Date of Award

12-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Bioengineering

Committee Member

Dr. John DesJardins, PhD, Co-Committee Chair

Committee Member

Dr. Gregory Batt, PhD, Co-Committee Chair

Committee Member

Dr. Delphine Dean, PhD

Abstract

Each year, there are an estimated 3.8 million sports-related concussions that occur in the United States alone, the majority occurring during football collisions. These staggering numbers occur even with the use of mandated protective helmets, which are designed to decrease potential brain injuries. The outer shell of a football helmet acts as a shield for vulnerable areas of the cranium by providing the initial impact force dispersion to allow a more distributed load to be transferred to the inner foam padding. The current material standard for the exterior casing is a polycarbonate blend. Multiple studies demonstrate insufficiencies in current helmets due to limitations in energy absorption and dissipation. This study focuses on examining twenty-two different composites configurations for an initial down-selection to determine potential use in the outer shell of the football helmet. Composites were composed of variations of multiple fibers including: Innegra, Kevlar, basalt, E-glass, S-glass, and carbon. Composite materials have proven to be beneficial in a variety of applications due to their decreased weight and exceptional energy absorption and dissipation performance in low velocity impact conditions, which are representative of typical football collisions. Flat panel composite specimens underwent dynamic drop weight impacts at low velocity impact conditions of 20 J according to ASTM D7136-12. A Cushion Testing system, the Lansmont Corporation TP3 Data Analysis Software, and an Olympus i-Speed3 High Speed Camera were used to capture and analyze the response of the composite during the impact event. The acceleration, duration, and change in impact and rebound velocities were recorded, analyzed, and compared to the response of polycarbonate under impact conditions. Several composite configurations demonstrated promising results. These composites were fabricated with lower densities than polycarbonate and experienced a greater change in kinetic energy compared to polycarbonate; illustrating the potential for their use in the outer shell of football helmets for improved energy absorption. Based upon the results, the top ten composite performers during impact testing have been chosen to advance on to Phase II testing to evaluate the response of these materials under greater impact energies.

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