Development of a Biofidelic Human Head Model

Overview

Traumatic brain injuries from head impact are a major issue across areas such as defence, automotive and sports, and can be costly to research using experimental testing. These injuries can be explored, though, through 3D models created from scan data and computer simulations. Simpleware has worked with the US Naval Research Laboratory to develop a cutting-edge human head model suitable for a wide range of head injury simulations. Major innovations of the modelling workflow include the ability to generate multiple meshes from the same pre-segmented data (rather than fixed meshes), and the level of detail and flexibility possible for adding new parts and integrating CAD with image data.

Characteristics:

Data acquired from high-resolution MRI scan
Image data segmented into regions of interest
Multi-part mesh generated for FE simulations
Pre-segmented data allows new meshes to be created for different applications

References

Cotton et al., 2015. Development of a geometrically accurate and adaptable finite element head model for impact simulation: the Naval Research Laboratory Simpleware Head Model. Comput Meth Biomech Biomed Eng, [in press].

Pearce, C., Young, P., 2015. On the Pressure Response in the Brain Due to Short Duration Blunt Impacts. PLOS One, 9(12), e114292.

Thanks to

University of Exeter: C.W. Pearce • P.G. Young
Naval Research Laboratory: N. Kota • A.C. Leung • A. Bagchi • S.M. Qidqai

Acknowledgments

This work was supported by the Office of Naval Research (ONR) through the US Naval Research Laboratory's Basic Research Program, and the Department of Defense (DoD) through the High Performance Computing Modernization Program (HPCMP).

Creating the Head Model

A high resolution in-vivo whole head MRI scan of a male volunteer was acquired at the Royal Devon and Exeter Hospital with a slice to slice separation of 1.04001 mm. The subject was 25 years old, 1.8m tall, and weighed 81 kg.

The data was imported to Simpleware ScanIP for segmentation, with a range of software tools used to identify multiple regions of interest, including skin, muscles, and soft tissue.

Simpleware CAD was employed to build additional regions, such as the facial and neck muscles, using voxelization methods. This method also allows helmets, pathologies and probes to be incorporated into image data.

FE Mesh Generation

Segmented image data can be converted into a multi-part mesh in Simpleware FE using two approaches – an EVOMAC-based approach (FE Grid) that converts voxels directly into finite elements, and more flexible surface triangulation followed by Delaunay tetrahedralization, producing unstructured, fully tet meshes that can be easily adapted (FE Free). Simpleware meshing also allows contacts, node sets and shells to be added, Boolean operations to be applied, and material properties to be assigned.

The NRL/Simpleware head model was generated as an unstructured tetrahedral mesh with 3.72 M volumetric elements using FE Free.

Validation and Customization

The NRL/Simpleware head model has been successfully used to run blunt impact and blast simulations in Abaqus/Explicit (200 Intel cores, 2 GB RAM, 2.6 GHz core speed). Blunt impact simulations showed good agreement with experimental studies on a post-mortem human subject. The NRL/Simpleware head model can be easily repurposed to create new models for different types of simulation, and to adapt to changes in computational power and imaging quality.