The mechanical properties of cortical bone vary not only from bone to bone; they
demonstrate a spatial viability even within the same bone due to its changing
microstructure. They also depend considerably on different loading modes and
orientations. To understand the variability and anisotropic mechanical behavior of a
cortical bone tissue, specimens cut from four anatomical quadrants of bovine
femurs were investigated both in tension and compression tests. The obtained
experimental results revealed a highly anisotropic mechanical behavior, depending
also on the loading mode (tension and compression). A compressive longitudinal
loading regime resulted in the best load-bearing capacity for cortical bone, while
tensile transverse loading provided significantly poorer results. The distinctive
stress-strain curves obtained for tension and compression demonstrated various
damage mechanisms associated with different loading modes. The variability of
mechanical properties for different cortices was evaluated with two-way ANOVA
analyses. Statistical significances were found among different quadrants for the
Young’s modulus. The results of microstructure analysis of the entire transverse
cross section of a cortical bone also confirmed variations of volume fractions of
constituents at microscopic level between anatomic quadrants: microstructure of the
anterior quadrant was dominated by plexiform bone, whereas secondary osteons
were prominent in the posterior quadrant. The effective Young’s modulus predicted
using the modified Voigt-Reuss-Hill averaging scheme accurately reproduced our
experimental results, corroborating additionally a strong effect of random and
heterogeneous microstructure on variation of mechanical properties in cortical bone.
Funding
The authors are grateful to the EPSRC UK (grant EP/G04886/1) for financial
support of these studies.
History
School
Mechanical, Electrical and Manufacturing Engineering
Published in
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
Volume
21
Pages
109 - 120 (12)
Citation
LI, S.-M., DEMIRCI, E. and SILBERSCHMIDT, V.V., 2013. Variability and anisotropy of mechanical behavior of cortical bone in tension and compression. Journal of the Mechanical Behavior of Biomedical Materials, 21, pp. 109-120.
This is the author’s version of a work that was accepted for publication in Journal of the Mechanical Behavior of Biomedical Materials. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in: Journal of the Mechanical Behavior of Biomedical Materials, 21, pp. 109-120. URL: http://dx.doi.org/10.1016/j.jmbbm.2013.02.021.