spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kasapi, M. A.
Right arrow Articles by Gosline, J. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kasapi, M. A.
Right arrow Articles by Gosline, J. M.

Journal of Experimental Biology, Vol 200, Issue 11 1639-1659, Copyright © 1997 by Company of Biologists

JOURNAL ARTICLES

Design complexity and fracture control in the equine hoof wall

MA Kasapi and JM Gosline
Department of Zoology, University of British Columbia, Vancouver, Canada.

Morphological and mechanical studies were conducted on samples of equine hoof wall to help elucidate the relationship between form and function of this complex, hierarchically organized structure. Morphological findings indicated a dependence of tubule size, shape and helical alignment of intermediate filaments (IFs) within the lamellae on the position through the wall thickness. The plane of the intertubular IFs changed from perpendicular to the tubule axis in the inner wall to almost parallel to the tubule axis in the outer wall. Morphological data predicted the existence of three crack diversion mechanisms which might prevent cracks from reaching the sensitive, living tissues of the hoof: a mid-wall diversion mechanism of intertubular material to inhibit inward and upward crack propagation, and inner- and outer-wall diversion mechanisms that prevent inward crack propagation. Tensile and compact tension fracture tests were conducted on samples of fully hydrated equine hoof wall. Longitudinal stiffness decreased from 0.56 to 0.30 GPa proceeding inwardly, whereas ultimate (maximum) properties were constant. Fracture toughness parameters indicated that no compromise results from the declining stiffness, with J-integral values ranging from 5.5 to 7.8 kJ m-2 through the wall thickness; however, highest toughness was found in specimens with cracks initiated tangential to the wall surface (10.7 kJ m-2). Fracture paths agreed with morphological predictions and further suggested that the wall has evolved into a structure capable of both resisting and redirecting cracks initiated in numerous orientations.


This article has been cited by other articles:


Home page
 J. Exp. Biol.Home page
K. J. Mach, D. V. Nelson, and M. W. Denny
Techniques for predicting the lifetimes of wave-swept macroalgae: a primer on fracture mechanics and crack growth
J. Exp. Biol., July 1, 2007; 210(13): 2213 - 2230.
[Abstract] [Full Text] [PDF]

Home page
 J. Exp. Biol.Home page
L. Farren, S. Shayler, and A. R. Ennos
The fracture properties and mechanical design of human fingernails
J. Exp. Biol., February 15, 2004; 207(5): 735 - 741.
[Abstract] [Full Text] [PDF]

Home page
 J. Exp. Biol.Home page
R. Ker, X. Wang, and A. Pike
Fatigue quality of mammalian tendons
J. Exp. Biol., January 4, 2000; 203(8): 1317 - 1327.
[Abstract] [PDF]

Home page
 J. Exp. Biol.Home page
M. Kasapi and J. Gosline
Micromechanics of the equine hoof wall: optimizing crack control and material stiffness through modulation of the properties of keratin
J. Exp. Biol., January 2, 1999; 202(4): 377 - 391.
[Abstract] [PDF]


© The Company of Biologists Ltd 1997