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ABSTRACT

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 >

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Tadashi Kasuya^1,*, A. Toshimitsu Yokobori Jr², Nobuyuki Ishikawa³, Manabu Enoki¹, Satoshi Minamoto⁴
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 120-120, 2019, DOI:10.32604/icces.2019.05227
Abstract Weld cold cracking is categorized as hydrogen cracking. To assess cold cracking susceptibility of steel HAZ (heat affected zone), it is necessary to estimate local hydrogen content and residual stress at a weld root that are in general numerically calculated by FEM and/or FDM. To conduct numerical calculations, physical and mechanical properties such as diffusion coefficient of hydrogen in steel are necessary. In this work, we have developed empirical formulae to calculate HAZ hardness, hydrogen diffusion coefficient and tensile properties. The present empirical formula of HAZ hardness is expressed using chemical compositions of a welded steel and weld thermal history.… More >

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ABSTRACT

Hitoshi Izuno¹, Masahiko Demura^1,*, Masaaki Tabuchi², Yohichi Mototake³, Masato Okada^1,3
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 121-121, 2019, DOI:10.32604/icces.2019.05270
Abstract An accurate creep deformation model is needed for detailed description of creep behavior of high temperature structural materials, e.g., Grade 91 steels used in boiler tubes of thermal power plants. Two types of creep constitutive equations are known, as follows: the one, e.g., modified theta method, assumes the existence of a steady state; and the other, e.g., theta method, does not. So far, both types have been selected on a case by case basis and there is no consensus on whether or not the steady state should be assumed even if limited in the Grade 91 steels. In this study,… More >

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608

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Dmitry S. Bulgarevich^1,*, Susumu Tsukamoto¹, Tadashi Kasuya², Masahiko Demura¹, Makoto Watanabe^1,3
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 122-122, 2019, DOI:10.32604/icces.2019.05271
Abstract The microstructure of steel greatly determines its mechanical properties/performance and holds information on chemical composition and processing history. Therefore, quantitative analysis of optical or SEM images on formed microstructure phases is one of the primary interests for metallurgy. So far, such analyses in laboratories are done manually by experts and are very time consuming. However, with modern microscopy techniques of automated image acquisitions over the large imaging areas and even by using of sample slicing for three-dimensional imaging, the amount of image data could be overwhelming for manual examinations. In this respect, there is a possibility that machine learning (ML)… More >

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643

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Masahiko Demura^1,*, Junya Sakurai^1,2, Masayoshi Yamazaki¹, Junya Inoue^1,2
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 123-123, 2019, DOI:10.32604/icces.2019.05303
Abstract Creep is a complicated and time-dependent phenomenon, which is affected by the initial state and the degradation of microstructures. It is thus considered that the information about the microstructure is essential to predict the creep rupture time. On the other hand, there is a strong, practical need for the prediction without the investigation of microstructures nor the disclosure of the detailed process that should control the initial microstructures. In this study, we examined how modern machine learning technique can help to predict the creep rupture time in heat-resistant ferrite-type steels without the direct information about the microstructures and the process… More >

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802

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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 >

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899

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594

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Fabien Briffod*, Alexandre Bleuset, Takayuki Shiraiwa, Manabu Enoki
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 125-125, 2019, DOI:10.32604/icces.2019.05319
Abstract The fatigue behavior of metallic materials is a multi-scale problem (from a time and length-scale perspective) intimately influenced by microstructural features that determine the early stages of crack propagation. Prediction of fatigue life is traditionally based on the evaluation of macroscopic mechanical fields at the structure level and on the application of empirical rules. However, these structure-oriented methods are material-specific and do not consider the material variability at lower scales. Hence, reliable prediction of fatigue performances and its variability requires on one side the characterization and quantification of early damage mechanisms and on the other side the incorporation of local… More >

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914

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614

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Hideaki NISHIKAWA*, Yoshiyuki FURUYA
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 126-126, 2019, DOI:10.32604/icces.2019.05354
Abstract Fatigue life is determined by microscopic fatigue crack initiation and growth. Since fatigue crack is generally initiated on the slip plane of microstructure and propagated by slip deformation of the crack tip, fatigue life should depends on microstructure. To computationally simulate the effect of microstructure on fatigue property, it is necessary to understand microstructural small fatigue crack initiation and growth behavior. Although Ti-6Al-4V alloy has superior fatigue strength, fatigue strength of forged pancake, used for such as airplane engine, is normally lower than that of rolled alloy. It is possibly comes from microstructural difference, such as micro-texture. However, it is… More >

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904

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618

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Hiromichi Nagao^1,2,*, Shin-ichi Ito^1,2, Tadashi Kasuya³, Junya Inoue^4,3
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 127-127, 2019, DOI:10.32604/icces.2019.05384
Abstract Data assimilation (DA) is a computational technique to integrate numerical simulation models and observational/experimental data based on Bayesian statistics. DA is accepted as an essential methodology for the modern weather forecasting, and is applied to various fields of science including structural materials science. We propose a DA methodology to evaluate unobservable parameters involved in multi-phase-field models with the aim of accurately predicting the observed grain growth, such as in metals and alloys. This approach integrates models and a set of observational image data of grain structures. Since the set of image data is not a time series, directly applying conventional… More >

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890

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555

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Junya Sakurai¹, Junya Inoue^2,3,4, Masahiko Demura^4,*, Yoichi Mototake⁵, Masato Okada^4,5, Masayoshi Yamazaki⁴
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 128-128, 2019, DOI:10.32604/icces.2019.05408
Abstract According to the inherent creep strength concept proposed by Kimura et al., microstructural strengthening effect is expiring after a long-term creep deformation at high temperature. In the region, the solid solution hardening effect becomes dominant so that the rupture time is expected to be a simple function of chemical composition and test conditions. In fact, they found that there was a linear relationship between logarithm rupture time and the amount of Mo for the carbon steel JIS STB410. They also found the positive correlations of Cr and Mn to the logarithmic rupture time. However, it is difficult to specify the… More >

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884

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576

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Yoh-ichi Mototake¹, Hitoshi Izuno², Kenji Nagata^3,4, Masahiko Demura² , Masato Okada^1,2,*
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 129-130, 2019, DOI:10.32604/icces.2019.05389
Abstract The creep deformation process is constructed by complex interactions of multiple factors, and the measurement of creep deformation requires enormous economic costs and a long experimental time, so there is a small amount of measurement data. In such a situation, multiple models are often proposed to explain the same experimental data. The coexistence of multiple models based on different physical assumptions makes it difficult to understand the creep deformation process.
The purpose of this study is to construct a framework to compare and evaluate coexistence models based on measurement data using the Bayesian model selection framework. Basically, in the… More >

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986

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608

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M. Watanabe*, S. Minamoto, T. Kadohira, K. Ito, M. Demura
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 131-132, 2019, DOI:10.32604/icces.2019.05416
Abstract This article has no abstract. More >

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933

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596

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Ikuo Ohnuma, Machiko Ode
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 133-133, 2019, DOI:10.32604/icces.2019.05431
Abstract Experimental investigation of phase equilibria in the Fe-Mn, Fe-Si, Fe-Al and Fe-Mn-Si-C systems was carried out. In the Fe-Mn system, α/γ equilibrium at temperatures below 600°C was revised by equilibration of severely deformed powder samples in which the α/γ equilibrated microstructures at low temperatures could be realized. In the Fe-Si and Fe-Al systems, the miscibility gap between A2, B2 and D0₃ phases as well as the A2/B2/D0₃ transition boundaries were determined precisely. Phase equilibria in the Al-rich region of the Fe-Al system were determined in detail. The α/γ equilibria in the Fe-Mn-C, Fe-Mn-C and Fe-Mn-Si-C systems were determined by FE-EPMA,… More >

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857

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565

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Kaita Ito*, Satoshi Minamoto, Takuya Kadohira, Makoto Watanabe, Masahiko Demura
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 134-134, 2019, DOI:10.32604/icces.2019.05440
Abstract In the Materials Integration (MI) system, workflow designers and players are implemented as ones of the core subsystems. When the user wants to predict a certain material parameter by using the MI system, the user selects a prediction module in the workflow designer that can output the objective parameter. If the all required input parameters of the prediction module are not given directly, further modules can be connected.
Each input and output parameters of the prediction module on the MI system is directly associated with one term of material science and engineering. It is not defined as a specific… More >

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883

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599

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Hoheok Kim¹, Tatsuki Yamamoto², Yushi Sato¹, Junya Inoue^1,3,4,*
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 135-135, 2019, DOI:10.32604/icces.2019.05453
Abstract The viability of establishing low-cost surrogate structure-property (S-P) linkages which applies a Bayesian model selection method to the Materials Knowledge System (MKS) homogenization framework is studied. The MKS framework employs the n-point correlation function, principal component analysis, and regression techniques for mapping between the structural factors and the property of a material. However, the framework chooses the factors not by their influence on the property but by their amount of inherent microstructural information. This also makes it difficult to find out which microstructural morphology affects the property. In the present work, we introduced a Bayesian model selection method to choose… More >

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890

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611

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Satoshi Minamoto*, Takuya Kadohira, Kaita Ito, Makoto Watanabe, Masahiko Demura
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 136-136, 2019, DOI:10.32604/icces.2019.05447
Abstract The Materials Integration (MI) System is a domestically developed system in the “Cross-ministerial Strategic Innovation Promotion Program” to analyze structural materials performance. The performance on structural materials having complicated inputs/outputs would be solved with the combination of different scientific programs or data from experiment. One of the merits of constructing a combined model (here we call workflow) is that calculations are performed and the data would be stored in the system automatically.
Furthermore, we developed a web application (“MIREA”: MI REgression Analyzer) that enables us to build high versatile prediction models based on machine learning techniques by using the… More >

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937

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622

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ABSTRACT

Toshihiro Ashino^1,*, Nobutaka Nishikawa²
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 137-137, 2019, DOI:10.32604/icces.2019.05454
Abstract Materials performance analysis process requires integration of many heterogeneous data and information resources, e.g. experimental data, empirical models and computational simulation. Virtual Research Environment (VRE) for materials science and engineering should support each data handling processes, data retrieval, conversion, statistical analysis, symbolic manipulation and visualization within single interactive and scripting environment.
Furthermore, in order to integrate heterogeneous data, it requires a common dictionary which describe semantic relationships among these data resources. It is required to identify corresponding data items from different data resources. It can be a flat structured table, but an ontology which describes semantic relationships among concepts,… More >

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925

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595

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ABSTRACT

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 >

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901

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614

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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 >

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864

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566

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Tao Yang, Zhaohui Meng, Hailong Ge, Xiangchen Fang*
The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 140-140, 2019, DOI:10.32604/icces.2019.04917
Abstract Vacuum residue (VR) is the heaviest distillation cuts of crude oil. Being very intractable, VR contains high amount of sulfur, metal and asphaltene. Conventional VR conversion technologies, including delayed coker and residue fluidized catalytic cracking, cannot remove those impurities efficiently, or have to employ strict pretreatments for feed stock to meet the equipment and catalyst requirements. Hydroprocessing and hydrocracking process can convert VR into lighter oils, and remove sulfur and metal content at high efficiency; the refining nature of hydrogenation reactions could also improve the molecular structures of product cuts, increasing the commercial values. According to the fluidization state of… More >

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