Lu, X;
Fernandez, MP;
Bradley, RS;
Rawson, SD;
O'Brien, M;
Hornberger, B;
Leibowitz, M;
... Withers, PJ; + view all
(2019)
Anisotropic crack propagation and deformation in dentin observed by four-dimensional X-ray nano-computed tomography.
Acta Biomaterialia
, 96
pp. 400-411.
10.1016/j.actbio.2019.06.042.
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Abstract
Understanding the cracking behaviour of biological composite materials is of practical importance. This paper presents the first study to track the interplay between crack initiation, microfracture and plastic deformation in three dimensions (3D) as a function of tubule and collagen fibril arrangement in elephant dentin using in situ X-ray nano-computed tomography (nano-CT). A nano-indenter with a conical tip has been used to incrementally indent three test-pieces oriented at 0°, 45° and 70° to the long axis of the tubules (i.e. radial to the tusk). For the 0° sample two significant cracks formed, one of which linked up with microcracks in the axial-radial plane of the tusk originating from the tubules and the other one occurred as a consequence of shear deformation at the tubules. The 70° test-piece was able to bear the greatest loads despite many small cracks forming around the indenter. These were diverted by the microstructure and did not propagate significantly. The 45° test-piece showed intermediate behaviour. In all cases strains obtained by digital volume correlation were well in excess of the yield strain (0.9%), indeed some plastic deformation could even be seen through bending of the tubules. The hoop strains around the conical indenter were anisotropic with the smallest strains correlating with the primary collagen orientation (axial to the tusk) and the largest strains aligned with the hoop direction of the tusk.
| Type: | Article |
|---|---|
| Title: | Anisotropic crack propagation and deformation in dentin observed by four-dimensional X-ray nano-computed tomography |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.actbio.2019.06.042 |
| Publisher version: | https://doi.org/10.1016/j.actbio.2019.06.042 |
| Language: | English |
| Additional information: | This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
| Keywords: | Time-lapse imaging, Indentation fracture, Digital image correlation (DIC), Crack shielding, Ivory |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10085067 |
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