~~THE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING
 
GEORGIA INSTITUTE OF TECHNOLOGY
 
Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Friday, October 21, 2016
1:00 PM
in MRDC 3515
 
will be held the
 
DISSERTATION PROPOSAL DEFENSE

for
 
Yoon Joo Na
 
"Strain Field Mining and Structure Analysis of Nonwoven Fiber Composite Materials"
 
Committee Members:
 
Prof. Christopher Muhlstein, Advisor, MSE
Prof. Arun Gokhale, MSE
Prof. Surya Kalidindi, ME
Prof. Meisha Shofner, MSE
Prof. Preet Singh, MSE
 
Abstract:
The mechanical properties of paper, the most common nonwoven fiber composite, have been studied extensively for more than five decades, but defining a constitutive relationship of paper has remained as a challenge due to its complicated structure and stochastic nature. The main challenges are deciding at what length scale to model the relationship, which variables to include, and how to account for the statistical distribution of various constituents. Quantifying the relevant length scale and identifying the material features that control the failure response of paper will allow further development of the constitutive relationship. 
In this doctoral work, digital image correlation (DIC) and strain field mining techniques are used to examine deformation behavior of nonwoven fiber network materials and identify structural elements that control the non-affine deformation behavior and cause the failure. Digital image correlation (DIC) allows both local variations in deformation and a macroscopic average tensile response of paper to be examined at the same time. The proposed research is to determine relationship between the deformation behavior of the nonwoven network material and its structure. Using several characterization methods, the structure of the fiber network will be reconstructed and the features that are responsible for the failure will be identified. The deformation behavior of different types of paper varying in grammage as well as other types of nonwoven composite materials will also be studied.