～真ひずみ関係の測定が比較的容易になった． 本研究では疲労亀裂伝播解析に役立てることを目的として，上述の機器を活用し，繰返し負荷時の真応力～真ひずみ関係の測定を実施した．. |
| 19. | 寺辻 和陸，内村 友哉，松田 和貴，後藤 浩二, 疲労強度改善のためのレーザ照射による結晶粒微細化に関する基礎検討 , 溶接学会九州支部研究発表会, 2022.09, 大型溶接構造物の損傷形態は疲労破壊が大半を占める．特に溶接止端部は応力集中部となることから，疲労亀裂発生の起点になりやすい．しかし，レーザ照射による溶接止端部の形状緩和や結晶粒微細化を施しても，表面部の腐食や摩耗などの経年劣化により，疲労寿命改善効果が消滅することが懸念される． 本講演では結晶粒微細化層を内部に形成し，位置や厚さを照射前から予測する手法とその発生条件について紹介する．. |
| 20. | 馮 永益，渡辺 範弘・山嵜 賢人，松田 和貴，後藤 浩二, 機械学習を援用した溶接施工条件および溶接音を入力変数としたすみ肉溶接ビード形状の予測に関する研究, 溶接学会九州支部研究発表会, 2022.09, 現在，溶接の外観検査は目視によるものが主流であるものの，溶接欠陥の見落としを根絶することが困難であるため，生産効率の低下が懸念される．そのため，検査時間の短縮や省人化によるコスト削減，及び作業精度や生産効率の向上を目的とした自動溶接検査システムの構築が期待されている．本講演では機械学習を用いた溶接施工ログデータとアーク音データを基に溶接欠陥の発生を推定する手法について紹介する．. |
| 21. | 後藤 浩二，中田 智也，内村 友哉，安藤 彰芳，松下 宗生，半田 恒久，伊木 聡, REM添加ワイヤを使用したレーザ・アークハイブリッド溶接の船体建造工程への適用拡大に向けた検討, 溶接学会2022年度秋季全国大会, 2022.09. |
| 22. | Norihiro Watanabe, Kento Yamasaki, Koji Gotoh, A Study for Automatic Inspection of Leg Length and Undercut in the T-shaped Joint using Deep Learning, IIW 2022 International Conference on Welding and Joining, 2022.07, The development of an automatic weld visual inspection system applicable to weld bead visual inspection in shipyards is expected to reduce costs through man-hour reduction, improve weld quality, and shorten the repair process. Although many studies have been conducted on the automation of weld bead visual inspection, most of them were based on image analysis. However, in order to apply image analysis, it is necessary to remove residual slag from the bead surface after welding before taking images, which is not desirable considering the production process in shipyards. The author's research group has been studying a method to predict weld bead appearance by deep learning using welder log data (current, voltage, and welding wire feed rate) and fixed welding conditions (torch angle, etc.) as inputs. In this study, several improvements were made to the prediction of the leg length and undercut depth of the T-shaped joint. These improvements significantly improved the adjusted coefficient of determination, a measure of prediction accuracy, to 0.96 for leg length prediction and 0.93 for undercut depth prediction, resulting in improved prediction accuracy for leg length and undercut depth.. |
| 23. | Tomoya Uchimura, Yosuke Koba, Tomomichi Simizu, Junichi Hirata, Hiroyuki Kobayashi, Koji Gotoh, Development of a Prototype 3D Measuring and Judging System to Improve the Accuracy of Visual Inspection of Weld Bead Appearance and to Digitise Inspection Results for Welder Qualification Tests, IIW 2022 International Conference on Welding and Joining, 2022.07, This study is concerned with the development of a system for automatically carrying out visual inspections of the external appearance of welders in the welder's skills certification examination, without requiring extensive experience in visual inspections, and presents the results of the development of a prototype of such a system. The developed system handles the weld bead shape measured with a 3D scanner as point data in 3D space, and matches it with the evaluation criteria for the welder qualification test, such as bead width, reinforcement of weld height and undercut depth, to enable a pass/fail decision to be made immediately after the test is taken. In addition, the joint geometry can be stored as high-precision point cloud digital data, allowing another visual inspection to be carried out even after the specimen has been processed for bending tests after visual inspection.. |
| 24. | 武内 崇晃, 村上 貴昭, 宇都宮 智昭, 後藤 浩二, 係留鎖の摩耗係数に関する実験的検討および3次元計測による解析的検討, 日本船舶海洋工学会 令和4年 春季講演会, 2022.05. |
| 25. | 渡邉 範弘, 山嵜 賢人, 後藤 浩二, 深層学習を用いた溶接ビード外観自動検査手法構築に向けた学習データの窓大きさと窓移動量に関する一検討, 日本船舶海洋工学会 令和4年 春季講演会, 2022.05. |
| 26. | 田門 岳大, 後藤 浩二, 森園 靖浩, 溶接継手の疲労強度改善のためのレーザ照射による局部浸炭処理に関する基礎検討, 日本船舶海洋工学会 令和4年 春季講演会, 2022.05. |
| 27. | Katsuhito ITO, Koji MURAKAMI, Koji GOTOH and Tomoaki UTSUNOMIYA, Development of a Test Machine to Reproduce the Wear Behavior of Chains Mooring Offshore Wind Turbines, 34th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2020/21), 2021.12, With global warming on the rise, various initiatives are being taken to promote the use of renewable energy sources to reduce greenhouse gas emissions. In particular, there are high expectations for the expansion of offshore wind power due to its high generating capacity. One of the challenges for the widespread use of offshore wind turbines is to reduce maintenance costs, especially for moorings. The floating motion of moored offshore wind turbines causes wear on the mooring chains. As the wear progresses, there is a possibility of rupture. In order to ensure the safety of floating offshore wind turbines, it is essential to establish a method for assessing the amount of wear on the mooring chain. This will enable an appropriate maintenance plan to be drawn up for the mooring system. This allows maintenance costs to be taken into account at the planning stage of the installation. It also identifies the challenges to achieving a maintenance-free system. Regarding the evaluation of wear of mooring chains for offshore wind turbines, Takeuchi et al. proposed a method for estimating the amount of wear based on the results of a floating response analysis that evaluates the tension acting on the chain and the sliding and rotation between the links. In this estimation method, a simple estimation equation as a function of inter-link tension and angle is applied. This simplified estimating equation is based on experiments to reproduce the wear behavior of mooring chains conducted in air environment or by dripping artificial seawater or freshwater on the contact area. However, in order to evaluate the wear development more quantitatively, it is necessary to conduct experiments with mooring chains completely submerged in water and reflect the results of the experiments. The experimental system was constructed to reproduce the wear behavior of a mooring chain with dimensions similar to those of the in-service machine, when it is completely submerged in water. The wear behavior was investigated under several tension conditions, and it was confirmed that the wear behavior in a fully submerged environment was different from that in air or in liquid drops. . |
| 28. | Takehiro TAMON and Koji GOTOH, A Study on Working Conditions for Improving Fatigue Strength of Welded Joints by Localized Carburizing Treatment Using Laser Irradiation, 34th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2020/21), 2021.12, Since the serious factor of damages in welded structures is generally fatigue and fracture originating from fatigue cracks. Fatigue cracks in welded structures usually initiate at the weld toe. High frequency mechanical impact treatment (HFMI) and peening are well known techniques to improve the fatigue life of structures. Most of these treatments for fatigue life improvement have to be carried out after welding, which is an extra step in terms of productivity. It is therefore desirable to be able to carry out fatigue strengthening treatment of welded joints continuously after welding on the same working line. As one of the methods, the authors have shown that local laser irradiation near the weld toe can improve the fatigue life by relaxing the stress concentration and by refining the grains in the irradiated area. However, in the case of long-term operation such as in ships and offshore structures, there is a concern that the improved weld toe geometry and grain refinement area may be lost over time due to corrosion. In order to cope with this situation, the authors found the possibility to apply the local carburizing of the weld toe area by laser irradiation. In this study, the conditions of the laser irradiation were investigated for the local carburizing. A certain amount of carbon was applied to the surface of mild steel plates, and the relationship between the laser irradiation conditions and the degree of hardening (width of hardened area and hardness value of the hardened layer) was investigated experimentally. From the results it was concluded that the hardness of the fusion zone could be evaluated in relation to the size of the fusion zone and the amount of the mixed carbon component. Next, based on the above hypothesis, local laser carburizing was carried out on the weld toes produced by arc welding, and the results showed the same tendency as in the basic investigation. However, porosities of various sizes generated in the fusion zone, and the degree of porosities varied with the steel grade. The cause of the porosities is thought to be a gasification reaction between the oxygen and carbon components in the steel or mixed in from the atmosphere. In general, the presence of oxygen is one of the most serious problems causing abnormal areas in actual carburizing, and in laser carburizing characterized by rapid heating and cooling, this problem is thought to be responsible for the occurrence of porosities. The result of this study suggest that the deoxidizing agent, silicon (Si) component, is significantly effective in controlling the porosities in order to form a sound carburizing layer at the weld toe.. |
| 29. | 渡邉 範弘，山嵜 賢人，後藤 浩二, 深層学習を用いた溶接ビード外観自動検査手法構築に向けたハイパーパラメータ自動探索法と入力データ処理法に関する一検討, 日本船舶海洋工学会 令和3年秋季講演会, 2021.11, 本研究では，溶接外観の自動検査システムの構築に向けて，深層学習モデルにおけるハイパーパラメータを自動的に決定する方法及び推定精度向上に資するための入力データ処理方法について検討した．. |
| 30. | 上村 崇杜，後藤 浩二, レーザ熱源を利用した突合せ継手の仮付溶接方法に関する考察, 日本船舶海洋工学会 令和3年秋季講演会, 2021.11, 本研究では，ハイブリッド溶接施工による突合せ継手製作を対象に仮付溶接部の特性について調査し，ハイブリッド溶接施工において必要な仮付溶接施工法について提案する．. |
| 31. | Shuichi Tsumura, Koji Gotoh, Deriving Welding Conditions of Full-Penetration Tee Joint for One-Side Single Pass Welding Fabricated with Laser-Arc Hybrid Welding, 2021 International Conference on Robust Quality Engineering (ICRQE 2021), 2021.09, Laser-arc hybrid welding is a high-quality welding technology, and it is expected to improve the productivity of manufacturing large welded structures such as ship hulls and offshore structures. Applications of this technology allow the replacement of fillet-welded joints in structures with full-penetration welded joints. This replacement should improve the fatigue performance and deformation. However, many welding conditions can become a control factor in hybrid welding due to using a laser heat source and an arc heat source at the same time, thereby making it very difficult to optimize the welding conditions using a multi-way layout. In addition, the robustness of hybrid welding is not enough to be applied to the shipbuilding. This study focused on the full-penetration tee joint for one-side single pass welding and reports the results of optimizing welding conditions using the L18 and L9 orthogonal tables. These experiments confirm even with the S/N ratio of smaller-is-better response, it is possible to derive welding conditions that are robust to the noise factors. Also, it is confirmed that the height of the laser irradiation position most affect the S/N ratio among the noise factors. In addition, the control factors related to the arc heat source were not expected to affect the bead shape of the non-welded side, but it confirmed that these control factors affect the S/N ratio of the non-welded side.. |
| 32. | 中田 智也，内村 友哉，上村 崇杜，後藤 浩二, レーザ・アークハイブリッド溶接における横向水平溶接の板厚範囲拡張に関する検討, 溶接学会九州支部研究発表会, 2021.08, レーザ・アークハイブリッド溶接は，アーク溶接よりも速い溶接速度で深溶込みの継手が製作可能であり，レーザ溶接よりも開先精度に対する裕度がある，大型構造物の高精度な建造に利用が期待される比較的新しい溶接法である． 本研究では，ハイブリッド溶接の適用可能な板厚，溶接姿勢を拡張することを目的に，板厚20 mmの突合せ継手製作を試み，施工法確立に向けた課題の整理を行った結果を報告する．. |
| 33. | 尾島 直樹，村上 幸治，後藤 浩二, デジタル画像相関法を用いた疲労亀裂先端の両振り塑性域寸法の測定に関する検討, 溶接学会九州支部研究発表会, 2021.08, 疲労亀裂進展の駆動源は亀裂先端近傍の両振り塑性域内で不可逆的に消費される引張・圧縮の繰返し塑性仕事であるため，この両振り塑性仕事や両振り塑性領域の寸法をパラメータとする疲労亀裂伝播則の構築が期待されている． 本研究では，デジタル画像相関法を用いて，複数の疲労試験に対して繰り返し負荷中の亀裂先端近傍の両振り塑性域寸法の測定を試み，同手法を適用するための問題点の検証を行った．. |
| 34. | T. Uemura, K. Gotoh, I. Uchino, Studies on Expansion of Laser-Arc Hybrid Welding to Horizontal and Vertical-Up Welding, IIW 2021 Commission XV Design, Analysis and Fabrication of Welded Structures, 2021.07, Laser arc hybrid welding (LAHW) is an advanced welding method that combines arc welding and laser welding and can achieve deep penetration and reduction of welding deformation compared to practical arc welding. Since the equipment of LAHW is relatively large, it is common to target flat position (PA) as the welding position. On the other hand, expansion of the applicable positions enables to apply the high-quality welded joints fabricated by LAHW to many welded joints in large steel structures. In this study, as establishment of weldability in the horizontal position (PC) and the vertical-up position (PF) to expand the applicable range of LAHW in the large steel structures, the LAHW system with a robot manipulator was used. Suitable LAHW conditions to fabricate the butt welded joint with a welding length 1,000 mm for these positions were established by various investigations including the molten pool observation. At the first stage of our investigation, the authors thought that it would be easier to use the backing sheet for the fabrication of the butt joint in the vertical-up position. But it was confirmed that the toughness of the joint might decrease because of dilution of specific components contained in the backing sheet into weld metal. Therefore, it was confirmed that the fabrication was performed without using the backing sheet. After that, the quality of these joints was evaluated in accordance with the “Laser Arc Hybrid Welding Guidelines” (ClassNK) by the Nippon Kaiji Kyokai and confirmed that they meet the standards.. |
| 35. | 後藤 浩二，村上 幸治，宇都宮 智昭，佐藤 郁, 没水環境下における係留鎖摩耗挙動再現試験装置の構築, 日本船舶海洋工学会 令和3年春季講演会, 2021.06. |
| 36. | 武内 崇晃，宇都宮 智昭，後藤 浩二，佐藤 郁, 浮体構造物係留鎖における転がりを考慮した簡易摩耗量推定手法の提案, 日本船舶海洋工学会 令和3年春季講演会, 2021.06. |
| 37. | 山口 絢也，後藤 浩二, 弾塑性FE解析を用いた亀裂先端の両振り塑性挙動を考慮した疲労亀裂伝播解析, 日本船舶海洋工学会 令和3年春季講演会, 2021.06. |
| 38. | 上村 崇杜，後藤 浩二，内野 一成，福田 時生，内村 友哉，村上 幸治, レーザ・アークハイブリッド溶接を用いた横向き及び立向き上進突合せ継手製作に関する諸検討, 日本船舶海洋工学会 令和3年春季講演会, 2021.06. |
| 39. | 上村 崇杜，後藤 浩二，内野 一成，内村 友哉，村上 幸治, レーザ・アークハイブリッド溶接を用いた長尺の完全溶込みT継手の実用的施工法に関する諸検討, 日本船舶海洋工学会 令和3年春季講演会, 2021.06. |
| 40. | 田門 岳大，上村 崇杜，後藤 浩二, レーザ照射による局所浸炭処理を活用した溶接継手の疲労寿命改善に関する基礎検討, 溶接学会九州支部研究発表会, 2020.11. |
| 41. | 高木 芳史，後藤 浩二，今井 康仁，小貫 翔馬, 弾塑性応力場におけるJ積分値簡易推定式の精度改善に向けた基礎検討, 溶接構造シンポジウム2019, 2019.12. |
| 42. | 村上 幸治，森下 瑞生，後藤 浩二, RPG荷重の自動計測手法に関する検討, 溶接構造シンポジウム2019, 2019.12. |
| 43. | 上村 崇杜，田口 慎，後藤 浩二, レーザ照射による金属結晶粒微細化技術を用いた溶接継手部の疲労強度改善に関する諸検討, 溶接構造シンポジウム2019, 2019.12. |
| 44. | 藤井 壽裕, 岡田 公一，出口 純一, 後藤 浩二, ブラスト処理による溶接止端部の疲労強度向上効果の検証 (その2)突合せ溶接継手に対する検証 , 日本船舶海洋工学会 令和元年秋季講演会, 2019.11, 本研究では，荷重伝達タイプの溶接継手に対してもブラスト処理影響により疲労強度が改善するか否かの検証を目的に，突合せ溶接継手に対応する疲労試験片を製作して疲労試験を実施した結果を報告する．. |
| 45. | 赤木 俊一，伊藤 聡志，小野寺 真吾，太田 涼介，髙石 靖彦，平尾 和浩，後藤 浩二, 造船所内での部品物流管理に対するRFID 利用可能性の検証, 日本船舶海洋工学会 令和元年秋季講演会, 2019.11, 本研究では，造船所内における物流管理をより円滑に実施することを目的に，他業界において多数の物品の管理に優位性を発揮しているRFID の利用可能性について検証した結果を報告する．. |
| 46. | Hisao Narimatsu, Masakazu Kuwada and Koji Gotoh, A Study on using Hot-rolled Steel Sheet for Ship Superstructure, The 14th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2019), 2019.09, Application of the hot-rolled steel sheet for the members of superstructure, where the strength requirement of these parts in ships is not severe, is expected as a solution to reduce the hull construction cost. Because the hot-rolled steel sheet is applied after recoiling by cold working to return it to a flat plate, the material properties is deteriorated due to excessive plastic working and the residual stress induced by the plastic work might affect for the thermal cutting and welding. There is a possibility that the hot-rolled steel sheet has poor properties comparing with the flat rolled steels applied for hull parts where the structural integrities are required by the classification societies’ rules. The difference of properties between the hot-rolled steel sheet and the flat rolled steel are investigated in this research. Investigated items are mechanical properties, microstructures, initial residual stress distributions, hardness distributions, distortion after thermal cutting and laser-arc hybrid welding.. |
| 47. | Koji Gotoh, Takamori Uemura, Issei Uchino, Hisao Narimatsu, Toshimitsu Maeda, Takumi Torigoe and Atsuo Moriyama., Overview of the Joint Industrial Project for Practical Application of Laser-Arc Hybrid Welding in Construction of General Merchant Ships in Japan, The 14th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2019), 2019.09, The application of advanced welding technologies is important for improving the efficiency of hull construction processes and reducing production costs. Laser-arc hybrid welding technology, which combines the advantages of laser and normal arc welding, is of high quality and is expected to improve productivity. The Japan Ship Technology Research Association has organized the joint industry project in collaboration with a university, a classification society and some shipyards to apply this technology in the construction of general merchant ships, in which the plate thickness of the main structural member is thicker than passenger ships and high speed craft. The overview of the first phase JIP results were introduced in PRADS 2016. In this presentation, an overview of main research results of the second and third phase JIP, which are listed below, are introduced.. |
| 48. | Koji GOTOH, Tetsuya UEDA, Koji MURAKAMI, TOMOAKI UTSUNOMIYA, Wear Performance of Mooring Chain in Wet Environment with Substitute Ocean Water, ASME 38th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2019), 2019.06, Floating wind turbine facilities installed in deep sea areas play an essential role in the promotion of green energy. One of the problems associated with the commercialization of facilities installed in the deep sea is the maintenance cost of mooring chains, because they are expensive and wear between links leads to chain breakage. Therefore, it is necessary to establish a quantitative wear evaluation method for mooring chains. An experimental facility to reproduce the wear caused by sliding between links at the scale of an actual floating wind turbine was developed to investigate the wear performance in seawater conditions, and wear tests were conducted. Substitute ocean water was applied to the experiment instead of seawater. In addition, a procedure for nonlinear finite element analysis was improved to estimate the behaviour of wear between links. Measured stress versus strain relations of the links was considered in the finite element analysis. The experiments and numerical analysis confirmed that the amount of wear in the substitute ocean water was less than that obtained in dry air and that the tensile force between links is an important factor for the degree of wear between links.. |
| 49. | Takayuki YOTSUZUKA, Yusuke ENDO, Eiji NIINO, Koji GOTOH, A Study on Unification of Welding Consumables in Construction of Chemical Cargo Tankers Made of Duplex Stainless Steel - Evaluation of Static Strength of Welded Joint -, ASME 38th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2019), 2019.06, Austenitic stainless steels such as SUS 316 LN and austenitic stainless clad steel are used in cargo holds of chemical tankers owing to their corrosion resistance. Recently, the use of duplex stainless steels has been increasing, owing to their better strength and corrosion resistance and lower content of expensive Ni, compared with those features of austenitic stainless steels. However, few duplex stainless clad steels have been approved by classification bodies. Furthermore, the application of duplex stainless steel is not yet mainstream as hull structural materials because a stable supply market has yet to be established. Therefore, when applying cladding steel to construction of chemical tankers, austenitic stainless clad steel is often used at present. The duplex stainless steel and the austenitic stainless clad steel are mixed at construction factories; hence, there is a risk of misuse of welding consumables. If misuse is suspected, it is not possible to judge the erroneous use from visual inspection after construction; therefore it is necessary to uniformly remove the weld and re-weld. However, if universal welding consumables were identified, this might avoid the problems of misuse and simplify the procurement of welding materials. In this paper, we report on our studies to verify welding consumables for use in the hull structures, involving a mixture of duplex stainless steel and the austenitic stainless clad steel. The static strength of the welded joints is a particular focus of this study, from which we confirmed the validity and limitations of welding consumables.. |
| 50. | Toshihiro FUJII, Koji GOTOH, Junichi DEGUCHI, Koji MURAKAMI, A Study on Improvement of Fatigue Performance by Shot Blasted Surface Treatment, ASME 38th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2019), 2019.06, Recently, the strength of the hull structure including fatigue strength has seen significant improvement because of application of IACS CSR (Common Structure rule), developed by IACS. Various methods which can increase the fatigue strength at welded joints are suggested, since the damage morphology on the recently welded structures was observed to be primarily fatigue failure. In Shipbuilding industry, smoothening of the welding bead toe by grinding is the method that is customarily adopted in order to increase fatigue strength. And recently, peening treatment at the welding bead has also been adopted. The peening treatment can reduce stress concentration by smoothening of the welding bead toe, and a compressive residual stress field generated by the impact of peening. In case of generating compressive residual stress by impact, the same effect could be expected by shot blasting, which is the steel surface treatment before painting. In this study, the condition of the residual stress generated at welding toe by shot blasting was investigated, and then from results of the fatigue test, the increase in fatigue strength due to residual stress is verified.. |
| 51. | 原 武蔵，渡邉 範弘，森平 尚樹，後藤 浩二, 溶接施工パラメータを情報とする溶接外観自動検査システム構築に向けた基礎検討, 令和元年度溶接学会九州支部研究発表会, 2019.06. |
| 52. | 福田 時生，原 武蔵，上村 崇杜，村上 幸治，後藤 浩二, レーザ・アークハイブリッド溶接施工における溶接姿勢拡張に向けた基礎検討, 令和元年度溶接学会九州支部研究発表会, 2019.06. |
| 53. | 山口 絢也，後藤 浩二, 亀裂結合力モデルに基づく亀裂先端近傍の繰返し塑性挙動を考慮した疲労亀裂成長挙動評価に向けた基礎検討, 令和元年度溶接学会九州支部研究発表会, 2019.06. |
| 54. | 森平 尚樹，渡邉 範弘，後藤 浩二, 機械学習による溶接外観の自動検査技術の構築に向けた基礎検討, 2019年日本船舶海洋工学会春季講演会, 2019.06. |
| 55. | 山口 絢也，後藤 浩二, 亀裂結合力モデルを用いた亀裂先端近傍の繰返し塑性挙動を考慮した疲労亀裂成長挙動評価に向けた基礎検討, 2019年日本船舶海洋工学会春季講演会, 2019.06. |
| 56. | 後藤 浩二，津村 秀一，岩田 知明，森山 厚夫, レーザ・アークハイブリッド溶接技術の一般商船建造工程への導入に向けた研究 －（その1）片側完全溶込みT 継手の施工条件導出と継手性能評価－, 2019年日本船舶海洋工学会春季講演会, 2019.06. |
| 57. | 後藤 浩二，竹下 竜平，上村 崇杜，森山 厚夫, レーザ・アークハイブリッド溶接技術の一般商船建造工程への導入に向けた研究 －（その2）溶接施工性に及ぼす諸因子の影響－, 2019年日本船舶海洋工学会春季講演会, 2019.06. |
| 58. | 後藤 浩二，上村 崇杜，村上 幸治，前田 利光，鳥越 功，森山 厚夫, レーザ・アークハイブリッド溶接技術の一般商船建造工程への導入に向けた研究 －（その3）実機レベルの溶接長を有する片側貫通T 継手製作の検討－, 2019年日本船舶海洋工学会春季講演会, 2019.06. |
| 59. | 後藤 浩二，上村 崇杜，内野 一成，村上 幸治，森山 厚夫, レーザ・アークハイブリッド溶接技術の一般商船建造工程への導入に向けた研究 －（その4）実機レベルの溶接長を有する突合せ継手製作の検討－, 2019年日本船舶海洋工学会春季講演会, 2019.06. |
| 60. | 後藤 浩二，上村 崇杜，内野 一成，成松 久雄，前田 利光，鳥越 功，森山 厚夫, レーザ・アークハイブリッド溶接技術の一般商船建造工程への導入に向けた研究, 第91回 レーザ加工学会 講演会, 2019.06, 我が国造船業で主に建造される船種（主要部板厚15~20mm 程度）への適用を可能とするレーザ・アークハイブリッド溶接技術に関して2012 年度より業界共同研究が実施されおり，第一期研究の概要は第82 回講演会において，第二期研究前半の概要を第86 回講演会において紹介した．今回は第二期研究後半の概要について紹介する． Japan Ship Technology Research Association (JSTRA) had organized the joint industry project in collaboration with university, classification society and some shipyards in order to apply this technology in construction of general merchant ships which the plate thickness in main structural member is thicker than passenger ships and high speed craft. Overview of main research results of the second and third phase JIP are introduced in this paper.. |
| 61. | 武内 崇晃，宇都宮 智昭，後藤 浩二，佐藤 郁, 浮体構造物係留鎖における定量的摩耗量推定の実施と検証, 2019年日本船舶海洋工学会春季講演会, 2019.06. |
| 62. | Koji GOTOH, Takamori UEMURA, Issei UCHINO, Hisao NARIMATSU and Atsuo MORIYAMA, Fundamental Studies on Application of Laser-Arc Hybrid Welding for Manufacturing Primary Structural Members in General Merchant Ships, The 8th International Congress on Laser Advanced Materials Processing (LAMP2019), The 8th International Symposium on High Power Laser Processing (HLP2019), 2019.05, The application of advanced welding technologies is important for improving the efficiency of hull construction processes and reducing production costs. Laser-arc hybrid welding technology, which combines the advantages of laser and normal arc welding, is of high quality and is expected to improve productivity. The Japan Ship Technology Research Association has organized the joint industry project in collaboration with a university, a classification society and some shipyards to apply this technology in the construction of general merchant ships, in which the plate thickness of the main structural member is thicker than passenger ships and high speed craft. Main research achievements are as follows. 1) Establishment of welding procedure to fabricate the full-penetration tee joint by one-side single-pass welding. 2) Confirmation of the influence of weld groove processing method (laser, plasma or gas cutting) and residual primer and oxide film on the quality of butt welded joint fabricated by the I shaped groove preparation and one pass welding and confirming the effectiveness of spatter reduction technique by applying the J-STAR® Welding as an arc welding.. |
| 63. | 四塚 卓之，新納 栄二，遠藤 裕介，後藤 浩二, 汎用二相ステンレス鋼の実船適用に向けた工作法に関する研究 －（その1）溶接継手の静的強度評価－, 日本船舶海洋工学会 平成30年秋季講演会, 2018.11. |
| 64. | 藤井 壽裕, 後藤 浩二, 出口 純一, 村上 幸治, ブラスト処理による溶接止端部の疲労強度向上効果の検証, 日本船舶海洋工学会 平成30年秋季講演会, 2018.11. |
| 65. | 森下 瑞生, 後藤 浩二, 穴井 陽祐, 丹羽 敏男, 位相差を有する面内二軸繰返し応力を受ける表面亀裂の伝播解析, 日本船舶海洋工学会 平成30年秋季講演会, 2018.11. |
| 66. | 成松 久雄, 桑田 正和, 後藤 浩二, 杉野 雄輝, ホットコイル材の船体上部構造への適用に関する諸検討, 日本船舶海洋工学会 平成30年秋季講演会, 2018.11. |
| 67. | 上村 崇杜, 杉野 雄輝, 内野 一成 後藤 浩二, 厚板のレーザ・アークハイブリッド突合せ溶接におけるギャップ裕度に関する数値解析検討, 平成30年度溶接学会九州支部研究発表会, 2018.07, 船体ブロック工作精度や船体構造中の溶接継手部の品質向上を目的として，レーザ・アークハイブリッド溶接の導入に向けた検討が進められている．我が国の造船所で主に建造される一般商船の建造工程に同溶接法を導入するには，船体構造に適用される板厚レベルでの溶接施工条件の確立が必要である上に，アーク溶接と比較してギャップ裕度が厳しいため，溶接施工中のギャップの挙動を詳細に把握しつつ，適切な対策を講じる必要がある． 本研究では，一般商船建造の板継工程を念頭に，レーザ・アークハイブリッド突合せ溶接時のギャップの挙動を熱弾塑性FE解析により推定し，実測結果との比較することで推定精度の妥当性を検討した結果を報告する．. |
| 68. | 杉野 雄輝, 上村 崇杜, 成松 久雄 後藤 浩二, ホットコイル材とレーザ・アークハイブリッド溶接を用いて製造された突合せ継手の角変形について, 平成30年度溶接学会九州支部研究発表会, 2018.07, 船体居住区建造を念頭に，従来のアーク溶接法と比較して溶接変形を低減できるレーザ・アークハイブリッド溶接（以下，単にハイブリッド溶接と称する）をコイル材に適用して突合せ継手を製作した場合の角変形について，圧延鋼板と比較した結果を報告する．. |
| 69. | Koji GOTOH, Masataka NAKAGAWA, Koji MURAKAMI, TOMOAKI UTSUNOMIYA, Effect of Tensile Force for Wear Performance of Mooring Chain, ASME 37th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2018), 2018.06, Floating wind turbine facilities, which are installed in the deep sea area, plays an essential role to promote the green energy application. One of the problems associated with the commercialization of facilities installed in the deep sea is the reduction of the maintenance cost of mooring chain, because breaking of the mooring chain caused by the wear between links leads to enormous economic losses. Therefore, it is necessary to establish a quantitative wear evaluation method for mooring chains. Experimental facility to reproduce the wear caused by sliding between links in actual scale applied for floating wind turbine, which had been proposed by the authors, was updated and the wear tests was conducted by setting some tensile force conditions between the links. Besides, procedure of the nonlinear finite element analysis was improved to estimate the behaviour of wearing between links. From experiments and numerical analysis, it has been confirmed that the tensile force between links is an important factor of the wear amount between links.. |
| 70. | 山根 和樹，中川 将孝, 宇都宮 智昭，後藤 浩二, ピン・オン・ディスク摩耗試験による係留チェーンの比摩耗量に関する検討, 日本船舶海洋工学会 平成30年春季講演会, 2018.05. |
| 71. | 武内 崇晃, 宇都宮 智昭，後藤 浩二, 浮体施設係留チェーンの動的挙動及び摩耗量推定手法に関する検討, 日本船舶海洋工学会 平成30年春季講演会, 2018.05. |
| 72. | 村上 幸治, 後藤 浩二, 疲労亀裂伝播試験におけるRPG荷重の反転法による測定精度に関する一考察, 溶接構造シンポジウム2017, 2017.12, 疲労亀裂伝播試験においてRPG荷重を測定する場合の精度を考察すると共に適切な実験指針を提示した．. |
| 73. | 高木 芳史, 後藤 浩二, 表面亀裂に対する応力拡大係数重み関数の拡張とParisの相反定理に基づく亀裂開口変位の推定, 溶接構造シンポジウム2017, 2017.12, WangとGlinkaにより提案され，後藤と大田黒により拡張された表面亀裂の応力拡大係数重み関数を，特に亀裂が深い場合に対しても適用できるように改良した．. |
| 74. | 穴井 陽祐, 丹羽 敏男, 後藤 浩二, 面内二軸繰返し荷重下における疲労表面亀裂の形状変化, 日本船舶海洋工学会 平成29年秋季講演会, 2017.11. |
| 75. | 山崎 真尚, 村上 幸治, 後藤 浩二, デジタル画像相関法を用いた疲労亀裂先端近傍の両振り塑性域寸法の測定, 日本船舶海洋工学会 平成29年秋季講演会, 2017.11. |
| 76. | Yoshifumi TAKAKI, Koji GOTOH, Weight Function for Stress Intensity Factor of a Surface Crack with a Wide Range of Aspect Ratio on Crack Shape, 31st Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2017), 2017.09, The weight function of stress intensity factor is useful to determining stress intensity factor under arbitrary stress field. In addition, the crack opening profile under arbitrary stress field can be determined by the reciprocity theorem concerning crack opening by Paris with the weight function of stress intensity factor. Although many weight functions for a through thickness crack were proposed, the weight function for a surface crack is insufficient because of the limitation of applicable crack shape. By considering that many cracks found in in-service welded structures are surface cracks, it is expected to develop the weight function for a surface crack with a wide range on crack shape. One of authors had proposed practical formulae of the weight function for a surface crack based on the expression of the weight function by Wang and Glinka. However, previous expression of the weigh function could not be applied in case of the deep crack of which the aspect ratio (crack depth / half crack length) is greater than 1.0. Expansion of the weight function for a deep surface crack and minor modifications for previous weight function are conducted in this study. . |
| 77. | Koji MURAKAMI, Koji GOTOH, Practical Determination Method of the Threshold Stress Intensity Factor Range DKth, 31st Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2017), 2017.09, It is necessary to identify relationship between the fatigue crack propagation rate and the stress intensity factor range, if the fracture mechanics approach is applied to evaluate the fatigue crack growth evolution. In addition, identification of the stress intensity factor range of fatigue crack growth threshold DKth is important to evaluate the structural integrity from the view of fatigue performance. ASTM standard E647 “Standard Test Method for Measurement of Fatigue Crack Growth Rates” is widely known as a de fact standard to determine the value of DKth. However, a considerably long time is required to perform the determination of DKth. Therefore, it is expected to shorten the experimental period for determination of DKth. Efficient and time saving method for determining DKth comparing with ASTM-E647 is proposed in this study. Many fatigue crack propagation test data were adopted to verify our proposed method. It is expected to be able to complete the experiment for determining DKth at a stage where the fatigue crack propagation rate is one order larger than the test according to ASTM-E647.. |
| 78. | Masataka NAKAGAWA, Koji GOTOH, Koji MURAKAMI, Tomoaki UTSUNOMIYA, A study on the wear performance of the mooring chain for floating wind turbine, 31st Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2017), 2017.09, To promote the wind power generation plant on offshore area over the world, the floating wind turbine facility installed in the deep sea area plays an important role. However, one of challenging issues related to the practical application of the commercial level of the floating facility installed in the deep sea area is the quantitative evaluation of the wear behavior of the mooring chain, which is essential to reduce the maintenance and management costs of the floating structures. Therefore, it is necessary to establish a quantitative wear evaluation method for mooring chains. In this study, the experimental facility to reproduce the wearing phenomena occurring between links in actual scale due to the floating body motion caused by waves was constructed and the reproducibility of inter-links wear behavior was confirmed. Subsequently, wear tests under some inter-links tensile forces was performed and the different abrasion behavior was observed because of the different inter-links tensile forces. Besides, possiblility of the numerical simulation to reproduce the experiments by applying the nonlinear finite element analysis with measured wear characteristics of applied material was confirmed.. |
| 79. | TAkaaki TAKEUCHI, Tomoaki UTSUNOMIYA, Kimihiro TOH, Koji GOTOH, Development of Wear Estimation Method for Mooring Chain of Floating Structures, 31st Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2017), 2017.09, Wear estimation method for mooring chain of floating facilities has not been established, and it currently relies on empirical methods. In this research, an attempt was made to propose an estimation method for wear amount by combining 1) wear analysis between links of the mooring chain with finite element analysis and 2) response analysis of floating body-mooring system. In addition, comparison was made for the estimated wear amount by this method with the measured wear amount in the actual sea area, in order to reveal whether this method is useful or not. As a result, it was found that this method considerably overestimates the wear amount compared with the actual measurements. One of the main reasons were supposed that elastic deformation of the mooring chain and external forces caused by tidal, current and wind were not taken into consideration and variations in the wear coefficient were large.. |
| 80. | Ryuhei TAKESHITA, Yuki SUGINO, Naoki MORIHIRA, Koji GOTOH, Some consideration for Application of Laser-Arc Hybrid Welding in Hull Construction Stages, 31st Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2017), 2017.09, The shipbuilding industry in Japan is urgently required to develop and introduce advanced welding method to improve the efficiency of hull construction processes and the hull structural integrity and to reduce the production cost. Laser-arc hybrid welding, which has the advantages of laser welding and arc welding, is expected to improve productivity. However, some difficulties are concerned when laser-arc hybrid welding is applied for the construction stages of general merchant ships due to insufficient knowledge. In this study, two research topics, which were the residual stress distribution and the angular distortion in the full-penetration tee joint fabricated and the influence of groove cutting method on the quality of butt welded joint, were investigated. . |
| 81. | 内野 一成, 後藤 浩二, レーザ・アークハイブリッド溶接おけるビード形状およびスパッタに対する溶接条件の影響に関する一検討, 溶接学会 平成29年度 秋季全国大会, 2017.09. |
| 82. | 竹下 竜平, 杉野 雄輝, 森平 尚樹, 後藤 浩二, レーザ・アークハイブリッド溶接施工おけるギャップ裕度拡大に向けた一検討, 溶接学会 平成29年度 秋季全国大会, 2017.09. |
| 83. | Taizo YAMAMOTO, B. LIAN, Koji GOTOH, Relationship between Temperature Property and Loading Frequency of Rotating Bending Fatigue Testing Machine of Cantilever Type, Seventh International Conference on Very High Cycle Fatigue (VHCF 7), 2017.07, Fatigue property in gigacycle regime is focused as an important subject in recent years. In such a long-life region, a tremendous long period is required to perform the tests. To overcome this difficulty, a part of authors has been developing the new rotating bending fatigue testing machine, which enables to reduce the test period and cost drastically. It was confirmed that the fatigue test dates are consistent with many experimental results obtained by hydraulic tension and compression fatigue testing machines and the rotating bending fatigue test machines of both-handed type known as Ono type. Although it prefers to reduce the fatigue test period as short as possible, the maximum frequency of a rotating bending fatigue test is limited by the standards because of the possibility of local temperature rise in specimen caused by the cyclic plastic work and the heat transfer from fatigue testing machine. Such local temperature rise might affect the fatigue property. However, the appropriate loading frequency limit is unclear because of the difficulty of the temperature measurement in the fracture portion of a specimen precisely during the rotating bending fatigue test. An in-situ temperature measuring technique is proposed to measure the temperature at the fracture portion of the specimen in real time during the fatigue testing, and the validity to determine the loading frequency of a rotating bending fatigue testing machine is discussed in this study.. |
| 84. | Koji GOTOH, Koji MURAKAMI, Masataka NAKAGAWA, TOMOAKI UTSUNOMIYA, A Study on the Wear Performance of the Mooring Chain for Floating Wind Turbine, ASME 36th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2017), 2017.06, To produce offshore wind power generation plants, deep-sea floating wind turbine facilities are required. Commercial installation of floating wind turbine facilities requires a reduction of the mooring cost. Mooring chain breaks due to progressive wear will lead to enormous damages. Therefore, a quantitative wear evaluation method for mooring chains needs to be established. In this study, an experimental setup was constructed to reproduce the wearing phenomenon in mooring chains due to the motion of the floating body induced by waves, and its usefulness was confirmed. The result of the wear test conducted in this study suggests that the tensile force between links affects the degree of wear. Additionally, numerical simulations were performed using a finite element model with measured wear characteristics of the link material to reproduce the phenomenon of wear between links and confirmed that the wear phenomenon could be represented by numerical simulation.. |
| 85. | 内野 一成, 竹下 竜平, 後藤 浩二, レーザ・アークハイブリッド溶接を厚板に適用するための課題とその解決に向けた諸検討, 平成29年度溶接学会九州支部研究発表会, 2017.06, 近年，レーザ・アークハイブリッド溶接を造船の船体建造工程へと適用した事例が幾つか報告されているが，その適用箇所は居住区といった上部構造や客船・巡視船に限られており，一般商船の船体平行部に用いられる厚板への適用事例は皆無である1)-2)．また，厚板を施工するためには比較的高いレーザ出力が必要となるが，高出力なレーザ設備を有する研究機関は国内でも僅かであることから，高出力レーザとアークの組み合わせによって生じるハイブリッド溶接特有の問題点に関する知見も乏しく，無数の溶接パラメータから最適条件を導出することは難を極める．そこで本研究ではレーザ・アークハイブリッド溶接を一般商船の船体部に適用することをターゲットとした上で実用化に向けた課題の抽出，そして10kWを超えるレーザ出力を前提に各溶接パラメータの組合せが与える影響に関する基礎研究を行った．. |
| 86. | 竹下 竜平, 杉野 雄輝, 森平 尚樹, 後藤 浩二, レーザ・アークハイブリッド溶接における接合面性状が継手品質に及ぼす影響, 平成29年度溶接学会九州支部研究発表会, 2017.06, 造船所における切断工程で多用されているプラズマ切断及びガス切断により開先加工された鋼板を用い，ハイブリッド溶接により製作した継手に対しビッカース硬さ試験や断面マクロ観察等の継手評価を実施することで，継手品質に及ぼす接合面性状の影響を調査した．. |
| 87. | 森平 尚樹, 杉野 雄輝, 竹下 竜平, 後藤 浩二, レーザ・アークハイブリッド溶接における入熱効率の同定, 平成29年度溶接学会九州支部研究発表会, 2017.06, レーザ・アークハイブリッド溶接によりビードオンプレート溶接施工した時の母材の熱履歴を測定すると共に，入熱効率を未知変数とする最適化問題として取り扱い，高い探索性能が報告されている実数値GAである親子間完全世代交代モデルJGG及び多親交叉REXを用いて入熱効率を同定した．. |
| 88. | 武内 崇晃, 藤 公博, 宇都宮 智昭, 後藤 浩二, 浮体施設の係留チェーン摩耗量推定手法に関する検討, 日本船舶海洋工学会 平成29年春季講演会, 2017.05. |
| 89. | 小林 康高, 伊達 栄二, 金城 周三, 奈良 圭祐, 宇治野 史人, 成松 久雄, 平尾 和浩, 小出 剛史, 宇野 証悟, 熊川 一 彦, 河元 泰裕, 白澤 秀夫, 後藤 浩二, 三次元スキャナを用いた船体ブロック計測による工作精度評価に関する一考察, 日本船舶海洋工学会 平成29年春季講演会, 2017.05. |
| 90. | 後藤 浩二, 竹下 竜平, 津村 秀一, 成松 久雄, 内野 一成, 我が国の造船分野におけるレーザ・アークハイブリッド溶接技術導入に関する業界共同研究の動向 , 第86回レーザ加工学会講演会, 2016.12, 我が国造船業で主に建造される船種（主要部板厚15~20mm程度）への適用を可能とするレーザ・アークハイブリッド溶接技術に関して2012年度より業界共同研究が実施されおり，第一期研究の概要は第82回講演会において紹介した．本講演では2014年度以降の第二期研究で実施した，片側貫通完全溶込みT継手並びに板厚17mmの突合せ溶接継手の施工及び継手強度評価の概要を紹介する．また，著者の一部らによる，アングル材を用いた薄板防撓パネル製作に向けた基礎検討の状況も紹介する．. |
| 91. | 後藤 浩二, 村上 幸治, 中川 将孝, 宇都宮 智昭, 浮体式洋上風力発電施設係留鎖の耐摩耗性能評価に関する予備検討, 日本船舶海洋工学会 平成28年秋季講演会, 2016.11. |
| 92. | 高木 芳史, 後藤 浩二, 過大圧縮荷重作用時に生じる初期亀裂面閉口挙動を考慮した疲労亀裂伝播挙動, 日本船舶海洋工学会 平成28年秋季講演会, 2016.11. |
| 93. | 清水 啓司, 後藤 浩二, 穴井 陽祐, 丹羽 敏男, 位相差を有する二軸載荷条件を受ける面外ガセット溶接継手の疲労亀裂伝播解析, 日本船舶海洋工学会 平成28年秋季講演会, 2016.11. |
| 94. | Koji GOTOH, Koji MURAKAMI, Masataka NAKAGAWA, Tomoaki UTSUNOMIYA, Experimental Study on the Wear Performance of the Mooring Chain, Advanced Maritime Engineering Conference (AMEC) 2016 of 7th Pan Asian Association of Maritime Engineering Scoeties (PAAMES), 2016.10, To spread the wind power generation plant on offshore over the world, the floating wind turbine facility which is installed in the deep sea area is essential. One of the issues related to the practical application of the commercial level of the facility installed in the deep sea is the reduction of a mooring cost. Breaking the mooring chain in the floating wind turbine facility installed in the deep sea area by progressing the wear will lead to enormous damage. Therefore, it is necessary to establish a quantitative wear evaluation method for mooring chains. In this study, the experimental facility to reproduce the wearing phenomena in actual scale mooring chains due to the motion of floating body caused by waves was constructed and confirmed the usefulness of our developed machine. Besides, the numerical simulation to estimate the amount of wear was attempted by using the finite element analysis with measured wear characteristics of applied material.. |
| 95. | Keishi SHIMIZU, Koji GOTOH, Yosuke ANAI, Toshio NIWA, Numerical Simulation of Fatigue Crack Propagation in an Out-of-plane Gusset Welded Joints under Biaxial Tensile Loadings with Different Phases, 30th Asia Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2016), 2016.10, Most of in-service welded built-up structures, which contain many welded joints as fatigue crack initiation sites, are subjected to many types of loading and these loadings have different axial components with different phases. However, the structural integrities are evaluated according to design codes based on theoretical and experimental investigations under a uniaxial loading condition. Most of these codes are based on the S-N curves approach. On the other hand, some of authors proposed the numerical simulation method of fatigue crack propagation histories of a cracked plate subjected biaxial loadings with phase difference of each loading component. In this study, numerical simulation of fatigue crack propagation in an out-of-plane gusset welded joint under biaxial loading with two different phase conditions were performed. Estimated fatigue crack propagation histories were compared with measured crack evolution for verification of our method.. |
| 96. | 後藤 浩二, 福井 努, 森山 厚夫, 津村 秀一, 沢登 寛, Overview of a joint industrial project for introducing laser - hybrid welding to the construction of general merchant ships in Japan., 13th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2016), 2016.09, The introduction and application of advanced welding methods and information technologies are important to improving the efficiency of hull construction processes and to reducing production costs. Laser-arc hybrid welding technology, which has the advantages of laser and normal arc welding, has good performance and is expected to improve productivity. The Japan Ship Technology Research Association has organized a joint industry project in collaboration with universities, classification societies and shipyards to introduce this technology to the construction of general merchant ships. This paper gives an overview of the joint research project and introduces guide-lines on laser-arc hybrid welding published by ClassNK.. |
| 97. | 森影 康, 伊木 聡, 田川 哲哉, 大井 健二, 村上 幸治, 後藤 浩二, Effect of compressive residual stress on fatigue crack propagation., 13th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2016), 2016.09, Fatigue failures have sometimes taken place in weld joints due to stress concentration and tensile residual stress at the weld toe. Therefore some treatments for delaying fatigue crack initiation and propagation are necessary for the enhancement of the fatigue life of welded steel structures. The hammer peening process is well known as one of methods to improve the fatigue life of weld joints by generating the compressive residual stress field near the weld toe where recognized as the fatigue crack initiation site. With respect to the fatigue life improvement of the large welded structure which applied the compressive residual stress field near the weld toe, not only improvement of fatigue crack initiation life but also that of fatigue crack propagation life must be discussed. However there have been few research work which deal with the fatigue crack estimation in the compressive residual stress field so far In this study, mechanism of fatigue crack propagation in the compressive residual stress field was clarified by experimental observation of crack propagation from a surface crack after hammer peening. Morphology of a propagating surface crack in plate and gusset weld joint specimens were measured by the beach mark method. As a result, it was clarified that morphology of surface crack propagated in the compressive residual stress field was different from that in neutral stress filed. And this phenomenon was clearly observed especially under the low stress intensity factor condition. . |
| 98. | 内野 一成, 青柳 了太, 竹下 竜平, 後藤 浩二, レーザ・アークハイブリッド突合せ溶接施工におけるギャップ裕度拡大に向けた基礎検討, 平成28年度溶接学会九州支部研究発表会, 2016.07, レーザ・アークハイブリッド溶接施工におけるルートギャップ裕度を広げるべく，サブマージアーク溶接では既知の工法であるセラミック製裏当て材と開先充填材（メタルパウダー）を，レーザ・アークハイブリッド溶接による突合せ継手製作に適用する新施工法の確立を目指し，実現性の評価及び課題抽出を行った．. |
| 99. | 高木 芳史, 後藤 浩二, 実亀裂面の亀裂閉口挙動を考慮した疲労亀裂伝播シミュレーション, 平成28年度溶接学会九州支部研究発表会, 2016.07, 初期亀裂面が接触する場合にも対応できるように亀裂開閉口モデル拡張し，平均応力の低い荷重条件, 平均応力が変動する条件, 航行中の船舶のホイッピング荷重履歴を模擬した荷重条件等において疲労亀裂伝播解析を実施し，実測結果との比較を行った．. |
| 100. | 中込 聡, 村上 幸治, 後藤 浩二, 片持ち式回転曲げ疲労試験による軽金属材料（A6N01とAZX611）母材及びそれらのFSW継手の疲労強度評価, 平成28年度溶接学会九州支部研究発表会, 2016.07, アルミニウム合金A6N01，難燃性マグネシウム合金AZX611及びそれぞれのFSW 継手の10^8回レベルまでの疲労強度を比較的短時間かつ，従来の試験方法に沿って実施可能な，片持ち梁式回転曲げ疲労試験機1)を用いて疲労強度評価を実施し，表面粗さの影響，小野式回転曲げ疲労試験及び軸疲労試験の試験結果との比較，母材とFSW継手の疲労強度比較を実施した．. |
| 101. | 清水 啓司, 後藤 浩二, 穴井 陽祐, 丹羽 敏男, 二軸繰返し応力を受ける面外ガセット継手の疲労亀裂伝播シミュレーション, 平成28年度溶接学会九州支部研究発表会, 2016.07, 位相差を有する二軸引張載荷を受ける面外ガセット溶接継手を対象に，著者らが提案した二軸載荷問題を近似的に単軸載荷問題に置き換える手法と，Toyosadaらによる等価分布応力法を用いた任意形状を有する亀裂材に対する疲労亀裂成長履歴の予測方法を活用することで，同継手における疲労亀裂成長履歴を推定した．. |
| 102. | Koji GOTOH, Shuichi TSUMURA, Fatigue Strength and Angular Distortion of the Full-Penetration Tee Type Joint Fabricated by One-Side Single-Pass Laser-Arc Hybrid Welding, ASME 35th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2016), 2016.06. |
| 103. | 竹下 竜平, 津村 秀一, 村上 幸治, 後藤 浩二, 堤 成一郎, レーザ・アークハイブリッド溶接により製作された完全溶込み T 継手に生じる溶接残留応力, 日本船舶海洋工学会 平成28年春季講演会, 2016.05. |
| 104. | 山下 紘平, 後藤 浩二, 表面亀裂に対する亀裂結合力モデル構築に向けた基礎検討, 日本船舶海洋工学会 平成28年春季講演会, 2016.05. |
| 105. | 津村 秀一, 青柳 了太, 後藤 浩二, レーザ・アークハイブリッド溶接を対象としたレーザ溶接による仮付け溶接の有用性に関する検討, 日本船舶海洋工学会 平成27年秋季講演会, 2015.11. |
| 106. | 宇都宮 智昭, 後藤 浩二, 北 勝利, 小林 修, 佐藤 郁, 高野 裕文, 岩下 智也, 浮体式洋上風力発電施設における係留コストの低減に関する開発・実証について, 日本船舶海洋工学会 平成27年秋季講演会, 2015.11. |
| 107. | 山下 紘平, 後藤 浩二, 弾塑性有限要素解析を用いた疲労亀裂伝播シミュレーションと塑性ひずみエネルギの蓄積を考慮した疲労亀裂伝播則の一検討, 日本船舶海洋工学会 平成27年秋季講演会, 2015.11. |
| 108. | Yasushi MORIKAGE, Satoshi IGI, Kenji OI, Yuichiro JO, Koji MURAKAMI, Koji GOTOH, Effect of Compressive Residual Stress on Fatigue Crack Propagation, 14th International Conference on Pressure Vessel Technology (ICPVT-14), 2015.09, Fatigue failures have sometimes taken place in weld joints due to stress concentration and tensile residual stress at the weld toe. Therefore managements of fatigue crack initiation and propagation contribute to the enhancement of the fatigue life of welded steel structures. The hammer peening process is well known as one of methods to improve the fatigue life of weld joints by generating the compressive residual stress field near the weld toe where recognized as the fatigue crack initiation site. With respect to the fatigue life estimation of the welded steel structure which applied the compressive residual stress field near the weld toe, it is important not only fatigue life estimation for the fatigue crack initiation but also that for the fatigue crack propagation. However there is few research work which deal with the fatigue crack estimation in the compressive residual stress field. In this study, mechanism of fatigue crack propagation in the compressive residual stress field was clarified by experimental observation of crack propagation from a surface crack after hammer peening. Morphology of a propagating surface crack in plate and gusset weld joint specimens were measured by the beach mark method. As a result, it was clarified that morphology of surface crack propagated in the compressive residual stress field was different from that in neutral stress filed. And this phenomenon was clearly o. |
| 109. | 森影 康, 伊木 聡, 大井 健次, 城 雄一郎, 村上 幸治, 後藤 浩二, 疲労き裂進展抑制に及ぼす圧縮残留応力の影響, 溶接学会 平成27年度秋季全国大会, 2015.09. |
| 110. | 佐々木 陽一, 後藤 浩二, 水谷 由美, 松尾 正人, 工学系グローバル・オープンイノベーション人材育成プログラムに参加して －九州大学工学部教育プログラムELEPおよびプログラム参加後の活動について－, 平成27年度工学教育研究講演会, 2015.09. |
| 111. | Koji GOTOH, Yumi MIZUTANI, Akinori YOSHIDA, Masato MATSUO, Engineering Leaders English Program (ELEP) for Engineering Students - Overview of Education Program in School of Engineering in Kyushu University - , 2015 JSEE Annual Conference, 2015.09, Overview of the education program, Engineering Leaders English Program (ELEP) in School of Engineering in Kyushu University is briefly introduced. ELEP was established to enhance the globalization and to cultivate the entrepreneurship of Japanese students, especially from the viewpoint of science and engineering fields. Customized English training program and the exercises of startup proposal are provided to achieve the objective of this program.. |
| 112. | 津村 秀一, 岩田 知明, 村上 睦尚, 藤本 修平, 後藤 浩二, レーザ・アークハイブリッド溶接により製作された造船用鋼溶接継手の強度評価, 溶接学会 平成27年度秋季全国大会, 2015.09. |
| 113. | 清水 啓司, 村上 幸治, 後藤 浩二, 重畳応力履歴下における疲労亀裂発生挙動に関する一検討, 平成27年度溶接学会九州支部研究発表会, 2015.07, 近年，船舶・海洋構造物の構造健全性評価に関し，複数周波数成分が重畳した載荷履歴条件下における疲労強度評価の必要性が指摘され，これに関する研究が数多く実施されているが，多くの場合はS-N曲線と線形累積損傷側に基づく方法であり，疲労亀裂発生挙動を定量的に検討した事例は著者らの知る限りでは報告されていない． 本報告では，著者の一部らが重畳応力履歴条件下における疲労亀裂伝播挙動に関して亀裂伝播に有効に寄与する応力成分の抽出方法を，豊貞らにより提案された無亀裂状態から第一結晶粒界に到達するまでの間の微視疲労亀裂の成長挙動評価手法を組み合わせることで，重畳応力履歴条件下における疲労亀裂発生挙動を検討した結果について紹介する．. |
| 114. | Yosuke ANAI, Toshio NIWA, Koji GOTOH, Practical Formula of the Shape Evolution of a Surface Crack Under Fatigue Loading, ASME 34th International Conference on Ocean, Offshore and Arctic Engineering, 2015.06, Fatigue life estimation for planar cracks, e.g. part-through surface cracks or embedded cracks is very important because most of fatigue cracks found in welded built-up structures show planar crack morphologies. Although authors had proposed the estimation procedure of crack shape evolution for a planar crack based on the fracture mechanics approach, this method cannot apply if the values of stress intensity factor at the vertices of the surface crack approximated as an ellipse cannot calculated. Then, development of the shape evolution procedure of a planer crack under the stress field with arbitrary gradient, because fatigue cracks in welded built-up structures exist near the stress concentrated region. A Practical estimation formula the shape evolution of a surface crack under stress field with the gradient is proposed in this study. This formula is established by considering the stress field under no crack condition and some former proposed formulae under uniform and pure bending stress fields. The validity of the proposed formula are confirmed by comparing some measured surface crack shape evolutions under some stress gradient conditions.. |
| 115. | Koji GOTOH, Practical Evaluation of the Strain Rate and Temperature Effects on Fracture Toughness of Steels, ASME 34th International Conference on Ocean, Offshore and Arctic Engineering, 2015.06, Overview of the quantitative evaluation procedure of strain rate and temperature effects on fracture toughness proposed by the authors is introduced. Important concept of former researches is that the fracture toughness is a function of the strain rate-temperature parameter (R), which enables to unify both strain rate and temperature effects for the mechanical properties of materials. Using this knowledge, the equivalent temperature shift values at arbitrary strain rate from static loading condition are proposed.. |
| 116. | 松田 和貴, 後藤 浩二, 複数周波数成分を有する重畳応力履歴の単一周波数応力履歴への置き換えに関する一考察, 日本船舶海洋工学会 平成27年春季講演会, 2015.05. |
| 117. | 森影 康, 伊木 聡, 大井 健次, 城 雄一郎, 村上 幸治, 後藤 浩二, 疲労き裂進展抑制に及ぼす圧縮残留応力の影響, 日本船舶海洋工学会 平成27年春季講演会, 2015.05. |
| 118. | 穴井 陽祐, 丹羽 敏男, 江島 翔太, 後藤 浩二, 単一疲労表面亀裂の成長挙動に関する研究, 日本船舶海洋工学会 平成27年春季講演会, 2015.05. |
| 119. | 津村 秀一, 村上 幸治, 後藤 浩二, レーザ・アークハイブリッド溶接法により製作された完全溶込み T 継手の疲労強度, 日本船舶海洋工学会 平成27年春季講演会, 2015.05. |
| 120. | 後藤 浩二, 津村 秀一, 内野 一成, 船体建造工程におけるレーザ・アークハイブリッド溶接技術の適用に向けた基礎検討, LMPシンポジウム2015, 2015.02, 船舶建造工程の生産性を高めるために，日本財団の助成を受け2012～2013年度に造船業界共同研究プロジェクトとして実施された，我が国造船業で主に建造される船種（主要部板厚15~20mm程度）への適用を可能とするレーザ・アークハイブリッド溶接技術に関する調査研究の概要のうち，継手強度の評価及び実証試験（溶接長5m）の概要を紹介する． Overview of a joint industry project concerning the application of laser-arc hybrid welding to shipbuilding, which was carried out from 2012 to 2013 and supported by The Nippon Foundation, is described. Mainly, the evaluation of structural integrities of welded joints which were made of steel plates with a thickness of about 15-20mm and fabricated by hybrid welding are reported in this paper. Plate thicknesses adopted in this JIP corresponds to the thickness of the main structures of the ship that are mainly built in Japanese shipyard. It is expected that the advantage of laser-arc hybrid welding comparing conventional arc welding applied by current shipyards in Japan enables to improve the hull construction accuracy.. |
| 121. | 後藤 浩二, 津村 秀一, 内野 一成, 造船分野におけるレーザ・アークハイブリッド溶接技術導入に向けた共同研究について , 第82回レーザ加工学会講演会, 2015.01, 船舶建造工程の生産性を高めるために，日本財団の助成を受け2012～2013年度に造船業界共同研究プロジェクトとして実施された，我が国造船業で主に建造される船種（主要部板厚15~20mm程度）への適用を可能とするレーザ・アークハイブリッド溶接技術に関する調査研究の概要のうち，継手強度の評価及び実証試験（溶接長5m）の概要を紹介する． Overview of a joint industry project concerning the application of laser-arc hybrid welding to shipbuilding, which was carried out from 2012 to 2013 and supported by The Nippon Foundation, is described. Mainly, the evaluation of structural integrities of welded joints which were made of steel plates with a thickness of about 15-20mm and fabricated by hybrid welding are reported in this paper. Plate thicknesses adopted in this JIP corresponds to the thickness of the main structures of the ship that are mainly built in Japanese shipyard. It is expected that the advantage of laser-arc hybrid welding comparing conventional arc welding applied by current shipyards in Japan enables to improve the hull construction accuracy.. |
| 122. | 松田 和貴, 後藤 浩二, 等価疲労応力を用いた複数周波数成分を有する変動荷重条件下における疲労亀裂伝播挙動解析, 溶接構造シンポジウム2014, 2014.12. |
| 123. | 津村 秀一, 村上 幸治, 後藤 浩二, レーザ・アークハイブリッド溶接により製作されたT継手に生じる角変形に関する一検討, 溶接構造シンポジウム2014, 2014.12. |
| 124. | 大沢 直樹, 後藤 浩二, 中村 哲也, 重畳応力履歴条件下における疲労強度評価に関する研究の現状について, 日本船舶海洋工学会2014年秋季講演会, 2014.11. |
| 125. | 深沢 塔一, 大沢 直樹, 後藤 浩二, 小川 剛孝, 疲労損傷報告に対するカウンターチェックリストの提案, 日本船舶海洋工学会2014年秋季講演会, 2014.11. |
| 126. | 出口 純一, 後藤 浩二, 過大ギャップを有する荷重非伝達すみ肉溶接 T 継手の疲労強度に関する一検討, 日本船舶海洋工学会2014年秋季講演会, 2014.11. |
| 127. | Shuichi TSUMURA, Koji MURAKAMI, Koji GOTOH, Fatigue strength of laser arc hybrid welded T-joint under full penetration welding, 28th Asian Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM2014), 2014.10. |
| 128. | Kazuki MATSUDA, Koji MURAKAMI, Koji GOTOH, Numerical simulation of fatigue crack propagation under superimposed loading histories - Mean stress effect for fatigue crack propagation -, 28th Asian Pacific Technical Exchange and Advisory Meeting on Marine Structures (TEAM2014), 2014.10, Fatigue crack propagation behavior under superposed loading histories which have various mean stresses is highlighted. Numerical simulation of fatigue crack propagation based on an advanced fracture mechanics approach using the RPG (Re-tensile Plastic zone Generating) load criterion for fatigue crack propagation is improved to enable the extraction of the effective loading history. The critical value of the plastic hysteresis for the stress versus strain relationship occurring in the vicinity of a crack tip is defined as the control parameter for extracting the effective loading history. Fatigue crack propagation tests under various superimposed loading conditions were performed and comparison of fatigue crack propagation curves obtained from the improved numerical simulations, with the measurements is performed. These comparisons show the validity of the proposed procedure for extracting the effective loading history from the superposed loading history containing different frequencies. Subsequently, traditional cumulative fatigue damage evaluation is conducted and consider the tendency of fatigue damage value affected by mean stresses.. |
| 129. | 内野 一誠, 津村 秀一, 濵崎 俊之, 後藤 浩二, レーザ・アークハイブリッド溶接の船体構造への適用に向けた基礎検討, 溶接学会九州支部研究発表会, 2014.07. |
| 130. | Koji GOTOH, Toshio NIWA, Yosuke ANAI, Fatigue crack growth behaviour of an out-of-plane gusset welded joints under biaxial tensile loadings with different phases, 20th European Conference on Fracture (ECF 20), 2014.07, [URL], Most of in-service welded built-up structures, which contain many welded joints as fatigue crack initiation sites, are subjected to many types of loading and these loadings have different axial components with different phases. However, the structural integrities are evaluated according to design codes based on theoretical and experimental investigations under a uniaxial loading condition. Most of these codes are based on the S-N curves approach. On the other hand, authors proposed the numerical simulation method of fatigue crack propagation histories of a cracked plate subjected biaxial loadings with phase difference of each loading component. Fracture mechanics approach is applied to establish our method. In this study, fatigue crack growth behaviour of an out-of-plane gusset welded joint under biaxial loading with two different phase conditions were investigated. The phase difference effect for fatigue crack shape evolution under biaxial loading was confirmed by measured ones. Besides, comparisons of measured crack evolution with the numerical simulation results were performed to validate of our fatigue crack growth simulation for welded joints.. |
| 131. | Ezzarhan Abdullah, Koji GOTOH, Effect of Gap Size on the Fatigue Performance of Non-Load-Carrying Fillet Welded Joint, 24th International Ocean and Polar Engineering Conference (ISPOE 2014), 2014.06, In the present study, the fatigue performance of the welded joint made by CO2 gas shielded welding with different gap sizes is investigated to obtain one of the supporting materials to modify the construction quality standards. Allowable limits on the gap size of welded joints is specified in many construction quality standards based on experimental and empirical results from the welded joints made by manual metal arc welding. The fatigue test results for the welded specimen with gap presents higher performance compared to the fatigue design S-N curves proposed by the International Institute of Welding (IIW).. |
| 132. | Kohei YAMASHITA, Koji GOTOH, Numerical Simulation of Fatigue Crack Propagation and Crack Opening and Closing Model by Considering the Strain-hardening Effect of Materials, 24th International Ocean and Polar Engineering Conference (ISPOE 2014), 2014.06, This paper presents an improved simulation procedure for fatigue crack growth based on the strip yield model with a weight function. The authors developed the numerical simulation model of fatigue crack growth by considering the strain hardening effect of materials using the modified strip yield model. Numerical simulations of fatigue crack growth under many types of loading are performed to investigate the validity of our new proposed model. Comparison of proposed simulation results with previous results and with experimental measurements confirms the superiority of the proposed method.. |
| 133. | Shuichi YAMATOKI, Yoshitaka HAMAMOTO, Koji GOTOH, Evaluation of the Stress Magnification Factor in Angled Discontinuities of Longitudinal Stiffeners, ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2014), 2014.06, In ship hull design, longitudinal stiffeners may be twisted or knuckled to keep the continuity of strength along the vessel. This occurs at angled discontinuities such as discontinuous connections at the transverse web between two longitudinal stiffeners having different angles, e.g., a side shell longitudinal stiffener in the rounded part of the ship’s hull. Although the criteria for selection of “twist”, “knuckle”, or “angled discontinuity” as it is should be strength criteria, there are no generalized criteria or published systematic studies, and ship hull designers usually depend on experimental rules. In this study we evaluate and compare the stress magnification factors and define the relative ratio between the stresses in the discontinuity and continuity structures by using finite element analysis from a strength-of-materials point of view. Our results show that under lateral load conditions the stress factor is larger in the twist structure than in the angled discontinuity structure, although under axial load conditions the stress factor in the knuckle and angle discontinuity structures is larger than in the twist structure. Additionally, we propose a formula that estimates the factor in the knuckle structure based on the strength-of-materials approach.. |
| 134. | Koji GOTOH, Masao TAKUNO, Koichi OKADA, Sadaharu KUSUBA, Numerical Simulation of Fatigue Crack Growth of a Welded Structural Component under Block Program Fatigue Test, ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2014), 2014.06, Numerical simulations of fatigue crack growth of welded structural component were performed under fatigue testing conditions with block loading and constant stress range and the fatigue crack growth profiles were measured under the same loading conditions. In the experiments, fatigue cracks developed at the boxing fillet welded toe and grew toward the top flange plates of the specimens. An advanced fracture mechanics approach based on the improved effective stress intensity factor range, which is the RPG (Re-tensile Plastic zone Generating) stress criterion, was applied to perform the numerical simulations of fatigue crack growth in the modeled components. A comparison of estimated fatigue crack growth profiles with measured ones verified that a reasonable estimation of fatigue crack growth can be estimated by applying the proposed numerical method.. |
| 135. | 山下 紘平, 江島 翔太, 後藤 浩二, 表面亀裂を対象とした亀裂結合力モデルと疲労亀裂伝播シミュレーション , 日本船舶海洋工学会2014年春季講演会, 2014.05. |
| 136. | 松田 和貴, 村上 幸治, 後藤 浩二, 重畳応力条件下における疲労亀裂伝播挙動解析 －（第二報）応力振幅及び平均応力変動の伝播挙動に及ぼす影響に関する検証－, 日本船舶海洋工学会2014年春季講演会, 2014.05. |
| 137. | 山下 紘平, 後藤 浩二, 構造用鋼に対する疲労亀裂伝播則の材料定数のばらつきに関する一考察 , 日本船舶海洋工学会2014年春季講演会, 2014.05. |
| 138. | 宅野 正夫, 岡田 公一, 楠葉 貞治, 後藤 浩二, ブロック変動荷重を受ける溶接構造物の疲労亀裂成長挙動評価, 日本船舶海洋工学会2013年秋季講演会, 2013.11. |
| 139. | Ezzarhan Abdullah, 後藤 浩二, Numerical Study of Fatigue Performance of Butt Welded Joint with U and V-notch Undercut , 日本船舶海洋工学会2013年秋季講演会, 2013.11. |
| 140. | 山下 紘平, 後藤 浩二, 材料の加工硬化特性を考慮したき裂結合力モデルに基づくき裂開閉口モデルと疲労き裂伝播解析 , 日本船舶海洋工学会2013年秋季講演会, 2013.11. |
| 141. | Koji GOTOH, Kazuhiro AOYAMA, Comparison of Hull Construction Quality Standards, 12th International Symposium of Practical Design of Ships and Other Floating Structures (PRADS 2013), 2013.10, Hull construction deviations are controlled according to the shipbuilding standards which are established by each societies or the international association of classification societies (IACS) to maintain the structural integrity of hull constructions. However, most of these quality standards are not revised even though the hull structural design, the welding techniques and materials, the hull materials have been developing. Then, the improvement of hull construction quality standards is expected by considering the development of shipbuilding technologies. Comparison of nine hull construction quality standards is conducted in this report. Although these comparisons cannot find out significant difference among the standards, some characteristics and the historical background of each standard are confirmed and recommended revised parts of the quality standards are confirmed.. |
| 142. | 山下 紘平, 後藤 浩二, 材料の加工硬化特性を考慮した亀裂結合力モデルに基づく疲労亀裂伝播解析, 溶接学会九州支部研究発表会, 2013.07, 材料の加工硬化現象を考慮できるように改善した亀裂結合力モデルを，疲労亀裂開閉口シミュレーションに実装することで，変動荷重履歴条件下での疲労き裂伝播挙動推定精度の向上を試みた結果を報告した． . |
| 143. | Shuichi YAMATOKI, Seitaro ARIMATSU, Koji GOTOH, Misalignment Effect on a Three-Dimensional Cruciform Welded Joint, ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2013), 2013.06, In the ship-hull design phase, the distance of a misalignment of a cruciform welded joint is enlarged, by up to 100 mm for example, until its effect is thought to be minimized. To control tolerance, we used a technique to estimate the coefficient of the misalignment effect: the ratio of the stress with misalignment to stress without misalignment. Current methods, created using the two-dimensional (2D) misalignment model and focusing on small misalignments, cannot be applied in the design phase. Misalignment models are needed, as there have been no studies of these joints and it is impractical to do finite element (FE) analysis in each case. We propose an estimation method of the coefficient of misalignment effect in three dimensions (3D). First, we created a new equation to estimate the coefficient in 2D. The equation accommodates larger misalignments. Second, we found the membrane component of a misaligned member stress is reduced as a 3D effect and the coefficient converges given a certain misalignment value. Third, a modified equation taking the effect into account indicates the coefficient in 3D. . |
| 144. | Koji GOTOH, Toshio NIWA, Yosuke ANAI, Tetsuya OMORI, Yoshihisa TANAKA, Koji MURAKAMI, Fatigue Crack Propagation under Biaxial Tensile Loading, - Effect of the Phase Difference on Biaxial Loading -, ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2013), 2013.06, Fatigue crack propagation under biaxial tensile loading is highlighted in this study. Ships and offshore structures are subjected to many types of loading, e.g. wave induced forces, gravity, and inertia forces. Generally, these loadings have different axial components with different phases. However, the structural integrities of structures and vessels are evaluated according to design codes based on theoretical and experimental investigations under a uniaxial loading condition. Most of these codes are based on the S-N curves approach. An approach that does not use S-N curves has been favored by researchers, with the fracture mechanics approach preferred for evaluating the fatigue life of structures. An advanced fracture mechanics approach was developed based on the Re-tensile Plastic zone Generating (RPG) stress criterion for fatigue crack propagation. In this study, fatigue crack propagation tests under biaxial loading with four different phase conditions are performed and the effect of the phase difference under biaxial loading is evaluated. A numerical simulation method of fatigue crack propagation based on the RPG stress criterion under different biaxial loading phase conditions is presented and compared to measured data.. |
| 145. | Kazuki MATSUDA, Koji GOTOH, Numerical Simulation of Fatigue Crack Propagation under Simulated Whipping Loading Arising in Hull Structures, ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2013), 2013.06, Fatigue crack propagation behavior under simulated whipping loadings which contain two different frequency components is highlighted. Numerical simulation of fatigue crack propagation based on an advanced fracture mechanics approach using the RPG (Re-tensile Plastic zone Generating) stress criterion for fatigue crack propagation is improved to enable the extraction of the effective loading history. The critical value of the plastic hysteresis for the stress versus strain relationship occurring in the icinity of a crack tip is defined as the control parameter for extracting the effective loading history. Comparison of fatigue crack propagation curves obtained from the improved numerical simulations with the measurements which were conducted by Sumi (2010) is performed. These comparisons show the validity of the proposed procedure for extracting the effective loading history from the superposed loading history containing different frequencies. In addition, imperfection of the S-N curves approach, which corresponds to the combination of the linear cumulative damage law and the loading cycle count by the rain flow method, is conducted.. |
| 146. | Ezzarhan Abdullah, 後藤 浩二, Practical Formula of Stress Concentration Factor for Butt Welded Joint with Undercut, 日本船舶海洋工学会2013年春季講演会, 2013.05. |
| 147. | 津村 秀一, 後藤 浩二, FE解析による側面すみ肉溶接継手の静的強度評価, 日本船舶海洋工学会2013年春季講演会, 2013.05. |
| 148. | 松田 和貴, 村上 幸治, 杉野 弘樹, 後藤 浩二, 重畳応力条件下における疲労き裂伝播挙動解析 －平均応力の伝播挙動に及ぼす影響に関する検証－, 日本船舶海洋工学会2013年春季講演会, 2013.05. |
| 149. | 日本貴 秀一, 後藤 浩二, ナックルモデルにおける応力変化に対する幾何形状の影響に関する一考察, 日本船舶海洋工学会2013年春季講演会, 2013.05. |
| 150. | 後藤浩二，赤星直紀, 任意ひずみ速度・温度条件下における応力－ひずみ関係推定手法の高精度化, 日本船舶海洋工学平成24年秋季講演会, 2012.11. |
| 151. | 日本貴秀一，有松征太郎，後藤浩二, 目違いによる応力上昇率の推定に関する一考察, 日本船舶海洋工学平成24年秋季講演会, 2012.11. |
| 152. | 日本貴秀一，有松征太郎，後藤浩二, 目違いに起因する強度低下に及ぼす荷重様式及び介在板厚の影響に関する一考察（第三報）, 日本船舶海洋工学平成24年秋季講演会, 2012.11. |
| 153. | 村上幸治，後藤浩二, 下限界応力拡大係数範囲ΔKth の同定方法に関する一考察, 日本船舶海洋工学平成24年秋季講演会, 2012.11. |
| 154. | 松田和貴，辻隆太郎，村上幸治，後藤浩二, せん断型から開口型に至る疲労き裂成長履歴推定手法の実験的検証, 日本船舶海洋工学平成24年秋季講演会, 2012.11. |
| 155. | 後藤浩二，丹羽敏男，穴井陽祐，大森徹也，田中義久, 二軸載荷条件下における疲労き裂伝播挙動 （第1 報）疲労き裂伝播挙動におよぼす位相差の影響, 日本船舶海洋工学平成24年秋季講演会, 2012.11. |
| 156. | 山下紘平，松田和貴，後藤浩二, 材料の加工硬化現象を考慮した疲労き裂伝播シミュレーション, 日本船舶海洋工学平成24年秋季講演会, 2012.11. |
| 157. | 山下紘平，松田和貴，後藤浩二, 材料の加工硬化現象を考慮した疲労き裂伝播シミュレーション, 日本船舶海洋工学平成24年秋季講演会, 2012.11. |
| 158. | Koji GOTOH, Kazuki MATSUDA and O Kitamura, NUMERICAL SIMULATION OF FATIGUE CRACK PROPAGATION UNDER SUPERPOSED LOADING HISTORIES WITH TWO DIFFERENT FREQUENCIES, 6th International Conference on HYDROELASTICITY in Marine Technology, 2012.09, Fatigue crack propagation behaviour under superposed loading histories which contain two different frequency components is highlighted. Numerical simulation of fatigue crack propagation based on an advanced fracture mechanics approach using the RPG (Re-tensile Plastic zone Generating) load criterion for fatigue crack propagation is improved to enable the extraction of the effective loading history. The critical value of the plastic hysteresis for the stress versus strain relationship occurring in the vicinity of a crack tip is defined as the control parameter for extracting the effective loading history. Comparison of fatigue crack propagation curves, obtained from the improved numerical simulations, with the measurements under the superposed loading histories, is performed. These comparisons show the validity of the proposed procedure for extracting the effective loading history from the superposed loading history containing different frequencies.. |
| 159. | Kohei YAMASHITA, Kazuki MATSUDA and Koji GOTOH, Numerical Simulation of Fatigue Crack Growth Based on the Strip Yield Model Considering the Strain Hardening Effect of Materials, The 26th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures , 2012.09, This paper presents an improved numerical simulation procedure for fatigue crack growth based on the strip yield model with a weight function. In the previous numerical model, one-dimensional bar elements plugged up the chink corresponding to the virtual crack opening displacement in the plastic zone to describe the crack wake over fatigue crack surfaces. However, this numerical simulation method gives poor growth estimations under large variable loading histories, e.g. spike overloading. It is possible that insufficient consideration of the strain hardening effect of materials leads to excess crack closure. The authors develop the numerical simulation model of fatigue crack growth by considering the strain hardening effect of materials using the modified strip yield model. Numerical simulations of fatigue crack growth under many types of loading are performed to investigate the validity of our new proposed model. Comparison of proposed simulation results with previous results and with experimental measurements confirms the superiority of the proposed method.. |
| 160. | Syuichi TSUMURA and Koji GOTOH, Strength evaluation of the Side Fillet Welded joints by FE analysis, The 26th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures , 2012.09, It is well known that the strength capacity of the side fillet welded joints loses as its weld length becomes longer. An analytical expression of the stress distribution over the throat section along weld length was given by Troelsch. His expression indicates that the stress along weld length shows peak values at both weld ends and decreases toward the mid position of weld length and that the weld bead except both end portions has little contribution as the load carrying components. Then, it is conducted that prolonging the weld length of side fillet welded joints is meaningless to improve the structural integrity of the joints. However, the effect of geometrical conditions, e.g. the size of leg length of fillet weld or dimensions of width and breadth of straps, was not considered in Troelsch’s expression. Authors carried out some finite element calculations to investigate the effect of geometrical conditions on the mechanical behavior of the side fillet welded joints. Comparison FE results of the stress distribution over the throat section along weld length with ones obtained by Troelsch’s analytical expression. These comparisons conduct that the allowable geometrical condition of Troelsch’s expression and some knowledge of the mechanical behavior of the side fillet welded joints.. |
| 161. | Syuichi YAMTOKI, Seitaro ARIMATSU and Koji GOTOH, Effect of Loading Mode and Thickness of an Intercalated Plate on Strength Degradation Caused by Misalignment, The 26th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structures , 2012.09, Multiple criteria concerning the misalignment of cruciform welded joints have been published and usually applied in ship-hull construction. These criteria only adopt a 2D model with axial load and generally do not consider the thickness of intercalated members. These are thought to be inapplicable to joints for which the misalignment is much larger than the thickness of a member. First, the authors investigate the way of stress increases by finite element (FE) analysis, and propose a new equation for strength-of-materials. Their results are in excellent agreement, thus validating the reliability of the equation in estimating stress variation from a misalignment. Second, 3D FE analyses of both the shell element and the solid element are described. By comparing the analytical results for both elements, the shell element is found to apply in misalignment analysis. Finally, by FE analyses of the shell element, the intercalated plate thickness is found to affect stress and the stress converges because of misalignment.. |
| 162. | 松田和貴，辻隆太郎，村上幸治，後藤浩二, RPG荷重基準に基づく疲労き裂発生評価モデルの実験的検証, 溶接学会九州支部研究発表会, 2012.07. |
| 163. | 津村秀一，後藤浩二，寺崎俊夫, 側面すみ肉溶接継手の静的強度に関する数値検討 （その1）Troelschの式に関する一考察, 溶接学会九州支部研究発表会, 2012.07. |
| 164. | Koji GOTOH and Keisuke HARADA, Improvement of Fatigue Crack Growth Simulation Based on the Strip Yield Model Considering the Strain Hardening Effect of Materials, 31st International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2012), 2012.07, This paper presents an improved numerical simulation procedure for fatigue crack growth based on the strip yield model with a weight function. In the previous numerical model, one-dimensional bar elements plugged up the chink corresponding to the virtual crack opening displacement in the plastic zone to describe the crack wake over fatigue crack surfaces. However, this numerical simulation method gives poor growth estimations under large variable loading histories, e.g. spike overloading. It is possible that insufficient consideration of the strain hardening effect of materials leads to excess crack closure. The authors develop the numerical simulation model of fatigue crack growth by considering the strain hardening effect of materials using the modified strip yield model. Numerical simulations of fatigue crack growth under many types of loading are performed to investigate the validity of our new proposed model. Comparison of proposed simulation results with previous results and with experimental measurements confirms the superiority of the proposed method.. |
| 165. | 後藤浩二，松田和貴, 複数周波数成分を有する重畳応力条件下における疲労き裂伝播挙動解析手法, 日本船舶海洋工学会春季講演会, 2012.05. |
| 166. | 後藤浩二，大田黒哲哉, 表面および埋没き裂の応力拡大係数重み関数に関する一提案, 日本船舶海洋工学会春季講演会, 2012.05. |
| 167. | 日本貴秀一，有松征太郎，後藤浩二, 目違いに起因する強度低下に及ぼす荷重様式及び介在板厚の影響に関する一考察（第二報）, 日本船舶海洋工学会春季講演会, 2012.05. |
| 168. | 内村秀之，宅野正夫，後藤浩二, ステンレスケミカルタンカーを模した十字継手の疲労寿命推定シミュレーション, 溶接構造シンポジウム2011, 2011.11. |
| 169. | 堤成一郎，大和真征，後藤浩二，Fionn DUNNE, 巨視的弾性繰り返し負荷条件下の軟化挙動に関する基礎的検討, 溶接構造シンポジウム2011, 2011.11. |
| 170. | 津川博光，真鍋圭，榎並靖之，中山祐蔵，町田定信，泉耕広，河野真嗣，後藤浩二, 船殻工作精度管理方法の効率化に向けた一考察, 日本船舶海洋工学会西部支部秋季講演会, 2011.11. |
| 171. | 日本貴秀一，有松征太郎，後藤浩二, 目違いに起因する強度低下に及ぼす荷重様式及び介在板厚の影響に関する一考察, 日本船舶海洋工学会西部支部秋季講演会, 2011.11. |
| 172. | 内村秀之，藤井一申，後藤浩二, ステンレスケミカルタンカーにおける荷重伝達型十字継手の疲労強度に関する一考察, 日本船舶海洋工学会西部支部秋季講演会, 2011.11. |
| 173. | Keisuke HARADA and Koji GOTOH, Improvement of the Dugdale Strip Yield Model Considering the Work Hardening Effect of Materials, The 25th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structure (TEAM 2011), 2011.09. |
| 174. | Kazuki MATSUDA, Hirokazu TAKAHASHI and Koji GOTOH, Numerical simulation of fatigue crack propagation under variable amplitude loading with different frequency components, The 25th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structure (TEAM 2011), 2011.09. |
| 175. | Hideyuki UCHIMURA, Koji MURAKAMI, Masao TAKUNO, Tetsuya OMORI and Koji GOTOH, Fatigue crack growth behaviour of austenitic stainless steels applied to the cargo tank of chemical carriers, The 25th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structure (TEAM 2011), 2011.09. |
| 176. | Koji GOTOH, Koji MURAKAMI, Masaru HASHIMOTO and Toshiaki IWATA, Fatigue crack growth behaviour of commercial pure titanium applied to hull structures, The 25th Asian-Pacific Technical Exchange and Advisory Meeting on Marine Structure (TEAM 2011), 2011.09. |
| 177. | Yosuke ANAI, Koji MURAKAMI and Koji GOTOH, A Conventional Growth Estimation Formula of the Representative Surface Crack Replacing Plural Surface Cracks Generated at the Sound Stress Concentration Site, International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM' 11), 2011.09. |
| 178. | 宮本大地，後藤浩二, 低圧ガス導管EFソケット継手融着長さの設定に関する基礎検討, 溶接学会九州支部 研究発表会, 2011.07. |
| 179. | 松田和貴，村上幸治，後藤浩二, RPG荷重基準に基づく疲労き裂発生評価モデルの実験的検証, 溶接学会九州支部 研究発表会, 2011.07. |
| 180. | Koji GOTOH, Keisuke HARADA and Yosuke ANAI, Estimation of the Shape Evolution and the Growth History of an Embedded Crack by Fatigue Loading , 30th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2011), 2011.06. |
| 181. | 穴井陽祐，村上幸治，後藤浩二, 応力集中部から発生する複数疲労表面き裂の成長評価法に関する研究 －広域から発生する複数疲労表面き裂への適用－, 日本船舶海洋工学会 平成23年春季講演会, 2011.05. |
| 182. | 後藤浩二，鵜池健, 二軸繰り返し応力場における疲労き裂成長シミュレーション手法に関する基礎検討, 日本船舶海洋工学会西部支部講演会, 2010.11. |
| 183. | 村上幸治，橋本勝，後藤浩二, 疲労き裂伝播試験規格ASTM-E647の妥当性に関する数値検討, 日本船舶海洋工学会西部支部講演会, 2010.11. |
| 184. | 原田圭輔，後藤浩二, 材料の加工硬化現象を考慮したき裂結合力モデルについて, 日本船舶海洋工学会西部支部講演会, 2010.11. |
| 185. | 後藤浩二，氏平直樹, 載荷速度の影響を考慮した高密度ポリエチレン管材料の応力～ひずみ関係, 日本船舶海洋工学会西部支部講演会, 2010.11. |
| 186. | 後藤浩二，高橋宏和, 重畳波負荷条件下における疲労き裂伝播挙動に関する数値検討, 日本船舶海洋工学会西部支部講演会, 2010.11. |
| 187. | Yoich Sumi, Hiroshi Yajima, Masahiro Toyosada, Takao Yoshikawa, Shuji Aihara, Toshiyuki Matsumoto, Kazuhiro Hirota, Hideyuki Hirasawa, Masanobu Toyoda and Koji Gotoh, Overview of Japanese Joint Research Project on Safety-Related Issue of Extremely Thick Steel Plate Applied to Large Container Ships, 11th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2010), 2010.09. |
| 188. | 橋本勝，村上幸治，後藤浩二, 疲労き裂伝播試験規格ASTM-E647における問題点の数値検討, 溶接学会九州支部 研究発表会, 2010.07. |
| 189. | Koji GOTOH and Keisuke HARADA, Numerical Simulation of Fatigue Crack Growth Based on Strip Yield Model Considering Work Hardening of Materials , 29th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2010), 2010.06. |
| 190. | 後藤浩二，豊貞雅宏，角洋一，北村欧，松本俊之，豊田昌信, 極厚鋼板溶接継手部の内在欠陥の疲労き裂成長と脆性破壊発生限界長さについて, 日本船舶海洋工学会講演会, 2010.06. |
| 191. | Seiichiro TSUTSUMI, Naoyuki YAMATO, Koji GOTOH and Fionn DUNNE, Clystal Plasticity FE Analysis on Initiation of Local-plastic Strain in Polycrystalline Metals, The 23rd Asian-Pacific Technical Exchange and Advisory Meeting on Marine Sturctures (TEAM 2009), 2009.12. |
| 192. | Keisuke HARADA, Hirokazu TAKAHASHI, Koji GOTOH and Masahiro TOYOSADA, Estimation of Shape Evolution and Growth History of a Fatigue Crack Emanating from an Embedded Elliptical Defect, The 23rd Asian-Pacific Technical Exchange and Advisory Meeting on Marine Sturctures (TEAM 2009), 2009.12. |
| 193. | Minoru NAKATA, Min Choel CHO and Koji GOTOH, Applicability Evaluation of Generalized Strip Yield Model, The 23rd Asian-Pacific Technical Exchange and Advisory Meeting on Marine Sturctures (TEAM 2009), 2009.12. |
| 194. | Yasuo NODA, Koji MURAKAMI and Koji GOTOH, Fatigue Crack Growth Behaviour of Aluminium Alloy A5083 Series and its Welded Joints, The 23rd Asian-Pacific Technical Exchange and Advisory Meeting on Marine Sturctures (TEAM 2009), 2009.12. |
| 195. | 堤成一郎，大和真征，後藤浩二，Fionn Dunne, 結晶塑性FE解析による巨視的弾性条件下の塑性ひずみ発生に関する考察, 日本船舶海洋工学会西部支部講演会, 2009.11. |
| 196. | 原田圭輔，後藤浩二，豊貞雅宏, 埋没き裂を起点とした疲労き裂の形状変化推定手法に関する検討, 日本船舶海洋工学会西部支部講演会, 2009.11. |
| 197. | 高橋宏和，後藤浩二, 表面・埋没き裂の応力拡大係数重み関数の同定について, 溶接構造シンポジウム2009, 2009.11. |
| 198. | Koji GOTOH and Yukinobu NAGATA, Improvement of Slice Synthesis Methodology to Estimate Stress Intensity Factor of an Embedded Crack in Finite body, The 12th International Conference on Fracture (ICF 12), 2009.07. |
| 199. | Koji GOTOH and Keisuke HARADA, Numerical Study of Enhancement of Fatigue Crack Propagation Life by Grain Refinement, The Nineteenth (2009) International Offshore and Polar Engineering Conference (ISOPE 2009), 2009.06. |
| 200. | Koji GOTOH and Yukinobu NAGATA, Applicability Evaluation of the Weight Function Based Strip Yield Model for an Embedded Crack Problem, The 28th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2009), 2009.06. |
| 201. | 永田幸伸，後藤浩二, き裂結合力モデルを用いた埋没き裂のき裂開口変位推定について, 日本船舶海洋工学会春季講演会, 2009.05. |
| 202. | 後藤浩二，永田幸伸，原田圭輔，門脇孝爾, 材料の加工硬化特性を考慮した疲労き裂伝播シミュレーション, 日本船舶海洋工学会春季講演会, 2009.05. |
| 203. | 後藤浩二，村上幸治，野田康男，秋月啓治，瀧本努, 船殻用アルミニウム合金A5083の疲労き裂伝播性能に関する基礎検討, 日本船舶海洋工学会春季講演会, 2009.05. |
| 204. | 永田幸伸，福留邦繁，後藤浩二, き裂結合力モデルの三次元き裂問題への拡張に関する基礎検討, 日本船舶海洋工学会西部支部秋季講演会, 2008.11. |
| 205. | CHO Min-Choel, KADOWAKI Koji, NAGATA Yukinobu and GOTOH Koji, Improvement of Equivalent Distributed Stress Methodology Applied to Numerical Fatigue Crack Growth Simulation, 8th International Welding Symposium (Organized by Japan Welding Society), 2008.11. |
| 206. | Koji GOTOH and Yukinobu NAGATA, Stress Intensity Factors for Three Dimensional Cracks by Applying Slice Synthesis Methodology, The Eighteenth (2008) International Offshore and Polar Engineering Conference (ISOPE 2008), 2008.07. |
| 207. | 永田幸伸，後藤浩二, Slice Synthesis Methodologyを用いた三次元き裂の応力拡大係数算定手法について, 日本船舶海洋工学会, 2008.05. |
| 208. | 後藤浩二，堤慎之介, き裂結合力モデルの切欠材への拡張に関する基礎的検討, 日本船舶海洋工学会, 2008.05. |
| 209. | Koji GOTOH, Ryohei KAWASHIMA and Masahiro TOYOSADA, A practical estimation of welding deformation in the assembly stage of hull panel structures, International Conference of Computational and Experimental Engineering and Sciences 2008 (ICCES'08), 2008.03. |
| 210. | Min-Choel CHO and Koji GOTOH, Applicability Limit of Generalized Strip Yield Model, Thrid Asia-Pacific Congress on Computational Mechanics in conjuction with Eleventh International Conference on Enhancement and Computational Methods in Engineering and Science (APCOM'07 in conjuction with EPMESC XI), 2007.12. |
| 211. | 後藤浩二，川嶋亮平，豊貞雅宏, 船殻パネル製作時に生じる溶接変形の推定について, 日本船舶海洋工学会西部支部, 2007.11. |
| 212. | Koji GOTOH, Yukinobu NAGATA and Masahiro TOYOSADA, Fatigue life estimation for a long through thickness cracks in large-scale specimen in imitation of hull skin plate, The Seventeenth (2007) International Offshore and Polar Engineering Conference, 2007.07. |
| 213. | Seiichiro TSUTSUMI, Masahiro TOYOSADA, Daiki YAJIMA, Koji MURAKAMI and Koji GOTOH, Cyclic Plasticity under Macroscopically Elastic Stress Condition, The Seventeenth (2007) International Offshore and Polar Engineering Conference, 2007.07. |
| 214. | 堤成一郎，村上幸治，矢嶋泰基，後藤浩二，豊貞雅宏, 巨視的弾性条件下で発現する疲労現象への適用を目的とした繰返し・損傷弾塑性モデル, 平成19年度溶接学会九州支部研究発表会, 2007.07. |
| 215. | 永田幸伸，原田圭輔，後藤浩二，豊貞雅宏, シェル要素によるFEM解析結果を用いた溶接止端部板厚方向応力分布推定手法 , 平成19年度溶接学会九州支部研究発表会, 2007.07. |
| 216. | 永田幸伸，福留邦繁，後藤浩二, 単一疲労表面き裂の形状変化推定手法に関する検討, 平成19年度溶接学会九州支部研究発表会, 2007.07. |
| 217. | 永田幸伸，門脇孝爾，後藤浩二，豊貞雅宏, 船体外板を想定した大型疲労試験片に対するき裂の成長解析, 平成19年度溶接学会九州支部研究発表会, 2007.07. |
| 218. | 後藤浩二，永田幸伸，豊貞雅宏, 疲労表面き裂の成長時における形状変化推定法について, 日本船舶海洋工学会春季講演会, 2007.05. |
| 219. | 後藤浩二，永田幸伸，豊貞雅宏, 船体外板を模擬した大型試験体における長大疲労き裂の成長予測, 日本船舶海洋工学会秋季講演会, 2006.11. |
| 220. | 穴井陽祐，村上幸治，後藤浩二，豊貞雅宏, 応力集中部から発生する複数疲労表面き裂の成長評価法に関する研究, 日本船舶海洋工学会秋季講演会, 2006.11. |
| 221. | Minchoel CHO, Koji GOTOH, Masahiro Toyosada, Plastic Constraint Factor for Compact Tension Specimens, The 20th Asian Technical Exchange and Advisory Meeting on Marine Structures (TEAM 2006), 2006.10, The strip yield model is a representative cohesive force model. Primitive strip yield model was applied to an infinitely wide plate with a crack or a centre cracked plate subjected to uniform remote tensile stress (CCT specimen). The strip yield model is extended for the plates with a through thickness crack subjected to arbitrary stress distributions. The plastic constraint factor is introduced to the strip yield model in order to ensure consistency with actual crack opening behaviours. Therefore, an appropriate value of plastic constraint factor must be obtained if the strip yield model is applied to evaluate crack opening behaviours. In this paper, the plastic constraint factor for compact tension (CT) specimen is investigated by comparing the crack opening profiles obtained by extended strip yield model with elastic-plastic finite element analyses. It makes clear that the extended strip yield model with an appropriate plastic constraint factor enables to be a good agreement with FE analyses. Plastic constraint factors for CT specimen are about twice of the factors for CCT specimen. It is considered that such a difference is derived from the difference of multi-axial stress state ahead of a crack tip between CT and CCT specimens.. |
| 222. | 後藤浩二，末田明，豊貞雅宏, 二重底コーナーブラッケット構造要素の疲労き裂発生・伝播挙動の解析について, 日本機械学会2006年度年次大会, 2006.09. |
| 223. | 後藤浩二，永田幸伸，豊貞雅宏, シェル要素を用いたFEM解析結果からの溶接止端板厚方向応力分布推定, 日本機械学会2006年度年次大会, 2006.09. |
| 224. | 豊貞雅宏，小沼恵太郎，田鵬程，後藤浩二, 仮想CODの物理的意味について, 日本機械学会2006年度年次大会, 2006.09. |
| 225. | 豊貞雅宏，後藤浩二, 等価分布応力概念と仮想単独表面き裂について, 日本機械学会2006年度年次大会, 2006.09. |
| 226. | 杉谷大輔，村上幸治，後藤浩二，豊貞雅宏, 切欠底に位置する結晶粒内でのき裂成長曲線について, 日本機械学会2006年度年次大会, 2006.09. |
| 227. | 豊貞雅宏，後藤浩二，藤村浩史，北條純一, 九州大学ものづくりスーパー中核人材育成事業：溶接設計コース, 平成１８年度 工業・工学教育研究講演会, 2006.07. |
| 228. | Keitaro KONUMA, Masahiro TOYOSADA and Koji GOTOH, Fatigue Damage at the Root of the Gatelip of the Water Gate Under Variable Water Pressure Due to Tide And Ocean Wave, The 25th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2006), 2006.06. |
| 229. | Koji GOTOH, Yukinobu NAGATA and Masahiro TOYOSADA, A Simple Estimation Method of the Stress Distribution Normal to Cross Section at Weld Toe in non-load carrying welded joints, The 25th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2006), 2006.06. |
| 230. | Seiichiro TSUTSUMI, Masahiro TOYOSADA, Daiki YAJIMA, Koji GOTOH and Koichi HASHIGUCHI, Mechanical Fatigue Simulation by Unconventional Plasticity Model, The 25th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2006), 2006.06. |
| 231. | Akira SUEDA, Keitaro KONUMA, Koji GOTOH and Masahiro TOYOSADA, Fatigue life assessment for structural element with bracket by numerical fatigue crack growth simulation, The 19th Asian Technical Exchange and Advisory Meeting on Marine Structures, 2005.12. |
| 232. | Masahiro TOYOSADA, Koji GOTOH, Keitaro KONUMA and Akira SUEDA, A Comparative Study of Computational Models for Fatigue Crack Propagation, International Conference on Computational and Experimental Engineering 2005, 2005.12. |
| 233. | Seitiro TUSTSUMI, Masahiro TOYOSADA, Koji GOTOH and Koichi HASHIGUCHI, FE Analysis on Mechanical Fatigue, International Conference on Computational and Experimental Engineering 2005, 2005.12. |
| 234. | 永田幸伸，末田明，後藤浩二，豊貞雅宏, 面内ガセット溶接継手の疲労き裂成長シミュレーション, 日本船舶海洋工学会, 2005.11. |
| 235. | 穴井陽祐，村上幸治，後藤浩二，豊貞雅宏, 応力集中部から発生する複数疲労表面き裂成長評価法に関する研究, 溶接学会九州支部研究発表会, 2005.07. |
| 236. | 永田幸伸，末田明，後藤浩二，豊貞雅宏, 面内ガセット溶接継手における疲労き裂成長予測, 溶接学会九州支部研究発表会, 2005.07. |
| 237. | Masahiro TOYOSADA and Koji GOTOH, Physical Meaning of the Fictitious Crack Opening Displaecement in Dugdale Model, International conference on fracture 2005, 2005.03. |
| 238. | Seiichro TSUTSUMI, Koichi HASHIGUCHI, Masahiro TOYOSADA and Koji GOTOH, Stable Softening of Pressure Sensitive and Non-Associated Plastic Flow Materials, PLASTICITY'05, 2005.01. |
| 239. | 永田幸伸，豊貞雅宏，後藤浩二，村上幸治, 溶接止端部近傍の結晶粒微細化による疲労強度向上対策, 溶接学会 溶接構造シンポジウム2004, 2004.11. |
| 240. | Koji GOTOH and Stig BERGE, Low Cycle Fatigue Strength of X65 Pipeline Girth Welds, International Pipeline Conference (IPC 2004), 2004.10. |
| 241. | Seiichro TSUTSUMI, Koichi HASHIGUCHI, Masahiro TOYOSADA and Koji GOTOH, Non-proportional Loading Behavior of Elastoplastic Solids, The 2004 International Conference on Computational and Experimental Engineering and Science, 2004.07. |
| 242. | 堤成一郎，豊貞雅宏，後藤浩二，橋口公一, 主応力軸回転時の非弾性変形発生に関する考察 −異方性および接線塑性に基づく非共軸の影響−, 平成16年度溶接学会九州支部講演会, 2004.07. |
| 243. | 永田幸伸，豊貞雅宏，後藤浩二，村上幸治, 結晶粒微細化による溶接鋼構造物の疲労強度向上対策に関する研究, 平成16年度溶接学会九州支部講演会, 2004.07. |
| 244. | Masahiro TOYSADA and Koji GOTOH, The Significance of Plastic Zone Growth under Cyclic Loading and Crack Opening/Closing Model in Fatigue Crack Propagation, Fourth International Conference on Materials Structure and Micromechanics of Fracture, 2004.06. |
| 245. | Masahiro TOYOSADA, Koji GOTOH, Keitaro KONUMA and Akira SUEDA, The Fatigue Life Estimation Method from the Stress Concentration Region with Zero Defect -An Application to the Fatigue Crack Growth Simulation code ``FLARP'' for the In-plane Gusset Welded Joint-, The 23rd International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2004), 2004.06. |
| 246. | 豊貞雅宏，後藤浩二，村上幸治，末田明, 面内ガセット継手の疲労寿命評価 −疲労き裂成長シミュレーションコードFLARPの適用−, 溶接学会九州支部研究発表会, 2003.07. |
| 247. | Yunyoung KIM，Koji GOTOH，Masahiro TOYOSADA and Jewoong Park, Optimal Torch Path Planning Considering Minimum Heat Effect, 8th International Marine Design Conference (IMDC 2003), 2003.05. |
| 248. | 小沼恵太郎，後藤浩二，豊貞雅宏, 波形鋼板Web橋梁構造に生じる溶接残留応力分布の推定について, 土木学会西部地区研究発表会, 2003.03. |
| 249. | 後藤浩二，豊貞雅宏，小沼恵太郎, 発生と伝播を統一的に評価する疲労き裂成長シミュレーション −角回し溶接止端部から発生・伝播する疲労き裂−, 土木学会西部地区研究発表会, 2003.03. |
| 250. | 中山伸，後藤浩二，豊貞雅宏, 任意温度/ひずみ速度下における構成方程式を記述するパラメータに関する一考察, 溶接構造シンポジウム2002, 2002.11. |
| 251. | 中山伸，後藤浩二，豊貞雅宏, ひずみ速度および温度の影響を考慮した構成方程式の高精度化に関する研究, 秋季造船三学会連合大会, 2002.11. |
| 252. | 豊貞雅宏，後藤浩二，村上幸治，中山伸，渡辺崇, Dugdale modelにおける仮想き裂の物理的意味に関する一考察, 秋季造船三学会連合大会, 2002.11. |
| 253. | Masahiro TOYOSADA and Koji GOTOH, Investigation of Enhancement of Fatigue Strength for Welded Built-up Structures by Flame Line heating, 2002 International Conference on Computational Engineering and Science (ICES 2002), 2002.07. |
| 254. | Koji GOTOH and Masahiro TOYOSADA, A Practical Estimation Method of the Skin Plate Distortion Caused by Fillet Weld, 21st International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2002), 2002.06. |
| 255. | Yunyoung KIM, Koji GOTOH, Masahiro TOYOSADA and Jewoong Park, Micro-Genetic Algorithms for Hard Combinatorial Optimization Problems, 12th International Offshore and Polar Engineering Conference (ISOPE 2002), 2002.05. |
| 256. | Masahiro TOYOSADA, Koji GOTOH and Shin NAKAYAMA, A Study of Crack Depth Effect and Scattering of Fracture Toughness in Three Point Bend COD Specimens, 10th International Conference on Fracture (ICF10), 2001.12. |
| 257. | Masahiro TOYOSADA, Koji GOTOH, Yasunari WATANABE and Shin NAKAYAMA, Evaluation of a Brittle Fracture Accident that Occurred at the Hyogo-Ken Nanbu Earthquake, 10th International Conference on Fracture (ICF10), 2001.12. |
| 258. | 豊貞雅宏，後藤浩二，村上幸治，高松知宏，渡辺眞一，渡辺佳彦, アルミニウム合金製浮沈式生簀の損傷事故解析, 秋季造船三学会連合大会, 2001.11. |
| 259. | 豊貞雅宏，後藤浩二，中山伸, 統計力学を応用した破壊靭性値の評価指標に関する研究, 2001.11. |
| 260. | Yunyoung KIM, Masahiro TOYOSADA, Koji GOTOH and Jewoong Park, Air-Borne Selection in Micro-Genetic Algorithms for Combinatorial Optimization, 2001.10. |
| 261. | 後藤浩二，豊貞雅宏，武市祥司, すみ肉溶接時に生じるねじれ変形の簡易推定法, 日本造船学会, 2001.05. |
| 262. | 豊貞雅宏，後藤浩二，中山伸, 三点曲げ試験片の破壊靱性値に及ぼすき裂深さの影響とばらつきに関する一考察, 秋季造船三学会連合大会, 2000.11. |
| 263. | Ragnar T. Igrand, Svein Saevik, Yong Bai, Stig Berge, Leif Collberg, Koji GOTOH, Philippe Mancon and Christian Thaulow, Deepwater Pipelines and Flowlines, Offshore Technology Conference, 2000.05. |
| 264. | Koji GOTOH and Stig BERGE, Low Cycle Fatigue Strength of X65 Pipeline Girth Welds, 19th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2000), 1999.12. |
| 265. | 豊貞雅宏，後藤浩二，村上幸治，石井稔，永田陽造，古城昭, 熱切断変形に関する基礎的検討, 秋季造船三学会連合大会, 1999.11. |
| 266. | Masahiro TOYOSADA and Koji GOTOH, Assessment of Brittle Fracture of Welded Structures under Seismic Wave, International Conference on Computational Engineering and Science (ICCES 1998), 1998.10. |
| 267. | 豊貞雅宏，後藤浩二，上田孝彦，渡辺泰成, 鋳鋼管橋脚柱頭部の脆性破壊事故に関する一検討, 土木学会, 1998.10. |
| 268. | Masahiro TOYOSADA and Koji GOTOH, Effect of Welding Sequence and Line Heating on Fatigue Strength for Welded Structures, 17th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2002), 1998.07. |
| 269. | Masahiro TOYOSADA and Koji GOTOH, Strength Evaluation Method for Brittle Fracture at Arbitrary Strain Rates, ASME PVP, 1998.07. |
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