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Nobuhisa Suzuki - One of the best experts on this subject based on the ideXlab platform.

  • Crack geometry effect on Stress strain fields for Crack under biaxial loading
    Journal of Pressure Vessel Technology-transactions of The Asme, 2010
    Co-Authors: Fumiyoshi Minami, Daisuke Watanabe, Takahiro Kubo, Mitsuru Ohata, Nobuhisa Suzuki
    Abstract:

    With increasing demand of high-strength and high-pressure pipelines in gas transmission industries, the fracture control design of pipelines has been a driving factor to ensure the integrity of the pipeline. This paper addresses the Stress and strain fields for a Crack in a wide plate component under biaxial loading, which simulates a large-diameter pipe subjected to inner pressure coupled with axial loading. Attention is focused on the initiation of brittle fracture (Stress controlled type) as well as ductile fracture (strain controlled type). Three-dimensional finite element-analyses are conducted. It was found that biaxial loading has a significant effect on the Stress fields of through-thickness Crack; the near-Crack-Tip Stress is elevated to a large extent by biaxial loading. By contrast, the Stress field for a surface Crack is not sensitive to biaxial loading, while the near-Crack-Tip Stress at the Crack corner is increased locally by biaxial loading. The Weibull Stress criterion was applied to discuss the biaxial loading effect on the brittle fracture strength of the wide plate. Ductile Crack initiation properties are also discussed with two-parameter (plastic strain and Stress triaxiality) diagram. The ductile damage is increased by biaxial loading for a through-thickness Crack, whereas a surface Crack has little effect of biaxial loading on the ductile damage.

  • Crack geometry effect on Stress strain fields for Crack under biaxial loading
    2008 7th International Pipeline Conference Volume 3, 2008
    Co-Authors: Fumiyoshi Minami, Daisuke Watanabe, Takahiro Kubo, Mitsuru Ohata, Nobuhisa Suzuki
    Abstract:

    With increasing demand of high strength and high pressure pipelines in gas transmission industries, the fracture control design of pipelines has been driven primarily. This paper addresses the Stress and strain fields for a Crack in a wide plate component under biaxial loading, which simulates a large diameter pipe subjected to inner pressure coupled with axial loading. Three-dimensional FE-analyses are conducted. It was found that biaxial loading has a significant effect on the Stress fields of through-thickness Crack; the near Crack-Tip Stress is elevated to a large extent by biaxial loading. By contrast, the Stress field for a surface Crack is not sensitive to biaxial loading, while the near Crack-Tip Stress at the Crack corner is increased locally by biaxial loading. The Weibull Stress criterion was applied to discuss the biaxial loading effect on the brittle fracture strength of the wide plate. Ductile Crack initiation properties are also discussed with two-parameter (plastic strain and Stress triaxiality) diagram. The ductile damage is increased by biaxial loading for a through-thickness Crack, whereas a surface Crack has little effect of biaxial loading on the ductile damage.Copyright © 2008 by ASME

  • Crack geometry effect on Stress strain fields for Crack under biaxial loading
    2008 7th International Pipeline Conference Volume 3, 2008
    Co-Authors: Fumiyoshi Minami, Daisuke Watanabe, Takahiro Kubo, Mitsuru Ohata, Nobuhisa Suzuki
    Abstract:

    With increasing demand of high strength and high pressure pipelines in gas transmission industries, the fracture control design of pipelines has been driven primarily. This paper addresses the Stress and strain fields for a Crack in a wide plate component under biaxial loading, which simulates a large diameter pipe subjected to inner pressure coupled with axial loading. Three-dimensional FE-analyses are conducted. It was found that biaxial loading has a significant effect on the Stress fields of through-thickness Crack; the near Crack-Tip Stress is elevated to a large extent by biaxial loading. By contrast, the Stress field for a surface Crack is not sensitive to biaxial loading, while the near Crack-Tip Stress at the Crack corner is increased locally by biaxial loading. The Weibull Stress criterion was applied to discuss the biaxial loading effect on the brittle fracture strength of the wide plate. Ductile Crack initiation properties are also discussed with two-parameter (plastic strain and Stress triaxiality) diagram. The ductile damage is increased by biaxial loading for a through-thickness Crack, whereas a surface Crack has little effect of biaxial loading on the ductile damage.Copyright © 2008 by ASME

Paul C Paris - One of the best experts on this subject based on the ideXlab platform.

  • A brief history of the Crack Tip Stress intensity factor and its application
    Meccanica, 2014
    Co-Authors: Paul C Paris
    Abstract:

    The primary objective of this work is to discuss the origins, background and development of the elastic Crack Tip Stress intensity factor, K , as they occurred. The further development of the three modes and the compilations of related formulas in the literature are discussed. The origins of applications to static Crack growth stability, and sub-critical growth due to fatigue and environmental effects are included. Significant events such as the formation of the ASTM committee on Fracture Mechanics, the adoption of Damage Tolerance Analysis by the aircraft industry using Fracture Mechanics as a basis, and the further extension of the methods to large-scale plasticity conditions are presented. Finally a discussion of early predictions of Crack paths is discussed.

  • secondary elastic Crack Tip Stresses which may influence very slow fatigue Crack growth
    Fatigue & Fracture of Engineering Materials & Structures, 2002
    Co-Authors: Paul C Paris
    Abstract:

    Secondary elastic Crack Tip Stress intensity factors are defined in a convenient way consistent with the primary Stress intensity factor definition. Methods of evaluation of these secondary Stress intensity factors are developed. They are evaluated for example configurations with Cracks. It is shown that the first secondary term may be sufficient to evaluate the effects of secondary Stresses beyond the usual Stress intensity factor and nominal normal Stresses parallel to the Crack direction.

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

  • characterisation of overloads in fatigue by 2d strain mapping at the surface and in the bulk
    Fatigue & Fracture of Engineering Materials & Structures, 2016
    Co-Authors: P Lopezcrespo, Mahmoud Mostafavi, Axel Steuwer, Joe Kelleher, T Buslaps, P J Withers
    Abstract:

    Two complementary experimental techniques have been used to study the evolution of Crack-Tip strain fields in a thin (plane Stress dominated) compact tension sample following a single overload (OL) event. The total strain has been characterised at the surface by digital image correlation (DIC), while the elastic strain field in the bulk (interior) behaviour has been characterised by means of synchrotron X-ray diffraction (XRD). Surface and bulk information allowed us to visualise the evolution of the strain fields before the OL event, during the OL event, just after it and at various stages after it. Unlike previous work, complete 2D maps of elastic strains around the Crack-Tip were acquired at 60 µm spatial resolution by XRD. The strain data were used to estimate the effective Crack driving force at the surface and at the mid plane. The DIC shows less Crack opening displacement after overload and the XRD a lower Crack-Tip peak Stress after OL until the Crack has grown past the compressive Crack-Tip residual Stress after which the behaviour returned to that for the baseline fatigue response. While the compressive residual Stress introduced by the OL offsets the Crack-Tip Stress field as it grows through the overload plastic zone, the changes in Crack-Tip Stress over each cycle are the same before and at all stages after OL.

  • 2d mapping of plane Stress Crack Tip fields following an overload
    Fracture and Structural Integrity, 2015
    Co-Authors: P J Withers, P Lopezcrespo, Mahmoud Mostafavi, Axel Steuwer, Joe Kelleher, T Buslaps
    Abstract:

    The evolution of Crack-Tip strain fields in a thin (plane Stress) compact tension sample following an overload (OL) event has been studied using two different experimental techniques. Surface behaviour has been characterised by Digital Image Correlation (DIC), while the bulk behaviour has been characterised by means of synchrotron X-ray diffraction (XRD). The combination of both surface and bulk information allowed us to visualise the through-thickness evolution of the strain fields before the OL event, during the overload event, just after OL and at various stages after it. Unlike previous work, complete 2D maps of strains around the Crack-Tip were acquired at 60m spatial resolution by XRD. The DIC shows less Crack opening after overload and the XRD a lower Crack-Tip peak Stress after OL until the Crack has grown past the compressive Crack-Tip residual Stress introduced by the overload after which the behaviour returned to that for the baseline fatigue response. While the peak Crack-Tip Stress is supressed by the compressive residual Stress, the Crack-Tip Stress field changes over each cycle are nevertheless the same for all Kmax cycles except at OL.

  • evolution of Crack bridging and Crack Tip driving force during the growth of a fatigue Crack in a ti sic composite
    Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2012
    Co-Authors: P J Withers, P Lopezcrespo, Albrecht Kyrieleis, Yuchen Hung
    Abstract:

    High spatial resolution diffraction and imaging using synchrotron X-rays are combined to monitor the incremental growth of a fatigue Crack through the matrix of a Ti-6Al4V/SCS-6 SiC monofilament metal matrix composite. X-ray tomography is used to quantify the Crack opening displacement (COD) and diffraction to measure the Crack-Tip Stress field in each phase, the wear degraded interfacial strengths, as well as the Crack face tractions applied by the bridging fibres, at maximum (Kmax) and minimum (Kmin) loading as a function of Crack length. In this way, it has been possible to quantify the Crack-Tip driving force (the Stress intensity range effective at the Crack-Tip) in three ways: from the COD, the bridging Stresses and the Crack-Tip Stress field. The fibre Stresses act to prop open the Crack at Kmin and shield the Crack at Kmax such that the change in COD is small over the fatigue cycle. Consequently, the effective Stress intensity range at the Crack Tip remains around 10 MPa √ m as the Crack lengthens, as more and more fibres bridge the Crack despite the normally applied Stress intensity rising to 60 MPa √ m. The implications of the derived fracture mechanics parameters are assessed and the wider potential of X-ray diffraction and imaging for Crack-Tip microscopy is discussed.

  • real time acquisition of fatigue Crack images for monitoring Crack Tip Stress intensity variations within fatigue cycles
    Journal of Strain Analysis for Engineering Design, 2009
    Co-Authors: F. Yusof, P J Withers
    Abstract:

    Digital images Of fatigue Crack behaviour have been acquired in real time at high cycle fatigue rates (77Hz) using a high-speed camera at 1000 frames/s. Digital image correlation has then been used to determine the Crack-Tip position and Stress intensity variations (K-I and K-II) within selected cycles. This has been achieved for a pre-Cracked aluminium compact tension (CT) specimen subjected to constant load amplitude fatigue Crack cycling. The Crack-Tip displacement field has been determined at 14 points within each cycle. In this proof of concept study, despite noise in the inferred displacement fields, by least squares fitting the displacement field rather than the strain field to the Muskhelishvili's form Crack-Tip Stress field, the Crack-Tip Stress intensity inferred from the measured Crack-Tip displacement field was found to good accuracy (around 0.2 MPa m(1/2)). Furthermore, the observed sinusoidal variation was in excellent agreement with the nominal Delta K obtained from the applied fatigue amplitude confirming the accuracy of the method; a drift of around 0.42 MPa m(1/2) was observed in K-mean from cycle to cycle. No evidence Of Closure was observed at low K. In principle this method permits the identification of Crack-Tip Closure and Crack growth, as well as the application of constant Delta K-eff cycling, through intermittent monitoring throughout the duration of a fatigue test. The current method is well suited to more complex cases where Crack closure, residual Stresses, or more complex geometries mean that it is difficult to predict Delta K-eff a priori and a number of potential applications of the method are identified.

Fumiyoshi Minami - One of the best experts on this subject based on the ideXlab platform.

  • Crack geometry effect on Stress strain fields for Crack under biaxial loading
    Journal of Pressure Vessel Technology-transactions of The Asme, 2010
    Co-Authors: Fumiyoshi Minami, Daisuke Watanabe, Takahiro Kubo, Mitsuru Ohata, Nobuhisa Suzuki
    Abstract:

    With increasing demand of high-strength and high-pressure pipelines in gas transmission industries, the fracture control design of pipelines has been a driving factor to ensure the integrity of the pipeline. This paper addresses the Stress and strain fields for a Crack in a wide plate component under biaxial loading, which simulates a large-diameter pipe subjected to inner pressure coupled with axial loading. Attention is focused on the initiation of brittle fracture (Stress controlled type) as well as ductile fracture (strain controlled type). Three-dimensional finite element-analyses are conducted. It was found that biaxial loading has a significant effect on the Stress fields of through-thickness Crack; the near-Crack-Tip Stress is elevated to a large extent by biaxial loading. By contrast, the Stress field for a surface Crack is not sensitive to biaxial loading, while the near-Crack-Tip Stress at the Crack corner is increased locally by biaxial loading. The Weibull Stress criterion was applied to discuss the biaxial loading effect on the brittle fracture strength of the wide plate. Ductile Crack initiation properties are also discussed with two-parameter (plastic strain and Stress triaxiality) diagram. The ductile damage is increased by biaxial loading for a through-thickness Crack, whereas a surface Crack has little effect of biaxial loading on the ductile damage.

  • Crack geometry effect on Stress strain fields for Crack under biaxial loading
    2008 7th International Pipeline Conference Volume 3, 2008
    Co-Authors: Fumiyoshi Minami, Daisuke Watanabe, Takahiro Kubo, Mitsuru Ohata, Nobuhisa Suzuki
    Abstract:

    With increasing demand of high strength and high pressure pipelines in gas transmission industries, the fracture control design of pipelines has been driven primarily. This paper addresses the Stress and strain fields for a Crack in a wide plate component under biaxial loading, which simulates a large diameter pipe subjected to inner pressure coupled with axial loading. Three-dimensional FE-analyses are conducted. It was found that biaxial loading has a significant effect on the Stress fields of through-thickness Crack; the near Crack-Tip Stress is elevated to a large extent by biaxial loading. By contrast, the Stress field for a surface Crack is not sensitive to biaxial loading, while the near Crack-Tip Stress at the Crack corner is increased locally by biaxial loading. The Weibull Stress criterion was applied to discuss the biaxial loading effect on the brittle fracture strength of the wide plate. Ductile Crack initiation properties are also discussed with two-parameter (plastic strain and Stress triaxiality) diagram. The ductile damage is increased by biaxial loading for a through-thickness Crack, whereas a surface Crack has little effect of biaxial loading on the ductile damage.Copyright © 2008 by ASME

  • Crack geometry effect on Stress strain fields for Crack under biaxial loading
    2008 7th International Pipeline Conference Volume 3, 2008
    Co-Authors: Fumiyoshi Minami, Daisuke Watanabe, Takahiro Kubo, Mitsuru Ohata, Nobuhisa Suzuki
    Abstract:

    With increasing demand of high strength and high pressure pipelines in gas transmission industries, the fracture control design of pipelines has been driven primarily. This paper addresses the Stress and strain fields for a Crack in a wide plate component under biaxial loading, which simulates a large diameter pipe subjected to inner pressure coupled with axial loading. Three-dimensional FE-analyses are conducted. It was found that biaxial loading has a significant effect on the Stress fields of through-thickness Crack; the near Crack-Tip Stress is elevated to a large extent by biaxial loading. By contrast, the Stress field for a surface Crack is not sensitive to biaxial loading, while the near Crack-Tip Stress at the Crack corner is increased locally by biaxial loading. The Weibull Stress criterion was applied to discuss the biaxial loading effect on the brittle fracture strength of the wide plate. Ductile Crack initiation properties are also discussed with two-parameter (plastic strain and Stress triaxiality) diagram. The ductile damage is increased by biaxial loading for a through-thickness Crack, whereas a surface Crack has little effect of biaxial loading on the ductile damage.Copyright © 2008 by ASME

Yuchen Hung - One of the best experts on this subject based on the ideXlab platform.

  • evolution of Crack bridging and Crack Tip driving force during the growth of a fatigue Crack in a ti sic composite
    Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2012
    Co-Authors: P J Withers, P Lopezcrespo, Albrecht Kyrieleis, Yuchen Hung
    Abstract:

    High spatial resolution diffraction and imaging using synchrotron X-rays are combined to monitor the incremental growth of a fatigue Crack through the matrix of a Ti-6Al4V/SCS-6 SiC monofilament metal matrix composite. X-ray tomography is used to quantify the Crack opening displacement (COD) and diffraction to measure the Crack-Tip Stress field in each phase, the wear degraded interfacial strengths, as well as the Crack face tractions applied by the bridging fibres, at maximum (Kmax) and minimum (Kmin) loading as a function of Crack length. In this way, it has been possible to quantify the Crack-Tip driving force (the Stress intensity range effective at the Crack-Tip) in three ways: from the COD, the bridging Stresses and the Crack-Tip Stress field. The fibre Stresses act to prop open the Crack at Kmin and shield the Crack at Kmax such that the change in COD is small over the fatigue cycle. Consequently, the effective Stress intensity range at the Crack Tip remains around 10 MPa √ m as the Crack lengthens, as more and more fibres bridge the Crack despite the normally applied Stress intensity rising to 60 MPa √ m. The implications of the derived fracture mechanics parameters are assessed and the wider potential of X-ray diffraction and imaging for Crack-Tip microscopy is discussed.