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Date of Award

2025

Document Type

Campus Access Dissertation

Degree Name

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

Administrative Home Department

Department of Mechanical and Aerospace Engineering

Advisor 1

Gregory M. Odegard

Committee Member 1

Ibrahim Miskioglu

Committee Member 2

Trisha Sain

Committee Member 3

Shankara Gowtham

Abstract

Polymer matrix composites (PMCs) are widely used in the aerospace industries due to their outstanding mechanical and thermal properties, as well as their resistance to fatigue and corrosion, low dielectric constant, and low thermal expansion. During processing and manufacturing, these materials undergo multiple heating and cooling cycles, causing volumetric shrinkage in the polymer matrix, while the reinforcement remains unaffected. This shrinkage, resulting either from covalent bond formation during the curing of thermosets or from crystallization in semicrystalline polymers, can generate residual stresses, which negatively affect the final product's performance. This study introduces a process modeling approach to minimize the formation induced residual stresses during manufacturing of composite materials for future Integrated Computational Materials Engineering (ICME) and Materials Genome Initiative (MGI) applications.

To address the induced residual stresses during the processing of composite materials, a comprehensive characterization of the resin is required. This process is both time-consuming and costly due to the complex nature of polymer resins. The evolution of thermo-mechanical properties must be studied as a function of processing parameters like temperature and processing time. In this research, a multiscale modeling approach is used to predict the evolution of thermo-mechanical properties of semi-crystalline PEEK as function of crystallinity content and processing time. Molecular dynamics (MD) and the Multiscale Generalized Method of Cells (MSGMC) have been employed to provide a comprehensive understanding of crystallization kinetics and evolution. All the predicted properties were compared to the experimental validation in the literature.

Additionally, this work examines the role of all-atom MD simulations in predicting the thermo-mechanical properties of polymer resins at the molecular level, particularly focusing on the system size's effect on predictive precision and computational efficiency. A study on epoxy systems is conducted to determine the optimal system size, balancing accuracy and simulation cost.

Lastly, the research presents a process modeling framework for ArocyL10 which is a bisphenol E cyanate ester resins and highly valued in high-temperature applications due to their excellent thermal stability. To understand the effect of process parameter on the final properties of ArocyL10, MD simulations and cure kinetics modeling are utilized to predict the evolution of the volumetric shrinkage and thermo-mechanical properties of ArocyL10 as the curing progress at different curing cycles.

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