Date of Award

12-2011

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Bioengineering

Advisor

LaBerge, Martine

Committee Member

Grujicic , Mica

Committee Member

Bowman , Larry

Abstract

Mild traumatic brain injury (mTBI), colloquially known as a concussion, is the most common injury in modern wars. This domination of mTBI is hypothesized to be due to a combination of unconventional explosives and better protection and care of the patients, increasing survivability. While the majority of the body is covered in armor, the head is left relatively unprotected. The current Advanced Combat Helmet (ACH) has been designed to protect the warfighter against ballistic impacts and impacts against a hard surface, with little to no regard to blast loading. Polyureas, a class of microsegregated, elastomeric copolymers, has been shown to be effective in shock mitigation. A combined Eulerian/Lagrangian transient nonlinear dynamics computational fluid/solid interaction analysis will be used to examine the effects of different polyurea augmentations (utilizing the polyurea in the suspension pads, as well as introducing a thin polyurea inner lining/outer coating ) to the current ACH design under blast loading conditions attributed to causing mTBI. Quantifications of shock mitigation efficacy will be determined by: (a) establishing the main forms of mTBI, (b) identifying the mechanical causes for these injuries, and (c) quantifying the magnitude changes for the mechanical causes.
Mild TBI can be broken down into three main injuries: diffuse axonal injury (DAI), subdural hemorrhage, and contusion. DAI occurs due to the stretching and shearing of axons, leading to a disruption in the cytoskeleton which inhibits neuronal transport. Subdural hemorrhage occurs when the relative motion of the brain causes shear forces large enough to rupture blood vessels bridging the brain and the dura mater. Contusions occur due to coup-contrecoup injuries, where the coup region is the initial shock impact site and the contrecoup site is the opposite of the coup site. The shear stresses, maximum principal stresses, and relative distance between the brain and the skull will be monitored.
It was found that the addition of a polyurea inner lining was most effective in blast mitigation; however, this augmentation did not provide a significant amount of protection compared to the standard ACH.

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