Sponsor
Partial support was provided to SSK by the National Institutes of Health (EB007077 and MD003350).
Published In
Journal of Biomechanics
Document Type
Post-Print
Publication Date
9-1-2009
Subjects
Tissues -- Mechanical properties, Anisotropy, Tissues -- Optical measurements
Abstract
Tracking tissue deformation is often hampered by material inhomogeneity, so local measurements tend to be insufficient thus lending to the necessity of full-field optical measurements. This study presents a novel approach to factoring heterogeneous deformation of soft and hard tissues in a fracture callus by introducing an anisotropic metric derived from the deformation gradient tensor (F). The deformation gradient tensor contains all the information available in a Green-Lagrange strain tensor, plus the rigid-body rotational components. A recent study [Bottlang et al., J. Biomech. 41(3), 2008] produced full-field strains within ovine fracture calluses acquired through the application of electronic speckle pattern interferometery (ESPI). The technique is based on infinitesimal strain approximation (Engineering Strain) whose scheme is not independent of rigid body rotation. In this work, for rotation extraction, the stretch and rotation tensors were separately determined from F by the polar decomposition theorem. Interfragmentary motions in a fracture gap were characterized by the two distinct mechanical factors (stretch and rotation) at each material point through full-field mapping. In the composite nature of bone and soft tissue, collagen arrangements are hypothesized such that fibers locally aligned with principal directions will stretch and fibers not aligned with the principal direction will rotate and stretch. This approach has revealed the deformation gradient tensor as an appropriate quantification of strain within callus bony and fibrous tissue via optical measurements.
DOI
10.1016/j.jbiomech.2009.06.009
Persistent Identifier
http://archives.pdx.edu/ds/psu/8359
Citation Details
Kim, W., & Kohles, S. S. (2009). Optical acquisition and polar decomposition of the full-field deformation gradient tensor within a fracture callus. Journal Of Biomechanics, 42(13), 2026-2032.
Description
This is the author's version of a work that was accepted for publication in Journal of Biomechanics. Changes resulting from the publishing process, such as peer revieinitive version was subsequently published in Journal of Biomechanics, doi:10.1016/j.jbiomech.2009.06.009