研究者詳細 - 多田　直哉

MISC - 多田　直哉

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G0310201 多結晶純チタン表面に設けた平行溝間およびV字断面溝内微小領域の圧縮塑性変形(材料力学部門一般セッション:変形・ひずみ(2))

清水一郎, 磯川克洋, 原昂佑, 多田直哉

年次大会 : Mechanical Engineering Congress, Japan 2014 "G0310201 - 1"-"G0310201-3" 2014年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

The compressive deformation behavior in micro areas of industrial pure titanium was investigated, by using a new method in which the deformation constraints from the neighboring areas were reduced by fabricating micro parallel grooves or V-shaped cross-section grooves, by focused ion beam machining. Uniaxial compression test was performed in the direction parallel to the grooves, and the deformation behavior in the areas between the grooves was observed by scanning electron microscopy. The parallel grooves were fabricated to across the deformation twin that appeared by pre-compression, and then the influence of deformation constraint on twinning was discussed. Meanwhile, the V-shaped cross-section grooves were fabricated on several grains to examine the crystal orientation dependency of the deformation of the micro areas. In both cases, the possibility was found to change the primary deformation mechanism in the areas by fabricating micro grooves.

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OS0118 Ti-Nb合金の二軸圧縮における等塑性仕事曲面の合金組成依存性

清水一郎, 久田一樹, 石川慎一, 多田直哉

M&M材料力学カンファレンス 2014 "OS0118 - 1"-"OS0118-2" 2014年7月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

Metastable beta type titanium alloys have been attracting attention in various industrial fields because of their special properties such as high specific strength, good formability, high corrosion resistance, and biocompatibility. However, plastic deformation characteristics of the titanium alloys have scarcely been clarified especially under biaxial loading conditions, despite of their importance on metal forming processes. In the present study, uniaxial and biaxial compression tests were performed on titanium-niobium (Ti-Nb) alloys with four different niobium contents, in order to investigate the influences of beta stabilizer content upon compressive deformations. The microstructure of Ti-Nb alloys was found to change from α, α' to p structure with increase of the niobium content. With this change of microstructure, the primary plastic deformation mechanisms were revealed to change from slip and stress-induced martensite to deformation twin and coarse slip with increase of the niobium content and thus the change influenced on the uniaxial and biaxial compressive plastic behaviors.

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115 有限要素法を用いた積層型電子部品の圧縮プロセス中の変形解析

山地健, 多田直哉, 成瀬文雄, 八尋俊明

講演論文集 2014 ( 52 ) "115 - 1"-"115-2" 2014年

114 有限要素法を用いたアルミニウム合金角形管の側面局部圧縮および三点曲げにおける吸収エネルギー評価

伊藤将志, 小野忠則, 清水一郎, 多田直哉

講演論文集 2014 ( 52 ) "114 - 1"-"114-2" 2014年

113 永久磁石を使用した試験装置による大気中,純水中および3.5wt.% NaCl溶液中での銅コア鉛フリーはんだボールの接合強度評価

真砂宏康, 多田直哉

講演論文集 2014 ( 52 ) "113 - 1"-"113-2" 2014年

1419 ポリプロピレンの弾粘塑性変形に関するミクロ・メソ・マクロスケールモデリング

内田真, 多田直哉

計算力学講演会講演論文集 2013 ( 26 ) "1419 - 1"-"1419-2" 2013年11月

OS0402 AZ31マグネシウム合金の等二軸圧縮と単軸引張りにおける塑性変形挙動の比較

清水一郎, 西崎聖記, 多田直哉

M&M材料力学カンファレンス 2013 "OS0402 - 1"-"OS0402-3" 2013年10月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

Tension-compression asymmetry of plastic deformation of magnesium alloys has been known to affect plastic formability in several metal forming processes. However, in most of works on the tension-compression asymmetry, the result of uniaxial tension was compared with that of uniaxial compression. In the present study, the plastic deformation behavior of AZ31 magnesium alloys in uniaxial tension was investigated and compared with those in equi-biaxial compression, in which the macroscopic deformation was equivalent to that of uniaxial tension. It was found that the equi-plastic work point obtained by equi-biaxial compression was on the same isotropic yield curve with that by uniaxial tension, in the early stage of plastic deformation. The crystal orientation measurement results also revealed that the twin area fractions as well as active twin systems by uniaxial tension were almost the same with those by equi-biaxial compression. These results imply that the difference between deformation patterns by uniaxial tension and by uniaxial compression is primary cause of the tension-compression asymmetry of magnesium alloys.

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OS0408 純チタンの引張りにおけるナノレベルの表面高度変化と微視的弾塑性変形に関する検討

多田直哉, 内田真, 八木伸曉

M&M材料力学カンファレンス 2013 "OS0408 - 1"-"OS0408-3" 2013年10月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

A tensile test of pure titanium plate specimen was performed on the stage of digital holographic microscope, and a change in the height of each grain on the surface was evaluated during the tests. The load was increased stepwise in the tensile test and the distribution of height change of each grain was evaluated at all steps in nanometer order. The identification of region before and after each loading step was done by the Digital Height Correlation Method (DHCM). The height change of each grain between low loading levels corresponded to that between relatively high loading levels, which suggests that the height change in plastic deformation occurred mainly by crystallographic slips can be predicted by that in elastic deformation. Slip lines after the plastic deformation were observed and the correlation of the slip lines and height change of the grain was discussed.

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G031031 半楕円体状局部減肉を有する平板の直流電位場解析([G031-03]材料力学部門,一般セッション : 画像,計測)

野原学, 多田直哉, 内田真

年次大会 : Mechanical Engineering Congress, Japan 2013 "G031031 - 1"-"G031031-4" 2013年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

The direct-current potential difference method (DC-PDM) is an inspection technique to evaluate defects in structures. Although the method needs large direct current and relatively large equipment, many studies on the applicability of DC-PDM to non-destructive inspection have been performed because of low cost, cheap, and good reproducibility of results. DC-PDM has been applied to evaluate general wall thinning. But very few papers deal with the application of DC-PDM to local wall thinning. In this study, approximated solution for electric potential field analysis of a semi-ellipsoidal wall thinning existing on the back surface of a conductive plate was proposed and its validity was examined by comparing with the results by finite element method. The approximated solution agreed with the finite element analysis.

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G031014 デジタルホログラフィック顕微鏡を用いた純チタンの引張りにおける微視的表面高度変化とすべり線分布の関係に関する検討([G031-01]材料力学部門,一般セッション : 非鉄金属の強度と変形(1))

山本雄大, 多田直哉, 内田真

年次大会 : Mechanical Engineering Congress, Japan 2013 "G031014 - 1"-"G031014-5" 2013年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

Polycrystalline metals are composed of grains with different crystal orientations and sizes, and show inhomogeneous elastic-plastic deformation behavior. Especially for grains on the surface, the inhomogeneous deformation appears accompanied by the change in the height distribution. On the other hand, recently, digital holographic microscope is used to measure the height distribution on the materials surface with high accuracy in a short time. In this study, a cyclic tensile test of polycrystalline pure titanium was carried out and the change in the height distribution was studied using the digital height correlation method. Increase in average height of each grain by unit load in elastic region correlated with those in plastic region, which suggests that the plastic deformation is predictable from the elastic deformation.

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G031022 平行溝によって変形拘束を低減させた純チタン結晶粒内領域の圧縮変形の観察([G031-02]材料力学部門,一般セッション : 非鉄金属の強度と変形(2))

磯川克洋, 清水一郎, 多田直哉

年次大会 : Mechanical Engineering Congress, Japan 2013 "G031022 - 1"-"G031022-4" 2013年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

In the present study, a new method to reduce deformation constraint in a grain of industrial polycrystalline pure titanium was introduced, by fabricating micro parallel grooves in the grain by means of a focused ion beam method. Uniaxial compression test was then performed in the direction parallel to the grooves, and the influence of reduced deformation constraint upon the characteristics of plastic deformation in the area between the grooves was investigated. The comparisons of the plastic deformation of the area with that without grooves revealed that the plastic deformation behavior as well as the deformed feature of the grain clearly changed by the presence and absence of the deformation constraint. The influence of deformation constraint upon the plastic deformation behavior of titanium grain was thus discussed with taking into consideration the crystallographic orientation.

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G031016 準安定β型Ti-Nb合金の比例ひずみ経路冷間二軸圧縮変形挙動に及ぼす合金組成の影響([G031-01]材料力学部門,一般セッション : 非鉄金属の強度と変形(1))

久田一樹, 清水一郎, 竹元嘉利, 多田直哉

年次大会 : Mechanical Engineering Congress, Japan 2013 "G031016 - 1"-"G031016-4" 2013年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

Metastable β-type titanium alloys have many features such as high specific strength, good ability of plastic deformation, excellent corrosion resistance, biocompatibility, and low Young's modulus, which are useful in aerospace, biomedical and chemical industries. However, plastic deformation behaviors of metastable β-type titanium alloys under multi-axial compressive conditions have not been clarified. In the present study, four types of Ti-Nb alloys, Ti-20mass%Nb, Ti-30mass%Nb, Ti-35mass%Nb, and Ti-45mass%Nb were prepared. The uniaxial and biaxial compression tests with proportional strain paths were then performed on Ti-Nb alloys by using a biaxial compression testing machine. The results of uniaxial compression tests revealed that stress induced martensite transformation, deformation twin, coarse slip occurred on Ti-20 and 30Nb, Ti-35Nb, and Ti-45Nb, respectively. It was found by biaxial compression tests that the plastic deformation behavior including anisotropic hardening also changes with Nb content.

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G011044 直流電位差法による円管-フランジ溶接部のき裂の位置および寸法の評価に関する有限要素解析([G011-04]計算力学部門,一般セッション(4) : 疲労・き裂・欠陥2)

小坂将樹, 多田直哉, 内田真

年次大会 : Mechanical Engineering Congress, Japan 2013 "G011044 - 1"-"G011044-4" 2013年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

Detection of cracks initiated at pipe-flange welded part by using direct current potential difference method had been proposed and the related researches have been conducted. However, the evaluation of the position and shape of the crack has not been discussed. In this study, three-dimensional electric potential field analysis was carried out by finite element method assuming that crack was initiated at the interface between flange and weld metal and effect of the circumferential angle and the central position of the crack on change in potential difference at the boundary between weld metal and flange was evaluated. As a result, potential difference along the circumferential direction significantly changed around the both tips of crack and the position where potential difference shows extreme value approximately corresponded to the crack tips.

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J042032 片状黒鉛鋳鉄の黒鉛面積分率と引張り破断面の角度・位置の関係に関する検討([J042-03]工業材料の変形と強度・解析)

稲田雄介, 多田直哉, 清水一郎, 井口克之

年次大会 : Mechanical Engineering Congress, Japan 2013 "J042032 - 1"-"J042032-3" 2013年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

Gray cast iron is used as structural materials for many machines. It has been assumed homogeneous when its strength was evaluated. But it has a composite structure of perlite and graphite. It is necessary to consider its microstructure for accurate strength evaluation of reliable products. In this study, the distribution of graphite was observed by SEM and its area ratio A_G was evaluated in equally divided areas of parallel part of specimen. It was found that high A_G region corresponded to the fracture surface of tensile test. This fact suggests that the position of fracture surface is predictable by the distribution of graphite.

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G031071 硬質アルマイト処理およびKURACERA処理を施したA5052アルミニウム合金試験片の単軸引張りに伴う変形と破壊([G031-07]材料力学部門,一般セッション : 表面処理)

森藤駿, 多田直哉, 清水一郎, 槇野行修, 峪田宜明, 田尻さや香

年次大会 : Mechanical Engineering Congress, Japan 2013 "G031071 - 1"-"G031071-4" 2013年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

Recently, aluminum alloys are important structural materials because of high specific strength, lightweight, excellent in recycling. Various surface treatments for aluminum alloys have been developed for improvement of corrosion and wear resistances. Among them, environment-friendly anodizing in which oxide coating is formed on the material surface with easy process has been applied to a wide range of structural material. Also, plasma electrolytic oxidation (PEO) treatment was developed. Since KURACERA coating, it is classified PEO coating, is harder than anodic oxide coating, it is expected spacious application. In this study, in order to research the effect of oxide coating on deformation and fracture behavior, hard anodizing and KURACERA treated test specimen were observed with microscope during tensile test and the results were compared. The following results were obtained. With increasing the coating thickness, longitudinal elastic constant of coating, tensile strength and strain at fracture decreased. Longitudinal elastic constant of KURACERA coating was larger than that of hard anodic oxide coating. Also, since surface roughness was large in specimens with thick coating, more stress concentration occurred in thick coating larger and made necking and cracking easy.

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J012022 直流電位差法による銅コア鉛フリーはんだボール/銅接合界面き裂評価に関する有限要素解析([J012-02]電子情報機器、電子デバイスの強度・信頼性評価と熱制御(2))

甲斐巴樹, 多田直哉

年次大会 : Mechanical Engineering Congress, Japan 2013 "J012022 - 1"-"J012022-5" 2013年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

In this study, Direct-Current Potential Difference Method (DC-PDM) was proposed for quantitative evaluation of crack initiation and propagation on joining between copper-cored lead-free solder ball and copper plate specimen when copper plate specimen was subjected to cyclic tension. Finite element method was used for three dimensional potential analysis to clarify the relationship between change in potential difference and change in crack depth. In addition, influence of crack depth and joint condition on potential difference was considered. It was found that the relationship between crack size and potential difference is represented by a master curve with modification coefficient of core independently of joint condition.

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G031015 比例・非比例ひずみ経路の二軸圧縮試験によるAZ31マグネシウム合金鋳造材の圧縮成形限界に関する検討([G031-01]材料力学部門,一般セッション : 非鉄金属の強度と変形(1))

秋山大輔, 清水一郎, 多田直哉

年次大会 : Mechanical Engineering Congress, Japan 2013 "G031015 - 1"-"G031015-3" 2013年9月

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

Magnesium alloys have special features such as light weight, high specific strength, and good reusability. However, information on the compressive formability of magnesium alloys in multi-axial compressive stress conditions is still limited, nevertheless of their importance in plastic working processes such as forging and extrusion. In the present study, biaxial compression tests of initially isotropic cast AZ31 magnesium alloy were performed along proportional and non-proportional strain paths at room temperature. In the tests, the change of microstructure was observed using a scanning electron microscope. The results revealed that the compressive forming limit of AZ31 magnesium alloy was affected not only by the maximum shear stress but also by the hydrostatic stress. The area fraction of twin, which influences on the compressive flow behavior, was found to vary according to the strain paths.

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207 温度変化と引張り負荷を受けるポリカーボネート基板上金薄膜の有限要素法による変形解析

格日力斯布達, 多田直哉, 清水一郎, 胡亜菲

講演論文集 2013 ( 51 ) "207 - 1"-"207-2" 2013年2月

208 塑性ヒンジ理論を用いた角形鋼管の側面局部圧縮および三点曲げにおける変形吸収エネルギー評価

小原壮人, 小野忠則, 清水一郎, 多田直哉

講演論文集 2013 ( 51 ) "208 - 1"-"208-2" 2013年2月

A Fundamental Study on Plastic Deformation of Metastable Beta-Type Ti-Nb Alloys under Uniaxial and Biaxial Compressions

Ichiro Shimizu, Kazuaki Hisada, Naoya TADA, Yoshito TAKEMOTO

Abstract Book of the International Conference on Experimental Mechanics 2013 & the 12th Asian Conference on Experimental Mechanics 48 - 48 2013年

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