Faculty Profiles - TADA Naoya

Estimation of Active Slip Plane in Tensile Plastic Deformation of Polycrystalline Copper with EBSD Method

Other Link： https://jlc.jst.go.jp/DN/JALC/00229769016?from=CiNii

KONDOU Ryouji, ABE Takeji, TADA Naoya, SHIMIZU Ichiro

Transactions of the Japan Society of Mechanical Engineers Series B 69 ( 681 ) 924 - 931 2003.5

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

Relationship between the slip line and the orientation of grains in polycrystalline copper during tensile plastic deformation is studied. Slip plane of each grain is calculated from the orientation obtained using EBSD technique, and the slip line of specimen surface is observed by SEM image. A method of estimation of active slip plane in each grain of polycrystalline copper during tensile plastic deformation is proposed based on the experimental results. Direction of slip line is calculated from the geometrical relationship between the specimen surface and the slip plane whose orientation is obtained using EBSD method. The estimated results and the observed results are compared by use of their correlation factor. The constraint between grains in the normal direction to the specimen surface is expected to be smaller than that between grains in the surface plane. Namely, the active slip plane is decided from the condition that the component of the specimen inward direction or the direction on the specimen surface of the shearing stress on the slip plane is maximum. It is also shown that the small size grain deforms on the slip plane whose orientation is close to the active slip plane of the neighboring grain with the maximum size. The estimated results are in good agreement with the experimental results.

DOI： 10.1299/kikaia.69.924

Evaluation of Size, Shape and Location of a Semi-Elliptical Surface Crack Using Direct Current Electrical Potential Method Reviewed

Other Link： https://jlc.jst.go.jp/DN/JALC/00208632522?from=CiNii

Numerical Simulation of the Microscopic Damage progress in Type IV Creep Failure of Low Alloy Steel Welds Reviewed

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

Proc. Seventh Workshop on the Ultra-Steel, "Ultra Steel: Requirements from New Design of Constructions", National Institute for Materials Science 2003

Orientation change measured by the EBSD method and the plastic deformation of grains in polycrystalline copper Reviewed

T Abe, R Kondou, N Tada, Shimizu, I

ENGINEERING PLASTICITY FROM MACROSCALE TO NANOSCALE PTS 1 AND 2 233-2 535 - 540 2003

Observation of the tensile deformation behavior of polycrystalline titanium with the scanning probe microscope Reviewed

T Abe, Y Li, N Tada

ENGINEERING PLASTICITY FROM MACROSCALE TO NANOSCALE PTS 1 AND 2 233-2 529 - 534 2003

Advanced Creep Damage Analysis of Low-Alloy Steel Welds Considering the Microscopic Damage Progress Reviewed

Fumiko Kawashima, Takumi Tokiyoshi, Toshihide Igari, Akira Shibashi, Naoya Tada

Proc. International Conference on Advanced Technology in Experimental Mechanics 2003, The Japan Society of Mechanical Engineers 2003

Observation of creep cavity growth in smooth and notched specimens of low alloy steel in the heat-affected zone Reviewed

N Tada, H Maruyama, T Igari, F Kawashima

STRUCTURAL INTEGRITY AND MATERIALS AGING 113 - 118 2003

Fatigue Fracture of Third Generation Nickel-Base Single Crystal Superalloy CMSX-10 at High Temperature -Acceleration of Cracking by Stress Hold- Reviewed

Naoya TADA, Ryuichi OHTANI, Masanori SHIBATA, Shigeaki TANIYAMA

Proc. Fourth Japan-China Bilateral Symposium on High Temperature Strength of Materials, The Society of Materials Science, Japan 2001

Prediction of Inner Cracking Behavior in Heat-Resistant Steel under Creep-Fatigue Condition by Means of Three-Dimensional Numerical Simulation Reviewed

Naoya TADA, Ryuichi OHTANI

Proc. the Fifth IUTAM Symposium on Creep in Structures, “IUTAM Symposium on Creep in Structures”, Kluwer Academic Publishers, Dordrecht, The Netherlands 2001

Mesurement of cavities and evaluation of creep damage parameters Reviewed

N Tada, R Ohtani

PROCEEDINGS OF THE SEM IX INTERNATIONAL CONGRESS ON EXPERIMENTAL MECHANICS 409 - 412 2000

TADA Naoya, NAKAYAMA Eisuke

48 ( 10 ) 697 - 704 1999.10

Initiation and Arrest of Small Cracks of AS4/PEEK in Transverse Tension

EJIMA Tsuneyuki, KOIZUMI Masahisa, TADA Naoya, KITAMURA Takayuki, OHTANI Ryuichi

Journal of the Society of Materials Science, Japan 48 ( 9 ) 1022 - 1028 1999.9

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

In order to investigate the fracture process of CFRP with high toughness, a plate specimen of a uni-directionally reinforced AS4/PEEK is subjected to transverse tension at room temperature. The results obtained are summarized as follows ; (1)At 83% of fracture stress, small cracks are initiated along the interfaces of fiber and matrix in a group on or near the edge of specimen. (2)The cracks are semi-circular and they are arrested just after the initiation. (3)Although the number of the cracking regions increases as the applied stress increases, the area of each cracking region does not grow due to the crack arrest. (4)The boundary element analysis and the finite element analysis reveal that the arrest is caused by the cylindrical shape of the interface. (5)The cracks restart to grow and make coalescence when the stress field near the crack tip satisfies the condition of crack kinking. (6)The main crack formed brings about the specimen breaks down when the stress intensity factor reaches the macroscopic toughness, which is evaluated by DCB specimen.

DOI： 10.2472/jsms.48.1022

Analysis of Direct Current Potential Field around Multiple Spherical Defects

Other Link： https://jlc.jst.go.jp/DN/JALC/00063348118?from=CiNii

TADA Naoya, NAKAYAMA Eisuke, KITAMURA Takayuki, OHTANI Ryuichi

Transactions of the Japan Society of Mechanical Engineers Series B 65 ( 632 ) 693 - 700 1999.4

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

A method for evaluating the distribution of electrical potential around multiple spherical defects was proposed. As the method is based on the known solution for a single defect, the electric field can be efficienly analyzed in comparison with the other methods, such as the finite element method. The electric field in a conductive material with multiple spherical defects at random locations is estimated by the method. The analysis shows that the increase in the potential difference normalized by the potential difference without defects, ΔV/V₀, is in proportion to the product of the volumetric density of defects and the mean of cubed defect radius, n_v [r³]_m. The universal relationship is independent of the location of defects and the distribution of defect radius. Thus, the damage due to the multiple defects can be evaluated by the increase in potential difference.

DOI： 10.1299/kikaia.65.693

Stress Analysis for Small Edge Crack in Transversely Reinforced Composite Laminate

Other Link： https://jlc.jst.go.jp/DN/JALC/00059919001?from=CiNii

EJIMA Tsuneyuki, TADA Naoya, KITAMURA Takayuki, OHTANI Ryuichi

Transactions of the Japan Society of Mechanical Engineers Series B 65 ( 631 ) 538 - 544 1999.3

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

Stress analysis was conducted for a transversely reinforced composite laminate with an edge crack in the matrix or along an interface by the boundary element method (BEM). The laminate is submitted to the tensile stress perpendicular to the laminate in plane strain condition. The results obtained are summarized as follows ; (1) When the laminate is composed of such two materials as don't show the free edge effect, the stress intensity factor (SIF) for a small edge crack coincides with that for a small inner crack. (2) In the case that the free edge effect is remarkable, when a crack is very small (or thort), the change in normalized SIFs, K₁ (K₁=K₁/K_lh, K_lh is SIF for a crack in a homogeneous orthotropic body) for a matrix crack and K₁, K₂ and K₁ for an interface crack depend on the magnitude of stress singularity by free edge effect. (3) As a crack becomes larger (or longer), K₁ for a matrix crack and K_i for an interface crack tends to converge on the constant values. The convergent values are calculated by the energy release rate for a crack in the homogeneous orthotropic body which has the same elastic constants as those of the composite macroscopically. (4) The magnitude of SIF for a small edge crack can be calculated by the stress distribution near the edge without a crack.

DOI： 10.1299/kikaia.65.538

Fracture of Sintered Silicon Nitride in Tension, Creep, Fatigue and Creep-Fatigue at High Temperatures(Special Issue on Strength of Materials at Elevated Temperatures)

Other Link： https://jlc.jst.go.jp/DN/JALC/00059805069?from=CiNii

TADA Naoya, KITAMURA Takayuki, OHTANI Ryuichi, KIKURA Makoto, TANAKA Toyonobu

Journal of the Society of Materials Science, Japan 48 ( 2 ) 173 - 180 1999.2

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

In order to investigate the fracture process of a sintered silicon nitride at high temperatures, tensile, static creep, and fatigue tests were carried out at temperatures from room temperature up to 1573K, and the fracture surface of each specimen was carefully observed by means of optical and scanning electron microscopes. Fracture of the silicon nitride can be classified into two types from the viewpoint of cracking morphology. One is"single cracking type"where only a single crack brings about the fracture. As the crack is initiated at the largest pre-existing defect, distribution and size of the defects greatly affect the fracture strength. The other is"multiple cracking type"where several cracks were observed on the fracture surface as well as on the specimen surface. As the cracks are initiated by viscous sliding of grassy phase along grain boundaries, pre-existing defects affest little the fracture strength. The latter type is apt to appear in the tests with lower tensile stress or lower stress rate at higher temperature.

DOI： 10.2472/jsms.48.173

Transition from Small Crack to Large Crack for Composite Materials (BEM Analysis on Transversely Reinforced Composite Plate with an Interface Crack)

Other Link： https://jlc.jst.go.jp/DN/JALC/00059446088?from=CiNii

Evolution of creep-fatigue damage in type 304 stainless steel and its detection by electrical potential method

N. Tada, T. Kitamura, R. Ohtani, E. Nakayama

Acta Metallurgica Sinica (English Letters) 11 ( 6 ) 463 - 469 1998

EJIMA Tsuneyuki, SAKAGUCHI Shohei, TADA Naoya, KITAMURA Takayuki, OHTANI Ryuichi

Transactions of the Japan Society of Mechanical Engineers Series B 63 ( 615 ) 2338 - 2344 1997.11

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

Stress analysis was conducted for a traversely reinforced composite plate with an interface crack at the center under tension in plane strain condition by the boundary element method (BEM). The results obtained are summarized as follows ; (1) When the normalized crack length, a=a/d, (a : crack length, d : thickness of matrix layer) is much smaller than unity, the magnitude of stress intensity factors (SIFs), K₁, K₂, and K_i=(K²₁+K²₂)^1/2, are close to the SIFs for an interface crack in a dissimilar infinite body. The crack is termed as the small crack for composite materials. (2) As a becomes larger, the normalized SIF, K_i decreases and shows the minimum near a=1, where K_i is the SIF, K_i, divided by the SIF for a homogeneous orthotropic body composed of a Mode I crack, K₁h. It increases and converges on a constant value as a increases. (3) The energy release rate calculated from the convergent K_i coincides with that of the crack in a homogeneous orthotropic body where the elastic constants are determined by a mixture of those in the matrix and fibers. The crack is termed as the large crack for composite materials. (4) Since the region of oscillated stress distribution is confined in the vicinity of the crack tip, the stress intensity is represented by K_i, of which values are nearly equal to the SIF of the large crack in a homogeneous orthotropic body.

DOI： 10.1299/kikaia.63.2338