Kyushu University Academic Staff Educational and Research Activities Database
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Koji GOTOH Last modified date:2018.05.17

Professor / Structural Engineering of Ship and Marine Systems
Department of Marine Systems Engineering
Faculty of Engineering


Graduate School
Undergraduate School
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E-Mail
Homepage
http://www.nams.kyushu-u.ac.jp/~gotoh/index.html
Personal infromation .
http://www.nams.kyushu-u.ac.jp/~gotoh/index_e.html
Personal information .
http://www.nams.kyushu-u.ac.jp/common/production/
General information of our laboratory .
http://www.nams.kyushu-u.ac.jp/common/production/index_e.html
General information of our laboratory .
Fax
092-802-3368
Academic Degree
Doctor of Engineering
Country of degree conferring institution (Overseas)
No
Field of Specialization
Fatigue and Fracture,Welding mechanics,Production Systems for welded built-up structures, Pipeline technology (strength evaluation)
Total Priod of education and research career in the foreign country
01years00months
Outline Activities
See the following "Reserach and Educational activities.

We show the general information for prospective foreign students and postdoctral research fellow in our lab on the following web site.
 http://www.nams.kyushu-u.ac.jp/common/production/index_e.html
Research
Research Interests
  • Fatigue life estimation methods based on fracture mechanics approach
    keyword : Fatigue, Numerical simulation of fatigue crack growth, Fatigue crack nucleation model, variable amplitude loading
    1995.04Fatigue strength of the large welded built-up steel structures. Numerical simulation of fatigue crack growth without initial defect..
  • Application of the laser-arc hybrid welding technology for the ship hull construction stages.
    keyword : laser-arc hybrid welding, hull construction
    2012.04.
  • Wear performance of the mooring chain
    keyword : Floating wind turbine, Mooring chain, Wear
    2015.04.
  • Evaluation of fatigue strength for structural metals.
    keyword : Fatigue strength, Aluminum alloys, Titanium alloys, stainless steels, Flame-retardant magnesium alloys
    2006.04Selection criteria of alminum alloy for hull structural components Fatigue strength of alminum alloy for hull structural componetns.
  • Structural integrity of welded built-up steel structures under dynamic loading
    keyword : dynamic/impact loading, unstable fracture (brittle fracture), fracture toughness, stress versus strain relation, strain rate, temperature, notch and crack
    1990.04Strength evaluation for the steel welded built-up structures under dynamic/impact loading (i.e. arbitrary strain rate and temperature field).
  • Practrical estimation procedure of the deformation and residual stress caused by welding in large welded-built up structures.
    keyword : Welding deformation and residual stress, inherent strain and stress, Finite element analysis
    1997.04Estimation of the welding deformation and residual stress in the large welded built-up steel structures.
  • Structural integrity evaluation of city gas pipeline made from polyethylene.
    keyword : city gas pipeline, polyethylene, strain rate, earthquake loading, fusion bonding
    2006.04~2013.03Mechanical characteristics of city gas pipeline made of polyethylene.
  • Extending of the strip yield model.
    keyword : Strip Yield Model, Crack opening displacement
    2005.06Generalization of strip yield model in arbitray stress distributions.
Academic Activities
Reports
1. Fatigue Strength of Welded Joints
Koji GOTOH
Journal of the Japan Welding Society,Vol.78,No.7,pp.639-643,2009.
2. Development of Numerical Simulation of Fatigue Crack Growth
Koji GOTOH
Journal of the Japan Welding Society,Vol.77,No.4,pp.273-277,2008.
Papers
1. 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. .
2. 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), September, 2016..
3. 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..
4. 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.
5. Kohei YAMASHITA and Koji GOTOH,
Numerical simulation of fatigue crack propagation with crack opening and closing based on the strip yield model considering the strain hardening effect of materials,
Journal of the Japan Society of Naval Architects and Ocean Engineers,
Vol.21, June 2015, pp.31-42.
6. 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..
7. 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..
8. 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..
9. Koji GOTOH, Shuich TSUMURA and Issei UCHINO;
Overview of the joint research project for introducing laser-arc hybrid welding in Japanese shipbuilding industries,
Proceedings of the 82nd Laser Materials Processing Conference, January 2015, pp.83-39.
.
10. 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..
11. Kazuki, Matsuda, Koji Murakami and Koji Gotoh;
Numerical Simulation of Fatigue Crack Propagation under Superimposed Stress Histories with Several Constant and
Variable Mean Stresses,
Journal of the Japan Society of Naval Architects and Ocean Engineers,
Vol.20, 2014, pp.131-137..
12. 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..
13. 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..
14. 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. .
15. 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. .
16. 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..
17. 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..
18. Improvement of the Dugdale strip yield model considering the work hardening effect of materials,
Keisuke HARADA and Koji GOTOH
Journal of the Japan Society of Naval Architects and Ocean Engineers,
Vol.14, pp.39-46.
.
19. 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.
20. 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.
21. 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.
22. 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.
23. 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, Proceedings of The 23rd Asian-Pacific Technical Exchange and Advisory Meeting on Marine Sturctures (TEAM 2009), pp.8-12, 2009.12.
24. 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.
25. 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.
26. Stress Intensity Factor and Crack Opening Displacement in Elastic Condition for Embedded Cracks
by Applying Slice Synthesis Methodology,
Yukinobu NAGATA and Koji GOTOH,
Journal of the Japan Society of Naval Architects and Ocean Engineering, Vol.9, ,2009, pp.191-199, [URL].
27. A Calculation Method of Crack Opening Displacement \\by Using Slice Synthesis Methodology And Strip Yield Model for An Embedded Elliptical Crack in Elastic-Perfect Plastic Bodies with Finite Plate Thickness,
Yukinobu NAGATA and Koji GOTOH,
Journal of the Japan Society of Naval Architects and Ocean Engineering, Vol.9, ,2009, pp.201-209, [URL].
28. 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.
29. 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.
30. 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.
31. 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.
32. 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.
33. 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.
34. Numerical Simulation of Fatigue Crack Initiation and Propagation for In-plane Gusset Welded Joints,.
35. Masahiro TOYOSADA and Koji GOTOH, Physical Meaning of the Fictitious Crack Opening Displaecement in Dugdale Model, Proceedings of 10th International Conference on Fracture, ICF11 4620, 2005.03.
36. 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.
37. A fatigue life prolonging method for welded built-up steel structures
by the grain fining around weld toe
Yukinobu NAGATA,Masahiro TOYOSADA,Koji GOTOH,Koji MURAKAMI
Proceedings of Welded Built-up Structures Integrity Symposium 2004, Japan Welding Society, pp.343-346.
38. 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.
39. 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.
40. 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.
41. 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.
42. 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.
43. 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.
44. Development of Evaluation Parameter for Fracture Toughness Based on Statistical Mechanics,
Journal of the Society of Naval Architects of Japan, Vol.190.
45. 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.
46. Evaluation of Brittle Fracture Accidents Occurred at the Hyogo-Ken Nanbu Earthquake,
Journals of the Japan Society of Civil Engineers, No.647 / I-51.
47. A Study on Deformation due to Thermal Cutting,
Transactions of the West-Japan Society of Naval Architects, No.99.
48. 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.
49. 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.
Presentations
1. 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..
2. Koji GOTOH, Shuichi TSUMURA and Issei UCHINO;
Overview of the joint research project for introducing laser-arc hybrid welding in Japanese shipbuilding industries,
The 82nd Laser Materials Processing Conference,
National Institute of Advanced Industrial Science and Technology (AIST) Tokyo Waterfront,
January 2015..
3. 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..
4. 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..
5. 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..
6. 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..
7. 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).
8. 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 .
9. 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.
10. 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).
11. A Simple Estimation Method of the Stress Distribution Normal to Cross Section at Weld Toe in non-load carrying welded joints.
12. A Comparative Study of Computational Models for Fatigue Crack Propagation.
13. Physical Meaning of the Fictitious Crack Opening Displaecement in Dugdale Model.
Membership in Academic Society
  • Japan Laser Processing Society
  • The Society of Naval Architecture and Ocean Engineering of Japan
  • Japan Welding Society
  • Japan Society of Civil Engineers
Awards
  • The following paper was selected as the best paper award on materials technology symposium.
    Title: Fatigue Crack Propagation under Bi-axial Tensile Loading, - Effect of the Phase Difference on bi-axial loading-
    Authors: Koji GOTOH, Toshio NIWA, Yosuke ANAI, Tetsuya OMORI, Yoshihisa TANAKA and Koji MURAKAMI
Educational
Educational Activities
[Gracuate school, Master course]
Welding Desing I and II
Advanced Course in Fracture Control Design

[Undergraduate]
Materials and Production in Large welded built-up sturctures
Fracture Control Design
Naval Architecture and Marine Systems Engineering Laboratories (Round bar tensile tests)
Introduction to Earth, Civil and Energy Sciences and Engineering II
Other Educational Activities
  • 2007.08.
  • 2006.07.
  • 2005.08.
Social
Professional and Outreach Activities
ISSC 2003 (15th International Ship and Offshore Structures Congress) Observer
ISSC 2006 (16th International Ship and Offshore Structures Congress) Observer
ISSC 2009 (17th International Ship and Offshore Structures Congress) Observer.