The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform

E Smith - One of the best experts on this subject based on the ideXlab platform.

  • The Mode I Elastic Stress Distribution Near the Root of a Deep Notch With a Parabolic Root Profile
    Volume 6: Materials and Fabrication, 2007
    Co-Authors: E Smith
    Abstract:

    The basis of a fracture mechanics type methodology for fracture initiation at a Blunt Notch is the elastic stress distribution immediately ahead of a Notch root. Earlier work, presented at the 2006 ASME PVP Conference [7], for the Mode III deformation of a deep Notch with a parabolic root profile, has shown that the shear stress σ(x) at a distance x ahead of the root is uniquely defined by the peak stress σp, x and ρ (the Notch root radius of curvature), when x and ρ are both small compared with the Notch depth, irrespective of the loading characteristics and the Notch shape away from the root. This paper is concerned with the corresponding Mode I deformation situation, with the objective of providing support for the viability of a similar conclusion for Mode I deformation.

  • The Mode III elastic stress distribution near the root of (a) an intrusion-type Notch and (b) a key-hole Notch
    International Journal of Engineering Science, 2006
    Co-Authors: E Smith
    Abstract:

    Abstract An important element of a research programme aimed at developing a fracture mechanics methodology for Blunt Notches, is the representation of the elastic stress distribution in the immediate vicinity of a Notch root. Earlier work for a general two-dimensional Blunt Notch model has shown that, for Mode III deformation, the stress at a distance x  ≪  ρ (Notch root radius of curvature) ahead of the Notch root only depends on x , ρ and σ p (peak stress), irrespective of the Notch shape and the loading characteristics. This uniqueness has been confirmed in earlier work for an elliptically cylindrical Notch, a special case being a circular cylindrical Notch. This paper provides further underpinning for the uniqueness conclusion by analysis of the models of (a) an intrusion-type Notch and (b) a key-hole Notch.

  • the mode iii elastic stress distribution near the root of a deep sharp Notch with a parabolic root profile
    ASME 2006 Pressure Vessels and Piping ICPVT-11 Conference, 2006
    Co-Authors: E Smith
    Abstract:

    In developing a fracture initiation methodology for Blunt Notches, the basic starting point is the elastic stress distribution immediately ahead of a Notch root. Earlier work for Mode III deformation of a two-dimensional Blunt Notch has shown that the shear stress immediately ahead of the Notch root (i.e. at a distance small compared with the Notch root radius of curvature) is dependent on the peak stress and Notch root radius, but is independent of the Notch shape and the loading characteristics. However there are many situations, i.e. with sharp Notches, where we are interested in the stress at a distance that is not necessarily small compared with the Notch root radius. Thus this paper shows that with a Notch that has a parabolic root profile, when this distance and the Notch root radius are both small compared with the Notch depth, then the stress at this distance is again dependent on the peak stress and Notch root radius, but is independent of the Notch shape away from the root and the loading characteristics.Copyright © 2006 by ASME

  • The Mode III Elastic Stress Distribution in the Immediate Vicinity of an Inclusion
    Volume 6: Materials and Fabrication, 2005
    Co-Authors: E Smith
    Abstract:

    As part of a wide ranging research programme aimed at developing a fracture mechanics methodology for Blunt Notches, earlier work for a general two-dimensional Blunt Notch Mode III model has shown that the stress at a distance × ≪ ρ (Notch root radius of curvature) ahead of the Notch root only depends on x, ρ and the peak stress σp, irrespective of the Notch shape and the loading characteristics. This uniqueness has been confirmed for various Notch profiles and loading scenarios. In this paper we show that the uniqueness of the local stress distribution is peculiar to a Notch and does not apply to an inclusion.

  • The elastic stress distribution near a circular cylindrical Notch due to external dislocations
    International Journal of Engineering Science, 2004
    Co-Authors: E Smith
    Abstract:

    Abstract The author is involved in a wide ranging research programme aimed at extending sharp crack fracture mechanics to Notches so that credit can be taken for their non-sharpness. A key feature of this programme is the representation of the elastic stress distribution in the vicinity of a Blunt Notch and a recent paper has analysed the model of a circular cylindrical Notch in an infinite solid. It was shown, for a general loading, that with Mode III deformation, the local stress is uniquely defined by the radius of the Notch and the peak stress σp but is independent of the loading characteristics, whereas with Mode I deformation, the local stress does depend on the loading characteristics. In this paper, we quantify the effect of external dislocations, so as to provide support for the conclusions reached in the earlier paper.

Long-qing Chen - One of the best experts on this subject based on the ideXlab platform.

  • The phase field model for hydrogen diffusion and γ-hydride precipitation in zirconium under non-uniformly applied stress
    Mechanics of Materials, 2006
    Co-Authors: San-qiang Shi, C.h. Woo, Long-qing Chen
    Abstract:

    This special issue contains papers, which were selected from the presentations at the International Symposium on Macro-, Meso-, Micro- and Nano-Mechanics of Materials (MM2003), held on December 8–10, 2003 at the Hong Kong University of Science and Technology (HKUST), Hong Kong.Zirconium and its alloys are primary structure materials in nuclear industry. They often absorb hydrogen from environment and form hydrides. This will cause degradation of the materials. In this work, the hydrogen diffusion and hydride formation process near a Blunt Notch in a continuum media have been simulated by phase field models. The results agree with the experiments.Department of Mechanical Engineerin

  • The phase field model for hydrogen diffusion and γ-hydride precipitation in zirconium under non-uniformly applied stress
    Mechanics of Materials, 2005
    Co-Authors: San-qiang Shi, C.h. Woo, Long-qing Chen
    Abstract:

    Zirconium and its alloys are primary structure materials in nuclear industry. They often absorb hydrogen from environment and form hydrides. This will cause degradation of the materials. In this work, the hydrogen diffusion and hydride formation process near a Blunt Notch in a continuum media have been simulated by phase field models. The results agree with the experiments.

  • modeling of hydrogen diffusion process at a Blunt Notch in zirconium
    北京科技大学学报：英文版, 2005
    Co-Authors: X Q, San-qiang Shi, C.h. Woo, Long-qing Chen
    Abstract:

    The two-dimensional diffusion of interstitial hydrogen atoms in zirconium in a non-uniform stress field was simulated us- ing the phase-field method. The interaction between hydrogen interstitials and the stress field was described by Khachaturyan's elastic theory. The Cahn-Hilliard diffusion equation was then solved by an explicit finite difference method. The result shows that hydrogen atoms diffuse to the high-tensile hydrostatic region near the tip of the Notch. The content of hydrogen near the tip of the Notch increases by 13%, while the stress distribution caused by hydrogen interstitials around the Notch is modified by only 0.7%.

A. Amine Benzerga - One of the best experts on this subject based on the ideXlab platform.

  • Void growth and coalescence in a magnesium alloy studied by synchrotron radiation laminography
    Acta Materialia, 2018
    Co-Authors: Babak Kondori, Thilo Morgeneyer, Lukas Helfen, A. Amine Benzerga
    Abstract:

    Damage accumulation is studied in a rolled, partially annealed magnesium alloy by means of synchrotron tomography. To avoid failure by plastic instability and generate an effective damage process zone, round Notched bars are deformed up to crack initiation then sheet-like samples are cut out for subsequent tomography observations. The effect of the hydrostatic stress is explored by considering two Notch radii. In a given specimen, advantage is taken of the naturally occurring gradients in plastic strain and stress triaxiality to gain insight into the various stages of damage progression, damage-to-fracture transition, as well as crack propagation. The key finding is that damage is quite diffuse in both types of specimens. The observations document extensive void nucleation, growth and coalescence, reminiscent of the most ductile and tough metallic materials. Crack growth is found to be inherently anisotropic. Crack initiation is found to occur predominately at the center of the specimen with a Blunt Notch, and near the Notch root in the specimen with a sharp Notch. Quantitative measurements based on about 1000 microvoids and Blunted microcracks enable values of void volume fraction and microcrack Blunting to be fairly estimated, at macroscopic crack initiation.

Mirco Daniel Chapetti - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of the fatigue limit of Blunt-Notched components
    International Journal of Fatigue, 2001
    Co-Authors: Mirco Daniel Chapetti
    Abstract:

    Abstract A prediction of the fatigue limit of Blunt-Notched components of a low carbon steel was made on the basis that the fatigue limit of polycrystalline metals represents the critical conditions for the propagation of nucleated cracks. An expression for the material resistance to crack propagation as a function of the crack length is obtained for the first part of the short crack regime, which defines the Blunt Notch sensitivity to fatigue. The material resistance curve is modeled from a depth d, given by the position of the strongest microstructural barrier to microstructurally short crack propagation, which defines the plain fatigue limit. A microstructural threshold, ΔKd, is suggested as an intrinsic material resistance to microstructurally short crack propagation, defined by the plain fatigue limit Δσe0 and the position of the strongest microstructural barrier d. The modeled Notch sensitivity fits reasonably well the experimental results for a low carbon steel.

  • Static strengthening and fatigue Blunt-Notch sensitivity in low-carbon steels
    International Journal of Fatigue, 2001
    Co-Authors: Mirco Daniel Chapetti, N. Katsura, Tetsuya Tagawa, Takashi Miyata
    Abstract:

    Abstract The influence of four different static strengthenings on the fatigue Blunt-Notch sensitivity of a low-carbon steel with a ferrite–pearlite microstructure was analyzed and modeled. The analysis was made using a model previously derived which estimates the fatigue limit of Blunt Notched components by means of the parameter ktd defined as the stress concentration introduced by the Notch at a distance d from the Notch root surface equal to the distance between microstructural barriers. While the distance d between microstructural barriers is kept constant by keeping constant the grain size, the effective resistance of the microstructural barriers to crack propagation is increased by static strengthening. The analyses have shown the influence of the distribution and effective resistance of the first two or three microstructural barriers on fatigue Blunt-Notch sensitivity.

San-qiang Shi - One of the best experts on this subject based on the ideXlab platform.

  • The phase field model for hydrogen diffusion and γ-hydride precipitation in zirconium under non-uniformly applied stress
    Mechanics of Materials, 2006
    Co-Authors: San-qiang Shi, C.h. Woo, Long-qing Chen
    Abstract:

    This special issue contains papers, which were selected from the presentations at the International Symposium on Macro-, Meso-, Micro- and Nano-Mechanics of Materials (MM2003), held on December 8–10, 2003 at the Hong Kong University of Science and Technology (HKUST), Hong Kong.Zirconium and its alloys are primary structure materials in nuclear industry. They often absorb hydrogen from environment and form hydrides. This will cause degradation of the materials. In this work, the hydrogen diffusion and hydride formation process near a Blunt Notch in a continuum media have been simulated by phase field models. The results agree with the experiments.Department of Mechanical Engineerin

  • The phase field model for hydrogen diffusion and γ-hydride precipitation in zirconium under non-uniformly applied stress
    Mechanics of Materials, 2005
    Co-Authors: San-qiang Shi, C.h. Woo, Long-qing Chen
    Abstract:

    Zirconium and its alloys are primary structure materials in nuclear industry. They often absorb hydrogen from environment and form hydrides. This will cause degradation of the materials. In this work, the hydrogen diffusion and hydride formation process near a Blunt Notch in a continuum media have been simulated by phase field models. The results agree with the experiments.

  • modeling of hydrogen diffusion process at a Blunt Notch in zirconium
    北京科技大学学报：英文版, 2005
    Co-Authors: X Q, San-qiang Shi, C.h. Woo, Long-qing Chen
    Abstract:

    The two-dimensional diffusion of interstitial hydrogen atoms in zirconium in a non-uniform stress field was simulated us- ing the phase-field method. The interaction between hydrogen interstitials and the stress field was described by Khachaturyan's elastic theory. The Cahn-Hilliard diffusion equation was then solved by an explicit finite difference method. The result shows that hydrogen atoms diffuse to the high-tensile hydrostatic region near the tip of the Notch. The content of hydrogen near the tip of the Notch increases by 13%, while the stress distribution caused by hydrogen interstitials around the Notch is modified by only 0.7%.