Nanoscale reinforced laminated nanocomposite materials systems for high-performance structural applications
Abstract
Polymer-based laminated composite materials are widely used in many industries due to
their superior mechanical properties. The main disadvantage of using composites is their
delamination failure that occurs due to poor interlaminar properties because of a lack of
reinforcement through the thickness direction. One of the unique ways to address this problem in
traditional composites is the use of nanoscale reinforcements such as carbon nanostructures that
has demonstrated promising results during the past two decades. In the first part of this report,
closed-form analytical solutions were developed for effective transverse Young’s modulus and
Poisson’s ratios of a three-phase carbon nanotube (CNTs)-based orthotropic nanocomposite
cylindrical model subjected to a uniform external pressure, and then solutions for deformations,
strains, and stresses were obtained. In the second part of this research, design of experiment (DOE)
was used to study the effects of process parameters on the tensile properties of epoxy resin per
ASTM D638. The test results were used to carefully optimize the process parameters for the
fabrication of our nanocomposite materials which was the main subject of this dissertation. Our
previous studies had demonstrated that helical CNTs (HCNTs) perform much better than straight
CNTs (SCNTs), due to a mechanical interlocking mechanism that the Heli-coil geometry of the
HCNTs provides between the microfiber reinforcements and within the solidified polymeric
resins. In this research, various weight percentages of HCNTs were processed and used to fabricate
laminated nanocomposite panels and then mechanically tested and characterized (as per ASTM
D790, D5868, D2344, D3039, and E384 standard test methods) to study the effectiveness of the
HCNTs reinforcements. Overall, the test results showed significant improvements in several
material properties that demonstrate the benefits of HCNTs as an effective reinforcement for highperformance
structural applications of composite laminates.
Description
Thesis (Ph.D.)-- Wichita State University, College of Engineering, Dept. of Mechanical Engineering