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A viscoplastic study of crack-tip deformation and crack growth in a nickel-based superalloy at elevated temperature

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posted on 13.11.2012, 11:30 by Liguo ZhaoLiguo Zhao, Jie Tong
Viscoplastic crack-tip deformation behaviour in a nickel-based superalloy at elevated temperature has been studied for both stationary and growing cracks in a compact tension (CT) specimen using the finite element method. The material behaviour was described by a unified viscoplastic constitutive model with non-linear kinematic and isotropic hardening rules, and implemented in the finite element software ABAQUS via a user-defined material subroutine (UMAT). Finite element analyses for stationary cracks showed distinctive strain ratchetting behaviour near the crack tip at selected load ratios, leading to progressive accumulation of tensile strain normal to the crack-growth plane. Results also showed that low frequencies and superimposed hold periods at peak loads significantly enhanced strain accumulation at crack tip. Finite element simulation of crack growth was carried out under a constant ΔK-controlled loading condition, again ratchetting was observed ahead of the crack tip, similar to that for stationary cracks. A crack-growth criterion based on strain accumulation is proposed where a crack is assumed to grow when the accumulated strain ahead of the crack tip reaches a critical value over a characteristic distance. The criterion has been utilized in the prediction of crack-growth rates in a CT specimen at selected loading ranges, frequencies and dwell periods, and the predictions were compared with the experimental results.

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Citation

ZHAO, L. and TONG, J., 2008. A viscoplastic study of crack-tip deformation and crack growth in a nickel-based superalloy at elevated temperature. Journal of the Mechanics and Physics of Solids, 56 (12), pp.3363-3378.

Publisher

© Elsevier

Version

AM (Accepted Manuscript)

Publication date

2008

Notes

This is the author’s version of a work that was accepted for publication in the Journal of the Mechanics and Physics of Solids. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at: http://dx.doi.org/10.1016/j.jmps.2008.09.006

ISSN

0022-5096

Language

en