The objective of this study was to define the constitutive response of brainstem undergoing finite shear deformation. Brainstem was characterized as a transversely isotropic viscoelastic material and the material model was formulated for numerical implementation. Model parameters were fit to shear data obtained in porcine brainstem specimens undergoing finite shear deformation in three directions: parallel, perpendicular, and cross sectional to axonal fiber orientation and determined using a combined approach of finite element analysis (FEA) and a genetic algorithm (GA) optimizing method. The average initial shear modulus of brainstem matrix of 4-week old pigs was , and therefore the brainstem offers little resistance to large shear deformations in the parallel or perpendicular directions, due to the dominant contribution of the matrix in these directions. The fiber reinforcement stiffness was , indicating that brainstem is anisotropic and that axonal fibers have an important role in the cross-sectional direction. The first two leading relative shear relaxation moduli were 0.8973 and 0.0741, respectively, with corresponding characteristic times of 0.0047 and , respectively, implying rapid relaxation of shear stresses. The developed material model and parameter estimation technique are likely to find broad applications in neural and orthopaedic tissues.
Skip Nav Destination
e-mail: margulie@seas.upenn.edu
Article navigation
December 2006
Technical Papers
A Transversely Isotropic Viscoelastic Constitutive Equation for Brainstem Undergoing Finite Deformation
Xinguo Ning,
Xinguo Ning
Department of Bioengineering,
University of Pennsylvania
, Philadelphia, PA 19104-6382
Search for other works by this author on:
Qiliang Zhu,
Qiliang Zhu
Department of Bioengineering,
University of Pennsylvania
, Philadelphia, PA 19104-6382
Search for other works by this author on:
Yoram Lanir,
Yoram Lanir
Department of Bioengineering,
University of Pennsylvania
, Philadelphia, PA 19104-6382
Search for other works by this author on:
Susan S. Margulies
Susan S. Margulies
Department of Bioengineering,
e-mail: margulie@seas.upenn.edu
University of Pennsylvania
, Philadelphia, PA 19104-6382
Search for other works by this author on:
Xinguo Ning
Department of Bioengineering,
University of Pennsylvania
, Philadelphia, PA 19104-6382
Qiliang Zhu
Department of Bioengineering,
University of Pennsylvania
, Philadelphia, PA 19104-6382
Yoram Lanir
Department of Bioengineering,
University of Pennsylvania
, Philadelphia, PA 19104-6382
Susan S. Margulies
Department of Bioengineering,
University of Pennsylvania
, Philadelphia, PA 19104-6382e-mail: margulie@seas.upenn.edu
J Biomech Eng. Dec 2006, 128(6): 925-933 (9 pages)
Published Online: June 29, 2006
Article history
Received:
September 15, 2005
Revised:
June 29, 2006
Citation
Ning, X., Zhu, Q., Lanir, Y., and Margulies, S. S. (June 29, 2006). "A Transversely Isotropic Viscoelastic Constitutive Equation for Brainstem Undergoing Finite Deformation." ASME. J Biomech Eng. December 2006; 128(6): 925–933. https://doi.org/10.1115/1.2354208
Download citation file:
Get Email Alerts
Related Articles
The Influence of Test Conditions on Characterization of the Mechanical Properties of Brain Tissue
J Biomech Eng (June,2008)
Myocardial Material Parameter Estimation—A Comparative Study for Simple Shear
J Biomech Eng (October,2006)
Mechanical Characterization of Anisotropic Planar Biological Soft
Tissues Using Large Indentation: A Computational Feasibility
Study
J Biomech Eng (June,2006)
Modified Bilston Nonlinear Viscoelastic Model for Finite Element Head Injury Studies
J Biomech Eng (October,2006)
Related Proceedings Papers
Related Chapters
Parameter Estimation of the Duffing Oscillator Using Poincaré Map and an Elitist Genetic Algorithm
Intelligent Engineering Systems through Artificial Neural Networks, Volume 20
Brain Tissue Segmentation in MRI Images Using Random Forest Classifier and Gossip Based Neighborhood
International Conference on Computer Technology and Development, 3rd (ICCTD 2011)
Experimental Studies
Nanoparticles and Brain Tumor Treatment