Date of Award

2023

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Mechanical Engineering-Engineering Mechanics (PhD)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Gregory Odegard

Committee Member 1

Susanta Ghosh

Committee Member 2

Ranjit Pati

Committee Member 3

Gowtham

Abstract

There is an increase in demand for new lightweight structural materials in the aerospace industry for more efficient and affordable human space travel. Polymer matrix composites (PMCs) with reinforcement material as carbon nanotubes (CNTs) have shown exceptional increase in the mechanical properties. Flattened carbon nanotubes (flCNTs) are a primary component of many carbon nanotube (CNT) yarn and sheet materials, which are promising reinforcements for the next generation of ultra-strong composites for aerospace applications. These flCNT/polymer materials are subjected to extreme pressure and temperature during curing process. Therefore there is a need to investigate the evolution of properties during the curing process. Also, to facilitate the design, fabrication, and testing of flCNT-based composites for aerospace structures, experimental methods can be expensive and time consuming. Hence, computational modeling tools like molecular dynamics (MD) can be used to efficiently used to accurately predict properties. Thus, reducing the overall time in designing next generation of composite materials.

In this research, MD tool is implemented to model the flCNT sheets and polybenzoxazine (PBZ) based composite material to study the interfacial properties and wetting properties of flCNT-PBZ. flCNT - amorphous carbon (AC) structures were modeled to investigate the role of AC on the interfacial properties of flCNT-AC using Reactive force field (ReaxFF). Furthermore, defects and crosslinks were introduced within and between the two flCNTs sheets, to investigate the effect of radiation induced damage and crosslinks on the transverse and axial properties of flCNTs. Finally, Reactive Interface force field (IFF-R) was used to model the PBZ resin system and evolution of properties with degree of cure was predicted. These nanoscale properties provide a set of inputs for microscale analysis to predict the evolution of residual stresses for process modeling of composites.

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