Date of Award

Summer 2021

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Materials Science

Committee Chair

Jerome Downey

First Advisor

Stephen Sofie

Second Advisor

Dario Prieto

Third Advisor

Peter Lucon

Fourth Advisor

Sudhakar Vadiraja

Abstract

Research in the development of impact resistant materials has been an expanding field for the better part of a hundred years. The development of a light penetration resistant and man-portable system that can resist extreme quantities of kinetic energy has been a subject of substantial study. In particular, the use of composite materials, polymers, ceramics, and metals has been critical to the development of the field. With the advent of complex computational programs for defining material properties, it has become possible to use simulations as a starting point for the development of next generation armored systems. To that end, it has become valuable to analyze the behavior of non-classical composite forms of conventional materials in novel ways.

A unique form of impact resistant composite has been developed by adhering to results from a computational system. By modifying a textile with high-density hard-metal inclusions a density based scattering effect has been observed to occur within the material. The scattering results in the creation of localized stress fields that have otherwise not been observed in conventional impact resistant composites. A novel discrete mathematical model was developed to define the observed scattering behavior, representing a significant step forward in the science of impact mechanics. Physical tests were conducted and it was observed that using the scattering properties, a large amount of kinetic energy could be stored within the material during impact events, effectively strain-hardening the composite. It was observed that energy distributed within the material increased from the range of 100 Joules to the range of 300 Joules with the inclusion of hard inserts. This increase in energy absorbance substantially increases overall resistance, along with the direct brittle failure of the distributed hardpoints within an ultra high molecular weight polyethylene (UHMWPE) matrix.

By retaining a low overall composite density ( ) while substantially increasing the

quantity of energy absorbed by the composite during an impact event, the material represents a novel for impact resistant designs. The mathematical expression of the impact resistance provides a basis to future research into similar composite structures that scatter internal shockwaves via density variation. The development of new engineering in man-portable defensive systems in this research may identify more economical alternatives to the already expensive designs in use as well as save lives.

Comments

A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy: Materials Science

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