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Journal Articles

Stress measurement of stainless steel piping welds by complementary use of high-energy synchrotron X-rays and neutrons

Miura, Yasufumi*; Suzuki, Kenji*; Morooka, Satoshi; Shobu, Takahisa

Quantum Beam Science (Internet), 8(1), p.1_1 - 1_14, 2024/03

Journal Articles

Relationship between internal stress distribution and microstructure in a suspension-sprayed thermal barrier coating with a columnar structure

Yamazaki, Yasuhiro*; Shinomiya, Keisuke*; Okumura, Tadaharu*; Suzuki, Kenji*; Shobu, Takahisa; Nakamura, Yuiga*

Quantum Beam Science (Internet), 7(2), p.14_1 - 14_12, 2023/05

Journal Articles

Actual stress analysis of small-bore butt-welded pipe by complementary use of synchrotron X-rays and neutrons

Suzuki, Kenji*; Miura, Yasufumi*; Shiro, Ayumi*; Toyokawa, Hidenori*; Saji, Choji*; Shobu, Takahisa; Morooka, Satoshi

Zairyo, 72(4), p.316 - 323, 2023/04

Journal Articles

A Study on stress measurement of weld part using double exposure method

Suzuki, Kenji*; Kura, Komoe*; Miura, Yasufumi*; Shiro, Ayumi*; Toyokawa, Hidenori*; Saji, Choji*; Kajiwara, Kentaro*; Shobu, Takahisa

Zairyo, 71(12), p.1005 - 1012, 2022/12

This paper describes a stress measurement from a welded part of an austenitic stainless steel using synchrotron X-rays. Difficulty measuring the X-ray stress of the welded part is caused by the broadening of the diffraction spot in the radial and circumferential directions. The bending strains of the rectangular bar made of the welded part were measured using synchrotron white X-rays and the double exposure method. To improve the energy resolution, monochromatic synchrotron X-ray of 70 keV was used. The diffraction pattern showed the sharp arc like a pattern from texture material. The diffraction profile was obtained from the integral of the diffraction intensity in the direction of the circumference. The diffraction angle was determined using the double exposure method. As a result, the distribution of the residual stresses of the welded part could be measured.

Journal Articles

Stress measurements of quasi-coarse grained material using double exposure method with high-energy monochromatic X-rays

Suzuki, Kenji*; Yamada, Minami*; Shiro, Ayumi*; Shobu, Takahisa; Toyokawa, Hidenori*; Saji, Choji*

Zairyo, 71(4), p.347 - 353, 2022/04

We have already succeeded in the residual stress of aluminum alloys using the double exposure method (DEM) with 30 keV synchrotron radiation X-rays. However, the DEM has not be applied in the range of high-energy synchrotron X-rays. In this study, the stress measurements of a shrink-fitted ring using the DEM with synchrotron monochromatic X-rays beyond about 70 keV were performed. A CdTe pixel detector and a CCD camera were used as a detector. The shrink-fitted specimen of SUS304 was quasi-coarse grains of 43 micro-meters, and the diffraction rings were spotty. Despite quasi-coarse grains, it was possible to measure the stresses of the shrink-fitted specimen using the DEM. As a result, the DEM is excellent method to measures the stress for coarse grained materials. In addition, it is better to make the length between the detection positions longer to improve precision of the DEM. On the other hand, it was ineffective to increase the positions of detection.

Journal Articles

Double-exposure method with synchrotron white X-ray for stress evaluation of coarse-grain materials

Suzuki, Kenji*; Shiro, Ayumi*; Toyokawa, Hidenori*; Saji, Choji*; Shobu, Takahisa

Quantum Beam Science (Internet), 4(3), p.25_1 - 25_14, 2020/09

It is difficult to evaluate stress by the strain scanning method using a conventional diffractometer and a point detector since the two-dimensional diffraction pattern of a material composed of coarse grains does not have a ring but a spotty. To solve this problem, we proposed a double exposure method using a two-dimensional detector and monochromatized X-rays. In this study, we have developed a technique to apply that technique to white X-rays. The diffraction obtained by irradiating white X-rays for a material with of coarse grains becomes a Laue spot. Therefore, we have carried out developing a CdTe pixel two-dimensional detector that can limit the energy to be detected, and we evaluated the stress using that detector. As a result, we succeeded to measure the strain distribution of a bending specimen made to austenitic stainless steel. In the future, we would like to improve this technology and apply it to actual machine materials.

Journal Articles

Stress measurement of coarse grains using double exposure method

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi*

Zairyo, 68(4), p.312 - 317, 2019/04

Materials after thermal processing such as welding often have coarse grains. To understand the residual stress after processing is very important from the viewpoint of the soundness of the structure. In this study, we proposed a double exposure method that combines a two-dimensional detector and high-energy synchrotron radiation as an X-ray stress measurement method for materials with coarse grains, and confirmed its practicality. As a result of measuring the residual stress of the plastic bending specimen and the indentation specimen of the aluminum alloy (A5052), the effectiveness of this measurement method was clarified because the residual stress distribution was in good agreement with the finite element analysis.

Journal Articles

Intergranular strains of plastically deformed austenitic stainless steel

Suzuki, Kenji*; Shobu, Takahisa

E-Journal of Advanced Maintenance (Internet), 10(4), p.9 - 17, 2019/02

In materials with an elastic anisotropy, a stress difference is generated between crystals when plastic deformation occurs, and it is known that this is deeply involved in material fracture. In this study, the residual stress for load direction in the plastically deformed material was investigated for each crystal orientation using the high-energy synchrotron radiation diffraction method. As a result, it was found that the residual stress is a tensile residual stress at an index with a high X-ray elastic constant (Young's modulus obtained for each diffraction surface) and a compressive residual stress at an index with a low X-ray elastic constant. We believe that this result will be useful for the technique of controlling the crystal orientation like the texture as improving the material strength.

Journal Articles

Observation and evaluation of plastic collapse for double-notch pipe

Suzuki, Ryosuke*; Matsubara, Masaaki*; Sakamoto, Kenji*; Suzuki, Masato*; Shiraishi, Taisuke*; Yanagihara, Seiji*; Izawa, Satoru*; Wakai, Takashi

Experimental Techniques, 40(1), p.253 - 260, 2016/09

 Times Cited Count:0 Percentile:0.03(Engineering, Mechanical)

The plastic collapse behavior and strength were investigated for an austenitic stainless steel pipe with two 90$$^{circ}$$ through-wall notches perpendicular to the pipe axis direction. Double-notch specimens with various notch separation distances were coated with photo-plastic film. Arbitrary combined axial tensile and bending loads were applied to the specimens. Changes in the photo-plastic fringe pattern were observed during the tests to investigate the plastic collapse behavior. The plastic collapse strength was evaluated using a model based on an elastic-perfectly plastic body. The photo-plastic fringe patterns at the experimental plastic collapse point differed based on the loading history. Thus, the plastic collapse behavior depends on the loading history. In addition, the plastic collapse strength differed based on the loading history and hardly depended on the notch separation distance. The experimental plastic collapse occurred before reaching the theoretical plastic point for only some pure-tension loading tests. Thus, the model analysis based on an elastic-perfectly plastic body used in this study might give an unconservative estimate for the plastic collapse of a stainless steel pipe subjected to a pure tension load.

Journal Articles

Evaluation of welding residual stresses using diffraction spot trace method

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi; Zhang, S.*

Advanced Materials Research, 996, p.76 - 81, 2014/08

 Times Cited Count:0 Percentile:0

Journal Articles

Stress evaluation in material with coarse grains using area detector

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi; Zhang, S.*

Zairyo, 63(7), p.527 - 532, 2014/07

The spiral slit-system and DSTM (diffraction spot trace method) are under development in order to evaluate internal stresses of materials with coarse grains. The bending stress in the specimen with coarse grains was measured in order to confirm performance of this advanced spiral slit-system. It was proved that the combination of the advanced spiral slit-system and the DSTM is useful for the internal stress measurement of materials with coarse grains. The welded specimen of a Mg-alloy plate was prepared by melt-run with TIG welding. The residual stress map in the cross-section of the specimen was made using the DSTM. On the other hand, the residual stresses of the welded specimen were simulated by a finite element method. The measured residual stresses were similar to the simulated results, and the residual stresses due to extrusion were measured also using the DSTM. Therefore, the DSTM is suitable for the stress measurement of weld parts.

Journal Articles

Internal stress measurement of weld part using diffraction spot trace method

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi; Zhang, S.*

Materials Science Forum, 777, p.155 - 160, 2014/02

 Times Cited Count:3 Percentile:82.41

Journal Articles

Development of a linear motion antenna for the JT-60SA ECRF system

Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Hoshino, Katsumichi; Suzuki, Sadaaki; Hiranai, Shinichi; Yokokura, Kenji; Sawahata, Masayuki; Terakado, Masayuki; Hinata, Jun; et al.

Fusion Engineering and Design, 88(6-8), p.935 - 939, 2013/10

 Times Cited Count:4 Percentile:32.63(Nuclear Science & Technology)

An antenna having a first mirror driven in the linear motion (LM) and a fixed second mirror was proposed for electron cyclotron range of frequency (ECRF) heating and current drive system, to minimize the risk of cooling-water-leakage. Basic mechanical feasibilities of the bellows covering the movable structures of the antenna were previously investigated using a mock-up. This time, a support structure of the shaft has been designed using a metallic sliding bearing with solid lubricant. The sliding bearing can support combination of linear and rotational motions while a ball bearing supports either linear or rotational motion. We have newly installed the sliding bearing into the mock-up. A vacuum pumping test has been carried out paying attention to the influence of the solid lubricant by mass analysis. To design the LM antenna for JT-60SA in detail, heating and current drive characteristics for typical experimental scenarios of JT-60SA has been investigated by calculation.

Journal Articles

Residual stresses of water-jet peened austenitic stainless steel

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi

Zairyo, 62(7), p.437 - 442, 2013/07

The specimen material was austenitic stainless steel, SUS316L. The residual stress was induced by water-jet peening. The residual stress was measured using the 311 diffraction with conventional X-rays. The measured residual stress showed the equi-biaxial stress state. To investigate thermal stability of the residual stress, the specimen was aged thermally at 773 K in air to 1000 h. The residual stress kept the equi-biaxial stress state against the thermal aging. Lattice plane dependency of the residual stress induced by water-jet peening was evaluated using hard synchrotron X-rays. The residual stress measured by the soft lattice plane showed the equi-biaxial stress state, but the residual stress measured by the hard lattice plane did not. In addition, the distributions of the residual stress in the depth direction were measured using a strain scanning method with hard synchrotron X-rays and neutrons.

Journal Articles

Dual frequency ECRF system development for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; et al.

Fusion Science and Technology, 63(1T), p.160 - 163, 2013/05

 Times Cited Count:7 Percentile:49.41(Nuclear Science & Technology)

A dual frequency electron cyclotron range of frequency system has been developed for JT-60SA, by which a second frequency (135 $$sim$$ 140 GHz) is generated in addition to the first frequency of 110 GHz. A development of a dual frequency gyrotron is a key to realize the dual frequency system. The second frequency was chosen to be 138 GHz from the above frequency range from the viewpoint of gyrotron design. In order to realize high-power ($$>$$ 1 MW) and long-pulse operation for both frequencies, we designed main components of the gyrotron (the diamond window, cavity resonator and quasi-optical mode converter). We found the optimum parameter set from the parameters of these components, which has discrete characteristics. It was confirmed that the output power higher than 1 MW is obtained for both frequencies as a result of numerical design. Based on the above design, a dual frequency gyrotron was newly fabricated. In the conditioning operation, an output power was obtained as we expected.

Journal Articles

Plastic collapse strength and maximum load evaluation method of flawed stainless piping subjected to axial tension and bending

Yanagihara, Seiji*; Matsubara, Masaaki*; Suzuki, Ryosuke*; Suzuki, Masato*; Shiraishi, Taisuke*; Sakamoto, Kenji*; Wakai, Takashi

Nihon Kikai Gakkai M&M 2012 Zairyo Rikigaku Kanfarensu Koen Rombunshu (CD-ROM), 2 Pages, 2012/09

Journal Articles

Collapse strength of SUS304 steel pipes with circumferential multiple notches subjected to axial tension and bending

Shiraishi, Taisuke*; Matsubara, Masaaki*; Suzuki, Ryosuke*; Suzuki, Masato*; Yanagihara, Seiji*; Sakamoto, Kenji*; Wakai, Takashi

Nihon Kikai Gakkai M&M 2012 Zairyo Rikigaku Kanfarensu Koen Rombunshu (CD-ROM), 3 Pages, 2012/09

Journal Articles

Dual frequency gyrotron development for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; et al.

Proceedings of 37th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2012) (USB Flash Drive), 2 Pages, 2012/09

A new dual frequency (110 GHz and 138 GHz) gyrotron development began for JT-60SA. An output power and efficiency higher than 1 MW and 30% with a peak heat load lower than 1.4 kW/cm$$^{2}$$ were obtained for both frequencies in calculation. High mode conversion efficiencies of the quasioptical mode converter (96.8% for 110 GHz and 98.3% for 138 GHz), which is higher than the previously developed 110 GHz long pulse gyrotron (96.5%), was obtained. The new gyrotron was fabricated and conditioning operation has been started from the middle of June 2012. The gyrotron output power of approximately 200 kW was obtained, so far, as we expected in the design of the gyrotron at low beam current of 10 A and low beam voltage of 75 kV.

Journal Articles

Collapse strength of multiple notched pipes under combined load

Shiraishi, Taisuke*; Matsubara, Masaaki*; Suzuki, Ryosuke*; Suzuki, Masato*; Wakai, Takashi; Sakamoto, Kenji*

Proceedings of 5th International Workshop New Methods of Damage and Failure Analysis of Structural Parts (CD-ROM), 6 Pages, 2012/09

Journal Articles

Residual stresses in dissimilar metal joint by multi-pass welds

Suzuki, Kenji*; Yamagishi, Aoi*; Nishikawa, Satoru*; Shobu, Takahisa

Hozengaku, 11(2), p.91 - 98, 2012/07

In this study, a residual stress distribution in a dissimilar plate butt-welded joint was simulated by a thermo-elastic finite element method. The base metal was the austenitic stainless steel SUS316L. The other base metal was nickel super-alloy NCF600, and the weld metal was the alloy 82 (YNiCr-3). The dimensions of the plate butt-welded joint were a width of 200 mm, a length of 250 mm and a thickness of 25 mm. The welding joint was fabricated by TIG welding with 22 passes. For comparison, the residual stress distribution for the similar butt-welded joint of SUS316L was simulated as well as the dissimilar welded joint. According to the simulated results, there was not the difference in the thermal field between the similar and the dissimilar welded joints. The residual stress distribution in the similar welded joint became symmetrical to the welding center after removal of the weld bead. For the dissimilar welded joint, the peak of the residual stresses moved to the NCF600 side a little. The residual stress level of the dissimilar welded joint was large compared with the similar welded joint. The residual stress of the welding direction was larger than that of the transverse direction.

127 (Records 1-20 displayed on this page)