posted on 2015-02-04, 10:09authored byFarukh Farukh, Liguo Zhao, Rong Jiang, Philippa A.S. Reed, Daniela Proprentner, Barbara Shollock
Experimental studies and computational modelling of crack deformation and growth
in a nickel-based superalloy at elevated temperature have been carried out for a threepoint
bending specimen subjected to fatigue loading condition. In order to remove the
influence of oxidation which can be considerable at elevated temperature, crack
growth was particularly tested in a nominal vacuum/minimal oxidation environment
with a focus on dwell effects. For simulation, the material behaviour was described by
a cyclic viscoplastic constitutive model with nonlinear kinematic and isotropic
hardening rules. Computational analyses of a stationary crack showed the progressive
accumulation of plastic strain near the crack tip, which has been subsequently used as
a fracture criterion to predict crack growth using the extended finite element method
(XFEM). The crack was assumed to grow when the accumulated plastic strain ahead
of the crack tip reached a critical value which was calibrated from crack growth test data in vacuum. During the simulation, the crack length was recorded against the
number of loading cycles, and the results are in good agreement with the experimental
data which proves the model’s capability to predict fatigue crack growth in nickelbased
superalloys at high temperature. It is also shown, both experimentally and
numerically, that an increase of dwell period leads to an increase of crack growth rate
due to the increased creep deformation near the crack tip, but this effect is marginal
when compared to the dwell effects under fatigue-oxidation conditions.
Funding
The work was funded by the EPSRC (Grants EP/K026844/1, EP/K027271/1 and EP/K027344/1) of the UK and in collaboration with Nasa, Alstom, E.On and Dstl.
History
School
Mechanical, Electrical and Manufacturing Engineering
Published in
Mechanics of Advanced Materials and Modern Processes
Volume
1
Issue
1
Pages
1 - 40 (40)
Citation
FARUKH, F. ... et al, 2015. Fatigue crack growth in a nickel-based superalloy at elevated temperature - experimental studies, viscoplasticity modelling and XFEM predictions. Mechanics of Advanced Materials and Modern Processes, 1 (2), 13pp.
This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by/4.0/
Publication date
2015
Notes
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.