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Reaz A. Chaudhuri – 1st expert on this subject based on the ideXlab platform
On through-thickness distribution of Stress intensity factors and energy release rates in the vicinity of crack frontsEngineering 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.
three dimensional Asymptotic Stress fields at the front of a trimaterial junctionComposite 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.
three dimensional Asymptotic Stress field in the vicinity of an adhesively bonded scarf joint interfaceComposite 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.
P Ferro – 2nd expert on this subject based on the ideXlab platform
influence of phase transformations on the Asymptotic residual Stress distribution arising near a sharp v notch tipModelling 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.
Asymptotic thermal and residual Stress distributions due to transient thermal loadsFatigue & 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 – 3rd expert on this subject based on the ideXlab platform
Three-term Asymptotic Stress Field Expansion for Analysis of Surface Cracked Elbows in Nuclear Pressure VesselsJournal 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.