Document Type

Thesis

Date of Award

Summer 8-31-2017

Degree Name

Master of Science in Biomedical Engineering - (M.S.)

Department

Biomedical Engineering

First Advisor

Bryan J. Pfister

Second Advisor

N. Chandra

Third Advisor

Maciej Skotak

Abstract

It is widely accepted that under extreme loadings the soft tissue of the brain will deform inside the skull, creating large amounts of both stress and strain on the tissue. This can result in a focal injury, or in the case of acceleration and deceleration, diffuse injuries. Any attempt at understanding the underlying mechanisms and effects of TBI, have to start by focusing on what is actually occurring within the brain. The objective of this experiment is to record differences in the spatial and temporal patterns of deformation within the brain during blunt trauma when changing impact parameters. A linear impactor is used to deliver controlled blows to the head surrogate, mimicking real-world blunt injury scenarios. Visual markers within head surrogates are used to motion track deformations and extract strains (principal tension, principal compression, max shear). The loading conditions include impact velocities at 3 and 5 miles per hour, impact locations at the crown of the skull and the forehead, and with the brain composition being either a 10% or 20% ballistics gelatin. To generalize, crown injuries cause higher strains than front impacts, and 5mph impacts cause larger strains than 3mph impacts. The 10% gelatin produce larger strain than 20% gelatin, but with large standard deviations. Contour maps of the maximum strains occurring in the brain reveal regional differences when comparing crown and front impacts at the mid sagittal plane. The results suggest differences in loading conditions cause heterogeneity in trauma outcomes.

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