研究者詳細 - 多田　直哉

ゴム粒子を充填した結晶性ポリマーの変形挙動のマルチスケールモデリング

内田真, 多田直哉, 冨田佳宏

日本機械学会論文集. A編 = Transactions of the Japan Society of Mechanical Engineers. A 73 ( 725 ) 73 - 79 2007年1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

To elucidate the toughening mechanism in rubber particle modified semi-crystalline polymers in which the average matrix ligament thickness plays important roles, the micro-to mesoscopic deformation behavior of rubber/semi-crystalline polymer blends was modeled by using large-deformation finite element homogenization method. In this paper, the deformation behavior of three kinds of models which have different size of rubber particles was investigated. A series of computational simulation clarified that highly localized deformation is induced by the initial orientation of lamellae at interface region for the case of smaller size of rubber particles, and it produces larger strain in the matrix due to localization and propagation of the deformation zone. Furthemore, the microscopic deformation is mainly absorbed by not only a slip along chain direction in the crystalline phase, but also interlamellar shear in the amorphous phase, which must be closely related to the toughening mechanism of the rubber/semi-crystalline polymer blends.

DOI： 10.1299/kikaia.73.73

２１／４Ｃｒ‐１Ｍｏ鋼溶接部ＴｙｐｅＩＩＩおよびＴｙｐｅＩＶクリープ損傷のミクロ・マクロシミュレーション査読

その他リンク： https://jlc.jst.go.jp/DN/JALC/00289895106?from=CiNii

川島扶美子, 猪狩敏秀, 時吉巧, 多田直哉

材料 56 ( 2 ) 106 - 113 2007年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：The Society of Materials Science, Japan

A simulation method of the creep damage progress combining the random fracture resistance model and FEM elastic-creep analysis was proposed and was applied to the evaluation of Type III and Type IV creep damage respectively in the coarse and fine grain heat affected zone (HAZ) in welded joints of 2 1/4Cr-1Mo steel. Firstly following the previous work on the fine grain HAZ, parameters for the coarse grain HAZ were identified for simulating the increase of number density of small defects on the basis of the random fracture resistance modeling. Secondly the simultaneous damage simulation for both fine and coarse grain HAZ was applied to both the welded joint model test and the burst test of elbow. A possibility of predicting the final failure time of welded joint was also discussed on the basis of the effective stress against the final failure surface. The proposed simulation successfully reproduced the increase of the number density of small defects in the fine and the coarse grain HAZ, and could predict the failure time of welded joints.

DOI： 10.2472/jsms.56.106

直流電位差法を用いたはんだボール/銅接合界面き裂のモニタリングに関する有限要素法解析

その他リンク： https://jlc.jst.go.jp/DN/JALC/00289912612?from=CiNii

Tensile test of notched metal film by means of thermal expansion of plastics 査読

Naoya Tada, Ichiro Shimizu, Kazumasa Uemori

2007 INTERNATIONAL CONFERENCE ON ELECTRONIC MATERIALS AND PACKAGING 114 - 120 2007年

Plastic behavior of polycrystalline aluminum during biaxial compression with strain path change 査読

Ichiro Shimizu, Naoya Tada

ENGINEERING PLASTICITY AND ITS APPLICATIONS FROM NANOSCALE TO MACROSCALE, PTS 1 AND 2 340-341 883 - + 2007年

多田直哉, 安藤貴宏, 神谷徹

日本機械学会論文集. A編 = Transactions of the Japan Society of Mechanical Engineers. A 73 ( 724 ) 1825 - 1831 2006年12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 order to validate the applicability of the direct current potential difference method (DC-PDM) to identification of interface cracks, electric field analysis was carried out for a copper plate with a solder ball joined on the surface by the finite element method. The analysis was carried out for different crack depths under the following four conditions; (a) when the shape of interface cracks between solder ball and copper changes, (b) when the radius of solder ball changes, (c) when the distance between the bottom of the copper wire and the interface changes, and (d) when the angle of copper wire changes. It was found from the analysis that the larger crack area ratio gave the larger increase in potential difference and that the effect of the crack shape and the angle of copper wire on the potential difference was small. Finally, the relationship between the crack area ratio and the increase in potential difference was given by a single formulated curve for all the conditions discussed in the present analysis

DOI： 10.1299/kikaia.72.1825

多点測定型直流電位差法による表面き裂の3次元的同定に関する実験的検討

その他リンク： https://jlc.jst.go.jp/DN/JALC/00289043842?from=CiNii

多田直哉, 岩本淳, 岡田眞禎

日本機械学会論文集. A編 = Transactions of the Japan Society of Mechanical Engineers. A 72 ( 715 ) 332 - 339 2006年3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 method for identification of a crack on the surface of the material by means of direct-current electrical potential difference method of multiple-point measurement type was proposed and related experiments were carried out to verify the proposed method. The geometry of the crack was given by the two-dimensional location of the crack center, the surface and inward angles of the crack, the length and depth of the crack. The experiments were carried out for metal plates with various surface cracks made by electric discharge machining. When most of the area of potential disturbance by a crack was included in the measurement area, the geometry of the crack was successfully identified by the proposed method based on the potential differences measured at multiple locations around the crack.

DOI： 10.1299/kikaia.72.332

その他リンク： https://jlc.jst.go.jp/DN/JALC/00277226295?from=CiNii

Evaluation of interface crack between solder ball and copper based on the non-destructive monitoring of direct current potential difference 査読

Naoya Tada, Takahiro Andou

2006 INTERNATIONAL CONFERENCE ON ELECTRONIC MATERIALS AND PACKAGING, VOLS 1-3 659 - 665 2006年

3615 補助電流を付加した直流電位差法による背面き裂の同定に関する有限要素法解析(S13-4 疲労特性と設計,S13 実用構造材料の疲労問題と健全性評価)

多田直哉, 船越亮, 石井祐介

年次大会講演論文集 2006 767 - 768 2006年

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 conventional direct-current potential difference method (DC-PDM), uniform current is supplied far from a crack and the change in the potential difference by the crack is measured. The identification of the crack is done based on it. But in the case of a crack on the back surface, the change is not large enough and the identification is usually difficult. In this study, auxiliary current is supplied in addition to the remote uniform current and the improvement of identification of the crack existing on the back surface is investigated using the finite element method. Based on the analysis results, effect of the location of the auxiliary current and its strength on the measured potential difference is discussed.

DOI： 10.1299/jsmemecjo.2006.1.0_767

多結晶金属の引張塑性変形に伴う表面あれの自己相関関数による検討

P65 圧痕の形状変化に基づく材料表面の3次元的ひずみ評価に関する解析的検討(GS1)

杉本義展, 多田直哉, 細井康成

材料力学部門講演会講演論文集 2006 647 - 648 2006年

宋華林, 阿部武治, 多田直哉

材料 54 ( 4 ) 407 - 413 2005年4月

記述言語：日本語出版者・発行元：社団法人日本材料学会

The microscopic plastic deformation and the surface roughening behavior of free surface of polycrystalline aluminum sheet during uniaxial tension were experimentally investigated. The free surface roughness profiles are measured during plastic deformation with a confocal laser-scanning microscope. The surface roughness curve was analyzed employing the autocorrelation function and simplified model of surface roughness curve. It is shown that the average inclination of the surface profile curve increases lineally with increasing applied strain, and the grain rotation out of the surface plane is dominant contributor to the surface roughness. The roughness in grains are less than 30% and the roughness of slip bands are less than 7% , respectively, of the total surface profile roughness. The wavelength of the surface roughness curve is about 5〜9 times the averaged grain size, which increases with the applied tensile strain. Discussions are made on the autocorrelation length, the wavelength of surface profile and the grain boundary position on the surface profile.

DOI： 10.2472/jsms.54.407

多結晶高純度アルミニウムの引張塑性変形に伴う微視的表面形状変化査読

その他リンク： https://jlc.jst.go.jp/DN/JALC/00249206751?from=CiNii

王暁群, 阿部武治, 多田直哉, 清水一郎

軽金属 55 ( 2 ) 68 - 74 2005年2月

Tensile Test of Thin Titanium Plate Actuated by Thermal Expansion of Polycarbonate 査読

Naoya Tada, Ichiro Shimizu, Keigo Kanamura, Hiroyuki Tada

Proc. the Sixth International Congress on Thermal Stresses (Thermal Stresses 2005), Vienna University of Technology 2005年

Evaluation of Multiple Through-Cracks with Random Angles by Direct Current Electrical Potential Difference Method 査読

Naoya TADA

Proc. the Third US-Japan Symposium on Advancing Applications and Capabilities, The American Society for Nondestructive and Testing 2005年

Micro-macro damage simulation of low-alloy steel welds subject to type IV creep failure

T. Igari, F. Kawashima, T. Tokiyoshi, N. Tada

Acta Metallurgica Sinica (English Letters) 17 ( 4 ) 393 - 399 2004年8月

走査型レーザ顕微鏡による多結晶アルミニウムの微視的塑性変形挙動の評価

宋華林, 阿部武治, 清水一郎, 多田直哉, 鳥居太始之

材料 53 ( 5 ) 473 - 480 2004年5月

記述言語：日本語出版者・発行元：社団法人日本材料学会

The microscopic plastic deformation behavior of aluminum sheet during uniaxial tension is experimentally investigated by a confocal laser-scanning microscope. The surface roughening is closely related to the inhomogeneity of polycrystalline metals, that is, to the inhomogeneous plastic deformation of respective grains. In order to clarify the deformation behavior of polycrystalline metals, new measuring methods and 4 types of strains of grains are introduced and inhomogeneous of strain of grains are investigated. Digital image processing technique is applied to the surface image taken by the CCD camera for measurement. It is shown that the grain-area strain, the maximum dimension and mean dimension strain, the grain-boundary length strain and the standard deviations of these parameters statistically increase in proportion to the applied strain. Discussions are made on the differences between these measuring methods of strain parameters of grains, variations of measured statistical results including comparison with equilateral polygon model during tensile deformation.

DOI： 10.2472/jsms.53.473