The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform

Masahiro Goto - One of the best experts on this subject based on the ideXlab platform.

  • Stress-dependent opening- and shear-mode propagation behavior of fatigue Cracks in ultrafine-grained Cu fabricated by equal channel angular pressing
    International Journal of Fatigue, 2021
    Co-Authors: Masahiro Goto, S. Z. Han, T. Yakushiji, S.s. Kim, Takaei Yamamoto, J. Kitamura, J.h. Ahn, R. Takanami, T. Utsunomiya, J. Lee
    Abstract:

    Abstract Constant and two-step stress amplitude tests were conducted to study the surface Crack Growth mechanism of ultrafine-grained copper processed by equal channel angular pressing (ECAP) in high- and low-cycle fatigue regimes. The Crack Growth Direction varied depending on the location on the circumference of the round bar specimen and applied stress amplitude. On the surface where an intersection between the shear plane of final pressing and the specimen’s surface made an angle of 45° with respect to the loading axis, the Crack grew with a 45° inclination to the loading axis at stress amplitudes ≥ 180 MPa. At stress amplitudes

  • Fatigue damage formation and microstructure of ultrafine grained copper under two-step loading
    Computational Methods and Experimental Measurements XVI, 2013
    Co-Authors: Masahiro Goto, S. Z. Han, K. Euh, T. Yakushiji, Norihiro Teshima, Norio Kawagoishi
    Abstract:

    In order to study the effect of stress change on the surface damage formation of ultrafine grained copper, two step fatigue stress tests were conducted. The microstructural evolution and Crack Growth Direction of ultrafine-grained copper fatigued under constant stressing depends on the magnitude of the applied stress amplitude. The Growth Direction occurred perpendicular to the loading axis at low stresses, and changed to 45o to the loading axis at high stresses. In the case of high-to-low block stressing, the 45o inclined Growth Direction under high stress changed to the perpendicular Direction under subsequent low stress. In low-to-high block stressing, although the Growth Direction perpendicular to the loading axis at low stresses was still retained at subsequent high stress, the degree of zigzag behavior in the Crack Growth drastically increased after the stress change. The sizes and topographies of evolved microstructures, which have a great effect on the Crack path formation, depended on stress histories (order, cycle number and magnitude of the applied stress). The formation behavior of the fatigue damage under high- and low-stress amplitudes and the effect of pre-stressing on Crack Growth Direction are discussed from the viewpoints of the microstructural evolution under different stress histories.

  • 036 Effect of Pre-stressing on the Growth Direction of Surface Cracks in Ultrafine Grained Copper
    2013
    Co-Authors: K. Kamil, Masahiro Goto, S. Z. Han, K. Euh, T. Yakushiji, Y. Tatsukawa
    Abstract:

    Crack Growth Direction of ultrafine grained copper under constant stressing depended on the magnitude of the applied stress amplitude, perpendicular to the loading axis at low stresses, and inclined at 45° to the loading axis at high stresses. To clarify the different Growth mechanisms between the highand low-stress amplitudes, two-step fatigue stress tests were conducted. In the case of high-to-low block stressing, the 45° inclined Growth Direction under high stress changed to the perpendicular Direction under subsequent low stress. In macroscale low-to-high block stressing, the Crack Growth Direction before and after the stress change was nearly perpendicular to the loading axis. On a microscale, however, the degree of zigzag manner in the Crack Growth drastically increased after the stress change. The formation mechanism of the Crack paths under highand low-stress amplitudes and the effect of pre-stressing on subsequent Crack Growth Direction were discussed from the viewpoints of the evolution of damaged areas around the Crack tip.

  • Fatigue-induced grain coarsening and Crack Growth behavior in ultrafine-grained copper under different loading histories
    International Journal of Fatigue, 2013
    Co-Authors: Masahiro Goto, K. Kamil, S. Z. Han, K. Euh, S.s. Kim, J. Lee
    Abstract:

    Abstract The Crack Growth Direction in ultrafine-grained copper under constant stressing depends on the applied stress amplitude. The Growth Direction is perpendicular to the loading axis at low stresses and inclines at 45° to the loading axis at high stresses. To clarify physical causes of such different behaviors at high and low stress amplitudes, two-step fatigue stress tests are conducted. The formation mechanisms of Crack paths at high and low stress amplitudes and effect of pre-stressing on subsequent Crack Growth Direction are discussed considering the morphological features of surface-damage formed under different cyclic-stress histories.

  • Formation behavior of different topographies of Crack Growth path under high and low cyclic stresses in ultrafine-grained copper
    Scripta Materialia, 2012
    Co-Authors: Masahiro Goto, K. Kamil, S. Z. Han, K. Euh, Yuji Yokoho, S.s. Kim
    Abstract:

    Fatigue tests of ultrafine-grained copper specimens were conducted. The Crack Growth Direction under constant stress depended on the magnitude of the stress amplitude. It occurred perpendicular to the loading axis at low stresses and was inclined at 45° to the loading axis at high stress. To clarify the different Growth mechanisms between the high- and low-stress amplitudes, two-step fatigue stress tests were conducted. The Crack path formation under high- and low-stress amplitude is discussed from the viewpoint of the evolution of damaged areas around the Crack.

Alojz Ivankovic - One of the best experts on this subject based on the ideXlab platform.

  • Interlaminar fracture toughness of CFRPs interleaved with stainless steel fibres
    Composite Structures, 2019
    Co-Authors: Dong Quan, Clemence Rouge, Stephen Flynn, Marta Artuso, Neal Murphy, Alojz Ivankovic
    Abstract:

    Abstract Ductile stainless steel fibres were used as interlayers to enhance the interlaminar fracture toughness of carbon fibre reinforced plastics (CFRPs). The stainless steel fibres were placed at the mid-plane of CFRPs either longitudinally or transversely to the Crack Growth Direction. Mechanical properties and fracture toughness of the CFRPs were studied using uniaxial tensile test and double cantilever beam test, respectively. The Young’s modulus and tensile strength of CFRPs remained essentially the same due to the incorporation of steel fibres longitudinally to the loading Direction, and decreased slightly for adding steel fibres transversely to the loading Direction. Significant improvements in the fracture energy of CFRPs were achieved for adding stainless steel fibres, i.e. the mean fracture propagation energy increased from 482 J/m2 for the control to 2295 J/m2 for CFRPs with transverse steel fibres at a density of 320 filaments/mm. The main toughening mechanisms of the steel fibres were investigated to be extensive steel fibre bridging and tensile failure. A more pronounced toughness increment was observed for adding steel fibres transversely to the Crack Growth Direction due to the additional mechanisms of carbon fibre delamination and breakage.

  • The enhancement of adhesively-bonded aerospace-grade composite joints using steel fibres
    Composite Structures, 2018
    Co-Authors: Dong Quan, Josu Labarga Urdániz, Clemence Rouge, Alojz Ivankovic
    Abstract:

    Abstract Ductile steel fibres with high stiffness of 193 GPa, high strain-to-failure of 20% and diameter of 22  μ m were used to enhance fracture toughness of composite adhesive joints. Two nano-toughened structural adhesives with significantly different mechanical and fracture properties were used to bond aerospace-grade composite substrates. Steel fibres were placed in the adhesive layer either longitudinally or transversely to the Crack Growth Direction. Mode-I and mode-II fracture behaviour of the composite adhesive joints were studied using double cantilever beam test and end-loaded split test, respectively. The incorporation of steel fibres significantly increased both mode-I and mode-II fracture toughness, irrespective of the adhesive used. The improvement of mode-I and mode-II fracture energies was more pronounced when the steel fibres were placed transversely to the Crack Growth Direction, due to the increased level of steel fibre bridging.

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

S. Z. Han - One of the best experts on this subject based on the ideXlab platform.

  • Stress-dependent opening- and shear-mode propagation behavior of fatigue Cracks in ultrafine-grained Cu fabricated by equal channel angular pressing
    International Journal of Fatigue, 2021
    Co-Authors: Masahiro Goto, S. Z. Han, T. Yakushiji, S.s. Kim, Takaei Yamamoto, J. Kitamura, J.h. Ahn, R. Takanami, T. Utsunomiya, J. Lee
    Abstract:

    Abstract Constant and two-step stress amplitude tests were conducted to study the surface Crack Growth mechanism of ultrafine-grained copper processed by equal channel angular pressing (ECAP) in high- and low-cycle fatigue regimes. The Crack Growth Direction varied depending on the location on the circumference of the round bar specimen and applied stress amplitude. On the surface where an intersection between the shear plane of final pressing and the specimen’s surface made an angle of 45° with respect to the loading axis, the Crack grew with a 45° inclination to the loading axis at stress amplitudes ≥ 180 MPa. At stress amplitudes

  • Fatigue damage formation and microstructure of ultrafine grained copper under two-step loading
    Computational Methods and Experimental Measurements XVI, 2013
    Co-Authors: Masahiro Goto, S. Z. Han, K. Euh, T. Yakushiji, Norihiro Teshima, Norio Kawagoishi
    Abstract:

    In order to study the effect of stress change on the surface damage formation of ultrafine grained copper, two step fatigue stress tests were conducted. The microstructural evolution and Crack Growth Direction of ultrafine-grained copper fatigued under constant stressing depends on the magnitude of the applied stress amplitude. The Growth Direction occurred perpendicular to the loading axis at low stresses, and changed to 45o to the loading axis at high stresses. In the case of high-to-low block stressing, the 45o inclined Growth Direction under high stress changed to the perpendicular Direction under subsequent low stress. In low-to-high block stressing, although the Growth Direction perpendicular to the loading axis at low stresses was still retained at subsequent high stress, the degree of zigzag behavior in the Crack Growth drastically increased after the stress change. The sizes and topographies of evolved microstructures, which have a great effect on the Crack path formation, depended on stress histories (order, cycle number and magnitude of the applied stress). The formation behavior of the fatigue damage under high- and low-stress amplitudes and the effect of pre-stressing on Crack Growth Direction are discussed from the viewpoints of the microstructural evolution under different stress histories.

  • 036 Effect of Pre-stressing on the Growth Direction of Surface Cracks in Ultrafine Grained Copper
    2013
    Co-Authors: K. Kamil, Masahiro Goto, S. Z. Han, K. Euh, T. Yakushiji, Y. Tatsukawa
    Abstract:

    Crack Growth Direction of ultrafine grained copper under constant stressing depended on the magnitude of the applied stress amplitude, perpendicular to the loading axis at low stresses, and inclined at 45° to the loading axis at high stresses. To clarify the different Growth mechanisms between the highand low-stress amplitudes, two-step fatigue stress tests were conducted. In the case of high-to-low block stressing, the 45° inclined Growth Direction under high stress changed to the perpendicular Direction under subsequent low stress. In macroscale low-to-high block stressing, the Crack Growth Direction before and after the stress change was nearly perpendicular to the loading axis. On a microscale, however, the degree of zigzag manner in the Crack Growth drastically increased after the stress change. The formation mechanism of the Crack paths under highand low-stress amplitudes and the effect of pre-stressing on subsequent Crack Growth Direction were discussed from the viewpoints of the evolution of damaged areas around the Crack tip.

  • Fatigue-induced grain coarsening and Crack Growth behavior in ultrafine-grained copper under different loading histories
    International Journal of Fatigue, 2013
    Co-Authors: Masahiro Goto, K. Kamil, S. Z. Han, K. Euh, S.s. Kim, J. Lee
    Abstract:

    Abstract The Crack Growth Direction in ultrafine-grained copper under constant stressing depends on the applied stress amplitude. The Growth Direction is perpendicular to the loading axis at low stresses and inclines at 45° to the loading axis at high stresses. To clarify physical causes of such different behaviors at high and low stress amplitudes, two-step fatigue stress tests are conducted. The formation mechanisms of Crack paths at high and low stress amplitudes and effect of pre-stressing on subsequent Crack Growth Direction are discussed considering the morphological features of surface-damage formed under different cyclic-stress histories.

  • Formation behavior of different topographies of Crack Growth path under high and low cyclic stresses in ultrafine-grained copper
    Scripta Materialia, 2012
    Co-Authors: Masahiro Goto, K. Kamil, S. Z. Han, K. Euh, Yuji Yokoho, S.s. Kim
    Abstract:

    Fatigue tests of ultrafine-grained copper specimens were conducted. The Crack Growth Direction under constant stress depended on the magnitude of the stress amplitude. It occurred perpendicular to the loading axis at low stresses and was inclined at 45° to the loading axis at high stress. To clarify the different Growth mechanisms between the high- and low-stress amplitudes, two-step fatigue stress tests were conducted. The Crack path formation under high- and low-stress amplitude is discussed from the viewpoint of the evolution of damaged areas around the Crack.

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