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Finite Element Modeling of CNS White Matter Kinematics: Use of a 3D RVE to Determine Material Properties.

Pan Y, Sullivan D, Shreiber DI, Pelegri AA - Front Bioeng Biotechnol (2013)

Bottom Line: An inverse FE procedure was developed to identify material parameters of spinal cord white matter by combining the results of uniaxial testing with FE modeling.A satisfactory balance between simulation and experiment was achieved via optimization by minimizing the squared error between the simulated and experimental force-stretch curve.The combination of experimental testing and FE analysis provides a useful analysis tool for soft biological tissues in general, and specifically enables evaluations of the axonal response to tissue-level loading and subsequent predictions of axonal damage.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey , Piscataway, NJ , USA.

ABSTRACT
Axonal injury represents a critical target area for the prevention and treatment of traumatic brain and spinal cord injuries. Finite element (FE) models of the head and/or brain are often used to predict brain injury caused by external mechanical loadings, such as explosive waves and direct impact. The accuracy of these numerical models depends on correctly determining the material properties and on the precise depiction of the tissues' microstructure (microscopic level). Moreover, since the axonal microstructure for specific regions of the brain white matter is locally oriented, the stress, and strain fields are highly anisotropic and axon orientation dependent. Additionally, mechanical strain has been identified as the proximal cause of axonal injury, which further demonstrates the importance of this multi-scale relationship. In this study, our previously developed FE and kinematic axonal models are coupled and applied to a pseudo 3-dimensional representative volume element of central nervous system white matter to investigate the multi-scale mechanical behavior. An inverse FE procedure was developed to identify material parameters of spinal cord white matter by combining the results of uniaxial testing with FE modeling. A satisfactory balance between simulation and experiment was achieved via optimization by minimizing the squared error between the simulated and experimental force-stretch curve. The combination of experimental testing and FE analysis provides a useful analysis tool for soft biological tissues in general, and specifically enables evaluations of the axonal response to tissue-level loading and subsequent predictions of axonal damage.

No MeSH data available.


Related in: MedlinePlus

Stress-stretch curves of E18 chick embryo spinal cord: the converged simulation vs. experimental in Shreiber et al. (2009).
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Figure 4: Stress-stretch curves of E18 chick embryo spinal cord: the converged simulation vs. experimental in Shreiber et al. (2009).

Mentions: The von Mises stress contours of the ECM and the axons subjected to a stretch rate of 1.06 in the z-axis are shown in Figures 2A,B, respectively. Since the interaction between matrixes and axons depends on the geometry of the axons, the stresses are highly localized. The overall average uniaxial stress-strain curves are plotted in Figure 4, where S33 is the nominal engineering stress component in the z-direction.


Finite Element Modeling of CNS White Matter Kinematics: Use of a 3D RVE to Determine Material Properties.

Pan Y, Sullivan D, Shreiber DI, Pelegri AA - Front Bioeng Biotechnol (2013)

Stress-stretch curves of E18 chick embryo spinal cord: the converged simulation vs. experimental in Shreiber et al. (2009).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126384&req=5

Figure 4: Stress-stretch curves of E18 chick embryo spinal cord: the converged simulation vs. experimental in Shreiber et al. (2009).
Mentions: The von Mises stress contours of the ECM and the axons subjected to a stretch rate of 1.06 in the z-axis are shown in Figures 2A,B, respectively. Since the interaction between matrixes and axons depends on the geometry of the axons, the stresses are highly localized. The overall average uniaxial stress-strain curves are plotted in Figure 4, where S33 is the nominal engineering stress component in the z-direction.

Bottom Line: An inverse FE procedure was developed to identify material parameters of spinal cord white matter by combining the results of uniaxial testing with FE modeling.A satisfactory balance between simulation and experiment was achieved via optimization by minimizing the squared error between the simulated and experimental force-stretch curve.The combination of experimental testing and FE analysis provides a useful analysis tool for soft biological tissues in general, and specifically enables evaluations of the axonal response to tissue-level loading and subsequent predictions of axonal damage.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey , Piscataway, NJ , USA.

ABSTRACT
Axonal injury represents a critical target area for the prevention and treatment of traumatic brain and spinal cord injuries. Finite element (FE) models of the head and/or brain are often used to predict brain injury caused by external mechanical loadings, such as explosive waves and direct impact. The accuracy of these numerical models depends on correctly determining the material properties and on the precise depiction of the tissues' microstructure (microscopic level). Moreover, since the axonal microstructure for specific regions of the brain white matter is locally oriented, the stress, and strain fields are highly anisotropic and axon orientation dependent. Additionally, mechanical strain has been identified as the proximal cause of axonal injury, which further demonstrates the importance of this multi-scale relationship. In this study, our previously developed FE and kinematic axonal models are coupled and applied to a pseudo 3-dimensional representative volume element of central nervous system white matter to investigate the multi-scale mechanical behavior. An inverse FE procedure was developed to identify material parameters of spinal cord white matter by combining the results of uniaxial testing with FE modeling. A satisfactory balance between simulation and experiment was achieved via optimization by minimizing the squared error between the simulated and experimental force-stretch curve. The combination of experimental testing and FE analysis provides a useful analysis tool for soft biological tissues in general, and specifically enables evaluations of the axonal response to tissue-level loading and subsequent predictions of axonal damage.

No MeSH data available.


Related in: MedlinePlus