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Title: Moisture, anisotropy, stress state, and strain rate effects on bighorn sheep horn keratin mechanical properties

Our paper investigates the effects of moisture, anisotropy, stress state, and strain rate on the mechanical properties of the bighorn sheep (Ovis Canadensis) horn keratin. The horns consist of fibrous keratin tubules extending along the length of the horn and are contained within an amorphous keratin matrix. We tested samples in the rehydrated (35 wt.% water) and ambient dry (10 wt.% water) conditions along the longitudinal and radial directions under tension and compression. Increased moisture content was found to increase ductility and decrease strength, as well as alter the stress state dependent nature of the material. Furthermore, the horn keratin demonstrates a significant strain rate dependence in both tension and compression, and also showed increased energy absorption in the hydrated condition at high strain rates when compared to quasi-static data, with increases of 114% in tension and 192% in compression. Compressive failure occurred by lamellar buckling in the longitudinal orientation followed by shear delamination. Tensile failure in the longitudinal orientation occurred by lamellar delamination combined with tubule pullout and fracture. Finally, the structure-property relationships quantified here for bighorn sheep horn keratin can be used to help validate finite element simulations of ram’s impacting each other as well as being usefulmore » for other analysis regarding horn keratin on other animals.« less
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4] ;  [1]
  1. Mississippi State Univ., Mississippi State, MS (United States). Dept. of Mechanical Engineering and Center for Advanced Vehicular Systems (CAVS)
  2. US Army Engineer Research and Development Center, Vicksburg, MS (United States)
  3. Mississippi State Univ., Mississippi State, MS (United States). Center for Advanced Vehicular Systems (CAVS)
  4. Mississippi State Univ., Mississippi State, MS (United States). Center for Advanced Vehicular Systems (CAVS) and Dept. of Agricultural and Biological Engineering
Publication Date:
Grant/Contract Number:
EE0002323
Type:
Accepted Manuscript
Journal Name:
Acta Biomaterialia
Additional Journal Information:
Journal Name: Acta Biomaterialia; Journal ID: ISSN 1742-7061
Publisher:
Acta Materialia, Inc.
Research Org:
Mississippi State Univ., Mississippi State, MS (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; sheep horn; keratin; stress state dependence; strain rate dependence; mechanical properties; structure-property relations
OSTI Identifier:
1330102

Johnson, K. L., Trim, M. W., Francis, D. K., Whittington, W. R., Miller, J. A., Bennett, C. E., and Horstemeyer, M. F.. Moisture, anisotropy, stress state, and strain rate effects on bighorn sheep horn keratin mechanical properties. United States: N. p., Web. doi:10.1016/j.actbio.2016.10.033.
Johnson, K. L., Trim, M. W., Francis, D. K., Whittington, W. R., Miller, J. A., Bennett, C. E., & Horstemeyer, M. F.. Moisture, anisotropy, stress state, and strain rate effects on bighorn sheep horn keratin mechanical properties. United States. doi:10.1016/j.actbio.2016.10.033.
Johnson, K. L., Trim, M. W., Francis, D. K., Whittington, W. R., Miller, J. A., Bennett, C. E., and Horstemeyer, M. F.. 2016. "Moisture, anisotropy, stress state, and strain rate effects on bighorn sheep horn keratin mechanical properties". United States. doi:10.1016/j.actbio.2016.10.033. https://www.osti.gov/servlets/purl/1330102.
@article{osti_1330102,
title = {Moisture, anisotropy, stress state, and strain rate effects on bighorn sheep horn keratin mechanical properties},
author = {Johnson, K. L. and Trim, M. W. and Francis, D. K. and Whittington, W. R. and Miller, J. A. and Bennett, C. E. and Horstemeyer, M. F.},
abstractNote = {Our paper investigates the effects of moisture, anisotropy, stress state, and strain rate on the mechanical properties of the bighorn sheep (Ovis Canadensis) horn keratin. The horns consist of fibrous keratin tubules extending along the length of the horn and are contained within an amorphous keratin matrix. We tested samples in the rehydrated (35 wt.% water) and ambient dry (10 wt.% water) conditions along the longitudinal and radial directions under tension and compression. Increased moisture content was found to increase ductility and decrease strength, as well as alter the stress state dependent nature of the material. Furthermore, the horn keratin demonstrates a significant strain rate dependence in both tension and compression, and also showed increased energy absorption in the hydrated condition at high strain rates when compared to quasi-static data, with increases of 114% in tension and 192% in compression. Compressive failure occurred by lamellar buckling in the longitudinal orientation followed by shear delamination. Tensile failure in the longitudinal orientation occurred by lamellar delamination combined with tubule pullout and fracture. Finally, the structure-property relationships quantified here for bighorn sheep horn keratin can be used to help validate finite element simulations of ram’s impacting each other as well as being useful for other analysis regarding horn keratin on other animals.},
doi = {10.1016/j.actbio.2016.10.033},
journal = {Acta Biomaterialia},
number = ,
volume = ,
place = {United States},
year = {2016},
month = {10}
}