GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Thursday, December 9, 2021

at 12:00 PM

via

BlueJeans Video Conferencing

https://bluejeans.com/825121664/4708

will be held the

DISSERTATION PROPOSAL DEFENSE

for

Karla Wagner

"Characterization and Effects of Heterogeneities on Shock Compression Response in Additively Manufactured High-Solids Loaded Polymer Composites"

Committee Members:

Prof. Naresh Thadhani, Advisor, MSE

Prof. Min Zhou, ME

Prof. Blair Brettmann, MSE/CHBE

Prof. Arun Gokhale, MSE

Brian Jensen, Ph.D., Los Alamos National Lab

Abstract:

High-solids loaded polymer composites contain several hierarchies of heterogeneities that are of interest for use as, for example, ceramic green bodies or energetic crystals embedded in a polymer matrix. The recent and rapid growth of additive manufacturing (AM) and the engineering need for more complex geometries and individualized products has led to a surge of interest in fabricating high-solids loaded particle composites. AM via direct ink write extrusion processes introduces further complexity in fabrication of composites due to formation of process-inherent heterogeneities such as particle aggregation or porosities. The microstructure of such materials varies across different length scales, resulting in processing and mechanical behavior that is often difficult to control and predict. 

The shock-compression behavior of heterogeneous particle-filled polymer composites often involves complex interactions, which can make it difficult to predict their dynamic mechanical properties. The shock-compression behavior is often dominated by mesoscale defects (including porosity) or interactions of the shock wave with interfaces and particulates. Traditional diagnostic methods, such as velocity interferometry, enable temporally-resolved measurements, but are limited in spatial resolution and generally provide a volume-averaged response. Spatially resolved measurements are necessary to measure the shock compression properties and provide sufficient information regarding the mesoscale processes which dominate performance of such materials. The goals of the proposed work are: to quantitatively characterize additively manufactured particle composite microstructures, determine their shock compression response, and correlate the observed shock response with the microstructural characteristics of the process inherent heterogeneities.