M. S. Alam¹, M.A. Wahab^1,2

Structural Durability & Health Monitoring, Vol.1, No.3, pp. 171-184, 2005, DOI:10.3970/sdhm.2005.001.171

Abstract Fatigue life of curved structural joints in ship structures under constant amplitude cyclic loading has been studied in this research. A new approach for the simulation of fatigue crack growth in welded joints has been developed and the concept has been applied to welded curved butt-joints. The phenomena of crack propagation and interface debonding can be regarded as the formation of new surfaces. Thus, it is possible to model these problems by introducing the mechanism of surface formation. In the proposed method, the formation of new surface is represented by interface element based on the interface surface potential energy. The… More >

Hidekazu Murakawa

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.4, pp. 187-187, 2019, DOI:10.32604/icces.2019.05179

Abstract It is known that fatigue life of welded structures, such as ships and bridges, is greatly influenced by welding residual stress. In case of real structures, the orientation of the stresses produced by dead load and that produced by applied load and that of welding residual stress are generally different from each other and they form a highly complex multiaxial stress states. On the other hand, the fatigue behavior has been mostly studied for uniaxial stress state without residual stress. The crack growth rate is related to the Range of stress intensity factor ΔK such as in the Paris’ Low.… More >

Kazuki Ikushima^1,*, Shintaro Maeda², Masakazu Shibahara¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.4, pp. 175-175, 2019, DOI:10.32604/icces.2019.05542

Abstract Large-scale thin-plate structures including ships are constructed by welding, and distortion can occur after welding. Welding deformation can increase cost and work time, and so it is important to investigate welding deformation before construction. In this research, to predict welding deformation on the construction of a large thin-plate structure, Idealized Explicit FEM (IEFEM) was applied to the analysis of welding deformation on the construction of a ship hull block. In addition, to efficiently analyze deformation of the whole structure of a large-scale structure, an algebraic multigrid (AMG) method was introduced into the IEFEM. Then, this multigrid IEFEM (MGIEFEM) was applied… More >

M. Inomoto^1,*, S. Aihara², T. Kasuya², T. Kawabata², Y. Okazaki¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 139-139, 2019, DOI:10.32604/icces.2019.05781

Abstract Prediction of toughness of weld heat-affected zone (HAZ) of steels is a difficult task because it is controlled by many parameters including grain-size, brittle microphase, hardness, etc. No reliable model has been established, yet. In the present study, a numerical model for predicting Charpy impact toughness of weld HAZ of steels has been developed. The model comprises two parts: phase transformation and toughness prediction. In the former part, phase fraction, size distribution of martensite-austenite brittle microphase, hardness, size of grain boundary ferrite and bainitic ferrite plate, etc. are calculated and these parameters are used in the latter part, in which… More >

Nobuyuki Ishikawa^1,*, Yuya Sato¹, A. Toshimitsu Yokobori Jr.², Tadashi Kasuya³, Satoshi Minamoto⁴, Takehiro Endo³, Manabu Enoki³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 138-138, 2019, DOI:10.32604/icces.2019.05518

Abstract Prediction model for weld hydrogen cracking (so called cold cracking) in high strength steel weld was developed by a coupled thermo-elastic-plastic and hydrogen diffusion analysis in the y-grooved weld joint. Critical conditions of cracking was given as the function of principal stress and accumulated hydrogen concentration in the root region where the cracking occurs. In order to clarify the critical conditions of cold cracking, y-grooved cold cracking tests were first conducted using the steel plate with tensile strength level of 780MPa. Plate thickness of the plates were 25 mm and 50 mm. Hydrogen concentration in the weld metal was changed… More >

Takayuki Shiraiwa*, Fabien Briffod, Manabu Enoki

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 124-124, 2019, DOI:10.32604/icces.2019.05311

Abstract The purpose of this study is to evaluate fatigue performances of welded structures using numerical simulations. The fatigue life of welded joint is complicatedly affected by various factors such as geometries, defects, residual stress and microstructure. Conventional fatigue life assessments are generally based on fracture mechanics and predict the fatigue life for long crack propagation. In order to predict the total fatigue life more accurately, it is necessary to consider the lifetime for crack initiation and microstructually short crack (MSC) growth. In this study, a numerical framework to predict the fatigue life including crack initiation, MSC growth and long crack… More >

L. Donati, L. Tomesani

The International Conference on Computational & Experimental Engineering and Sciences, Vol.12, No.1, pp. 37-38, 2009, DOI:10.3970/icces.2009.012.037

Abstract In recent years aluminum extruded hollow profiles are increasingly used in near-net shape manufacturing processes such as bending and hydroforming; in fact, by applying these secondary processes, it is possible to obtain very high complex parts, especially for the transport industry. It is known that hollow profiles obtained by direct hot extrusion necessarily have some longitudinal welding lines (so called seam welds) produced inside the die and it is common experience, during secondary forming processes, the appearance of early cracking in proximity of those lines [1,2]. At the same time, the direct hot extrusion is the only process able to… More >

Kuen Ming Shu¹, Chien Chih Chen²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.11, No.4, pp. 109-110, 2009, DOI:10.3970/icces.2009.011.109

Abstract Ultrasonic welding is the joining or reforming of thermoplastics through the use of heat generated from high-frequency mechanical motion. Rotary welding is a technique to press two parts together and one part is hold fixed the other rotates at high speed, the friction between the two parts generate heat which causes the parts to melt at the interface, when rotation stops, the weld cools down and solidifies. In this research, an experimental set-up integrated these two different welding processes in one machine set was designed and fabricated to provide a tool to study the integrated welding mechanism.
In this study,… More >

K. Yamamoto¹, M. Tanaka¹, S. Tashiro¹, K. Nakata¹, K. Yamazaki², E. Yamamoto², K. Suzuki², A. B. Murphy³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.1, pp. 1-6, 2008, DOI:10.3970/icces.2008.007.001

Abstract Authors have used a numerical model of stationary helium TIG arc welding taking into account the iron, chromium and manganese vapors produced from the weld pool surface and have simulated the distribution of the metal vapors, plasma temperature, fluid flow velocity and the formation of the weld pool. The concentration of manganese vapor in arc plasma was much higher compared with the composition of manganese for stainless steel. More >

A.Toshimitsu Yokobori Jr^1,*, Go. Ozeki¹, Toshihito OHMI^1,2, Tadashi Kasuya³, Nobuyuki Ishikawa⁴, Manabu Enoki³, Satoshi Minamoto⁵

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 119-119, 2019, DOI:10.32604/icces.2019.05177

Abstract Authors have been founded that hydrogen diffusion and concentration behavior for notched specimens of multi-materials with space distribution of various material properties were dominated not only by the space gradient of hydrostatic stress caused by the notch tip, ∇σ_p but also by that of diffusion coefficient, ∇D(T, HV, ε_p) caused by space distributions of temperature, hardness and plastic strain due to multi-materials. In this research, on the basis of our proposed coupled analysis of heat transfer induced thermal stress driven hydrogen diffusion, the effect of ∇D(T, HV, ε_p) ) on hydrogen concentration behavior was clarified by solving the problem of… More >