The Experts below are selected from a list of 450 Experts worldwide ranked by ideXlab platform

Cláudio Geraldo Schön - One of the best experts on this subject based on the ideXlab platform.

  • Effect of sample pre-cracking method and notch geometry in plane strain fracture toughness tests as applied to a PMMA resin
    Polymer Testing, 2012
    Co-Authors: Joelmir Mariano De Souza, Fabiano Moreno Peres, Humberto Naoyuki Yoshimura, Cláudio Geraldo Schön
    Abstract:

    Abstract The influence of test method factors (notch shape, square or angular, and pre-cracking method, by tapping onto or pressing a razor blade) on the results obtained in plane strain fracture toughness test according to standard ASTM D5045 using SENB specimens made of a commercial PMMA resin were investigated. Results were analyzed quantitatively by comparing the obtained KIc values and qualitatively by observing their effect on the Moire Fringes observed using photoelasticity, showing that, at 95% significance level, the KIc values are affected by the pre-cracking method, with the most conservative value being obtained when natural pre-cracks were introduced by tapping onto a razor blade (KIc = 1.15 ± 0.11 MPa·m0.5). This correlates with a perturbation in the stress field close to the pre-crack tip observed in the photoelasticity test sample when it was introduced by pressing the razor blade. Surprisingly, notch geometry only slightly affects the results.

Joelmir Mariano De Souza - One of the best experts on this subject based on the ideXlab platform.

  • Effect of sample pre-cracking method and notch geometry in plane strain fracture toughness tests as applied to a PMMA resin
    Polymer Testing, 2012
    Co-Authors: Joelmir Mariano De Souza, Fabiano Moreno Peres, Humberto Naoyuki Yoshimura, Cláudio Geraldo Schön
    Abstract:

    Abstract The influence of test method factors (notch shape, square or angular, and pre-cracking method, by tapping onto or pressing a razor blade) on the results obtained in plane strain fracture toughness test according to standard ASTM D5045 using SENB specimens made of a commercial PMMA resin were investigated. Results were analyzed quantitatively by comparing the obtained KIc values and qualitatively by observing their effect on the Moire Fringes observed using photoelasticity, showing that, at 95% significance level, the KIc values are affected by the pre-cracking method, with the most conservative value being obtained when natural pre-cracks were introduced by tapping onto a razor blade (KIc = 1.15 ± 0.11 MPa·m0.5). This correlates with a perturbation in the stress field close to the pre-crack tip observed in the photoelasticity test sample when it was introduced by pressing the razor blade. Surprisingly, notch geometry only slightly affects the results.

  • Effect of sample pre-cracking method and notch geometry in plane strain fracture toughness tests as applied to a PMMA resin
    OXFORD, 2012
    Co-Authors: Joelmir Mariano De Souza, Yoshimura, Humberto Naoyuki, Peres, Fabiano Moreno, Schoen, Claudio Geraldo
    Abstract:

    The influence of test method factors (notch shape, square or angular, and pre-cracking method, by tapping onto or pressing a razor blade) on the results obtained in plane strain fracture toughness test according to standard ASTM D5045 using SENB specimens made of a commercial PMMA resin were investigated. Results were analyzed quantitatively by comparing the obtained K-IC values and qualitatively by observing their effect on the Moire Fringes observed using photoelasticity, showing that, at 95% significance level, the K-IC values are affected by the pre-cracking method, with the most conservative value being obtained when natural pre-cracks were introduced by tapping onto a razor blade (K-IC = 1.15 +/- 0.11 MPa.m(0.5)). This correlates with a perturbation in the stress field close to the pre-crack tip observed in the photoelasticity test sample when it was introduced by pressing the razor blade. Surprisingly, notch geometry only slightly affects the results. (C) 2012 Elsevier Ltd. All rights reserved.CAPESCNP

  • Effect of sample pre-cracking method and notch geometry in plane strain fracture toughness tests as applied to a PMMA resin
    ELSEVIER SCI LTD, 2012
    Co-Authors: Joelmir Mariano De Souza, Yoshimura, Humberto Naoyuki, Peres, Fabiano Moreno, Schoen, Claudio Geraldo
    Abstract:

    The influence of test method factors (notch shape, square or angular, and pre-cracking method, by tapping onto or pressing a razor blade) on the results obtained in plane strain fracture toughness test according to standard ASTM D5045 using SENB specimens made of a commercial PMMA resin were investigated. Results were analyzed quantitatively by comparing the obtained K-IC values and qualitatively by observing their effect on the Moire Fringes observed using photoelasticity, showing that, at 95% significance level, the K-IC values are affected by the pre-cracking method, with the most conservative value being obtained when natural pre-cracks were introduced by tapping onto a razor blade (K-IC = 1.15 +/- 0.11 MPa.m(0.5)). This correlates with a perturbation in the stress field close to the pre-crack tip observed in the photoelasticity test sample when it was introduced by pressing the razor blade. Surprisingly, notch geometry only slightly affects the results. (C) 2012 Elsevier Ltd. All rights reserved

Atsushi Momose - One of the best experts on this subject based on the ideXlab platform.

  • efficient phase imaging using wavelength resolved neutron talbot lau interferometry with tof method
    EPL, 2018
    Co-Authors: Yoshichika Seki, Atsushi Momose, Takenao Shinohara, Wataru Yashiro, Yoshie Otake, J D Parker, Wakana Ueno, Tetsuo Samoto, Yoshiaki Kiyanagi
    Abstract:

    For efficient differential-phase-contrast imaging, we have demonstrated the wavelength-resolved neutron Talbot-Lau interferometry with the wavelength resolution of 0.11 A over a wide wavelength range of 2.5–7.5 A at RADEN in the J-PARC Materials and Life Science Experimental Facility. The time-of-flight measurement has clearly showed that the visibility of Moire Fringes and intensity oscillations of the interferometer varied continuously with the wavelength, and the wavelength dependence of the differential phase of metal samples was measured. Based on the analysis utilizing this wavelength dependence, we achieved both high statistical precision and high accuracy in the differential-phase-contrast imaging, and succeeded in the quantitative evaluation of the optical potentials of metals.

  • trochoidal x ray vector radiography directional dark field without grating stepping
    Applied Physics Letters, 2018
    Co-Authors: Yash Sharma, Shivaji Bachche, Masashi Kageyama, Masaru Kuribayashi, Franz Pfeiffer, Tobias Lasser, Atsushi Momose
    Abstract:

    X-ray Vector Radiography (XVR) is an imaging technique that reveals the orientations of sub-pixel sized structures within a sample. Several dark-field radiographs are acquired by rotating the sample around the beam propagation direction and stepping one of the gratings to several positions for every pose of the sample in an X-ray grating interferometry setup. In this letter, we present a method of performing XVR of a continuously moving sample without the need of any grating motion. We reconstruct the orientations within a sample by analyzing the change in the background Moire Fringes caused by the sample moving and simultaneously rotating in plane (trochoidal trajectory) across the detector field-of-view. Avoiding the motion of gratings provides significant advantages in terms of stability and repeatability, while the continuous motion of the sample makes this kind of system adaptable for industrial applications such as the scanning of samples on a conveyor belt. Being the first step in the direction of ...

  • development of multi colored neutron talbot lau interferometer with absorption grating fabricated by imprinting method of metallic glass
    Journal of the Physical Society of Japan, 2017
    Co-Authors: Yoshichika Seki, Atsushi Momose, Takenao Shinohara, Joseph D Parker, Wataru Yashiro, Kosuke Kato, Hidemi Kato, Maryam Sadeghilaridjani, Yoshie Otake, Yoshiaki Kiyanagi
    Abstract:

    For the effective interferometric imaging at pulsed neutron sources, we have developed the Talbot–Lau interferometer which works at several wavelengths, and demonstrated its operation by observing the visibilities of Moire Fringes in different wavelength conditions. An absorption grating as an analyzer was fabricated by imprinting of metallic glass for the first time, and showed a well-controlled shape. Using such a grating, we have succeeded in interferometric imaging for the samples of metal rods at a wavelength of 5 A.

  • demonstration of x ray talbot interferometry
    Japanese Journal of Applied Physics, 2003
    Co-Authors: Atsushi Momose, Shinya Kawamoto, Ichiro Koyama, Y Hamaishi, Kengo Takai, Yoshio Suzuki
    Abstract:

    First Talbot interferometry in the hard X-ray region was demonstrated using a pair of transmission gratings made by forming gold stripes on glass plates. By aligning the gratings on the optical axis of X-rays with a separation that caused the Talbot effect by the first grating, Moire Fringes were produced inclining one grating slightly against the other around the optical axis. A phase object placed in front of the first grating was detected by Moire-fringe bending. Using the technique of phase-shifting interferometry, the differential phase corresponding to the phase object could also be measured. This result suggests that X-ray Talbot interferometry is a novel and simple method for phase-sensitive X-ray radiography.

Zonghoon Lee - One of the best experts on this subject based on the ideXlab platform.

  • evidence of local commensurate state with lattice match of graphene on hexagonal boron nitride
    ACS Nano, 2017
    Co-Authors: Na Yeon Kim, Hu Young Jeong, Jung Hwa Kim, Gwangwoo Kim, Hyeon Suk Shin, Zonghoon Lee
    Abstract:

    Transition to a commensurate state changes the local symmetry periodicity on two-dimensional van der Waals superstructures, evoking distinctive properties far beyond individual layers. We investigate the morphology of Moire superstructures of graphene on hexagonal boron nitride (hBN) with a low twist angle (≈0°) through Moire fringe analyses with dark field transmission electron microscopy. The Moire Fringes exhibit local variation, suggesting that the interaction between graphene and hBN depends on the stacking configuration and that local transition to the commensurate state occurs through the reduced crystalline mismatch (that is, by lattice stretching and twisting on the graphene lattices). This Moire superstructure analysis suggests an inventive method for studying the interaction between stacked van der Waals layers and for discerning the altered electronic and optical properties of graphene on hBN superstructures with a low twist angle, even at low magnification.

Jaekwan Kim - One of the best experts on this subject based on the ideXlab platform.

  • phase transformation of cu precipitates from bcc to fcc in fe 3si 2cu alloy
    Acta Materialia, 2013
    Co-Authors: Yoonuk Heo, Youngki Kim, Jaesung Kim, Jaekwan Kim
    Abstract:

    Abstract Phase transition of Cu precipitates during aging of an Fe–3Si–2Cu alloy was studied by transmission electron microscopy. The precipitation of 3–5-nm-sized body-centered cubic (bcc) Cu in ferrite matrix was confirmed by high-angle annular dark-field scanning transmission electron microscopy imaging. The bcc Cu precipitates transformed to 9R Cu as they grew. Many 9R Cu precipitates were twinned, but untwinned 9R Cu particles were also observed. The 9R Cu transformed to twinned face-centered cubic (fcc) Cu by the glide of ± a /3 [1 0 0] 9R Shockley-type partial dislocations. Formation of the 3R structure previously reported could not be confirmed in this study. Finally, twins in fcc Cu precipitates disappeared to form stable fcc Cu particles. The importance of electron beam-orientation-dependent Moire Fringes in the correct identification of Cu structure is discussed in detail.