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Z F Zhang - One of the best experts on this subject based on the ideXlab platform.

  • fatigue fracture mechanisms of cu lead free solders interfaces
    International Conference on Electronic Packaging Technology, 2010
    Co-Authors: Qingke Zhang, Q S Zhu, Z F Zhang
    Abstract:

    The fatigue fracture behaviors of a series of Cu/lead-free solder joints deformed under different directions of loadings were investigated in this study. Observation results showed that fatigue Cracks generally initiate around the IMC/solder interface when the loading axis is vertical to the interface. For all the solder joints, the interfacial deformations are resulting from strain localization induced by the stain mismatch. Fracture surface observations reveal that the Crack Propagation Path and fatigue resistance of the solder joints are affected by the yield strength and mechanical property of the solder. When the copper/solder interface is parallel to the loading axis, the interfacial IMC layer failed approximately perpendicular to the interface under the action of slip bands, and then the Cracks propagated to the IMC/solder interface, leading to the fracture along the interface.

  • fatigue fracture mechanisms of cu lead free solders interfaces
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010
    Co-Authors: Qingke Zhang, Q S Zhu, Hanfa Zou, Z F Zhang
    Abstract:

    In this study the authors present and discuss the results of the investigation on the fatigue fracture behaviors in a series of as-soldered and thermal-aged copper/lead-free solder joints deformed under both monotonic and cyclic loadings. The observation results showed that fatigue Cracks generally initiate around the IMC/solder interface when the loading axis is vertical to the interface. The intrinsic deformation behaviors are little different for different solder joints resulting from strain localization induced by the stain mismatch. Fracture surface observations revealed the Crack Propagation Path and fatigue resistance of the solder joints to be affected by the yield strength and mechanical property of the solder. When the copper/solder interface is parallel to the loading axis, the interfacial IMC layer failed approximately perpendicular to the interface when the cumulative strain exceeded the fracture strain, then the Cracks propagated to the IMC/solder interface, leading to the fracture along the interface. The failure mechanisms and factors influencing interfacial fatigue are discussed.

Hiroshi Noguchi - One of the best experts on this subject based on the ideXlab platform.

  • Microstructural mechanisms of fatigue Crack non-Propagation in TRIP-maraging steels
    International Journal of Fatigue, 2018
    Co-Authors: Zhao Zhang, Motomichi Koyama, Meimei Wang, Kaneaki Tsuzaki, Cemal Cem Tasan, Hiroshi Noguchi
    Abstract:

    Abstract In contrast to conventional martensitic steels, transformation-induced plasticity (TRIP)-maraging steels exhibit exceptional high ductility without sacrificing strength and excellent fatigue property owing to the retained austenite/maraging martensite laminated structure. In this study, TRIP-maraging steel (Fe-9Mn-3Ni-1.4Al-0.01C, wt.%) with fine grained austenite was used to investigate the mechanism of high cycle fatigue resistance. Our analyses revealed that soft austenite region acts as a preferential Crack Propagation Path, but the plastic deformation during Crack opening involves martensitic transformation, resisting subsequent Crack growth via transformation-induced local hardening or Crack closure. Moreover, Crack growth along the laminates and across the block boundary forms a zigzag Crack Path, which would act as roughness-induced Crack closure. The combined effect of these factors plays an important role in resisting fatigue Crack growth at high cycle fatigue.

  • Hydrogen-assisted failure in a bimodal twinning-induced plasticity steel: Delamination events and damage evolution
    International Journal of Hydrogen Energy, 2018
    Co-Authors: Abbas Mohammadi, Motomichi Koyama, Gregory Gerstein, Hans Jürgen Maier, Hiroshi Noguchi
    Abstract:

    Abstract The effect of the bimodal grain size distribution on the hydrogen susceptibility of a high-Mn fully austenitic twinning-induced plasticity (TWIP) steel was investigated by tensile testing under ongoing electrochemical hydrogen charging. Observation of the surface microstructure of the hydrogen-charged specimen yielded a correlation between the microstructure, Crack initiation sites, and Crack Propagation Path. The observed embrittlement arose from Crack initiation/Propagation along the grain and twin boundaries and delamination governed Crack growth. In the present bimodal TWIP steel, the fine grained regions mostly showed intergranular Cracking along the grain boundaries between the fine and coarse grains. By contrast, the coarse grained region exhibited transgranular Cracking along the twin boundaries. The delamination Cracking phenomena is rationalized by the evident nucleation, growth, and coalescence of microvoids in the tensile direction. The results reveal that the bimodal grain size distribution of TWIP steel plays a major role in hydrogen-assisted Cracking and the evolution of delamination-related damage.

Qingke Zhang - One of the best experts on this subject based on the ideXlab platform.

  • fatigue fracture mechanisms of cu lead free solders interfaces
    International Conference on Electronic Packaging Technology, 2010
    Co-Authors: Qingke Zhang, Q S Zhu, Z F Zhang
    Abstract:

    The fatigue fracture behaviors of a series of Cu/lead-free solder joints deformed under different directions of loadings were investigated in this study. Observation results showed that fatigue Cracks generally initiate around the IMC/solder interface when the loading axis is vertical to the interface. For all the solder joints, the interfacial deformations are resulting from strain localization induced by the stain mismatch. Fracture surface observations reveal that the Crack Propagation Path and fatigue resistance of the solder joints are affected by the yield strength and mechanical property of the solder. When the copper/solder interface is parallel to the loading axis, the interfacial IMC layer failed approximately perpendicular to the interface under the action of slip bands, and then the Cracks propagated to the IMC/solder interface, leading to the fracture along the interface.

  • fatigue fracture mechanisms of cu lead free solders interfaces
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010
    Co-Authors: Qingke Zhang, Q S Zhu, Hanfa Zou, Z F Zhang
    Abstract:

    In this study the authors present and discuss the results of the investigation on the fatigue fracture behaviors in a series of as-soldered and thermal-aged copper/lead-free solder joints deformed under both monotonic and cyclic loadings. The observation results showed that fatigue Cracks generally initiate around the IMC/solder interface when the loading axis is vertical to the interface. The intrinsic deformation behaviors are little different for different solder joints resulting from strain localization induced by the stain mismatch. Fracture surface observations revealed the Crack Propagation Path and fatigue resistance of the solder joints to be affected by the yield strength and mechanical property of the solder. When the copper/solder interface is parallel to the loading axis, the interfacial IMC layer failed approximately perpendicular to the interface when the cumulative strain exceeded the fracture strain, then the Cracks propagated to the IMC/solder interface, leading to the fracture along the interface. The failure mechanisms and factors influencing interfacial fatigue are discussed.

Kechun Shen - One of the best experts on this subject based on the ideXlab platform.

  • buckling and strain response of filament winding composite cylindrical shell subjected to hydrostatic pressure numerical solution and experiment
    Composite Structures, 2021
    Co-Authors: Kechun Shen, Guang Pan
    Abstract:

    Abstract In the present work, an analytical solution of the buckling problem of the filament winding composite cylindrical shell is presented. Based on this solution, a cylindrical shell model fabricated by filament winding process using T700-12 K carbon/epoxy is analyzed. Compared with the experimental data, the analytical solution is verified to accurately predict the critical buckling pressure with an error of only 3.47%. Besides, the buckling mode obtained by the numerical analysis is in good agreement with the experimental result. The relationship between strain response and the Crack Propagation Path are investigated. The results show: circumferential strain increases in the clockwise direction of the Crack Propagation Path, and decreased in the anticlockwise direction. Unlike the circumferential strain, the axial strain response exhibits contrary regularity. In terms of buckling deformation and collapse, the experimental result show that the shell does not lose the carrying capacity when the filament winding composite cylindrical shell buckles. Instead, it is observed that the collapse pressure is 13.04% higher than the critical buckling pressure when the cylindrical shell collapses and loses the ultimate load bearing capacity in this study.

  • exploring strain characteristics and bearing capacity of a carbon filament wound composite cylindrical shell under hydrostatic pressure
    Xibei Gongye Daxue Xuebao Journal of Northwestern Polytechnical University, 2020
    Co-Authors: Kechun Shen, Guang Pan, Yao Shi, Ranfeng Wei
    Abstract:

    In order to study the strain characteristics and bearing capacity of a filament-wound composite cylindrical shell and its different dome structures under hydrostatic pressure, experiments were carried out. Firstly, static tests were conducted to study the axial and circumferential strain of the composite cylindrical shell on its different positions. The bearing capacity of the ellipsoid dome was compared with that of the hemisphere dome. The blasting test and the nonlinear analysis of the strain were conducted. The relationship between the strain trend and the Crack Propagation Path was studied, and the structural failure mode was explored. The study shows that as the hydrostatic pressure increases, the strain increases and that the strain amplitudes of measuring points gradually appear different and show varying degrees of nonlinearity. Along the circumferential direction of the circumferential Crack, the axial strain amplitude gradually decreases by 20%. But the circumferential strain amplitude gradually increases by 94%. As the load of the composite cylindrical shell increases to a certain extent, its final failure mode is strength failure, but its instability is not obvious.

Naiqin Zhao - One of the best experts on this subject based on the ideXlab platform.

  • in situ al2o3 al interface contribution towards the strength ductility synergy of al cuo composite fabricated by solid state reactive sintering
    Scripta Materialia, 2021
    Co-Authors: Xudong Rong, Xiang Zhang, Dongdong Zhao, Chunsheng Shi, Enzuo Liu, Naiqin Zhao
    Abstract:

    Abstract Probing the interface is of great importance for tailoring the mechanical performance of Al matrix composites (AMCs) to achieve strength-ductility synergy. This work contributes an in-depth understanding of the in-situ Al2O3-Al interfaces integrating the ``Al2O3-intermixing region-Al'' interface structure and interfacial segregation/precipitation in Al-7 wt.% CuO (Al-7CuO) composite fabricated by solid-state reactive sintering. It was elucidated that the ``Al2O3-Al intermixing region'' would enhance the cohesion and plastic stability of the Al2O3-Al interface. Meanwhile, Cu segregation and CuAl2 precipitation turn to suppress dislocation nucleation/motion and increase the interfacial slippage resistance of the Al2O3-Al interface. Further characterization of the fracture morphology suggests that the robust in-situ Al2O3-Al interface exerts prominent contribution to the remarkable mechanical properties of Al-7CuO composite through effective load-transfer and changed Crack Propagation Path.

  • in situ al 2 o 3 al interface contribution towards the strength ductility synergy of al cuo composite fabricated by solid state reactive sintering
    2021
    Co-Authors: Xudong Rong, Xiang Zhang, Dongdong Zhao, Chunsheng Shi, Enzuo Liu, Naiqin Zhao
    Abstract:

    Probing the interface is of great importance for tailoring the mechanical performance of Al matrix composites (AMCs) to achieve strength-ductility synergy. This work contributes an in-depth understanding of the in-situ Al2O3-Al interfaces integrating the "Al2O3-intermixing region-Al" interface structure and interfacial segregation/precipitation in Al-7 wt.% CuO (Al-7CuO) composite fabricated by solid-state reactive sintering. It was elucidated that the "Al2O3-Al intermixing region" would enhance the cohesion and plastic stability of the Al2O3-Al interface. Meanwhile, Cu segregation and CuAl2 precipitation turn to suppress dislocation nucleation/movement and increase the interfacial slippage resistance of the Al2O3-Al interface. Further characterization of the fracture morphology suggests that the robust in-situ Al2O3-Al interface exerts prominent contribution to the remarkable mechanical properties of Al-7CuO composite through effective load-transfer and changed Crack Propagation Path.