亀裂成長履歴推定に基づく疲労強度評価手法に関する研究
キーワード：疲労，き裂成長シミュレーション，き裂発生モデル，変動荷重
1995.04.

機械学習や深層学習を活用した溶接工程の自動化に関する研究
キーワード：機械学習，深層学習，溶接
2019.04.

レーザ・アークハイブリッド溶接技術の船体建造工程への適用に向けた研究
キーワード：レーザ・アークハイブリッド溶接，船体建造
2012.04.

洋上風車係留鎖の摩耗挙動評価
キーワード：洋上風車，係留鎖，摩耗
2015.04.

種々の構造用金属材料に対する疲労強度評価
キーワード：疲労強度，アルミニウム合金，チタン合金，ステンレス鋼，難燃性マグネシウム合金
2006.04.

動的荷重下における鋼材・溶接鋼構造物の強度評価に関する研究
キーワード：動的/衝撃荷重，不安定（脆性）破壊，破壊靭性値，応力～ひずみ関係，ひずみ速度，温度，切欠材とき裂材
1990.04.

大型溶接構造物の実用的溶接変形・残留応力推定手法に関する研究
キーワード：溶接変形・残留応力，変形発生源，FEM
1997.04.

高分子材料（PE：ポリエチレン）製ガス導管の強度評価手法
キーワード：ポリエチレン，ガス導管，ひずみ速度，地震動，融着部
2006.04～2013.03.

亀裂結合力モデルの拡張に関する研究
キーワード：き裂結合力モデル，き裂開口変位
2005.06.

破壊駆動力評価における溶接残留応力影響の考慮法に関するFS委員会
2020.04～2023.03, 代表者：川畑 友弥, 東京大学, （公社）日本船舶海洋工学会
破壊駆動力評価における溶接残留応力取り扱い手法について、（1）種々の規格における溶接残留応力影響の考慮方法について、溶接方法や継手形式等の関連因 子影響の考慮方法についての調査、（2）用途やニーズに応じて関連因子の考慮優先度の整理、を行い、簡便かつ高精度な残留応力の取り扱い手法の構築に向けた問題点の整理を行う。.

ISSC（International Ship and Offshore Structures Congress）
2018.09～2022.09, ISSC（International Ship and Offshore Structures Congress）
ISSCに設置された第V.3委員会（Materials and Fabrication technology）の日本代表委員として同委員会の活動に貢献する．.

超高精度船体構造デジタルツインの研究開発
2018.04～2020.03, 一般財団法人　日本船舶技術研究協会
船舶の無人運航等、IoT やAI を活用した近未来の海上輸送システムを世界に先駆けて実現するためには、大洋上での気象・海象や船舶の状態（リアル空間における物理現象）をコンピュータ（サイバー空間）上で精緻に再現するだけでなく、船舶の設計・建造から運航、保守管理、解撤に至るまでをサイバー空間上で実行・管理できる技術が不可欠である。このサイバー空間上での実現象の再現技術は「デジタルツイン」と呼ばれる。この技術を活用し、個船ごとに運航状態や経年劣化度を考慮することにより、安全性は保持しつつ余剰な強度を排した、より競争力の高い（いわゆるジャパンプレミアム）船舶の設計・建造が可能となり、中韓において建造される船舶との有意な差別化が可能になると期待される。
本研究では、船体構造強度が船舶の安全性を担保する最重要要素であることを踏まえ、船体構造のデジタルツイン構築に不可欠な基盤技術である、「ハルモニタリング、および、データマネジメント技術」、「船体の運動・荷重、および、応力応答の超高精度シミュレーション技術」、並びに、「デジタルツインを機能させるためのシナリオ、評価、推論技術」の研究開発を行い、世界最先端の「超高精度船体構造デジタルツイン」の実用化を図ることを目的とする。

船体構造の安全性に影響を及ぼす諸要素（実海域における波浪外力、操船影響、建造精度、就航後の構造変化（腐食・疲労等））について検討し、船体構造デジタルツインのコンセプトデザインを行う。さらに、その根幹技術である波浪中の構造応答の超高精度シミュレーション手法について、計算法および数学モデル化を研究し、水槽試験による計測値と高い精度で一致させるための技術を確立する。これらを総合して実用化開発ロードマップを策定し、日本の海事産業が世界に先駆けて船体構造デジタルツインの実用化に取り組む環境を整備する。

船体構造デジタルツインのコンセプトデザインと、その根幹技術である超高精度構造応答シミュレーション手法の基礎を確立し、日本の海事産業が船体構造デジタルツイン技術の実用化に取り組む環境を整備することにより、以下の効果の発現を支援・促進する。
- 船体構造デジタルツインの実用化により、船舶の設計時・就航中の安全性を容易かつ高精度に予測・評価できるようになることから、遠隔モニタリングによる安全無人運航や劣化予測に基づく高精度メンテナンス、また、実海域の状況に即したより軽量で安全な合理的構造設計や、
日本の高精度建造技術を前提とした最適安全設計なども可能になると期待される。
- 船舶の無人運航をはじめ、世界に先駆けた「超スマート海事社会」の実現に貢献することができる。.

CO2排出削減対策強化誘導型技術開発・実証事業
2015.04～2018.03, 代表者：宇都宮 智昭, 九州大学, 環境省
サクションアンカーと合成繊維索からなる係留システムを新規に開発し、実海域において浮体基礎の係留システムとして実証することにより、係留コストを25%程度削減するとともに、係留チェーンの摩耗量評価手法を確立することで、係留チェーンのメンテナンスフリー化とコスト削減を実現し、浮体式洋上風力発電の導入拡大とCO2排出削減につなげる.
（分担者として，係留チェーン摩耗挙動に関する再現実験や素材特性調査を担当している．）.

レーザー溶接技術の船舶建造工程への適用に関する研究委員会
2014.04～2018.09, 代表者：後藤浩二, 九州大学
船舶の建造品質の維持・向上を図りつつ，生産性を更に高めていく取り組みとして，レーザー・アークハイブリッド溶接の船舶建造への適用に関する研究を行う．.

軽金属材料の疲労寿命予測方法に関するJIS開発
2014.04～2017.03, 代表者：中田一博, 大阪大学接合科学研究所, （一社）軽金属溶接協会
鉄道車両，自動車，航空機等の輸送機器に多用されるアルミニウム合金並びに今後適用が期待される難燃性マグネシウム合金について，母材と接合部及びアルミニウム合金と難燃性マグネシウム合金の異材接合部について高精度な疲労試験方法を開発・標準化（高機能JIS化）に取り組む．
後藤は本委員会の下に設置される「疲労試験分科会」の主査を担当する．.

レーザー溶接技術の船舶建造工程への適用に関する調査研究委員会
2012.04～2014.03, 代表者：片山聖二, 大阪大学　接合科学技術研究所
船舶の建造品質の維持・向上を図りつつ，生産性を更に高めていく取り組みとして，レーザー・アークハイブリッド溶接の船舶建造への適用に関する研究を行う．
後藤は委員会に設置される継手評価・検査WGの主査を担当する．.

疲労強度に及ぼす板厚影響に関する研究開発委員会
2011.09～2013.03, 代表者：角洋一, 横浜国立大学, 一般財団法人　日本海事協会
疲労強度に及ぼす板厚影響に関し，板厚50mmを超える極厚鋼板溶接継手に対して従来知見の適用妥当性を調査し，必要に応じて適切な板厚影響評価方法を検討する．.

大型コンテナ船極厚鋼板対策研究委員会
2009.04～2011.03, 代表者：角洋一（委員長）, 横浜国立大学, 日本船舶技術研究協会（日本）
大型コンテナ船のハッチコーミング部に採用が増加している極厚板（溶接部）の耐不安定破壊性能に関する検証を行う。
委員及び委員会幹事として参加する。.

超大型コンテナ船構造安全対策検討
2007.04～2009.03, 代表者：板垣浩（委員長），豊貞雅宏（WG2主査）, 日本船舶技術研究協会（日本）
近年，大型コンテナ船のハッチコーミング部に採用が増加している極厚板（溶接部）の耐不安定破壊性能に関する検証を行う。委員会は3つのWGより構成され，WG2委員として活動した。.

極厚板大入熱溶接部強度検討
2005.12～2007.03, 代表者：豊貞雅宏, 九州大学, 日本船舶海洋工学会（日本）
近年，大型コンテナ船のハッチコーミング部に採用が増加している極厚板（溶接部）の耐不安定破壊性能に関する検証を行う.

主要著書

主要原著論文

1.	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, Proceedings of ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2022), https://doi.org/10.1115/OMAE2022-87473, Vol.3: Materials Technology; Pipelines, Risers, and Subsea Systems, OMAE2022-87473, 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..
2.	Takamori Uemura, Koji Gotoh and Issei Uchino, Expansion of laser–arc hybrid welding to horizontal and vertical-up welding, Welding in the World, https://doi.org/10.1007/s40194-021-01236-7, 66, 495-506, 2022.01, Laser–arc hybrid welding (LAHW) is an advanced welding method that combines arc welding and laser welding and can achieve deep penetration and the reduction of welding deformation compared with conventional arc welding. As with other welding techniques, it is common to target the flat position (PA) as the welding position. However, the expansion of the applicable positions enables the application of high-quality welded joints fabricated by LAHW to many welded joints in large steel structures. This study used the LAHW system with a robot manipulator to establish weldability in the horizontal position (PC) and the vertical-up position (PF) to expand the applicable range of LAHW in large steel structures. Suitable LAHW conditions for fabricating the butt-welded joint with a welding length of 1,000 mm for these positions were established through various investigations, including molten pool observation. Finally, the quality of these joints was evaluated in accordance with the laser–arc hybrid welding guidelines (ClassNK) of Nippon Kaiji Kyokai, and it was confirmed that the joints satisfy the required standards..
3.	Mizuki Morishita, Koji Gotoh, Yosuke Anai, Shuichi Tsumura and Toshio Niwa., Fatigue surface crack growth behavior in flat plate and out-of-plane gusset-welded joints under biaxial cyclic loads with different phases, Journal of Marine Science and Technology, https://doi.org/10.1007/s00773-020-00762-1, 26, 3, 655-672, 2021.09, Although many in-service welded built-up structures, which contain many welded joints as fatigue crack initiation sites, are subjected to many types of loading, their structural integrities are evaluated according to design codes based on theoretical and experimental investigations under uniaxial loading conditions. Additionally, most of these codes implement the S–N curves approach. This study highlights the biaxial cyclic loading with different phases. The fracture mechanics approach toward fatigue life evaluation can obtain the fatigue crack growth history. This paper confirms the applicability of the previously proposed numerical simulation method for obtaining the fatigue crack propagation histories of a cracked plate subjected to biaxial loads with a phase difference for each loading component. A fracture mechanic approach was used to establish the proposed method. The fatigue surface crack growth behavior of a flat plate and an out-of-plane gusset-welded joint under biaxial cyclic loadings with different phases was investigated by extending the applicability of the proposed method to a through-thickness crack. Comparisons between the measured crack evolution and the numerical simulation results were carried out to validate our fatigue crack growth simulation for flat plane and welded joints..
4.	後藤 浩二，上村 崇杜，津村 秀一，竹下 竜平，内野 一成，森山 厚夫, レーザ・アークハイブリッド溶接の一般商船建造工程への導入に向けた諸検討, 日本船舶海洋工学会論文集, 32, 231-245, 2020.12, The application of advanced welding technologies is important for improving the efficiency of hull construction processes and reducing production costs. Laser-arc hybrid welding (LAHW) technology, which combines the advantages of laser and normal arc welding, is of high quality and is expected to improve productivity. However, there are some challenges in applying LAHW to the hull construction stage of general merchant ships, because the thickness of the main structural members is thicker than that of passenger ships and high-speed ships. The present study focused on investigating the following key aspects for involving LAHW in construction stage of commercial vessels, and useful knowledge was obtained. (1) Suitable welding conditions to fabricate the full-penetration tee joint by one-side single-pass welding, (2) Influence of the weld groove cutting process method, (3) Influence of retained primer and oxide film on joint quality, (4) Confirmation in the production by prototyping with long welding length, and (5) Improvement of welding quality by applying the rare earth metal bearing weld wire..
5.	高木 芳史，後藤 浩二, 複数周波数成分が重畳する応力が間欠的に作用する条件下における疲労亀裂伝播挙動, 溶接学会論文集, https://doi.org/10.2207/qjjws.38.19, 38, 1, 19-24, 2020.03, In this study, fatigue crack propagation under the condition where the superimposed stress history with different frequency components was given intermittently was investigated by numerical simulation and fatigue crack propagation test． The numerical simulation of fatigue crack propagation used in this study can consider the opening and closing behavior of fatigue crack and implement stress history extraction algorithm that contributes to fatigue crack propagation under superimposed stress history with different frequency components． An advanced fracture mechanics approach based on the RPG (Re-tensile Plastic zone Generating) stress criterion to identify the effective stress intensity factor range was applied to estimate the fatigue crack propagation history． Fatigue crack propagation test under superimposed stress history containing different frequency component appearing intermittently were also conducted． Validity of our applied numerical simulation method was investigated by comparing numerical simulation results with experimental ones． As a result, the validity of our proposed numerical simulation procedure to estimate the fatigue crack propagation history under such a complicated applied stress history was confirmed.
6.	Yoshifumi Takaki and Koji Gotoh, Approximate weight functions of stress intensity factor for a wide range shapes of surface and an embedded elliptical crack, Marine Structures, https://doi.org/10.1016/j.marstruc.2019.102696, 70, 102696, 2020.03, This paper describes the application of weight function for stress intensity factor in a surface crack with a wide range of crack shapes. Based on the weight function representation proposed by Wang and Glinka (2009), an extended formulation of the weight function for surfaces and embedded cracks is performed. The unknown parameters in the formulations were determined from reference values of stress intensity factor for a surface and an embedded crack given by finite element analysis with the J integral method. The effectiveness of the proposed weight functions has been verified by comparing with the stress intensity factors given by finite element analysis and available approximated solutions under several loading conditions..
7.	森下 瑞生，穴井 陽祐，津村 秀一，後藤 浩二，丹羽 敏男, 位相差を有する面内二軸繰返し応力を受ける疲労表面亀裂の伝播解析, 日本船舶海洋工学会論文集, 30, 115-121, 2019.12, Most of in-service structures are subjected to many types of cyclic loading and these cyclic loadings have different axial components with different phase. In-addition, most of the fatigue cracks occurring in the structures are so-called surface cracks which can be approximate elliptical shape. However, the fatigue strength of structures is evaluated according to design standards established by theoretical and experimental investigations under uniaxial cyclic loading condition. On the other hand, authors proposed the numerical simulation procedure of through thickness fatigue crack propagation histories of a cracked plate subjected in-plane biaxial loadings with phase differences of each loading component from a viewpoint of fracture mechanics approach. In this study, fatigue surface crack growth behavior under in-plane biaxial loading with different phase conditions are investigated. The phase difference effect for fatigue surface crack shape evolution under in-plane biaxial loading is confirmed by measured ones. Besides, the numerical simulation method of fatigue crack growth is proposed and confirmed this method by comparisons of measured crack evolution with the numerical simulation..
8.	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, Practical Design of Ships and Other Floating Structures, Proceedings of the 14th International Symposium, PRADS 2019, https://doi.org/10.1007/978-981-15-4680-8, 3, 258-272, ISSN 2366-2557, ISSN 2366-2565(electronic), 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..
9.	Koji GOTOH, Tetsuya UEDA, Koji MURAKAMI, Tomoaki UTSUNOMIYA, Wear Performance of Mooring Chain in Wet Environment with Substitute Ocean Water, Proceedings of 38th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2019)., OMAE2019-95822, 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..
10.	Koji GOTOH, Masataka NAKAGAWA, Koji MURAKAMI, Tomoaki UTSUNOMIYA, Effect of Tensile Force for Wear Performance of the Mooring Chain, Proceedings of 37th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2018)., OMAE2018-77960, 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..
11.	Shuichi Tsumra, Koji Murakami and Koji Gotoh, A study on the angular distortion in tee type full penetrated welded joint fabricated by the laser-arc hybrid welding, Welding International, https://doi.org/10.1080/09507116.2016.1223234, 31, 12, 911-919, 2017.12, The reducing effect of the angular distortion in T-type full penetrated welded joints fabricated by laser-arc hybrid welding was investigated. The angular distortion caused by the laser-arc hybrid welding were measured and compared with one caused by CO2 gas shielded-arc welding. As a result, the amount of angular distortion by laser-arc hybrid welding was the same level as one in the case of forming a leg size of F1 grade regulated by the Common Structural Rules for Bulk Carriers by applying arc welding. In addition, numerical analysis of the welding deformation was carried out by thermal elastic–plastic finite element analysis and these results were generally consistent with the measured results. Moreover, the effect on the FE result of the penetrated shape is discussed..
12.	Koji GOTOH, Koji MURAKAMI, Masataka NAKAGAWA, Tomoaki UTSUNOMIYA, A Study on the Wear Performance of the Mooring Chain for Floating Wind Turbine, Proceedings of 36th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2017)., OMAE2017-62195, 2017.07, 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..
13.	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-arc hybrid welding to the construction of general merchant ships in Japan., Proceedings of 13th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2016), ID 014, 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..
14.	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., Proceedings of 13th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2016), ID 097, 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..
15.	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, 35th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2016), OMAE2016-54173, 2016.06.
16.	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の開閉口モデルと亀裂伝播解析, 日本船舶海洋工学会論文集, 21, 31-42, 2015.06, This paper presents a numerical simulation for fatigue crack propagation based on improved strip yield model, which enables the strain hardening effect of materials to consider. One-dimensional bar elements, which consist of the strain hardening materials, are plugged up the gap corresponding to the fictitious crack opening displacement in the plastic zone to describe the role of crack wake generated over fatigue crack surfaces. Validity of this numerical model under monotonic loading, unloading and reloading conditions was verified by comparison of the COD profile and plastic zones size with elastic-plastic FE analysis. Proposed model was implemented into the numerical simulation of fatigue crack propagation considering the crack opening / closing. Proposed simulation of fatigue crack propagation, which enables the strain hardening effect of materials, was validated by comparing fatigue crack propagation histories obtained by the numerical simulations with measured ones..
17.	Koji GOTOH, Practical Evaluation of the Strain Rate and Temperature Effects on Fracture Toughness of Steels, 34th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2015), OMAE2015-41982, 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..
18.	Yosuke ANAI, Toshio NIWA, Koji GOTOH, Practical Formula of the Shape Evolution of a Surface Crack Under Fatigue Loading, 34th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2015), OMAE2015-41978, 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..
19.	Koji GOTOH, Toshio NIWA, Yosuke ANAI, Numerical simulation of fatigue crack propagation under biaxial tensile loadings with phase differences, Marine Structures, http://dx.doi.org/10.1016/j.marstruc.2015.03.003, 42, 53-70, 2015.03, Fatigue crack propagation under the biaxial tensile loading, which loading directions are normal and parallel to the initial crack position, is highlighted in this study. Most of in-service structures and vessels are subjected to many types of loading. 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 six different phase and loading 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..
20.	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論文集, 83-89, 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..
21.	Kazuki MATSUDA, Koji GOTOH, Numerical simulation of fatigue crack propagation under superimposed stress histories containing different frequency components with several mean stress conditions, Marine Structures, http://dx.doi.org/10.1016/j.marstruc.2014.12.005, 41, 77-95, 2015.01, Fatigue crack propagation behavior under superimposed stress histories containing different frequency components with several mean stress conditions was investigated. 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 was improved to extract the effective part from the applied stress history for fatigue crack propagation. The parameter, which is based on the plastic hysteresis energy consumed in the vicinity of a crack tip, was applied and implemented into the numerical simulation code of fatigue crack propagation. Fatigue crack propagation tests under various superimposed stress conditions with several mean stress conditions were performed and compared with the fatigue crack propagation histories obtained from the improved numerical simulations. These comparisons show the validity of the proposed procedure for extracting the effective stress history from the superimposed stress histories with different frequency components and mean stresses. Additionally, practical fatigue strength evaluations based on the linear cumulative fatigue damage parameter were conducted to investigate the tendency of the fatigue damage value under these stress conditions..
22.	松田 和貴, 村上 幸治, 後藤　浩二, 平均応力が変動する重畳応力条件下における疲労亀裂伝播挙動解析, 日本船舶海洋工学論文集, 20, 131-137, 2014.12, Fatigue crack propagation behavior under superimposed loading histories with several mean stress conditions 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 for fatigue crack propagation. The parameter, which is based on the plastic hysteresis consuming in the vicinity of a crack tip, is applied to extract the effective loading for fatigue crack propagation and implemented into the numerical simulation code of fatigue crack propagation. Fatigue crack propagation tests under various superimposed loading conditions, which contain several constants and variable mean stress, are performed and comparison of fatigue crack propagation histories 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 superimposed loading histories with different frequencies. Subsequently, practical fatigue strength evaluation based on the linear cumulative fatigue damage parameter were conducted to investigate the tendency of fatigue damage value affected by mean stresses..
23.	Koji GOTOH, Masao TAKUNO, Koichi OKADA, Sadaharu KUSUBA, Numerical Simulation of Fatigue Crack Growth of a Welded Structural Component under Block Program Fatigue Test, 33rd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2014), OMAE2014-23413, 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..
24.	Koji GOTOH, Toshio NIWA, Yosuke ANAI, Fatigue crack growth behaviour of an out-of-plane gusset welded joints under biaxial loadings with different phases, European Structural Integrity Society, 3, 1536-1541, 2014.06, [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..
25.	Kazuki MATSUDA, Koji GOTOH, Numerical Simulation of Fatigue Crack Propagation under Simulated Whipping Loading Arising in Hull Structures, 32nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2013), OMAE2013-10985, 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 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 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. .
26.	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 -, 32nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2013), OMAE2013-10980, 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. .
27.	Koji GOTOH, Kazuki MATSUDA and O Kitamura, NUMERICAL SIMULATION OF FATIGUE CRACK PROPAGATION UNDER SUPERPOSED LOADING HISTORIES WITH TWO DIFFERENT FREQUENCIES, Proceedings of Hydroelasticity in Marine Technology 2012, 287-297, 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..
28.	Koji GOTOH, 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 Ocean, Offshore and Arctic Engineering (OMAE 2012), OMAE2012-83664, 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..
29.	原田圭輔，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．, 日本船舶海洋工学会論文集, 14, 39-46, 2011.12, [URL].
30.	Koji GOTOH, Koji MURAKAMI and Yasuo NODA, Fatigue crack growht behaviour of A5083 series aluminium alloys and their welded joints, Journal of Marine Science And Technology, 16, 3, 343-353, 2011.09.
31.	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), OMAE2011-49457, 2011.06.
32.	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, Proceedings of 11th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2010), Vol.2, 980-989, 2010.09.
33.	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), OMAE2009-20726, 2010.06.
34.	Koji GOTOH and Yukinobu NAGATA, Improvement of Slice Synthesis Methodology to Estimate Stress Intensity Factor of an Embedded Crack in Finite Body, Proceedings of 12th International Conference on Fracture (ICF 12), ICF12 T02.011, 2009.07.
35.	Koji GOTOH and Keisuke HARADA, Numerical Study of Enhancement of Fatigue Crack Propagation Life by Grain Refinement, Proceedings of The Nineteenth International Offshore and Polar Engineering Conference (ISOPE 2009), 4, 435-439, The Seventh (2009) ISOPE High-Performance Materials Symposium, 2009.06.
36.	永田幸伸，後藤浩二, Slice Synthesis Methodology を用いた埋没き裂の応力拡大係数及び弾性き裂開口変位算定手法について, 日本船舶海洋工学会論文集, 9, 191-199, 2009.06, [URL].
37.	永田幸伸，後藤浩二, Slice Synthesis Methodology とき裂結合力モデルを用いた埋没き裂の弾塑性き裂開口変位推定手法, 日本船舶海洋工学会論文集, 9, 201-209, 2009.06, [URL].
38.	Koji GOTOH and Yukinobu NAGATA, Applicability Evaluation of the Weight Function Based Strip Yield Model for an Embedded Crack Problem, 28th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2009), OMAE2009-79562, 2009.06.
39.	Yukinobu NAGATA, Koji GOTOH and Masahiro TOYOSADA, Numerical Simulations of Fatigue Crack Initiation and Propagation Based on Re-tensile Plastic Zone Generating (RPG) Load Criterion for In-plane Gusset Welded Joints, Journal of Marine Science And Technology, Vol.14，No.1，pp.104-114, 2009.02.
40.	Koji GOTOH and Yukinobu NAGATA, Stress Intensity Factors for Three Dimensional Cracks by Applying Slice Synthesis Methodology, The Proceedings of The Eighteenth (2008) International Offshore and Polar Engineering Conference, Volume 4 (The Sixth (2008) ISOPE High-Performance Materials Symposium), pp.236-240, 2008.07.
41.	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, Proceedings of the Seventeenth (2007) International Offshore and Polar Engineering Conference, Vol.4, pp.3343-3347, 2007.07.
42.	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, 25th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2006), OMAE2006-92094, 2006.06.
43.	Masahiro Toyosada, Koji Gotoh, Keitaro Konuma and Akira Sueda, A Comparative Study of Computational Models for Fatigue Crack Propagation, Proceedings of International Conference on Computational and Experimental Engineering and Sciences, pp.1386-1391, 2005.12.
44.	永田幸伸，末田明，後藤浩二，豊貞雅宏, 面内ガセット継手の疲労き裂発生・成長シミュレーション, 日本船舶海洋工学会論文集, 第2号，pp.361-367, 2005.12.
45.	Masahiro TOYOSADA and Koji GOTOH, Physical Meaning of the Fictitious Crack Opening Displaecement in Dugdale Model, Proceedings of 11th International Conference on Fracture, ICF11 4620, 2005.03.
46.	Masahiro TOYOSADA and Koji GOTOH, The Significance of Plastic Zone Growth under Cyclic Loading and Crack Opening / Closing Model in Fatigue Crack Propagation, Materials Science Forum, 482, 95-102, Vol.482, pp.95-102, 2005.03.
47.	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講演論文集, pp.343-346, 2004.11.
48.	Koji GOTOH and Stig BERGE, Low Cycle Fatigue Strength of X65 Pipeline Girth Welds, Proceedings of IPC 2004, IPC04-0631, 2004.10.
49.	Masahiro TOYOSADA, Koji GOTOH and Toshio NIWA, Fatigue life assessment for welded structures without initial defects: an algorithm for predicting fatigue crack growth from a sound site, International Journal of Fatigue, 10.1016/j.ijfatigue.2003.12.005, 26, 9, 993-1002, Vol.26, No.9, pp.993-1002, 2004.09.
50.	Masahiro TOYOSADA, Koji GOTOH and Toshio NIWA, Fatigue crack propagation for a through thickness crack: a crack propagation law considering cyclic plasticity near the crack tip, International Journal of Fatigue, 10.1016/j.ijfatigue.2003.12.006, 26, 9, 983-992, Vol.26, No.9, pp.983-992, 2004.09.
51.	Masahiro TOYOSADA and Koji GOTOH, Investigation of Enhancement of Fatigue Strength for Welded Built-up Structures by Flame Line heating, Advances in Computational Engineering and Science, Proceedings of the 2002 International Conference on Computational Engineering and Science (ICES'2002), 2002.07.
52.	Koji GOTOH and Masahiro TOYOSADA, A Practical Estimation Method of the Skin Plate Distortion Caused by Fillet Weld, Proceedings of the 21st International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2002), OMAE2002-28181, 2002.06.
53.	Masahiro TOYOSADA, Koji GOTOH and Shin NAKAYAMA, A Study of Crack Depth Effect and Scattering of Fracture Toughness in Three Point Bend COD Specimens, Advances in Fracture Research, Proceedings of 10th International Conference on Fracture, ICF10 737, 2001.12.
54.	Masahiro TOYOSADA, Koji GOTOH, Yasunari WATANABE and Shin NAKAYAMA, Evaluation of a Brittle Fracture Accident that Occurred at the Hyogo-Ken Nanbu Earthquake, Advances in Fracture Research, Proceedings of 10th International Conference on Fracture, ICF10 148, 2001.12.
55.	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, 日本造船学会論文集，第190号, pp.569-577, 2001.12.
56.	Ragnar T. Igrand, Svein Saevik, Yong Bai, Stig Berge, Leif Collberg, Koji GOTOH, Philippe Mancon and Christian Thaulow, Deepwater Pipelines and Flowlines, Proceedings of Offshore Technology Conference, OTC 12187, 2000.05.
57.	豊貞雅宏，後藤浩二，渡辺泰成, 兵庫県南部地震時の脆性破壊事故に関する一考察, 土木学会論文集，No.647/I-51, pp.317-329, 2000.03.
58.	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, 西部造船会会報，第99号, pp.331-342, 2000.03.
59.	Masahiro TOYOSADA and Koji GOTOH, Strength Evaluation Method for Brittle Fracture at Arbitrary Strain Rates, PVP Vol.380 Fitness-for-Service Evaluations in Petroleum and Fossil Power Plants, ASME, pp.111-118, 1998.07.
60.	Masahiro TOYOSADA and Koji GOTOH, Effect of Welding Sequence and Line Heating on Fatigue Strength for Welded Structures, Proceedings of 17th International Conference on OMAE, OMAE98-2152, 1998.07.

主要総説, 論評, 解説, 書評, 報告書等

1.	Issei Uchino, Takamori Uemura and Koji Gotoh, A Study on Adopting Λ-Shape Groove for Laser-Arc Hybrid Welding to Construct Thick Plate Butt Welded Joints, Welding International, https://doi.org/10.1080/09507116.2021.1936931, 2021.07, Most Japanese shipyards that build general merchant ships use arc welding, but they always have the problem that the accuracy of the hull construction is poor as a result of the thermal deformation caused by arc welding. As one method to overcome this problem, it is expected to adopt laser arc hybrid welding that can suppress the total heat input as a result of heat input concentration, but the initial introduction cost is high and this welding method has a poorer gap tolerance than conventional arc welding. In addition, few experiences to apply laser arc hybrid welding for constructing the joints at the plate thickness level used for hull members of general merchant ships. An improved procedure to fabricate a butt joint with a plate with a thickness of 15 to 20 mm, which is widely applied as a hull member of general merchant ships, is proposed in this study. Proposed procedure is that the Λ-shaped groove with a very small angle and one-pass welding by laser arc hybrid welding with CO2 gas shielded arc welding to satisfy the weld reinforcement on the front side weld bead. The joint quality manufactured by using our proposed procedure was confirmed according to the Guidelines for Laser Arc Hybrid Welding by a classification society Nippon Kaiji Kyokai (ClassNK). It is expected to be introduced as an alternative method of plate joint welding for hull members, especially submerged arc welding with large heat input..
2.	後藤 浩二, 溶接構造物の疲労・破壊強度評価の進歩と今後の展望, ふぇらむ（（一社）日本鉄鋼協会開放）, Vol.24, No.1, 2019, pp.26-35., 2019.01.
3.	後藤　浩二, 船舶建造高品質化・効率化技術の調査研究 （レーザ溶接実用化のための調査研究） , 2014.03, 我が国造船業界の国際競争力向上の更なる発展を目標に，建造工程の生産性を高め，生産コスト低減を図る取組みの一環として，レーザ・アークハイブリッド溶接技術の船舶建造工程への適用に係る調査研究が，日本財団の研究助成を受けて（一財）日本船舶技術研究協会において実施された．（2012-13FY）．本PJの報告書である．なお，著者は実施担当内容について，分担執筆を担当した．.
4.	日本船舶技術研究協会　極厚板研究委員会委員, 大型コンテナ船の極厚板溶接継手からの脆性破壊発生防止に関する調査研究　報告書, 日本船舶技術研究協会, 委員会幹事・委員として分担執筆担当, 2011.04.
5.	後藤浩二, 溶接継手の疲労強度の基礎 (溶接接合教室　第3章溶接構造の力学と設計　3-6節), 溶接学会誌, Vol.78，No.7，pp.639-643, 2009.11.
6.	日本船舶技術研究協会：超大型コンテナ船の構造安全対策検討委員会, 超大型コンテナ船の構造安全対策の検討に係る調査研究報告書, 日本船舶技術研究協会, WG2委員として分担執筆担当, 2009.03.
7.	後藤浩二, ここまできた実構造物の疲労き裂進展シミュレーション, 溶接学会誌, Vol.77，No.4，pp.273-277, 2008.06.
8.	後藤浩二，豊貞雅宏，藤村浩史, 連載講座　溶接設計講座　第三回　溶接継手強度設計の基礎, 溶接技術, Vol.54，No.3，pp.130-137, 2006.03.

主要学会発表等

1.	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..
2.	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..
3.	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..
4.	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..
5.	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..
6.	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..
7.	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..
8.	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..
9.	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..
10.	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..
11.	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..
12.	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..
13.	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.
14.	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.
15.	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.
16.	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.
17.	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.
18.	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.
19.	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.
20.	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.
21.	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.
22.	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.
23.	Masahiro TOYOSADA and Koji GOTOH, Physical Meaning of the Fictitious Crack Opening Displaecement in Dugdale Model, International conference on fracture 2005, 2005.03.
24.	Koji GOTOH and Stig BERGE, Low Cycle Fatigue Strength of X65 Pipeline Girth Welds, International Pipeline Conference (IPC 2004), 2004.10.
25.	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.
26.	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.
27.	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.
28.	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.
29.	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.
30.	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.
31.	Masahiro TOYOSADA and Koji GOTOH, Strength Evaluation Method for Brittle Fracture at Arbitrary Strain Rates, ASME PVP, 1998.07.

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学術論文等の審査

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