研究者詳細 - 上森　武

論文 - 上森　武

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Crystal plastic homogenization finite element analysis of Ti-6242 alloy subjected to in-plane reverse loading

Takeshi UEMORI, Naoya TADA, Junji SAKAMOTO

Mechanical Engineering Journal 12 ( 2 ) 24 - 00340 2025年

Effect of artificial defect on tensile properties of thin titanium alloy wire 査読

Junji SAKAMOTO, Naoya TADA, Takeshi UEMORI, Koyo OISHI

Extended abstract of The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023 (ATEM-iDICs '23) 11 ( 6 ) 24-00129 2024年12月

荷重制御疲労試験時のTi-6Al-4V細線の破壞形態

坂本惇司, 多田直哉, 上森武

チタン 72 ( 3 ) 39 - 43 2024年12月

Crystal Grain Rotation during Tensile Test of Polycrystalline Pure Titanium Thin Sheet Based on Surface Height and Crystal Orientation 査読

Naoya Tada, Hiroaki Ohashi, Takeshi Uemori, Junji Sakamoto

Journal of Physics: Conference Series 2892 012002 2024年11月

Crystal plasticity analysis of fatigue crack initiation site considering crystallographic orientation in Ti–22V–4Al alloy

Jinta Arakawa, Koki Hirazumi, Takeshi Uemori, Yoshito Takemoto

Results in Engineering 23 2024年9月

Method for Predicting Crack Size Using Amplitude Change in Titanium Alloy under Bending Vibration 査読

坂本惇司, 多田直哉, 上森武

Book of Abstracts: Europian Conference on Fracture 2024 (ECF24) 472 2024年9月

Elucidation of small fatigue crack initiation and propagation behavior on polycrystal Ti-22V-4Al 査読

Jinta Arakawa, Koki Hirazumi, Takeshi Uemori, Yoshito Takemoto

Procedia Structural Integrity 66 38 - 48 2024年9月

アルミニウム合金の曲げ振動下の振動変化とき裂進展

坂本惇司, 多田直哉, 上森武

日本機械学会論文集 90 ( 930 ) 23-00246 - 23-00246 2024年

セルロースナノファイバー強化天然ゴムの繰返し引張特性と膨潤試験から得られるバウンドラバー体積分率の関係

奥井健斗, 多田直哉, 上森武, 坂本惇司, 榊原圭太

日本機械学会論文集 90 ( 932 ) 24-00008 - 24-00008 2024年

Prediction of active slip system for commercially pure titanium sheet by crystal plasticity finite element analysis 査読

Takeshi UEMORI, Naoya TADA, Junji SAKAMOTO, Masatoshi DOI

Extended abstract of The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023 (ATEM-iDICs '23) 19-G05 2023年10月

Prediction of slip activity of crystal grains around semi-circular and semi-elliptical notches in thin-sheet specimens of pure titanium using formulated macroscopic stress distribution and crystal orientation

Naoya Tada, Takeshi Uemori, Junji Sakamoto

Engineering Failure Analysis 107623 - 107623 2023年9月

Effect of Surface Roughness and Oxidation Treatment on Joint Strength between Aluminum Alloy and High-Density Polyethylene 査読

Naoya TADA, Takeshi UEMORI, Junji SAKAMOTO

2023年8月

Tensile properties and slip deformation behavior of pure titanium thin wire with a small diameter-to-grain-size ratio

Junji Sakamoto, Naoya Tada, Takeshi Uemori

Materials Science and Engineering A 863 2023年1月

掲載種別：研究論文（学術雑誌）

To investigate the tensile properties and slip deformation behavior of pure titanium thin wires with a small ratio of the diameter to the grain size, tensile tests and a stepwise tensile test were performed using specimens with a diameter of approximately 170 μm and grain sizes of 17 and 87 μm, corresponding to diameter-to-grain-size ratios of 10 and ∼2, respectively. The specimen with a diameter-to-grain-size ratio of 10 fractured through the growth of voids. The fracture morphology was similar to that of the bulk specimens. On the other hand, for specimens with a diameter-to-grain-size ratio of 2, fracture occurs owing to the local deformation, in which primary slip systems are activated in each grain. The stepwise tensile test of the specimen with a diameter-to-grain-size ratio of 2 indicated that the slip deformation tended to occur from the large grains. Moreover, the activities of the slip systems of grains were evaluated using the Schmid factor (SF) and critical resolved shear stress (CRSS) of each slip system. It was noted that slip systems with the highest SF∙CRSS−1 were activated for 30 out of 33 grains.

DOI： 10.1016/j.msea.2022.144532

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Slip Activity of Crystal Grains around Notch in Thin Sheet Specimen of Pure Titanium

Naoya Tada, Takeshi Uemori, Junji Sakamoto

Books of abstracts, 17th Asia-Pacific Conference on Fracture and Strength and 13th Conference on Structural Integrity and Failure 19 - 19 2022年12月

複素数階微分法の純チタン板材の結晶塑性解析への適用査読

上森武, 多田直哉, 坂本惇司

チタン 70 ( 2 ) 158 - 163 2022年4月

Effect of resin lamination on tensile strength characteristics of SUS304 stainless steel thin film 査読

Junji Sakamoto, Naoya Tada, Takeshi Uemori

International Journal of Advanced Manufacturing Technology 116 ( 3-4 ) 1081 - 1088 2021年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

The objective of this study is to clarify the effect of resin lamination on the tensile strength characteristics of SUS304 stainless steel thin films. We conducted tensile and stepwise tensile tests using several types of specimens prepared with 20-μm- and 40-μm-thick SUS304 films, 25-μm-thick polypropylene (PP) film, and 6-μm-thick polyethylene terephthalate (PET) film. Their macroscopic and microscopic tensile deformation behaviors were observed using an optical microscope and a reflection-configured digital holographic microscope, respectively. As a result, laminating the PP or PET films onto the SUS film did not significantly change the macroscopic and microscopic strain changes against the tensile load or microscopic surface changes in the low-strain region. Laminating the PET film onto the SUS film did not reduce the fracture strain, whereas laminating the PP film onto the SUS film did reduce it. One of the reasons may be that burrs formed on the side surface of the PP/SUS laminate. Polishing the side surface of the PP/SUS laminate may suppress the reduction in its fracture strain. The reduction of the fracture strain due to the PP lamination in the 20 μm thick SUS film was larger than that of the 40-μm-thick SUS film. In thin SUS films, small stress concentrators that have almost no effect on macroscopic and microscopic deformation might significantly reduce the fracture strain.

DOI： 10.1007/s00170-021-07510-8

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Prediction of the fracture location by tensile tests of gray cast iron based on the dimensional changes of graphite flakes 査読

Naoya Tada, Takeshi Uemori, Junji Sakamoto

Journal of Pressure Vessel Technology, Transactions of the ASME 143 ( 2 ) 2021年4月

掲載種別：研究論文（学術雑誌）

© 2021 American Society of Mechanical Engineers (ASME). All rights reserved. Gray cast iron has been used as a component in various mechanical parts, such as the blocks and heads of automobile and marine engines, cylinder liners for internal combustion engines, and machine tool bases. It is desirable because of its good castability and machinability, damping characteristics, and high performance-To-cost ratio. On the other hand, weak graphite flakes present in gray cast iron serve as stress concentrators and adversely affect the material strength. Therefore, it is crucial to examine the relationship between the distribution of graphite flakes and the strength or fracture of gray cast iron. In this study, tensile tests on gray cast iron were carried out using a plate specimen and observed by scanning electron microscopy, and the microscopic deformation was observed on the specimen surface. Particularly, the change in the size of graphite flakes during the tensile tests was examined, and the observed trend was discussed. The experimental results reveal that the dimensional changes in the graphite flakes vary in the observed area and that the final fracture occurs in an area where a large dimensional change is observed, suggesting that the fracture location or critical parts of gray cast iron can be predicted from the dimensional changes of the graphite flakes at an early stage of deformation.

DOI： 10.1115/1.4048063

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Effect of Mechanical Surface Treatment and Post-treatment Polishing on Tensile Strength and Fatigue Life of High-speed Tool Steel 査読

N.Karunathilaka, N.Tada, T.Uemori, J.Sakamoto, R.Hanamitsu, M.Fujii, Y.Omiya, M.Kawano

International Journal of Peening Science and Technology 2 ( 1 ) 35 - 60 2021年

Finite Element Study of the Effect of Internal Cracks on Surface Profile Change due to Low Loading of Turbine Blade 査読

Junji Sakamoto, Naoya Tada, Takeshi Uemori, Hayato Kuniyasu

Applied Sciences 10 ( 14 ) 4883 - 4883 2020年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

Turbine blades for thermal power plants are exposed to severe environments, making it necessary to ensure safety against damage, such as crack formation. A previous method detected internal cracks by applying a small load to a target member. Changes in the surface properties of the material were detected before and after the load using a digital holographic microscope and a digital height correlation method. In this study, this technique was applied in combination with finite element analysis using a 2D and 3D model simulating the turbine blades. Analysis clarified that the change in the surface properties under a small load varied according to the presence or absence of a crack, and elucidated the strain distribution that caused the difference in the change. In addition, analyses of the 2D model considering the material anisotropy and thermal barrier coating were conducted. The difference in the change in the surface properties and strain distribution according to the presence or absence of cracks was elucidated. The difference in the change in the top surface height distribution of the materials with and without a crack was directly proportional to the crack length. As the value was large with respect to the vertical resolution of 0.2 nm of the digital holographic microscope, the change could be detected by the microscope.

DOI： 10.3390/app10144883

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Evaluation of strength of stainless steel bolt without heat treatment considering Bauschinger effect during manufacturing process 査読

S. Narita, K. Hayakawa, T. Uemori, Y. Kubota

Journal of Materials Processing Technology 278 116481 - 116481 2020年4月

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