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Afewerki, H. (2016) Biofidelity Evaluation of Thoracolumbar Spine Model in THUMS. Göteborg : Chalmers University of Technology (Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, nr: 2016:54).
BibTeX
@mastersthesis{
Afewerki2016,
author={Afewerki, Henok},
title={Biofidelity Evaluation of Thoracolumbar Spine Model in THUMS},
abstract={Thoracolumbar spine injuries in motor vehicle crashes are occurring and the mechanisms
are poorly understood. It has been hypothesized to be connected to vehicle’s restraint
systems but further studies are required to understand and subsequently address the problem
in future restraint systems. Finite Element (FE)-Human body models are invaluable
tools for crash analysis, however, quality of the response depends on the biofidelity of
the model. The objective of this thesis is to evaluate biofidelity of the thoracolumbar
spine model in Total Human Model for Safety (THUMS), Toyota Motor Corporation and
Toyota Central R&D Labs .
In this thesis work three dynamic and one static thoracolumbar experiments were simulated.
THUMS’ ligaments were verified against cadaveric data. Two modified disc material
models were inserted in to THUMS and the results compared against experimental
data. The Global Human Body Model Concertium model (GHBMC), GHMBC, LLC was
also evaluated against cadaveric data from two experiments. All simulations were run
in LS-DYNA and pre and postprocessing tasks were performed in LS-PrePost and Matlab.
The response of the lumbar FSUs in THUMS’ under the dynamic compression test was
similar to the experimental data but was three to four times less stiff. On the other hand,
the T12-L5 segment showed fair correlation of reaction force whereas reaction moment
was significantly lower. Kinematics of the cadaveric spine under flexion and extension
tests was not captured. Reaction moment, shear force and vertical displacement were
found to deviate from the response of the cadaveric specimens during the dynamic flexion
and shear test. Only horizontal displacement showed good correlation in this test.
THUMS performance was good in the static flexion and shear test but poor in flexion
only test. Furthermore, the Capsular Ligaments (CL) and the Ligamentum Flavum (LF)
in THUMS were found to be about three times shorter and stiffer, respectively. In all
the simulations the intervertebral contacts were responsible for the sudden and large increase
and vibrations occurring at about the experimental failure point. The modified
disc material models improved response of only the lumbar FSUs under the compression
test.
In conclusion, biofidelity of the thoracolumbar spine model in THUMS is found to be
poor and remodelling is necessary. The compliant nature of the intervertebral discs, the
shorter length of the CL and higher stiffness of the LF and the smaller initial invetervertebral
gap were identified as the main weaknesses of the model.},
publisher={Institutionen för tillämpad mekanik, Fordonssäkerhet, Chalmers tekniska högskola},
place={Göteborg},
year={2016},
series={Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, no: 2016:54},
keywords={Thoracolumbar, Biofideltiy, Kinematics, Flexion, Extension, Shear, Stiffness},
}
RefWorks
RT Generic
SR Electronic
ID 239080
A1 Afewerki, Henok
T1 Biofidelity Evaluation of Thoracolumbar Spine Model in THUMS
YR 2016
AB Thoracolumbar spine injuries in motor vehicle crashes are occurring and the mechanisms
are poorly understood. It has been hypothesized to be connected to vehicle’s restraint
systems but further studies are required to understand and subsequently address the problem
in future restraint systems. Finite Element (FE)-Human body models are invaluable
tools for crash analysis, however, quality of the response depends on the biofidelity of
the model. The objective of this thesis is to evaluate biofidelity of the thoracolumbar
spine model in Total Human Model for Safety (THUMS), Toyota Motor Corporation and
Toyota Central R&D Labs .
In this thesis work three dynamic and one static thoracolumbar experiments were simulated.
THUMS’ ligaments were verified against cadaveric data. Two modified disc material
models were inserted in to THUMS and the results compared against experimental
data. The Global Human Body Model Concertium model (GHBMC), GHMBC, LLC was
also evaluated against cadaveric data from two experiments. All simulations were run
in LS-DYNA and pre and postprocessing tasks were performed in LS-PrePost and Matlab.
The response of the lumbar FSUs in THUMS’ under the dynamic compression test was
similar to the experimental data but was three to four times less stiff. On the other hand,
the T12-L5 segment showed fair correlation of reaction force whereas reaction moment
was significantly lower. Kinematics of the cadaveric spine under flexion and extension
tests was not captured. Reaction moment, shear force and vertical displacement were
found to deviate from the response of the cadaveric specimens during the dynamic flexion
and shear test. Only horizontal displacement showed good correlation in this test.
THUMS performance was good in the static flexion and shear test but poor in flexion
only test. Furthermore, the Capsular Ligaments (CL) and the Ligamentum Flavum (LF)
in THUMS were found to be about three times shorter and stiffer, respectively. In all
the simulations the intervertebral contacts were responsible for the sudden and large increase
and vibrations occurring at about the experimental failure point. The modified
disc material models improved response of only the lumbar FSUs under the compression
test.
In conclusion, biofidelity of the thoracolumbar spine model in THUMS is found to be
poor and remodelling is necessary. The compliant nature of the intervertebral discs, the
shorter length of the CL and higher stiffness of the LF and the smaller initial invetervertebral
gap were identified as the main weaknesses of the model.
PB Institutionen för tillämpad mekanik, Fordonssäkerhet, Chalmers tekniska högskola,PB SAFER - Fordons- och Trafiksäkerhetscentrum , Chalmers tekniska högskola,
T3 Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, no: 2016:54
LA eng
LK http://publications.lib.chalmers.se/records/fulltext/239080/239080.pdf
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