Faculty Profiles - TADA Naoya

Multiscale Modeling of Deforation Behavior of Rubber Blended Semi-Crystalline Polymer

UCHIDA Makoto, TADA Naoya, TOMITA Yoshihiro

Transactions of the Japan Society of Mechanical Engineers Series B 73 ( 725 ) 73 - 79 2007.1

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

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

Micro-Macro Simulation of Type III and Type IV Creep Damage in 2 1/4Cr-1Mo Steel Welds Reviewed

Other Link： https://jlc.jst.go.jp/DN/JALC/00289895106?from=CiNii

KAWASHIMA Fumiko, IGARI Toshihide, TOKIYOSHI Takumi, TADA Naoya

journal of the Japan Society for Testing Materials 56 ( 2 ) 106 - 113 2007

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：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

Finite Element Analysis for Monitoring Interface Crack between Solder Ball and Copper by Direct Current Potential Difference Method

Other Link： https://jlc.jst.go.jp/DN/JALC/00289912612?from=CiNii

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

Naoya Tada, Ichiro Shimizu, Kazumasa Uemori

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

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

Ichiro Shimizu, Naoya Tada

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

TADA Naoya, ANDOU Takahiro, KAMITANI Toru

Transactions of the Japan Society of Mechanical Engineers Series B 73 ( 724 ) 1825 - 1831 2006.12

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

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

Experimental Study of Three-Dimensional Identification of Surface Crack by Means of Direct-Current Electrical Potential Difference Method of Multiple-Point Measurement Type

Other Link： https://jlc.jst.go.jp/DN/JALC/00289043842?from=CiNii

TADA Naoya, IWAMOTO Jun, OKADA Masayoshi

Transactions of the Japan Society of Mechanical Engineers Series B 72 ( 715 ) 332 - 339 2006.3

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

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

Other Link： 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 Reviewed

Naoya Tada, Takahiro Andou

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

3615 Finite Element Analysis for Identification of Back Surface Crack by Direct Current Potential Difference Method with Auxiliary Current

TADA Naoya, FUNAKOSHI Akira, ISHII Yusuke

The proceedings of the JSME annual meeting 2006 767 - 768 2006

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

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

Analysis of Surface Roughening with Uniaxial Tension of Polycrystalline Aluminum by Autocorrelation Function

P65 Analytical Study of Three-Dimensional Evaluation of Strain on Material's Surface Based on Shape Change of Indentation

SUGIMOTO Yoshinobu, TADA Naoya, HOSOI Yasunari

Proceedings of the 1992 Annual Meeting of JSME/MMD 2006 647 - 648 2006

SONG Hualin, ABE Takeji, TADA Naoya

Journal of the Society of Materials Science, Japan 54 ( 4 ) 407 - 413 2005.4

Language：Japanese Publisher：The Society of Materials Science, Japan

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

Change in microscopic surface profile during tensile plastic deformation of high purity aluminum polycrystals Reviewed

Other Link： https://jlc.jst.go.jp/DN/JALC/00249206751?from=CiNii

WANG Xiaoqun, ABE Takeji, TADA Naoya, SHIMIZU Ichiro

55 ( 2 ) 68 - 74 2005.2

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

Naoya Tada, Ichiro Shimizu, Keigo Kanamura, Hiroyuki Tada

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

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

Naoya TADA

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

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 2004.8

Evaluation of Microscopic Plastic Deformation of Polycrystalline Aluminum by Laser-Scanning Microscope

SONG Hualin, ABE Takeji, SHIMIZU Ichiro, TADA Naoya, TORII Tashiyuki

Journal of the Society of Materials Science, Japan 53 ( 5 ) 473 - 480 2004.5

Language：Japanese Publisher：The Society of Materials Science, Japan

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