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Yang H.,Key Laboratory of Engineering Structural Analysis and Safety Assessment | Li Z.,Huazhong University of Science and Technology | Huang M.,Key Laboratory of Engineering Structural Analysis and Safety Assessment
Computational Materials Science | Year: 2013

In order to fully capture dislocation cutting the precipitate (γ′ phase) in the nickel-based single crystal superalloy servicing in a wide range of temperatures, the superlattice intrinsic stacking fault (SISF) dissociation scheme is introduced into the three-dimensional discrete dislocation dynamics (3D-DDD) simulation framework by employing a total energy-based criterion for the transition from anti-phase boundary (APB) dissociation scheme to SISF one. The computational results show that the present 3D-DDD extension can successfully capture two key stages of the transition from APB to SISF dissociation. This extended 3D-DDD framework is also used to predict the overall stress-strain response of nickel-based single crystal superalloys at two typical temperatures 293 K and 873 K. Compared with the stress-strain curves predicted by the 3D-DDD framework only with consideration of APB dissociation scheme, the results by this extended 3D-DDD framework with consideration of both SISF and APB dissociations are closer to experimental data. © 2013 Published by Elsevier B.V. Source


Liu Y.,Huazhong University of Science and Technology | Liu Y.,Key Laboratory of Engineering Structural Analysis and Safety Assessment | Chen C.,Huazhong University of Science and Technology | Chen C.,Key Laboratory of Engineering Structural Analysis and Safety Assessment | And 2 more authors.
Acta Mechanica Solida Sinica | Year: 2010

Three-dimensional crack closure correction methods are investigated in this paper. The fatigue crack growth tests of surface cracks in 14MnNbq steel for bridge plate subjected to tensile and bending loadings are systematically conducted. The experimentally measured fatigue crack growth rates of surface cracks are compared with those of through-thickness cracks in detail. It is found that the crack growth rates of surface cracks are lower than those of through-thickness cracks. In order to correct their differences in fatigue crack growth rates, a dimensionless crack closure correction model is proposed. Although this correction model is determined only by the experimental data of surface cracks under tensile loading with a constant ratio R = 0.05, it can correlate the surface crack growth rates with reasonable accuracy under tensile and bending loadings with various stress ratios ranging from 0 to 0.5. Furthermore, predictions of fatigue life and crack aspect ratio for surface cracks are discussed, and the predicted results are also compared with those obtained from other prediction approaches. Comparison results show that the proposed crack closure correction model gives better prediction of fatigue life than other models. © 2010 The Chinese Society of Theoretical and Applied Mechanics. Source

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