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Reaz A. Chaudhuri - One of the best experts on this subject based on the ideXlab platform.
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On through-thickness distribution of Stress intensity factors and energy release rates in the vicinity of crack fronts
Engineering Fracture Mechanics, 2019Co-Authors: Reaz A. ChaudhuriAbstract:Abstract First, an eigenfunction expansion method is presented to obtain three-dimensional Asymptotic Stress fields in the vicinity of the front of a semi-infinite crack, subjected to the far-field extension/bending, in-plane shear/twisting and antiplane shear loadings, distributed through the plate thickness. A complex variable approach in conjunction with this eigenfunction expansion technique is employed here to derive the heretofore-unavailable through-thickness distribution of Stress intensity factors and energy release rates for a center-crack weakening an infinite plate. Interesting numerical results for three-dimensional Stress intensity factors and energy release rates for five different far-field loading scenarios are also presented.
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three dimensional Asymptotic Stress fields at the front of a trimaterial junction
Composite Structures, 2012Co-Authors: Jinyong Yoon, Reaz A. ChaudhuriAbstract:Abstract A recently developed eigenfunction expansion method is employed for obtaining three-dimensional Asymptotic displacement and Stress fields in the vicinity of the junction corner front of an infinite pie-shaped trimaterial wedge, of finite thickness, formed as a result of bimaterial (matrix plus reaction product or contaminant) deposit over a substrate or reinforcement. The wedge is subjected to extension/bending (mode I), inplane shear/twisting (mode II) and antiplane shear (mode III) far field loading. Each material is isotropic and elastic, but with different material properties. The material 2 (substrate) is always taken to be a half-space, while the wedge aperture angle of the material 1 is varied to represent varying composition of the bimaterial deposit. Numerical results pertaining to the variation of the mode I, II, III eigenvalues (or Stress singularities) with various moduli ratios as well as the wedge aperture angle of the material 1 (reaction product/contaminant), are also presented. Hitherto unavailable results, pertaining to the through-thickness variations of Stress intensity factors for symmetric exponentially decaying distributed load and its skew-symmetric counterpart that also satisfy the boundary conditions on the top and bottom surfaces of the trimaterial plates under investigation, bridge a longstanding gap in the Stress singularity/interfacial fracture mechanics literature.
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three dimensional Asymptotic Stress field in the vicinity of an adhesively bonded scarf joint interface
Composite Structures, 2009Co-Authors: Reaz A. Chaudhuri, Souhsiung Jaclc ChiuAbstract:A recently developed three-dimensional eigenfunction expansion approach for prediction of the singular Stress field in the neighborhood of the interfacial front of an adhesively bonded scarf joint is presented. The plate is subjected to extension/bending (mode I) and in-plane shear/twisting (mode II) far field loading. Each material is assumed to be isotropic and elastic, but with different material properties. Numerical results include the dependence of the lowest eigenvalue (or Stress singularity) on the wedge aperture angle of the plate material. Variation of the same with respect to the shear moduli ratio of the component plate and adhesive layer materials is also an important part of the present investigation. Hitherto unobserved interesting and physically meaningful conclusions are also presented.
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three dimensional Asymptotic Stress field in the vicinity of the circumference of a bimaterial penny shaped interfacial discontinuity
International Journal of Fracture, 2006Co-Authors: Reaz A. ChaudhuriAbstract:An eigenfunction expansion method is presented to obtain three-dimensional Asymptotic Stress fields in the vicinity of the circumference of a bimaterial penny-shaped interfacial discontinuity, e.g., crack, anticrack (infinitely rigid lamella), etc., located at the center, edge or corner, and subjected to the far-field torsion (mode III), extension/bending (mode I), and sliding shear/twisting (mode II) loadings. Five different discontinuity-surface boundary conditions are considered: (1) bimaterial penny-shaped interface anticrack or perfectly bonded thin rigid inclusion, (2) bimaterial penny-shaped interfacial jammed contact, (3) bimaterial penny-shaped interface crack, (4) bimaterial penny-shaped interface crack with partial axisymmetric frictionless slip, and (5) bimaterial penny-shaped interface thin rigid inclusion alongside penny-shaped crack. Solutions to these cases except (3) are hitherto unavailable in the literature. Closed-form expressions for Stress intensity factors subjected to various far-field loadings are also presented. Numerical results presented include the effect of the ratio of the shear moduli of the layer materials, and also Poisson’s ratios on the computed lowest real parts of eigenvalues for the case (5). Interesting and physically meaningful conclusions are also presented, especially with regard to cases (1) and (2).
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three dimensional Asymptotic Stress field in the vicinity of the circumferential tip of a fiber matrix interfacial debond
International Journal of Engineering Science, 2004Co-Authors: Reaz A. ChaudhuriAbstract:Abstract A heretofore unavailable Asymptotic solution pertaining to the Stress field in the neighborhood of the circumferential tip of an interfacial debond, between the fiber or inclusion and the unreinforced plate made of the matrix material, and subjected to far-field extension-bending (mode I), inplane shear-twisting (mode II) and torsional (mode III) loadings, is presented. A local orthogonal curvilinear coordinate system ( ρ , φ , θ ), is selected to describe the local deformation behavior of the afore-mentioned plate in the vicinity of the afore-mentioned circumferential line of interfacial debond. One of the components of the Euclidean metric tensor, namely g 33 , is approximated ( ρ / a ≪1) in the derivation of the kinematic relations and the ensuing governing system of three partial differential equations. A recently developed eigenfunction approach coupled with a novel local curvilinear coordinate system, is utilized to compute the Asymptotic displacement and Stress fields. The oscillatory behavior at the debond tip may be considered to be a first-order approximation of the interdiffusion of the component phases followed by molecular entanglement and other similar microscopic phenomena studied by materials scientists.
P Ferro - One of the best experts on this subject based on the ideXlab platform.
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influence of phase transformations on the Asymptotic residual Stress distribution arising near a sharp v notch tip
Modelling and Simulation in Materials Science and Engineering, 2012Co-Authors: P FerroAbstract:In this work, the residual Stress distribution induced by the solidification and cooling of a fusion zone in the vicinity of a sharp V-notch tip is investigated. The intensity of the residual Asymptotic Stress fields, quantified by the notch Stress intensity factors, was studied for two different V-notch specimen geometries under generalized plane-strain conditions. In order to analyze the influence of phase transformations on the obtained results, simulations with and without the effects of phase transformation were carried out on ASTM SA 516 steel plates. Thanks to the possibilities of numerical modelling, additional analyses were performed without taking into account the transformation plasticity phenomenon.It was found that phase transformation effects (both volume change and transformation plasticity) have a great influence on the intensity and sign of the Asymptotic Stress fields at the sharp V-notch tips. This result is believed to be very important for the correct numerical determination (and future applications) of notch Stress intensity factors resulting from Asymptotic residual Stress distributions induced by transient thermal loads. The analyses were performed with the finite element code SYSWELD.
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Asymptotic thermal and residual Stress distributions due to transient thermal loads
Fatigue & Fracture of Engineering Materials & Structures, 2009Co-Authors: P Ferro, Nicola PetroneAbstract:The paper deals with the development of thermal and residual Stress distributions arising from the solidification of a fusion zone near a V-notch tip. A set of numerical solutions of the problem was carried out under the hypothesis of generalized plane strain conditions by means of SYSWELD code. The intensity of the thermal and residual Asymptotic Stress fields at the sharp V-notch tip was studied for a given V-notch specimen geometry and a predefined fusion zone dimension after simulations on materials with different thermal, mechanical and phase transformation properties and after changing the clamping conditions at the specimen's boundary. The results were compared in terms of the elastic or elastic-plastic notch Stress intensity factors giving a contribution to the interpretation of the experimental behaviour of welded joint.
Fernando Labbe - One of the best experts on this subject based on the ideXlab platform.
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Three-term Asymptotic Stress Field Expansion for Analysis of Surface Cracked Elbows in Nuclear Pressure Vessels
Journal of Materials Engineering and Performance, 2007Co-Authors: Fernando LabbeAbstract:Elbows with a shallow surface cracks in nuclear pressure pipes have been recognized as a major origin of potential catastrophic failures. Crack assessment is normally performed by using the J-integral approach. Although this one-parameter-based approach is useful to predict the ductile crack onset, it depends strongly on specimen geometry or constraint level. When a shallow crack exists (depth crack-to-thickness wall ratio less than 0.2) and/or a fully plastic condition develops around the crack, the J-integral alone does not describe completely the crack-tip Stress field. In this paper, we report on the use of a three-term Asymptotic expansion, referred to as the J – A _2 methodology, for modeling the elastic-plastic Stress field around a three-dimensional shallow surface crack in an elbow subjected to internal pressure and out-of-plane bending. The material, an A 516 Gr. 70 steel, used in the nuclear industry, was modeled with a Ramberg–Osgood power law and flow theory of plasticity. A finite deformation theory was included to account for the highly nonlinear behavior around the crack tip. Numerical finite element results were used to calculate a second fracture parameter A _2 for the J – A _2 methodology. We found that the used three-term Asymptotic expansion accurately describes the Stress field around the considered three-dimensional shallow surface crack.
Arun Shukla - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Crack-Tip Stress and Displacement Fields Under Thermomechanical Loading in Functionally Graded Materials
Journal of Applied Mechanics, 2008Co-Authors: Vijaya Chalivendra, Arun ShuklaAbstract:Thermomechanical Stress and displacement fields for a propagating crack in functionally graded materials (FGMs) are developed using displacement potentials and Asymptotic analysis. The shear modulus, mass density, and coefficient of thermal expansion of the FGMs are assumed to vary exponentially along the gradation direction. Temperature and heat flux distribution fields are also derived for an exponential variation of thermal conductivity. The mode mixity due to mixed-mode loading conditions around the crack tip is accommodated in the analysis through the superposition of opening and shear modes. Using the Asymptotic Stress fields, the contours of isochromatics (contours of constant maximum shear Stress) are developed and the results are discussed for various crack-tip thermomechanical loading conditions.
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Asymptotic Stress fields for thermomechanically loaded cracks in fgms
Journal of Astm International, 2006Co-Authors: Nitesh Jain, Ravinder Chona, Arun ShuklaAbstract:The problem of a stationary crack in functionally graded materials (FGM), subjected to a combination of thermal and mechanical loading is considered. An Asymptotic analysis coupled with Westergaard's Stress function approach is used to characterize the Stress field around the crack tip. Thermal and mechanical properties (e.g., elastic modulus, coefficient of thermal expansion, and thermal conductivity) are assumed to vary exponentially. The crack is assumed to be inclined to the direction of the property gradation. The thermal loading is taken to be a uniform heat flow in a direction inclined to the crack. The principal of superposition from linear elasticity is used to solve the problem, whereby the problem is divided into a number of subproblems. The first four terms in the expansion of the Stress field are derived to explicitly bring out the influence of nonhomogeneity on the structure of the Stress field. It is observed that the presence of heat flow produced no additional singularity and hence the classical inverse square root singularity still prevails around the crack tip. Using these Stress field contours of constant maximum shear Stress are generated and the effect of thermal loading on the crack-tip Stress field is discussed.
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Asymptotic Stress fields for stationary cracks along the gradient in functionally graded materials
Journal of Applied Mechanics, 2002Co-Authors: Venkitanarayanan Parameswaran, Arun ShuklaAbstract:Stress field for stationary cracks, aligned along the gradient, in functionally graded materials is obtained through an Asymptotic analysis coupled with Westergaard's Stress function approach. The first six terms of the Stress field are obtained for both opening mode and shear mode loading. It is observed that the structure of the terms other than r?1/2 and r0 are influenced by the nonhomogeneity. Using this Stress field, contours of constant maximum shear Stress are generated and the effect of nonhomogeneity on these contours is discussed. ©2002 ASME
D Benicchio - One of the best experts on this subject based on the ideXlab platform.
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Asymptotic Stress field in a cracked orthotropic strip
Composite Structures, 1995Co-Authors: J Chaoufi, D Gamby, D BenicchioAbstract:Abstract Christensen's theory of viscoelastic fracture allows the crack propagation velocity to be determined in terms of dissipation whose calculation requires the knowledge of the Stress field in the vicinity of the crack tip: the simplest configuration leading to a constant velocity is that of a straight semi-infinite crack contained in an infinitely long strip whose clamped edges are displaced normal to the crack; although experimental data pertaining to this problem have been obtained for a number of materials, no analytical solution is available. When the material is highly anisotropic, an Asymptotic solution involving a small parameter related to the ratio of shear modulus to the larger Young's modulus can be attempted. As the corresponding perturbation problem is singular, a matched Asymptotic expansion has to be used: it is the sum of outer and inner approximations; both of these are solutions to simple boundary-value problems which can be solved in closed form. The so-constructed Asymptotic solution is shown to agree with finite element results, even when the small parameter is as large as 0.2.
