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Title: Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales

Pangolin scales form a durable armor whose hierarchical structure offers an avenue towards high performance bio-inspired materials design. In this paper, the fracture resistance of African pangolin scales is examined using single edge crack three-point bend fracture testing in order to understand toughening mechanisms arising from the structures of natural mammalian armors. In these mechanical tests, the influence of material orientation and hydration level are examined. The fracture experiments reveal an exceptional fracture resistance due to crack deflection induced by the internal spatial orientation of lamellae. An order of magnitude increase in the measured fracture resistance due to scale hydration, reaching up to ~ 25 kJ/m 2 was measured. Post-mortem analysis of the fracture samples was performed using a combination of optical and electron microscopy, and X-ray computerized tomography. Interestingly, the crack profile morphologies are observed to follow paths outlined by the keratinous lamellae structure of the pangolin scale. Most notably, the inherent structure of pangolin scales offers a pathway for crack deflection and fracture toughening. Finally, the results of this study are expected to be useful as design principles for high performance biomimetic applications.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Northwestern Univ., Evanston, IL (United States). Dept. of Mechanical Engineering
  2. Univ. of California, San Diego, CA (United States). Dept. of Mechanical and Aerospace Engineering; Chinese Academy of Sciences (CAS), Shenzhen (China). Shenzhen Inst. of Advanced Technology
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source
  4. Northwestern Univ., Evanston, IL (United States). Theoretical and Applied Mechanics Program
  5. Univ. of California, San Diego, CA (United States). Dept. of Mechanical and Aerospace Engineering
  6. Northwestern Univ., Evanston, IL (United States). Dept. of Mechanical Engineering. Theoretical and Applied Mechanics Program
Publication Date:
Grant/Contract Number:
AC02-06CH11357; AFOSR-FA9550-15-1-0009; PDF-502224-2017
Type:
Accepted Manuscript
Journal Name:
Journal of the Mechanical Behavior of Biomedical Materials
Additional Journal Information:
Journal Volume: 76; Journal ID: ISSN 1751-6161
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
Sponsoring Org:
USDOE; US Air Force Office of Scientific Research (AFOSR); Natural Sciences and Engineering Research Council of Canada (NSERC)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; pangolin scale; fracture toughness; hierarchical structure; bio-inspired design principles; biomaterials
OSTI Identifier:
1438225

Chon, Michael J., Daly, Matthew, Wang, Bin, Xiao, Xianghui, Zaheri, Alireza, Meyers, Marc A., and Espinosa, Horacio D.. Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales. United States: N. p., Web. doi:10.1016/j.jmbbm.2017.06.009.
Chon, Michael J., Daly, Matthew, Wang, Bin, Xiao, Xianghui, Zaheri, Alireza, Meyers, Marc A., & Espinosa, Horacio D.. Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales. United States. doi:10.1016/j.jmbbm.2017.06.009.
Chon, Michael J., Daly, Matthew, Wang, Bin, Xiao, Xianghui, Zaheri, Alireza, Meyers, Marc A., and Espinosa, Horacio D.. 2017. "Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales". United States. doi:10.1016/j.jmbbm.2017.06.009. https://www.osti.gov/servlets/purl/1438225.
@article{osti_1438225,
title = {Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales},
author = {Chon, Michael J. and Daly, Matthew and Wang, Bin and Xiao, Xianghui and Zaheri, Alireza and Meyers, Marc A. and Espinosa, Horacio D.},
abstractNote = {Pangolin scales form a durable armor whose hierarchical structure offers an avenue towards high performance bio-inspired materials design. In this paper, the fracture resistance of African pangolin scales is examined using single edge crack three-point bend fracture testing in order to understand toughening mechanisms arising from the structures of natural mammalian armors. In these mechanical tests, the influence of material orientation and hydration level are examined. The fracture experiments reveal an exceptional fracture resistance due to crack deflection induced by the internal spatial orientation of lamellae. An order of magnitude increase in the measured fracture resistance due to scale hydration, reaching up to ~ 25 kJ/m2 was measured. Post-mortem analysis of the fracture samples was performed using a combination of optical and electron microscopy, and X-ray computerized tomography. Interestingly, the crack profile morphologies are observed to follow paths outlined by the keratinous lamellae structure of the pangolin scale. Most notably, the inherent structure of pangolin scales offers a pathway for crack deflection and fracture toughening. Finally, the results of this study are expected to be useful as design principles for high performance biomimetic applications.},
doi = {10.1016/j.jmbbm.2017.06.009},
journal = {Journal of the Mechanical Behavior of Biomedical Materials},
number = ,
volume = 76,
place = {United States},
year = {2017},
month = {6}
}