Date of Award

5-2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Polymer and Fiber Science

Advisor

Brown, Philip

Committee Member

Blouin , Vincent

Committee Member

Cole , Christine

Abstract

Currently soldiers are being exposed a much higher number of improvised explosive devices (IEDs) and the resulting shockwaves. These shockwaves can cause traumatic brain injuries (TBIs) even without the occurrence of ballistic impact. The focus of this research was to reduce the amount of shockwaves soldiers are exposed to by inserting fibers and woven fabrics into a foam padding system. These fibers and fabrics facilitate the dissipation of the shockwave energy before it is able to penetrate the padding and cause TBIs.
The sound velocity of high-performance fibers, commodity fibers and woven fabric was measured using a Dynamic Modulus Tester. There was a significant difference between the sound velocities of the high-performance and commodity fibers. The instrument was also used to investigate the effect of crimping, denier, twist and multiple fiber system on the sound velocity. Tensile testing was conducted to find mechanical properties and predict the sound velocity theoretically. The comparison of the theoretical and experimental sound velocities showed small error. The acoustic impedance of the fibers was also calculated.
The sound velocity of various viscoelastic foams was also measured which showed certain foams would be more appropriate for the application at hand. Tensile testing of reticulated foam was performed to find the Poisson's ratio of the foams to predict their behavior. The energy absorption of various foams (viscoelastic and reticulated) was observed by using an Indentation/Rebound Drop Test and damping information. Optical images were obtained to visually evaluate the various foams. Thermal and infrared spectroscopy analysis was done to help characterize the foams.
Two tests were developed to investigate the energy absorption properties of fiber/foam composite padding systems. Various samples of foam with layers of woven Kevlar¨ fabric were evaluated using a Helmet Drop Test and Rebound Drop Test. In these tests rebound heights were related to the energy absorption of the samples. Using this method differentiation between the energy absorption of foams was seen and the behavior of viscoelastic and reticulated foams were observed. The effect of ball size and shape was also observed.

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