The University of Southampton
University of Southampton Institutional Repository

In situ high resolution synchrotron x-ray tomography of fatigue crack closure micromechanisms

In situ high resolution synchrotron x-ray tomography of fatigue crack closure micromechanisms
In situ high resolution synchrotron x-ray tomography of fatigue crack closure micromechanisms
Fatigue crack closure has been identified as an important factor in determining crack growth rates. However, the methods of measurement of crack closure remain the subject of ongoing controversy. To date, computed finite element models, analytical models and widely established compliance-based experimental methods have offered limited micromechanical insight and/or direct information on the active crack tip region within bulk material. To understand the absolute contributions of crack closure mechanisms, such as plasticity-induced and roughness-induced closure, to fatigue properties, an internal, three-dimensional insight into crack behaviour during loading and unloading is clearly of value. In this work, synchrotron radiation x-ray microtomography is carried out at a high resolution of 0.7 µm to provide unique three-dimensional in situ observation of steady state plane strain fatigue crack growth in a 2024-type Al alloy (Al–Cu–Mg–Mn). Using such high resolution imaging (additionally exploiting the phase contrast effect in interface imaging), the details of fatigue cracks are readily observed, along with the occurrence of closure. A novel microstructural crack displacement gauging method is used to quantify the mixed mode character of crack opening displacement and the closure effect. A liquid gallium grain boundary wetting technique is used in conjunction with the microtomography to visualize the correlation between the three-dimensional structure of the grains and fatigue crack behaviour. Subsequently, electron backscattering diffraction assessment of the grain orientation on the samples provides a uniquely complete 3D description of crack–microstructure interactions.
0953-8984
S3511-S3515
Khor, K.H.
c346626b-924f-413b-bde4-cf7b41f61921
Buffiére, J-Y.
3a734c2d-4bf3-4164-b822-acb80300398e
Ludwig, W.
b9c8b7d7-3d81-42d7-8ef0-ddc26bb7fbdd
Toda, H.
58aad293-4279-4830-8aea-b3558984725c
Ubhi, H.S.
a5d9da64-1387-416e-96ca-691abc679ae2
Gregson, P.J.
ddc3b65d-18fb-4c11-9fa1-feb7e9cbe9fe
Sinclair, I.
6005f6c1-f478-434e-a52d-d310c18ade0d
Khor, K.H.
c346626b-924f-413b-bde4-cf7b41f61921
Buffiére, J-Y.
3a734c2d-4bf3-4164-b822-acb80300398e
Ludwig, W.
b9c8b7d7-3d81-42d7-8ef0-ddc26bb7fbdd
Toda, H.
58aad293-4279-4830-8aea-b3558984725c
Ubhi, H.S.
a5d9da64-1387-416e-96ca-691abc679ae2
Gregson, P.J.
ddc3b65d-18fb-4c11-9fa1-feb7e9cbe9fe
Sinclair, I.
6005f6c1-f478-434e-a52d-d310c18ade0d

Khor, K.H., Buffiére, J-Y., Ludwig, W., Toda, H., Ubhi, H.S., Gregson, P.J. and Sinclair, I. (2004) In situ high resolution synchrotron x-ray tomography of fatigue crack closure micromechanisms. Journal of Physics: Condensed Matter, 16, S3511-S3515. (doi:10.1088/0953-8984/16/33/012).

Record type: Article

Abstract

Fatigue crack closure has been identified as an important factor in determining crack growth rates. However, the methods of measurement of crack closure remain the subject of ongoing controversy. To date, computed finite element models, analytical models and widely established compliance-based experimental methods have offered limited micromechanical insight and/or direct information on the active crack tip region within bulk material. To understand the absolute contributions of crack closure mechanisms, such as plasticity-induced and roughness-induced closure, to fatigue properties, an internal, three-dimensional insight into crack behaviour during loading and unloading is clearly of value. In this work, synchrotron radiation x-ray microtomography is carried out at a high resolution of 0.7 µm to provide unique three-dimensional in situ observation of steady state plane strain fatigue crack growth in a 2024-type Al alloy (Al–Cu–Mg–Mn). Using such high resolution imaging (additionally exploiting the phase contrast effect in interface imaging), the details of fatigue cracks are readily observed, along with the occurrence of closure. A novel microstructural crack displacement gauging method is used to quantify the mixed mode character of crack opening displacement and the closure effect. A liquid gallium grain boundary wetting technique is used in conjunction with the microtomography to visualize the correlation between the three-dimensional structure of the grains and fatigue crack behaviour. Subsequently, electron backscattering diffraction assessment of the grain orientation on the samples provides a uniquely complete 3D description of crack–microstructure interactions.

This record has no associated files available for download.

More information

Published date: 2004

Identifiers

Local EPrints ID: 22923
URI: http://eprints.soton.ac.uk/id/eprint/22923
ISSN: 0953-8984
PURE UUID: 25fb13b3-49a4-4495-9064-fe6c7cc8822f

Catalogue record

Date deposited: 23 Mar 2006
Last modified: 15 Mar 2024 06:42

Export record

Altmetrics

Contributors

Author: K.H. Khor
Author: J-Y. Buffiére
Author: W. Ludwig
Author: H. Toda
Author: H.S. Ubhi
Author: P.J. Gregson
Author: I. Sinclair

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×