Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.marstruc.2019.102696

Repository Public URL： http://hdl.handle.net/2324/4751320

Language：Japanese   Publishing type：Research paper (scientific journal)  

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.

Repository Public URL： http://hdl.handle.net/2324/4794743

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： https://doi.org/10.1007/978-981-15-4680-8

Repository Public URL： http://hdl.handle.net/2324/4752585

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4753064

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4753060

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1080/09507116.2016.1223234

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4753059

Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Overview of a joint industrial project for introducing laser-arc hybrid welding to the construction of general merchant ships in Japan.
Koji GOTOH,Tsutomu FUKUI,Atsuo MORIYAMA,Shuichi TSUMURA and Hiroshi SAWATO
Proceedings of 13th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2016), ID 014, September, 2016.

Repository Public URL： http://hdl.handle.net/2324/4794457

Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Effect of compressive residual stress on fatigue crack propagation.
Yasushi MORIKAGE, Satoshi IGI, Tetsuya TAGAWA,Kenji OI,Koji MURAKAMI and Koji GOTOH.
Proceedings of 13th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2016), September, 2016.

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4753057

Language：Japanese   Publishing type：Research paper (scientific journal)  

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.

Repository Public URL： http://hdl.handle.net/2324/4794431

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4793204

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4793205

Language：English   Publishing type：Research paper (scientific journal)  

DOI： http://dx.doi.org/10.1016/j.marstruc.2015.03.003

Repository Public URL： http://hdl.handle.net/2324/4751319

Language：Japanese   Publishing type：Research paper (other academic)  

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.

Language：English   Publishing type：Research paper (scientific journal)  

DOI： http://dx.doi.org/10.1016/j.marstruc.2014.12.005

Repository Public URL： http://hdl.handle.net/2324/4751318

Language：Japanese   Publishing type：Research paper (scientific journal)  

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.

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Other Link： http://www.sciencedirect.com/science/article/pii/S2211812814002491

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Fatigue crack growht behaviour of A5083 series aluminium alloys and their welded joints,
Koji GOTOH, Koji MURAKAMI and Yasuo NODA,
Journal of Marine Science And Technology,Vol.16, No.3, 2011, pp.343-353

Repository Public URL： http://hdl.handle.net/2324/4785260

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4793203

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4794822

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4793199

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4795137

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4793206

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4793197

Language：Japanese   Publishing type：Research paper (scientific journal)  

Other Link： http://www.jstage.jst.go.jp/article/jjasnaoe/9/0/9_201/_article

Language：Japanese   Publishing type：Research paper (scientific journal)  

Other Link： http://www.jstage.jst.go.jp/article/jjasnaoe/9/0/9_191/_article

Language：English   Publishing type：Research paper (scientific journal)  

Repository Public URL： http://hdl.handle.net/2324/4785261

Language：English   Publishing type：Research paper (international conference proceedings)  

Stress Intensity Factors for Three Dimensional Cracks by Applying Slice Synthesis Methodology
Koji GOTOH and Yukinobu NAGATA
The Proceedings of The Eighteenth (2008) International Offshore and Polar Engineering Conference

Repository Public URL： http://hdl.handle.net/2324/4793209

Language：English   Publishing type：Research paper (scientific journal)  

Repository Public URL： http://hdl.handle.net/2324/4793208

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4793200

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4785268

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Physical Meaning of the Fictitious Crack Opening Displaecement in Dugdale Model

Repository Public URL： http://hdl.handle.net/2324/4795136

Language：English   Publishing type：Research paper (scientific journal)  

Repository Public URL： http://hdl.handle.net/2324/4785266

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4795134

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijfatigue.2003.12.005

Repository Public URL： http://hdl.handle.net/2324/4794800

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijfatigue.2003.12.006

Repository Public URL： http://hdl.handle.net/2324/4794799

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4752588

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4752584

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4752589

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4752590

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4755283

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Repository Public URL： http://hdl.handle.net/2324/4753054

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4753056

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： https://hdl.handle.net/2324/7160652

Language：Japanese   Publishing type：Research paper (other academic)  

Repository Public URL： https://hdl.handle.net/2324/7160653

Language：Japanese   Publishing type：Research paper (other academic)  

Repository Public URL： https://hdl.handle.net/2324/7159846

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1080/09507116.2023.2282231

Repository Public URL： https://hdl.handle.net/2324/7159364

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.2355/isijinternational.ISIJINT-2023-168

Language：English   Publishing type：Research paper (international conference proceedings)  

Other Link： https://team2023.pknu.ac.kr/

Repository Public URL： https://hdl.handle.net/2324/7157262

Language：English   Publishing type：Research paper (international conference proceedings)  

Other Link： https://team2023.pknu.ac.kr/

Repository Public URL： https://hdl.handle.net/2324/7157020

Language：English   Publishing type：Research paper (international conference proceedings)  

Other Link： https://team2023.pknu.ac.kr/

Repository Public URL： https://hdl.handle.net/2324/7157018

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： https://hdl.handle.net/2324/6796166

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： https://hdl.handle.net/2324/6796165

Language：Japanese   Publishing type：Research paper (scientific journal)  

Cyclic true stress - true strain curves were obtained using general-purpose shipbuilding steel in the large strain region.
Test methods are incremental step test and static tensile test after cyclic loading.
The stress-strain curves for static and cyclic loading were compared to investigate the cause of the difference between each other.
A simple method for estimating the cyclic stress-strain curves was proposed.
The diameter and curvature of the smallest cross-section of the specimen were measured using telecentric measurement device, and the true stress - true strain curve was obtained using the Bridgman correction method.
Using the measurement method, cyclic stress-strain diagrams were obtained in the region where the true strain exceeded 1% by performing cyclic tensile tests using the incremental step method and static tensile tests after cyclic loading.
The influence of the test method and maximum displacement conditions on the cyclic stress-strain curve was small within the scope of this study.
There was little difference in the elongation between the static tensile test and the static tensile test after cyclic loading.
The difference in yield stress between static and cyclic loading was discussed in terms of macro-yield mechanisms at intergranular and transgranular.
A simple method for estimating cyclic stress-strain curves from a static stress-strain curve was proposed.
The specimens used in this study are general-purpose shipbuilding steels, and the results should be applicable to similar steels for welding and structures.

DOI： https://doi.org/10.2207/qjjws.41.217

Repository Public URL： https://hdl.handle.net/2324/6794871

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： http://hdl.handle.net/2324/4798534

Language：Japanese   Publishing type：Research paper (other academic)  

Repository Public URL： http://hdl.handle.net/2324/4822577

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： http://hdl.handle.net/2324/4822551

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： http://hdl.handle.net/2324/4822550

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4822552

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4822553

Language：Japanese   Publishing type：Research paper (other academic)  

Repository Public URL： http://hdl.handle.net/2324/4793671

Language：Japanese   Publishing type：Research paper (other academic)  

Repository Public URL： http://hdl.handle.net/2324/4794181

Language：Japanese   Publishing type：Research paper (other academic)  

Repository Public URL： http://hdl.handle.net/2324/4794429

Language：Japanese   Publishing type：Research paper (scientific journal)  

With the aim of introducing laser-arc hybrid welding (LAHW) into the field of large steel shipbuilding, a study was carried out to construct a T-shaped fully penetrating welded joint with a weld length of 3,000 mm in one pass.
Tack welding for the installation of members, which is a preliminary step of LAHW, was carried out by CO2 gas shielded arc welding.
Since the effect of the main welding by LAHW on the tack welding has not been sufficiently confirmed, preliminary investigations were also carried out.
As a result of repeated preliminary experiments, a T-shaped fully penetrating welded joint with a weld length of 3,000 mm was completed by the arc welding before the laser irradiation, unlike previous studies.
The performance of the joint was evaluated by Radiographic test and macroscopic observation of the weld line cross-section in accordance with the "Laser-Arc Hybrid Welding Guideline" published by the Nippon Kaiji Kyokai, (ClassNK) and it was confirmed that the T-shaped joint could be obtained within the acceptable range. Considering that fatigue is the main cause of damage in welded joints, the fatigue performance of the joints was also investigated.
As a result, the fatigue strength of the T-joint by LAHW using flux-cored wire was superior to that of the joint by LAHW preceded by laser irradiation using solid wire.
Furthermore, all the fatigue cracks, which were fluctuating in the previous study, were located at the weld toe on the back side of the flange in the method proposed in this study.
This result is favorable or the maintenance of the joint because it reduces the number of monitoring positions for fatigue cracks.
In addition, it was confirmed that the application of the Λ-shaped groove is promising as a method to increase the welding speed and to extend the range of possible thicknesses, which is a challenge for the LAHW method of welded joints in thick plates.

Repository Public URL： http://hdl.handle.net/2324/4763156

Language：Japanese   Publishing type：Research paper (scientific journal)  

Floating wind turbine facilities installed in deep sea areas play an essential role in carbon dioxide emissions reduction．
One of the problems associated with the commercialization of these facilities is the maintenance cost for mooring chains．
Therefore，it is necessary to establish a quantitative wear evaluation method for mooring chains．
Wear coefficient measured by wear tests is one of the essential physical parameters to evaluate the wear performance of metals．
The pin-on-disk wear test is generally performed for obtaining wear coefficient．However, wear coefficient measured by this method had significant variation in our past study．
Additionally, it has difficulty to use the heat-treated surface of the mooring chain under high pressure in fully immersed wet condition．
To reproduce the actual situation，new wear test machine was designed and wear tests were implemented to validate the accuracy．
As a result，it is confirmed that the proposed wear test method is possible to obtain the wear coefficient with significantly small variation compared with the conventional pin-on-disk wear test.

Repository Public URL： http://hdl.handle.net/2324/4763197

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： https://hdl.handle.net/2324/6757884

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： https://hdl.handle.net/2324/6757890

Language：Japanese   Publishing type：Research paper (scientific journal)  

Identification of the relationship between fatigue crack propagation rate (da/dN) and stress intensity factor range (∆K) is inevitable to apply the fracture mechanics approach to assess the growth of fatigue crack growth.
The relationship between da/dN and ∆K is widely applied to evaluate fatigue crack propagation behavior.
To evaluate the fatigue crack growth history under variable loading history, it is necessary to replace ∆K to the effective stress intensity factor range, which can quantitatively consider fatigue crack opening and closing behavior.
∆Keff proposed by Elber is well known as the effective stress intensity factor range, but even if ∆Keff is applied to evaluate the fatigue crack propagation behavior, a threshold value ((∆Keff)th) was occurred.
On the other hand, it is known that fatigue cracks propagate even at ∆Keff below (∆Keff)th under variable loading history.
This implies that ∆Keff is an insufficient parameter to describe fatigue crack propagation behavior. ∆KRPG, which has a close relationship with the cyclic plastic behavior in the vicinity of the crack tip proposed by Toyosada and Niwa, can give the solution of the problem of ∆Keff, and even under complicated variable loading history including multiple frequency components.
To apply the fatigue crack propagation law with ∆KRPG as a parameter, it is necessary to experimentally measure the RPG load and identify the propagation law constants (∆KRPG=C(∆KRPG)m) C and m.
A conventional method for identifying RPG loads requires the superposition of the hysteresis loop near the crack tip and its reversal loop as measured by the unloading elastic compliance method.
However, advanced skills in this method, such as understanding the characteristics of measurement errors associated with loops, is required.
In this study, we propose a method to automatically measure the RPG load equivalent to that of an expert, and compare the automatic measurement results by this method with the past conventional measurement results under multiple materials and loading conditions, and validate the automatic measuring method.

DOI： https://doi.org/10.2207/qjjws.39.125

Repository Public URL： http://hdl.handle.net/2324/4794831

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： https://doi.org/10.1115/OMAE2022-87473

Language：Japanese   Publishing type：Research paper (scientific journal)  

Recently, the strength of the hull structure including fatigue strength has seen significant improvement because of application of IACS CSR (Common Structural Rules).
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 to improve the fatigue performance.
Recently, many peening treatment methods at the welding bead has also been proposed.
These peening processes produce a compressive residual stress field near the peening location.
In addition, the peening process smoothes the toe shape of the weld bead and reduces stress concentration.
In case of generating compressive residual stress by impact, the same effect could be expected by shot blasting, which is the steel surface preparation for 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.
In addition, referring to the S-N curve based on the fatigue test results, the effect of the fatigue strength improvement effect due to blasting on the fatigue design of the hull structure was investigated, and the possibility of hull weight reduction was confirmed.

DOI： https://doi.org/10.2534/jjasnaoe.33.97

Repository Public URL： http://hdl.handle.net/2324/4794834

Language：Japanese   Publishing type：Research paper (other academic)  

二次元問題である板厚貫通亀裂材を対象に，亀裂先端近傍で生じる両振り塑性仕事を評価パラメータとする疲労亀裂伝播則を用いて，汎用弾塑性FE 解析コードによる疲労亀裂伝播解析手法に関し，先行研究での問題点を解消するための諸検討を実施した結果を報告する．

Language：Japanese   Publishing type：Research paper (other academic)  

実機レベルに近い寸法を有する係留鎖の摩耗挙動を没水環境下で再現する実験装置を構築し，摩耗試験を実施した結果を報告する．

Language：Japanese   Publishing type：Research paper (other academic)  

著者らが船体構造中に多数存在するすみ肉溶接継手の代替として検討している片側からの 1パス完全溶込み溶接により製造されるT継手を対象に，長尺の溶接継手製作に関して検討した結果を報告する．本研究では試験装置の制約の都合上，最大溶接長の検証範囲を 3,000 mmとしたが， 1ランでの施工長としては先行研究を超えるものである．

Language：Japanese   Publishing type：Research paper (other academic)  

ハイブリッド溶接の適用範囲拡張を目的として，突合せ継手を対象に横向および立向上進姿勢を対象に，溶接施工を可能とする諸検討を実施した結果を報告する．

Language：Japanese   Publishing type：Research paper (other academic)  

質点ばねモデルから得られる係留鎖応答に適用可能な係留鎖間に生じる転がりの考慮方法について検討を行い，簡易推定手法を提案した．

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.marstruc.2020.102927

Language：Japanese   Publishing type：Research paper (scientific journal)  

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.

Language：Japanese   Publishing type：Research paper (scientific journal)  

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 20mm, which is used as a hull member of a 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 performance of the joint 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.

DOI： https://doi.org/10.2207/qjjws.38.403

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Repository Public URL： http://hdl.handle.net/2324/4794747

Language：Japanese   Publishing type：Research paper (scientific journal)  

It is necessary to develop quantitative wear estimation method of mooring chains for floating structures such as floating offshore wind turbine.
In our previous research, a numerical analysis combining 1) wear analysis between links by finite element method and 2) response analysis of mooring system has been proposed and validated qualitatively in the case of a single moored buoy.
In this paper, the proposed method is applied to a spread moored floating spar with three mooring lines for further validation.
Here, the effect of wind in addition to waves on the wear of chains is examined.
As a result of comparison, it is found that the wear amounts estimated by the proposed method fairly agree with the measured values.
However, it is also found that the estimated wear amounts around the touchdown point and those next to a clump weight considerably overestimate the measured values.

Language：Japanese   Publishing type：Research paper (other academic)  

Repository Public URL： http://hdl.handle.net/2324/4794744

Language：Japanese   Publishing type：Research paper (other academic)  

Repository Public URL： http://hdl.handle.net/2324/4794745

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： https://doi.org/10.1007/978-981-15-4680-8

Repository Public URL： http://hdl.handle.net/2324/4752586

Language：Japanese   Publishing type：Research paper (scientific journal)  

Up to now, wear estimation method for mooring chain of floating facilities has not been established, and it currently relies on empirical methods.
In this research, numerical analysis combining 1) wear analysis between links by finite element method and 2) response analysis of mooring system was performed to establish a method for estimating wear amount of mooring chain during operation.
The validity of the proposed method was confirmed by comparing with the actual measurement value in the actual sea area.
As a result, it was found that the wear amount estimated by our proposed method is generally close to the measured value.
However, it was also confirmed that the estimated wear amount at the touchdown point between the seabed and mooring chain was considerably overestimated.
That result could be attributed to insufficient consideration of the effects caused between the links ( e.g. snap load, elastic deformation and friction), the behavior of the links ( e.g. sticking, rolling and non-contact) and the external forces ( e.g. wind and current ).

Language：Japanese   Publishing type：Research paper (scientific journal)  

Up to now, wear estimation method for mooring chain of floating facilities has not been established, and it currently relies on empirical methods.
In this research, numerical analysis combining 1) wear analysis between links by finite element method and 2) response analysis of mooring system was performed to establish a method for estimating wear amount of mooring chain during operation.
The validity of the proposed method was confirmed by comparing with the actual measurement value in the actual sea area.
As a result, it was found that the wear amount estimated by our proposed method is generally close to the measured value.
However, it was also confirmed that the estimated wear amount at the touchdown point between the seabed and mooring chain was considerably overestimated.
That result could be attributed to insufficient consideration of the effects caused between the links ( e.g. snap load, elastic deformation and friction), the behavior of the links ( e.g. sticking, rolling and non-contact) and the external forces ( e.g. wind and current ).

DOI： https://doi.org/10.2534/jjasnaoe.29.77

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： http://hdl.handle.net/2324/4794502

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4753062

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4753063

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4755271

Language：Japanese   Publishing type：Research paper (scientific journal)  

Floating wind turbine facilities, which are installed in the deep sea area, play 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.
Therefore, it is necessary to establish a quantitative wear evaluation method for mooring chains.
Specific wear is one of the essential physical parameter to evaluate the wear performance of metals. However, detailed investigation of the specific wear of the mooring chain has not been performed yet.
The pin-on-disk wear tests were performed to measure the specific wear in the air and in the substitute ocean water.
As a result of experiments, it has been confirmed that the specific wear in the substitute ocean water was remarkably smaller than in the air, and the wear state was stable.

DOI： https://doi.org/10.2534/jjasnaoe.28.145

Repository Public URL： http://hdl.handle.net/2324/4794500

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

船体建造におけるコストダウン対策の一つとして，居住区等の強度要件が余り厳しくない部分の製作に比較的調達が容易なコイル材を活用するという考えがある．一方，コイル材はその性状から，圧延鋼板と同様の利用を考えるとコイル状の素材を平板に戻す「リコイル」工程が必要であるが，コイルおよびリコイルという塑性加工により材質が劣化することや，塑性加工による残留応力が溶接後の部材変形に影響を及ぼすことが懸念される．
本研究では，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．

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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 (ΔΚth) 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 ΔΚth.
However, a considerably long time is required to perform the determination of ΔΚth value.
Therefore, it is expected to cut the experimental period for ΔΚth determination. Efficient and time saving procedure for determining ΔΚth value comparing with ASTM-E647 is proposed in this study.
Many fatigue crack propagation test data were applied to verify the validity of our proposed method. It is expected to be able to complete the experiment for determining ΔΚth value at a stage where the fatigue crack propagation rate is one order larger comparing with ASTM-E647.

DOI： https://doi.org/10.2207/qjjws.35.149

Repository Public URL： http://hdl.handle.net/2324/4794496

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： http://hdl.handle.net/2324/4794493

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： http://hdl.handle.net/2324/4794495

Language：Japanese   Publishing type：Research paper (scientific journal)  

Most of large frame-based welded structures are subjected to multiaxial cyclic loadings with different phases under in-service condition. However, the fatigue performance of these structures are evaluated according to the 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 in-plane biaxial loadings with phase difference of each loading component. Fracture mechanics approach was applied to establish our method. In this study, fatigue crack growth behaviour of an out-of-plane gusset welded joint under in-plane biaxial loading with two different phase conditions are investigated. The phase difference effect for fatigue 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 results.

Repository Public URL： http://hdl.handle.net/2324/4794491

Language：Japanese   Publishing type：Research paper (scientific journal)  

Numerical simulation method for the fatigue crack propagation in the case that the initial defect surface closes by the compressive
loading is proposed. Previous fatigue crack opening / closing model based on the strip yield model proposed by Toyosada et al. is
improved to consider the closure effect on the initial defect surfaces. This improved numerical simulation procedure for the fatigue
crack propagation was verified by comparing with measured fatigue crack propagation histories under various superimposed stress
histories.
In addition, numerical case studies were performed to investigate the influence of appearance degree of superimposed stress for
the fatigue crack propagation history by applying our improved numerical simulation procedure. These simulation results are suggested
that safe side evaluation for the fatigue crack propagation could be obtained by replacing the superimposed stress into the stress with
enveloping the superimposed stress.

Repository Public URL： http://hdl.handle.net/2324/4794492

Language：Japanese   Publishing type：Research paper (other academic)  

複数の画像から対象物の変形を計測するデジタル画像相関法を用いて，亀裂先端近傍に形成され疲労亀裂成長挙動を律すると考えられている両振塑性域寸法の測定を試みた結果を報告する．

Language：Japanese   Publishing type：Research paper (other academic)  

面内二軸繰返し荷重を受ける表面亀裂の形状変化履歴に対して，各因子がおよぼす影響を確認するとともに，面内単軸繰返し荷重条件下における表面亀裂の形状変化推定手法（著者らの先行研究）を活用することで，面内二軸繰返し荷重条件下における表面亀裂の形状変化を評価した結果について述べる．

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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 fatigue tests.
In order to overcome this difficulty, special types of fatigue testing machines in rotating bending whose loading type is cantilever bending has been developed.
It is known that this type of fatigue machine can be performed much quickly comparing with the tension and compression fatigue testing machines.
And these experimental results are consistent with much data obtained by using traditional testing machines like tension and compression fatigue testing machines and the rotating bending fatigue test machines whose loading type is uniform bending named as Ono type, though it is unclear that much data of an ultrasonic fatigue testing
machine are consistent with them.
Although it prefers to perform the fatigue tests as fast as possible, but the maximum frequency of a rotating bending fatigue test are limited because of the possibility of 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.

DOI： 10.1299/transjsme.16-00535

Repository Public URL： http://hdl.handle.net/2324/4794488

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4794497

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

三次元スキャナにより実船ブロックの測定を試み，三次元スキャナを活用した工作精度管理の可能性について検討した結果を紹介する．

Language：Japanese   Publishing type：Research paper (other academic)  

係留鎖の定量的な摩耗量評価手法確立のために，弾塑性FE解析と浮体-係留系の全体応答解析を用いた摩耗量推定を行い，実測データとの比較を行った結果を紹介する．

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Repository Public URL： http://hdl.handle.net/2324/4794467

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4794458

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4794432

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

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．

Language：Japanese   Publishing type：Research paper (scientific journal)  

The reducing effect of the angular distortion in Tee type full penetrated welded joint fabricated by the laser-arc hybrid welding was investigated.
The Angular distortion caused by the laser-arc hybrid welding were measured and compared with one caused by the CO2 gas shielded arc welding.
As a result, the amount of angular distortion by the laser-arc hybrid welding was the same level as one in case of forming the leg size of F1 grade regulated by Common Structural Rules for
Bulk Carriers (CSR-B) by applying arc welding.
In addition, numerical analysis of the welding deformation was carried out by the thermal elastic-plastic finite element analysis and these results were generally consistent with the measured
results.
Moreover the effect on FE result of the penetrated shape and joining process of stiffener and base plate were discussed.

DOI： http://doi.org/10.2207/qjjws.33.194

Repository Public URL： http://hdl.handle.net/2324/4794430

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

In the ship-hull design phase, the distance of longitudinal discontinuity 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 Strength-of-Materials misalignment model and focusing on small misalignment, cannot be applied in the design phase.
Longitudinal discontinuity 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 discontinuity effect in cruciform welded joint with shell plate.
First, we created a new equation to estimate the coefficient in Strength-of-Materials model.
Second, we found the membrane component of a discontinuous member stress is reduced because of the shell plate and the coefficient converges given a certain discontinuity value.
Third, a modified equation taking the effect into account indicates the coefficient in the joint with shell plate.

Other Link： https://www.jstage.jst.go.jp/browse/jjasnaoe/18/0/_contents

Language：Japanese   Publishing type：Research paper (scientific journal)  

Fatigue crack propagation under biaxial tensile loading containing phase differences 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 and two different loading components are performed and the effect of the phase difference under biaxial loading is evaluated.
We present a numerical simulation method of fatigue crack propagation based on the RPG stress criterion under different biaxial loading phase conditions and
the validity of our proposed method is confirmed by comparing the estimated fatigue crack propagation histories with measured data.

Other Link： https://www.jstage.jst.go.jp/browse/jjasnaoe/18/0/_contents

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (other academic)  

Numerical Study of Fatigue Performance of Butt Welded Joint with U and V-notch Undercut,
Ezzarhan Abdullah and Koji Gotoh,
Conference Proceedings, The Japan Society of Naval Architects and Ocean Engineers,
Vol.17, November 2013, pp.49-52, (Paper ID: 2013A-GS1-4)

Language：English   Publishing type：Research paper (international conference proceedings)  

Comparison of Hull Construction Quality Standards,
Koji GOTOH and Kazuhiro AOYAMA,
Proceedings of 12th International Symposium of Practical Design of Ships and Other Floating Structures (PRADS 2013),
2013, Volume I, pp. 94-101.

Language：Japanese   Publishing type：Research paper (other academic)  

著者らのグループでは，豊貞らが提唱したRPG荷重基準に基づく疲労亀裂伝播解析手法を実装した，疲労亀裂開閉口シミュレーションを構築し，種々の荷重履歴下における，同手法の妥当性を検証してきた．しかしながら，過大な荷重履歴変動を生じるブロック荷重履歴条件やスパイク荷重履歴条件における解析結果は，実測された伝播履歴と比べて過大な遅延現象を与えている．この理由として，従来の数値シミュレーションでは材料を弾完全塑性体としてモデル化し，材料の加工硬化現象を無視したため，疲労亀裂伝播に伴い亀裂面に取り込まれるcrack wake（残留引張変形層）が過大に評価され，その結果として亀裂が閉じやすくなるため，伝播挙動の遅延が過大になると推察された．
本研究では，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する．

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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) 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 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.
Besides, the insufficiency of S-N curves approach with the cumulative damage law for the superposed loading history condition containing different frequency components is conducted.

Other Link： https://www.jstage.jst.go.jp/browse/jjasnaoe/17/0/_contents

Language：Japanese   Publishing type：Research paper (scientific journal)  

This paper describes the application of weight function method for the calculation of stress intensity factors in a surface crack and an embedded crack under complex two dimensional loading conditions.
The crack shape is approximated by an ellipse.
Improved formulation of the point load weight functions are proposed based on the properties of weight functions and the available weight functions for two-dimensional cracks proposed by Wang and Glinka.
For a surface crack and an embedded crack of any aspect ratio, the unknown parameters in the general form can be determined from one reference stress intensity factor solution obtained by the finite element analysis with J integral method.
The derived weight functions are then validated against available stress intensity factor solutions for several linear and non-linear stress distributions. The derived weight functions are particularly useful for the fatigue crack growth analysis of a planer surface crack and an embedded crack subjected to
fluctuating non-linear stress.

Other Link： https://www.jstage.jst.go.jp/browse/jjasnaoe/17/0/_contents

Language：English   Publishing type：Research paper (other academic)  

Practical Formula of Stress Concentration Factor for Butt Welded Joint with Undercut,
Ezzarhan Abdullah and Koji GOTOH,
Conference Proceedings, The Japan Society of Naval Architects and Ocean Engineers,
Vol.16, May 2013, pp.531-534, (Paper ID: 2013S-GS6-11)

Language：Japanese   Publishing type：Research paper (scientific journal)  

A crystal plasticity FE analysis is conducted to understand the fatigue phenomena subjected to cyclic stresses.
For simplicity,　the crystal plasticity model assumes an isotropic hardening/softening and an isotopic elasticity.
The effects of inclusions with the　varieties of positions and mechanical properties on the initiation and accumulation of local-plastic strain at the stress level lower
than the dominant yielding stress state, i.e macroscopically elastic condition, are discussed in detail.

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (scientific journal)  

Fracture control of extremely thick welded steel plates applied to the deck structure of large container ships
Sumi, Yoichi; Yajima, Hiroshi; Toyosada, Masahiro; Yoshikawa, Takao; Aihara, Shuji; Gotoh, Koji; Ogawa, Yoshitaka; Matsumoto, Toshiyuki; Hirota, Kazuhiro; Hirasawa, Hideyuki; Toyoda, Masanobu; Morikage, Yasushi
JOURNAL OF MARINE SCIENCE AND TECHNOLOGY, Vol.18, No.4, 2013, pp.497-514.

DOI： 10.1007/s00773-013-0222-5

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authors investigate the fatigue crack propagation behavior of solid austenitic stainless steels SUS304L, SUS316L and SUS316LN in order to conduct the characteristics of fatigue behavior of each stainless steel. Not only the constant stress amplitude tests, but also the load decreasing tests called by ΔKth test regulated by ASTM E647 are performed to identify the material constants of fatigue crack propagation. Comparison of the fatigue crack growth behavior of SUS304L, SUS316L and SUS316LN with mild steels is also performed. Authors also investigate the fatigue life of load-carrying type cruciform joints of austenitic stainless steels, which are modeled upon the lower end of vertically corrugated bulkhead of chemical tankers. Besides, the possibility of quantitative numerical simulation of the fatigue crack propagation for the stainless steels is also investigated. This simulation procedure applies for the advanced effective stress intensity factor range based on a Re-tensile Plastic zone Generation (RPG) load and the fatigue crack closure phenomenon is quantitatively considered. The experimental results are compared with the numerical simulation results in this study and the validity of fatigue crack growth simulation procedure applied in this study is confirmed.

Other Link： https://www.jstage.jst.go.jp/article/jjasnaoe/16/0/16_89/_article

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

A Conventional Growth Estimation Formula of the Representative Surface Crack Replacing Plural Surface Cracks Generated at the Sound Stress Concentration Site,
Yosuke ANAI, Koji MURAKAMI and Koji GOTOH,
Proceddings of International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11), OS14F029, September, 2011

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4763157

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

A practical estimation of welding deformation in the assembly stage of hull panel structures
Koji GOTOH, Ryohei KAWASHIMA and Masahiro TOYOSADA
Proceedings of International Conference of Computational and Experimental Engineering and Sciences 2008 (ICCES'08)

Repository Public URL： http://hdl.handle.net/2324/4785267

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4793198

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4793196

Language：Japanese   Publishing type：Research paper (scientific journal)  

Repository Public URL： http://hdl.handle.net/2324/4794748

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10773-003-0152-9

Repository Public URL： http://hdl.handle.net/2324/4755282

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4752587

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4752583

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/4752591

Event date： 2015.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：産業技術総合研究所　臨海副都心センター   Country：Japan  

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.

Event date： 2014.6 - 2014.7

Language：English   Presentation type：Oral presentation (general)  

Country：Norway  

Other Link： http://www.sciencedirect.com/science/article/pii/S2211812814002491

Event date： 2014.6

Language：English   Presentation type：Oral presentation (general)  

Country：United States  

Event date： 2013.6

Language：English   Presentation type：Oral presentation (general)  

Country：France  

Event date： 2013.6

Language：English   Presentation type：Oral presentation (general)  

Country：France  

Event date： 2012.9

Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2012.7

Presentation type：Oral presentation (general)  

Country：Brazil  

Event date： 2011.6

Presentation type：Oral presentation (general)  

Country：Netherlands  

Event date： 2010.9

Presentation type：Oral presentation (general)  

Country：Brazil  

Overview of Japanese Joint Research Project on Safety-Related Issue of Extremely Thick Steel Plate Applied to Large Container Ships

Yoich Sumi, Hiroshi Yajima, Masahiro Toyosada, Takao Yoshikawa, Shuji Aihara, Toshiyuki Matsumoto, Kazuhiro Hirota, Hideyuki Hirasawa, Masanobu Toyoda and Koji Gotoh

11th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS 2010)

Event date： 2010.6

Presentation type：Oral presentation (general)  

Country：China  

Event date： 2009.11 - 2009.12

Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2009.7

Presentation type：Oral presentation (general)  

Country：Canada  

Improvement of Slice Synthesis Methodology to Estimate Stress Intensity Factor of an Embedded Crack in Finite body
Koji GOTOH and Yukinobu NAGATA
The 12th International Conference on Fracture (ICF 12)
Session T02-S3 Analytical Models

Event date： 2009.5 - 2009.6

Presentation type：Oral presentation (general)  

Country：United States  

Applicability Evaluation of the Weight Function Based Strip Yield Model for an Embedded Crack Problem
Koji GOTOH and Yukinobu NAGATA
The 28th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2009)
Session 3-6: Advances in Fracture, Fatigue and Sealing Analysis

Event date： 2008.7

Presentation type：Oral presentation (general)  

Country：Canada  

Stress Intensity Factors for Three Dimensional Cracks by Applying Slice Synthesis Methodology
Koji GOTOH and Yukinobu NAGATA
The Eighteenth (2008) International Offshore and Polar Engineering Conference (ISOPE 2008)

Presentation type：Oral presentation (general)  

Country：Portugal  

Presentation type：Oral presentation (general)  

Country：Norway  

Presentation type：Oral presentation (general)  

Country：Canada  

Presentation type：Oral presentation (general)  

Country：Italy  

Physical Meaning of the Fictitious Crack Opening Displaecement in Dugdale Model

Presentation type：Oral presentation (general)  

Country：India  

A Comparative Study of Computational Models for Fatigue Crack Propagation

Presentation type：Oral presentation (general)  

Country：Germany  

A Simple Estimation Method of the Stress Distribution Normal to Cross Section at Weld Toe in non-load carrying welded joints

Presentation type：Oral presentation (general)  

Country：United States  

Presentation type：Oral presentation (general)  

Country：United States  

Country：United States  

Presentation type：Oral presentation (general)  

Country：United States  

Presentation type：Oral presentation (general)  

Country：United States  

Presentation type：Oral presentation (general)  

Country：United States  

Event date： 2024.3

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：ミューザ川崎シンフォニーホール＋オンライン（ハイブリッド）   Country：Japan  

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．

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学 銀杏会館   Country：Japan  

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学 銀杏会館   Country：Japan  

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．

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学 銀杏会館   Country：Japan  

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学 銀杏会館   Country：Japan  

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．

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：出島メッセ長崎（長崎市）   Country：Japan  

Event date： 2023.11

Language：English   Presentation type：Oral presentation (general)  

Venue：International Conference Center Hiroshima   Country：Japan  

Other Link： https://fatigue2022.org/

Repository Public URL： https://hdl.handle.net/2324/7159845

Event date： 2023.10

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2023.10

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2023.10

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2023.10

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Repository Public URL： https://hdl.handle.net/2324/7152003

Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：建築会館   Country：Japan  

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．

Repository Public URL： https://hdl.handle.net/2324/7152001

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：日本大学工学部   Country：Japan  

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．

Repository Public URL： https://hdl.handle.net/2324/7151995

Event date： 2023.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学 伊都キャンパス   Country：Japan  

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．

Event date： 2023.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学 伊都キャンパス   Country：Japan  

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．

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：くにびきメッセ（島根県松江市）   Country：Japan  

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学 伊都キャンパス   Country：Japan  

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．

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学 伊都キャンパス   Country：Japan  

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．

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学 伊都キャンパス   Country：Japan  

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．

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Repository Public URL： https://hdl.handle.net/2324/4822552

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場（広島市）・Web会議   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場（広島市）・Web会議   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場（広島市）・Web会議   Country：Japan  

Event date： 2021.12

Language：English   Presentation type：Oral presentation (general)  

Country：Turkey  

Event date： 2021.12

Language：English   Presentation type：Oral presentation (general)  

Country：Turkey  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Web会議   Country：Japan  

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．

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Web会議   Country：Japan  

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．

Event date： 2021.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学 伊都キャンパス   Country：Japan  

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．

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学 伊都キャンパス   Country：Japan  

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．

Event date： 2021.7

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2021.5 - 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Web会議   Country：Japan  

Event date： 2021.5 - 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Web会議   Country：Japan  

Event date： 2021.5 - 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Web会議   Country：Japan  

Event date： 2021.5 - 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Web会議   Country：Japan  

Event date： 2021.5 - 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Web会議   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Web会議   Country：Japan  

Event date： 2019.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学 銀杏会館   Country：Japan  

Event date： 2019.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学 銀杏会館   Country：Japan  

Event date： 2019.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学 銀杏会館   Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：姫路西はりま地場産業センター（兵庫県姫路市）   Country：Japan  

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．

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：姫路西はりま地場産業センター（兵庫県姫路市）   Country：Japan  

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．

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北九州国際会議場，北九州市小倉北区   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北九州国際会議場，北九州市小倉北区   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北九州国際会議場，北九州市小倉北区   Country：Japan  

Event date： 2019.6

Language：English   Presentation type：Oral presentation (general)  

Country：United Kingdom  

Event date： 2019.6

Language：English   Presentation type：Oral presentation (general)  

Country：United Kingdom  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎県勤労福祉会館   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎県勤労福祉会館   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎県勤労福祉会館   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎県勤労福祉会館   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎県勤労福祉会館   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎県勤労福祉会館   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎県勤労福祉会館   Country：Japan  

Event date： 2019.5

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：柏の葉カンファレンスセンター（千葉県柏市）   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：柏の葉カンファレンスセンター（千葉県柏市）   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：柏の葉カンファレンスセンター（千葉県柏市）   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：柏の葉カンファレンスセンター（千葉県柏市）   Country：Japan  

Event date： 2018.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 百周年中村記念館，北九州市戸畑区  

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．

Event date： 2018.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 百周年中村記念館，北九州市戸畑区  

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．

Event date： 2018.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：ホテルコスモスクエア国際交流センター   Country：Japan  

Event date： 2018.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：ホテルコスモスクエア国際交流センター   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学　銀杏会館   Country：Japan  

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．

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学　銀杏会館   Country：Japan  

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．

Event date： 2017.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場   Country：Japan  

Event date： 2017.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場   Country：Japan  

Event date： 2017.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.9