Finite Element Analysis of the Effects of Head-Supported Mass on Neck Responses: Complete Phase Three Report

Affiliations

¹Royal Institute of Technology, School of Technology and Health, Division of Neuronic Engineering Stockholm, Sweden

Links

URL: http://www.dtic.mil/get-tr-doc/pdf?AD=ADA456789

Abstract and keywords

Technical Objectives: The objectives for the whole project were to:

determine the relationships between head supported mass and the risk of neck injuries. The results should be used in a Graphical user interface. In this phase three report has also the Graphical User Interphase (GUI) been evaluated and the question about the how the muscle activation affect the injury risk.
II. to develop and implement a 3D numerical muscle model.

Method: Ad. I was done using a detailed Finite Element (FE) model of the human neck developed at the Royal Institute of Technology, Stockholm, Sweden. Ad. II was based on an FE model with a new geometry of the cervical spine.

I. The simulation matrix included seven impact situations (frontal, rear end, lateral, vertical, and oblique impacts in the horizontal plane, frontal plane, and sagittal plane.), three impact severities (5, 13.5 and 22 G), three helmet masses (1, 2 and 3 kg), and nine locations of the Center of Gravity of the helmet (offset relative to the CG of the head with -2, 0, 2, 4 and 6 cm in the superior/inferior and anterior/posterior directions). The neck model with just enough muscle activation to keep the head and helmet in upright position was compared with the model set to 100% activation of the neck muscle force. The GUI was evaluated using helmet inertial properties from two real helmets in use by the US Army.
II. The Suboccipital muscles, Deep dorsal muscles, Ventral muscles, Muscles linking the skull with the shoulder girdle and the Muscles linking the vertebral column with the scapulas and the ribcage have been modeled using 4 node solid elements for the passive properties and spring elements for the active part. The surfaces defining the muscles in the cervical spine were detected by segmentation from MR-scans using the software AMIRA. The surfaces were then smoothed and adjusted using the software Hypermesh. The meshing of the muscles was then performed with the software Truegrid. Contacts were defined between the interacting muscles. The new muscle model has been compared to a model with a spring muscle model for both the passive and the active part.

Results:

I. The KTH neck model has successfully been used to generate results for the GUI. Results from all simulations have been reported and sent to Titan Corporation that is contracted by USAARL to program the GUI. The GUI that uses an interpolation method to calculate the neck injury risk for a general helmet with a user defined HSM configuration shows to give realistic interpolated values compared to the FE model of the neck.
II. The 3D muscle model for the cervical spine includes 22 pairs of muscles. The solid muscle model showed to stabilize the vertebral column better than the spring muscle model. The model is still under evaluation and need further validation to be used in the HSM evaluation project.

Keywords: Finite element analysis; cervical spine; injury; prevention; muscles

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Cited By (1)

Year	Entry
2018	Schoenfeld M. Cervical Intervertebral Kinematics and Neck Muscle Responses During Simulated Vehicle Rollovers [Master's thesis]. Vancouver, BC: University of British Columbia; August 2018.