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Nanofibril-mediated fracture resistance of bone

Tertuliano, Ottman and Edwards, Bryce W. and Meza, Lucas R. and Deshpande, Vikram S. and Greer, Julia R. (2021) Nanofibril-mediated fracture resistance of bone. Bioinspiration and Biomimetics, 16 (3). Art. No. 035001. ISSN 1748-3182. doi:10.1088/1748-3190/abdd9d.

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Natural hard composites like human bone possess a combination of strength and toughness that exceeds that of their constituents and of many engineered composites. This augmentation is attributed to their complex hierarchical structure, spanning multiple length scales; in bone, characteristic dimensions range from nanoscale fibrils to microscale lamellae to mesoscale osteons and macroscale organs. The mechanical properties of bone have been studied, with the understanding that the isolated microstructure at micro- and nano-scales gives rise to superior strength compared to that of whole tissue, and the tissue possesses an amplified toughness relative to that of its nanoscale constituents. Nanoscale toughening mechanisms of bone are not adequately understood at sample dimensions that allow for isolating salient microstructural features, because of the challenge of performing fracture experiments on small-sized samples. We developed an in-situ three-point bend experimental methodology that probes site-specific fracture behavior of micron-sized specimens of hard material. Using this, we quantify crack initiation and growth toughness of human trabecular bone with sharp fatigue pre-cracks and blunt notches. Our findings indicate that bone with fatigue cracks is two times tougher than that with blunt cracks. In-situ data-correlated electron microscopy videos reveal this behavior arises from crack-bridging by nanoscale fibril structure. The results reveal a transition between fibril-bridging (~1µm) and crack deflection/twist (~500µm) as a function of length-scale, and quantitatively demonstrate hierarchy-induced toughening in a complex material. This versatile approach enables quantifying the relationship between toughness and microstructure in various complex material systems and provides direct insight for designing biomimetic composites.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Tertuliano, Ottman0000-0003-0524-3944
Meza, Lucas R.0000-0003-0250-2621
Deshpande, Vikram S.0000-0003-3899-3573
Greer, Julia R.0000-0002-9675-1508
Additional Information:© 2021 IOP Publishing Ltd. Received 23 August 2020; Revised 11 November 2020; Accepted 19 January 2021; Published 5 April 2021. The authors thank Bill Johnson, Katherine Faber, Carlos Portela, Xiaoxing Xia, and Eric Luo for helpful discussions. The authors thank Matthew Sullivan and Carol Garland for assistance with experiments and instruments. The authors gratefully acknowledge the facilities and infrastructure provided by the Kavli Nanoscience Institute at Caltech. O.A.T would like to thank the National Science Foundation for financial support through the Graduate Research Fellowship Program (NSF GFRP). J.R.G. gratefully acknowledges financial support from the U.S. Department of Basic Energy Sciences under Grant DE-SC0006599. Data availability: The data that supports the findings of this study is available from the corresponding author upon reasonable request.
Group:Kavli Nanoscience Institute
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
Department of Energy (DOE)DE-SC0006599
Subject Keywords:Fracture, Bone, Toughening mechanisms, fatigue, micro-nanoscale mechanics
Issue or Number:3
Record Number:CaltechAUTHORS:20210122-082128326
Persistent URL:
Official Citation:Ottman A Tertuliano et al 2021 Bioinspir. Biomim. 16 035001
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107654
Deposited By: Tony Diaz
Deposited On:22 Jan 2021 17:13
Last Modified:12 Jul 2022 19:49

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