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Research Papers

Development and Validation of Subject-Specific Finite Element Models for Blunt Trauma Study

[+] Author and Article Information
Weixin Shen, Yuqing Niu, Adam Fournier, James H. Stuhmiller

 SET Division, L-3 Jaycor, 3394 Carmel Mountain Road, San Diego, CA 92121

Robert F. Mattrey, Jackie Corbeil, Yuko Kono

Department of Radiology, University of California, San Diego, CA 92103

J Biomech Eng 130(2), 021022 (Apr 11, 2008) (13 pages) doi:10.1115/1.2898723 History: Received March 16, 2006; Revised June 11, 2007; Published April 11, 2008

This study developed and validated finite element (FE) models of swine and human thoraxes and abdomens that had subject-specific anatomies and could accurately and efficiently predict body responses to blunt impacts. Anatomies of the rib cage, torso walls, thoracic, and abdominal organs were reconstructed from X-ray computed tomography (CT) images and extracted into geometries to build FE meshes. The rib cage was modeled as an inhomogeneous beam structure with geometry and bone material parameters determined directly from CT images. Meshes of soft components were generated by mapping structured mesh templates representative of organ topologies onto the geometries. The swine models were developed from and validated by 30 animal tests in which blunt insults were applied to swine subjects and CT images, chest wall motions, lung pressures, and pathological data were acquired. A comparison of the FE calculations of animal responses and experimental measurements showed a good agreement. The errors in calculated response time traces were within 10% for most tests. Calculated peak responses showed strong correlations with the experimental values. The stress concentration inside the ribs, lungs, and livers produced by FE simulations also compared favorably to the injury locations. A human FE model was developed from CT images from the Visible Human project and was scaled to simulate historical frontal and side post mortem human subject (PMHS) impact tests. The calculated chest deformation also showed a good agreement with the measurements. The models developed in this study can be of great value for studying blunt thoracic and abdominal trauma and for designing injury prevention techniques, equipments, and devices.

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Copyright © 2008 by American Society of Mechanical Engineers
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Figure 1

Demonstration of procedures for the model development and validation. (a) Raw anatomies of rib cage, torso walls, and soft organs were reconstructed from CT images. (b) Geometrical modeling of raw anatomies produced smoothed geometries that matched together and can easily be modified. (c) FE modeling of rib cage treated the rib as inhomogeneous composite beam/shell structure with bone material properties directly calculated from CT number. (d) FE meshes of soft organs, such as a lung, were generated by mapping a carefully constructed mesh template onto NURB surfaces. (e) Human and swine models were assembled for simulating animal and PMHS tests

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Figure 2

Comparison of the FE calculation of time traces of deformation, velocity, delivered energy, and lung pressure with experimental measurements obtained in test 14

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Figure 3

Comparison of FE calculation of peak response values with experimental values

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Figure 4

Comparison of injuries observed in tests with FE calculation of stresses. (a) Ribs fracture versus FE calculation of tensile stress distribution. (b) Lung contusion from necropsy and reconstructed postimpact CT images versus FE calculation of pressure distribution. (c) Liver injury versus FE calculation of compressive stress distribution.

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Figure 5

Comparison of calculated response time histories from three FE models. (1) Subject-specific model with optimized mesh. (2) Non-subject-specific model. (3) Subject-specific model with reduced mesh.

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Figure 6

Comparison of calculated rib, lung, and liver stress distribution from the three FE models. (a) Peak rib stress, (b) Lung pressure, and (c) liver compressive stress from model 1 (left), model 2 (middle), and model 3 (right).

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