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Chang-rong Chen - One of the best experts on this subject based on the ideXlab platform.

  • Comparison of cohesive zone model and Linear Elastic Fracture mechanics for a mode I crack near a compliant/stiff interface
    Engineering Fracture Mechanics, 2010
    Co-Authors: Chang-rong Chen, Yiu-wing Mai
    Abstract:

    Cohesive zone model has been widely applied to simulate crack growth along interfaces, but its application to crack growth perpendicularly across the interface is rare. In this paper, the cohesive zone model is applied to a crack perpendicularly approaching a compliant/stiff interface in a layered material model. One aim is to understand the differences between the cohesive zone model and Linear Elastic Fracture mechanics in simulating mode I crack growth near a compliant/stiff interface. Another aim is to understand the effects of Elastic modulus mismatch and cohesive strength of the stiff layer on the crack behavior near the interface. To simulate crack growth approaching an interface, the cohesive zone model which incorporates both the energy criterion and the strength criterion is an effective method.

  • comparison of cohesive zone model and Linear Elastic Fracture mechanics for a mode i crack near a compliant stiff interface
    Engineering Fracture Mechanics, 2010
    Co-Authors: Chang-rong Chen, Yiu-wing Mai
    Abstract:

    Cohesive zone model has been widely applied to simulate crack growth along interfaces, but its application to crack growth perpendicularly across the interface is rare. In this paper, the cohesive zone model is applied to a crack perpendicularly approaching a compliant/stiff interface in a layered material model. One aim is to understand the differences between the cohesive zone model and Linear Elastic Fracture mechanics in simulating mode I crack growth near a compliant/stiff interface. Another aim is to understand the effects of Elastic modulus mismatch and cohesive strength of the stiff layer on the crack behavior near the interface. To simulate crack growth approaching an interface, the cohesive zone model which incorporates both the energy criterion and the strength criterion is an effective method.

Jean-françois Molinari - One of the best experts on this subject based on the ideXlab platform.

  • Linear Elastic Fracture Mechanics Predicts the Propagation Distance of Frictional Slip
    Tribology Letters, 2015
    Co-Authors: David S. Kammer, Mathilde Radiguet, Jean-paul Ampuero, Jean-françois Molinari
    Abstract:

    When a frictional interface is subject to a localized shear load, it is often (experimentally) observed that local slip events propagate until they arrest naturally before reaching the edge of the interface. We develop a theoretical model based on Linear Elastic Fracture mechanics to describe the propagation of such precursory slip. The model’s prediction of precursor lengths as a function of external load is in good quantitative agreement with laboratory experiments as well as with dynamic simulations, and provides thereby evidence to recognize frictional slip as a Fracture phenomenon. We show that predicted precursor lengths depend, within given uncertainty ranges, mainly on the kinetic friction coefficient, and only weakly on other interface and material parameters. By simplifying the Fracture mechanics model, we also reveal sources for the observed nonLinearity in the growth of precursor lengths as a function of the applied force. The discrete nature of precursors as well as the shear tractions caused by frustrated Poisson’s expansion is found to be the dominant factors. Finally, we apply our model to a different, symmetric setup and provide a prediction of the propagation distance of frictional slip for future experiments.

  • Linear Elastic Fracture mechanics predicts the propagation distance of frictional slip
    arXiv: Materials Science, 2014
    Co-Authors: David S. Kammer, Mathilde Radiguet, Jean-paul Ampuero, Jean-françois Molinari
    Abstract:

    When a frictional interface is subject to a localized shear load, it is often (experimentally) observed that local slip events initiate at the stress concentration and propagate over parts of the interface by arresting naturally before reaching the edge. We develop a theoretical model based on Linear Elastic Fracture mechanics to describe the propagation of such precursory slip. The model's prediction of precursor lengths as a function of external load is in good quantitative agreement with laboratory experiments as well as with dynamic simulations, and provides thereby evidence to recognize frictional slip as a Fracture phenomenon. We show that predicted precursor lengths depend, within given uncertainty ranges, mainly on the kinetic friction coefficient, and only weakly on other interface and material parameters. By simplifying the Fracture mechanics model we also reveal sources for the observed non-Linearity in the growth of precursor lengths as a function of the applied force. The discrete nature of precursors as well as the shear tractions caused by frustrated Poisson's expansion are found to be the dominant factors. Finally, we apply our model to a different, symmetric set-up and provide a prediction of the propagation distance of frictional slip for future experiments.

D.h. Shaffer - One of the best experts on this subject based on the ideXlab platform.

  • Use of probability with Linear Elastic Fracture mechanics in studying brittle Fracture in pressure vessels
    International Journal of Pressure Vessels and Piping, 2003
    Co-Authors: G.m. Jouris, D.h. Shaffer
    Abstract:

    Abstract This paper deals with one phase in the development of statistical methodology for a Fracture mechanics analysis of the failure of nuclear steam supply system components, in particular that of brittle Fracture in the beltline region of the pressure vessel resulting from various transients. It introduces a probability structure into the deterministic Linear Elastic Fracture mechanics calculations. The resulting estimates of probability of brittle Fracture reflect not only variation due to heterogeneity of vessel material but also uncertainties in the effect of embrittlement of the vessel steel due to neutron irradiation. Using importance sampling in conjunction with Monte Carlo simulation we estimate that, for the operational transients considered, the probability of brittle Fracture conditional on the presence of an Appendix G flaw is less than 2 × 10 −10 .

Yukio Harada - One of the best experts on this subject based on the ideXlab platform.

  • EVALUATION ON LIMITATION OF Linear Elastic Fracture MECHANICS FOR SMALL FATIGUE CRACK GROWTH
    Fatigue & Fracture of Engineering Materials & Structures, 2007
    Co-Authors: Keiro Tokaji, Takeshi Ogawa, Yukio Harada
    Abstract:

    — The growth characteristics of small fatigue cracks were investigated under rotary bending in a high tensile strength steel, and the critical crack length above which Linear Elastic Fracture mechanics (LEFM) is applicable was evaluated systematically from the results of the present study and previous studies in which two steels having different microstructures and strengths were used. It is found that the critical crack length extends over two regions each exhibiting different growth mechanisms. These regions of microstructurally small cracks and mechanically small cracks are found to be a unique function of the microstructural unit size and the yield strength of the materials, respectively. Therefore, using these relationships, it is possible to estimate the critical crack length for a given material.

  • LIMITATIONS OF Linear Elastic Fracture MECHANICS IN RESPECT OF SMALL FATIGUE CRACKS AND MICROSTRUCTURE
    Fatigue & Fracture of Engineering Materials & Structures, 2007
    Co-Authors: Keiro Tokaji, Takeshi Ogawa, Yukio Harada, Zenji Ando
    Abstract:

    The growth characteristics of small fatigue cracks were investigated under rotary bending in a low alloy steel prepared with two prior austenite grain sizes of 15 μm (fine grain) and 91 μm (coarse grain). The influence of grain boundaries on crack growth rate and the crack aspect ratio was examined, and the critical crack length above which Linear Elastic Fracture mechanics (LEFM) is applicable was evaluated for a growing small crack. When the surface crack length is shorter than three grain diameters (3d), crack growth rates decrease near the grain boundaries. Aspect ratios are also affected by the microstructure and thus vary widely. Cracks longer than 3d are not influenced by the microstructure, but they grow faster than would be expected based on LEFM until their lengths reach 3d+ 150 μm. This behaviour may be attributed to the difference in crack closure between small cracks and large cracks. If the contribution of crack closure to the growth of small cracks can be established experimentally or analytically, the critical crack length above which LEFM is applicable would be 3d. However, because it is difficult to evaluate crack closure, 3d+ 150 μm is considered to be the critical crack length for engineering applications.

Yiu-wing Mai - One of the best experts on this subject based on the ideXlab platform.

  • Comparison of cohesive zone model and Linear Elastic Fracture mechanics for a mode I crack near a compliant/stiff interface
    Engineering Fracture Mechanics, 2010
    Co-Authors: Chang-rong Chen, Yiu-wing Mai
    Abstract:

    Cohesive zone model has been widely applied to simulate crack growth along interfaces, but its application to crack growth perpendicularly across the interface is rare. In this paper, the cohesive zone model is applied to a crack perpendicularly approaching a compliant/stiff interface in a layered material model. One aim is to understand the differences between the cohesive zone model and Linear Elastic Fracture mechanics in simulating mode I crack growth near a compliant/stiff interface. Another aim is to understand the effects of Elastic modulus mismatch and cohesive strength of the stiff layer on the crack behavior near the interface. To simulate crack growth approaching an interface, the cohesive zone model which incorporates both the energy criterion and the strength criterion is an effective method.

  • comparison of cohesive zone model and Linear Elastic Fracture mechanics for a mode i crack near a compliant stiff interface
    Engineering Fracture Mechanics, 2010
    Co-Authors: Chang-rong Chen, Yiu-wing Mai
    Abstract:

    Cohesive zone model has been widely applied to simulate crack growth along interfaces, but its application to crack growth perpendicularly across the interface is rare. In this paper, the cohesive zone model is applied to a crack perpendicularly approaching a compliant/stiff interface in a layered material model. One aim is to understand the differences between the cohesive zone model and Linear Elastic Fracture mechanics in simulating mode I crack growth near a compliant/stiff interface. Another aim is to understand the effects of Elastic modulus mismatch and cohesive strength of the stiff layer on the crack behavior near the interface. To simulate crack growth approaching an interface, the cohesive zone model which incorporates both the energy criterion and the strength criterion is an effective method.