The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Yi-heng Chen - One of the best experts on this subject based on the ideXlab platform.
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On the path dependence of the J-Integral in notch problems
International Journal of Solids and Structures, 2004Co-Authors: Yi-heng Chen, Tian Jian LuAbstract:Abstract This study attempts to clarify the conditions under which the J-Integral is path-independent in U- and V-shaped notch problems. The key is to determine the contribution to the J-Integral evaluated in the global coordinate system from the second component of the Jk-vector evaluated in the local coordinate system along the traction-free surfaces that form part of the integration path. It is found that the global J-Integral is path-independent only if the proJected contribution from the J2-Integral to J vanishes. The J-Integral for a V-shaped notch is, strictly speaking, path-dependent even under remote symmetrical loading. This is due to the fact that, unlike in the case of a line- or plane-crack, the value of the J-Integral calculated along a closed contour surrounding the V-shaped notch is dependent on the selection of the starting and ending points on the notch surface. In other words, the traction-free surface of the V-shaped notch does contribute to the J-Integral due to the non-zero proJected values induced from the J2-Integral. For a U-shaped notch, the path-independence of the J-Integral is established if the integration path completely encloses the notch root. This is because both the upper and lower notch surfaces of the U-shaped notch are parallel to the geometric symmetrical line (the x1-axis) and hence the proJected values from the J2-Integral vanish. Furthermore, it is found that the small arc at the root of the notch (whether U- or V-shaped) also contributes to the J-Integral even if the remote loading is symmetrical. These conclusions are derived by detailed analytical manipulations and by numerical examples; the analytical solution obtained by Lazzarin and Tovo [Int. J. Fracture 78 (1996) 3] and Lazzarin et al. [Int. J. Fracture 91 (1998) 269] for stress field in the vicinity of a notch root in an infinite elastic plane is used to calculate the contribution induced from the arc with different radii. Some useful results for studying the fracture and fatigue of notches are discussed.
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On two additional contributions of the higher order singular terms to the J-Integral
International Journal of Fracture, 1997Co-Authors: Dezhou Wang, Yi-heng ChenAbstract:It has been shown that the higher order singular terms (HOST) contribute to the J-Integral. Moreover, Hui and Ruina (1995) proved that, for mode III fracture, HOST give rise to two additional terms in the J-Integral, which are of the same order. We show that HOST yield two additional contributions to the J-Integral due to the introduction of the nonlinear zone, and the calculated results show that these contributions are of about the same order.
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On the contribution of a microhole in the near-tip stress field to the J-Integral
International Journal of Fracture, 1997Co-Authors: Yi-heng ChenAbstract:The J-Integral analysis is performed for the interaction of a macrocrack with a microhole in a homogeneous plane of a linear elastic solid. A simple relation is obtained between three kinds of the J-Integral induced by the macrocrack tip, the microhole and the remote stress field, respectively. The anti-shielding effect or the shielding effect of the microhole on the macrocrack can be confined easily from the J-Integral induced from the microhole.
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J-Integral analysis for microhole interacting with macrocrack
International Journal of Fracture, 1996Co-Authors: Yi-heng ChenAbstract:The contribution of the macrocrack and the microhole to the J Integral is dependent on the location of the microhole
Yung-chuan Chen - One of the best experts on this subject based on the ideXlab platform.
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The values of J-Integral within the plastic zone
Engineering Fracture Mechanics, 1996Co-Authors: Jao-hwa Kuang, Yung-chuan ChenAbstract:A study has been conducted to characterize the J-Integral within the plastic zone for different strain hardening materials. The relation between the calculated J-Integral and plastic energy enclosed by the selected integration contour is explored for different strain hardening materials. The equations between the J-Integral and plastic energy around the crack tip for 7075-T651 aluminum alloy and HY-130 steel have been derived. It is shown that the J-Integral is path dependent if the selected integration contour goes across the plastic zone. Results also indicated the plastic energy enclosed by the selected integration contour provides the dominant contribution to the J-Integral.
Martin Hughes - One of the best experts on this subject based on the ideXlab platform.
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On the modified monotonic loading concept for the calculation of the cyclic J-Integral
Journal of Pressure Vessel Technology-transactions of The Asme, 2015Co-Authors: Ross Beesley, Haofeng Chen, Martin HughesAbstract:This paper investigates an approach for calculating the cyclic J-Integral through a new industrial application. A previously proposed method is investigated further with the extension of this technique through a new application of a practical 3D notched component containing a semi-elliptical surface crack. Current methods of calculating the cyclic J-Integral are identified and their limitations discussed. A modified monotonic loading concept is adapted to calculate the cyclic J-Integral of this 3D Semi Elliptical Surface Crack under cyclic loading conditions. Both the finite element method (FEM) and the Extended Finite Element Method (XFEM) are discussed as possible methods of calculating the cyclic J-Integral in this investigation. Different loading conditions including uniaxial tension and out of plane shear are applied, and the relationships between the applied loads and the cyclic J-Integral are established. In addition, the variations of the cyclic J-Integral along the crack front are investigated. This allows the critical load that can be applied before crack propagation occurs to be determined as well as the identification of the critical crack direction once propagation does occur. These calculations display the applicability of the method to practical examples and illustrate an accurate method of estimating the cyclic J-Integral.
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On the cyclic J-Integral of a 3D semi elliptical surface crack
Volume 5: High-Pressure Technology; ASME NDE Division; 22nd Scavuzzo Student Paper Symposium and Competition, 2014Co-Authors: Ross Beesley, Haofeng Chen, Martin HughesAbstract:This paper investigates an approach for calculating the cyclic J-Integral (ΔJ) through a new industrial application. A previously proposed method is investigated further with the extension of this technique through a new application of a practical 3D notched component containing a semi-elliptical surface crack. Current methods of calculating the cyclic J-Integral are identified and their limitations discussed. A modified monotonic loading method is adapted to calculate the cyclic J- Integral of this 3D Semi Elliptical Surface Crack under cyclic loading conditions. Both the finite element method (FEM) and the Extended Finite Element Method (XFEM) are discussed as possible methods of calculating the cyclic J-Integral in this investigation. Different loading conditions including uni-axial tension and out of plane shear are applied, and the relationships between the applied loads and the cyclic J-Integral are established. In addition, the variations of the cyclic J-Integral along the crack front are investigated. This allows the critical load that can be applied before crack propagation occurs to be determined as well as the identification of the critical crack direction once propagation does occur. These calculations display the applicability of the method to practical examples and illustrate an accurate method of estimating the cyclic J-Integral.
Jao-hwa Kuang - One of the best experts on this subject based on the ideXlab platform.
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The values of J-Integral within the plastic zone
Engineering Fracture Mechanics, 1996Co-Authors: Jao-hwa Kuang, Yung-chuan ChenAbstract:A study has been conducted to characterize the J-Integral within the plastic zone for different strain hardening materials. The relation between the calculated J-Integral and plastic energy enclosed by the selected integration contour is explored for different strain hardening materials. The equations between the J-Integral and plastic energy around the crack tip for 7075-T651 aluminum alloy and HY-130 steel have been derived. It is shown that the J-Integral is path dependent if the selected integration contour goes across the plastic zone. Results also indicated the plastic energy enclosed by the selected integration contour provides the dominant contribution to the J-Integral.
Mikael Fonselius - One of the best experts on this subject based on the ideXlab platform.
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Determination of Critical J‐Integral for Wood
Journal of Structural Engineering-asce, 1992Co-Authors: Kirsti Riipola, Mikael FonseliusAbstract:The determination of the critical J‐Integral value for wood is considered. The methods are based on the American Society for Testing and Materials standard “JIC, a measure of fracture toughness.” A significant revision of the method proposed in the J‐Integral standard is needed. Three possibilities for analyzing of the results are developed. The graphical method presupposes no knowledge of the material properties and relies on the recorded Jhyphen;Integral versus crack growth curve. The compliance method uses the compliance data recorded during each loading and unloading cycle and the maximum load. The measured maximum load can also be inserted in an equation based on the finite element method. Another method based on the standard “plane strain fracture toughness of metallic materials” is used to study the dependence between the critical J‐Integral and the experimental and material parameters. The determined critical J‐Integral values are independent of the analysis method. The effect of time is observed:...
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DETERMINATION OF CRITICAL J-Integral FOR WOOD
Journal of Structural Engineering-asce, 1992Co-Authors: Kirsti Riipola, Mikael FonseliusAbstract:The determination of the critical J‐Integral value for wood is considered. The methods are based on the American Society for Testing and Materials standard “JIC, a measure of fracture toughness.” A significant revision of the method proposed in the J‐Integral standard is needed. Three possibilities for analyzing of the results are developed. The graphical method presupposes no knowledge of the material properties and relies on the recorded Jhyphen;Integral versus crack growth curve. The compliance method uses the compliance data recorded during each loading and unloading cycle and the maximum load. The measured maximum load can also be inserted in an equation based on the finite element method. Another method based on the standard “plane strain fracture toughness of metallic materials” is used to study the dependence between the critical J‐Integral and the experimental and material parameters. The determined critical J‐Integral values are independent of the analysis method. The effect of time is observed:...
