Structures and Materials Commons^™

Direct Ink Writing Of Functional Fiber/Granular Composites, Zhuoyuan Yang

Doctoral Dissertations and Master's Theses

Direct ink writing provides a versatile manufacturing route for fabricating functional fiber and granular composites with controlled architecture, tunable interfaces, and customized material distributions. Fiber reinforced composites offer high stiffness, strength, fatigue resistance, and functional anisotropy, while granular composites provide scalable access to particle based structures with high material efficiency and broad resource compatibility. However, the additive manufacturing of these composite systems remains challenging. For fiber based composites, precise control of fiber placement, matrix impregnation, interfacial bonding, and freestanding deposition is difficult to achieve during printing. For granular composites, stable particle flow, controllable packing, binder infiltration, and shape retention are …

Cohesive Zone Modelling Of Fiber–Matrix Interface In Composite Materials, Arjun Myadam

Doctoral Dissertations and Master's Theses

Carbon Fiber reinforced polymers (CFRPs) are widely used in aerospace, automotive, and structural applications due to their high specific strength, stiffness, and design flexibility. Their mechanical performance is critically governed by the fiber–matrix interface which controls stress transfer and directly influences damage initiation, crack propagation, and fracture behaviour. The interface properties are quantified through the Interfacial Shear Strength (IFSS) and fracture energy, both serving as key indicators of composite integrity. Effective interfacial bonding is therefore essential to the composite’s strength. Nanoscale fiber surface modifications provide a promising approach to enhance interfacial bonding and can also impart multifunctionality. These multifunctionalities can …

Advancing Sensing And Structural Health Monitoring Of Non-Conventional Space Structures, Scott Bender

Doctoral Dissertations and Master's Theses

Future lunar and deep-space missions will require new structural concepts that reduce mass while maintaining reliability. Two technologies that have received significant attention are inflatable habitats and additively manufactured structures; however, challenges remain in their characterization, validation, and long-term monitoring. This dissertation investigates methods to improve the testing and sensing of these non-conventional aerospace structures through the use of advanced photogrammetry and embedded distributed fiber-optic sensors. A color-filtering digital image correlation technique was developed to isolate orthogonal strain directions in woven inflatable structures, providing improved characterization of biaxially loaded softgoods. In addition, methods were developed to embed distributed fiber-optic sensors …

Instrumentation And Control Of A Novel Device To Simulate A Hypersonic Environment, Andrew Marcello

Doctoral Dissertations and Master's Theses

The hypersonic flow regime poses several challenges regarding the design of hypersonic vehicles. Among them is the massive energy and economic expense associated with ground- testing evaluation of material responses within this extreme environment. In order to provide a low-cost, rapid option for preliminary material analysis within hypersonic applications, a novel device is under production to replicate this environment on the surface of these materials. This device has been designed to work in conjunction with Argonne National Laboratory (ANL) Advanced Photo Source (APS) synchrotron, to allow for in-situ characterization of ablation and oxidation on the sample surface.

To achieve this, …

In-Situ Investigations Of Calcium-Magnesium-Aluminosilicates (Cmas) Infiltration Effects On Thermal Barrier Coatings Under Extreme Environments Replicating Jet Engines, Zachary Stein

Doctoral Dissertations and Master's Theses

Calcium-magnesium-aluminosilicate (CMAS) particulates, such as sand or volcanic ash, are ingested by gas turbine jet engines during operation. When operating within high abundance regions, these particulates negatively interact and degrade the high temperature thermal barrier coatings (TBC) protecting underlying superalloy turbine blades vital to engine operation. These CMAS particulates melt within the engine and infiltrate into the ceramic coatings. In electron-beam physical vapor deposited (EB-PVD) TBCs, the CMAS within the intercolumnar gaps stiffens the coatings and causes thermomechanical induced high stress concentrations, risking crack formation. While molten, the CMAS thermochemically alters and destabilizes the coating, also risking coating failure. Premature, …

Additively Manufactured Bioinspired Microstructures For Active Surface Modification, Zefu Ren

Doctoral Dissertations and Master's Theses

Advancements in additive manufacturing have facilitated the development of bioinspired microstructures, which hold promise for applications, such as liquid transport, self-cleaning, and anti-icing. However, the controllability of these microstructures remains an area requiring further exploration. This research explores the design, fabrication, and active control of 3D-printed bioinspired microstructures for dynamic wettability modulation. First, the anisotropic scales of butterfly wings were replicated through optimized two-photon polymerization printing strategies, achieving directional droplet motion controlled by structural geometry and arrangement. The reversed wetting trend compared with natural wings revealed key insights into the structure–performance relationship. Next, microstructures were integrated with dielectric elastomer actuators …

Impact Of Uncertainties On Structures Damage Tolerance Parameters, Breno De Bruns

Doctoral Dissertations and Master's Theses

This research aims to enhance the understanding and management of aerospace structural integrity. Traditional fracture control methods, such as damage tolerance analysis (DTA), assume deterministic factors, considering uncertainties inherent in material properties, inspections, and operational conditions only at the final stage by applying safety factors. This research seeks to incorporate these uncertainties throughout the analysis by integrating Monte Carlo simulation with Linear Elastic Fracture Mechanics (LEFM). The objective is to investigate how varying parameters affect crack growth prediction and the effectiveness of inspection strategies. The methodology involves systematically analyzing inspection intervals, considering factors like material properties, probability of detection (POD), …

Design For Additive Manufacturing: Simultaneous Optimization Of Structural Integrity And Minimal Support Structures, Naresh Ahuja

Doctoral Dissertations and Master's Theses

This dissertation addresses two core challenges limiting the widespread application of Topology Optimization (TO): the difficulty in fabricating its complex designs, especially for Additive Manufacturing (AM), and its significant computational costs. It develops a unified design framework that directly embeds AM constraints such as overhang angles and build direction into robust TO formulations. To enhance manufacturability, two distinct methodologies are proposed. Firstly, a Solid Isotropic Material with Penalization (SIMP) framework introduces a three-stage robust optimization algorithm. Secondly, the Geometric Projection Topology Optimization (GPTO) method inherently integrates overhang constraints by controlling individual geometric components and their inclined angles relative to a …

Analyzing The Interfacial Properties Of Natural Fiber Composites, Rahul Kumar Arram

Doctoral Dissertations and Master's Theses

In response to growing environmental concerns and the urgent demand for sustainable development, the composite materials industry is increasingly challenged to balance high performance with environmental responsibility. Conventional composites, typically composed of synthetic fibers and petroleum-based resins, offer outstanding mechanical properties but are associated with significant ecological drawbacks due to their non-biodegradable nature and energy-intensive production. This has led to increased interest in the development of sustainable composites that minimize environmental impact without compromising functionality. This study presents the development of eco-friendly composites reinforced with natural bast fibers—specifically ramie and jute—through a comprehensive program of materials processing and characterization. To …

Mno2 Nanoscale Interface Modification, Alexander C. Skoppe

Doctoral Dissertations and Master's Theses

Interface modification of carbon fibers has been shown to improve the mechanical performance of composites. In addition, interface modification of carbon fiber composites can impart multifunctionality into the resulting composite. This work will explore ZnO and MnO2 as interface modifications for use on carbon fibers. When exposed to high temperatures, carbon fibers undergo fiber degradation, leading to the need for low-temperature hydrothermal processes. This work will develop and characterize a nanoscale ZnO and MnO2 interface modification for use on carbon fibers. These nanomodifications will be developed with low-temperature processes, minimizing the fiber degradation that the fibers undergo. Fourier transform infrared …

Self-Regulated Thermal Management With Shape-Memory Alloy Torsional Tubes, Paula Sanjuan Espejo

Doctoral Dissertations and Master's Theses

The need for dynamic thermal management that adapts to varying system needs and requirements is a growing topic of interest in different engineering disciplines, most prominently aerospace and electronics. This demand for improved thermal management systems comes from the general increase of system efficiencies leading to an increase in component energy density. Shape-memory alloy actuators, which respond with a mechanical shape recovery to variations in temperature, can be used as self-regulated thermal management actuators that are able to respond to environmental thermal changes autonomously. In this dissertation, modeling and experimental analysis of a two-way shape-memory effect trained SMA torsional tube …

Embeddable Multi-Material Wireless Micro-Sensors Utilizing Additive Manufacturing And Enhanced Microstructure, Nicholas Reed

Doctoral Dissertations and Master's Theses

The development of embeddable, multi-material wireless microsensors offers transformative potential for structural health monitoring (SHM) in aerospace applications. This work integrates additive manufacturing (AM) techniques with advanced microstructural design to produce flexible, high-resolution sensors that can be directly embedded into polymer substrates. By utilizing the vat photopolymerization process, customized embedded sensors are seamlessly integrated into polymer AM structures. These sensors are then continuously refined, targeting increases in performance, both internal and external. Microstructural enhancements are explored to modify the rheological properties of the fabricated embedded sensing channels and enhance the adhesive bonding between the embedded sensor and the AM structure. …

Engineering Anisotropic Porosity In Green Parts From Binder Jet 3d Printing, Reshma Chandrashekhar Kubsad

Doctoral Dissertations and Master's Theses

Binder Jet Additive Manufacturing (BJAM) is a promising metal additive manufacturing technique that enables the fabrication of complex geometries without the need for support structures. However, the inherent porosity in green parts, remains a challenge in achieving desired mechanical properties and performance. Instead of treating porosity as a limitation, this thesis explores engineering of anisotropic porosity engineering, where controlled variations in porosity in the green parts can be used to enhance functionality and efficiency in specific applications. The objective of this research is to investigate and analyze the key print parameters that influence green part density. By systematically varying layer …

Modeling The Dynamics Of Flexible Aerospace Vehicles Using The Theory Of Functional Connections, Carlo Lombardi

Doctoral Dissertations and Master's Theses

Modeling and control of flexible vehicles is a topic of high interest in the aerospace field and a key challenge lies in finding accurate mathematical representations of the flexible dynamics of continuous elastic structures that allow simple integration into estimation and control algorithms. The answer was found in approximating the dynamics of these systems with sets of coupled Ordinary Differential Equations (ODE) for which a well-established estimation and control theory is available. Each of the techniques employed to achieve this goal is characterized by its own strengths and limitations. Hence, the main objective of this research is to develop the …

Discrete Particle Dynamics Models: Computational Aspects And Applications, Yuxuan Wu

Doctoral Dissertations and Master's Theses

Particle dynamics considers discrete particles as Newtonian point masses in diverse domains such as, pedestrian particles in pedestrian movement modeling and molecules in material science modeling. These dynamic modeling approaches share a commonality in computational approach where a series of ordinary differential equations are solved for the particle’s motion and equilibrium under active interactions and boundary conditions. In general, particle dynamics approaches are computationally intensive and address problems that require a vast parameter design space. In this dissertation, a computational paradigm is developed for large-scale particle dynamics modeling and demonstrated by three process design applications, (a) infection risk modeling for …

Data Intensive Method For Processing Defect Detection And Mitigation For Composites, Deepak Kumar

Doctoral Dissertations and Master's Theses

Composite manufacturing without processing defects is a crucial step in satisfying the production, performance, and quality requirements of composite materials in various industries. Autoclave processing enables manufacturing of high-quality composite parts with excellent mechanical properties, whereas additive manufacturing (AM) offers adaptability to complex designs and streamlined processes. However, each method presents unique challenges; despite the benefits, autoclave processes can still result in processing defects, and AM is particularly susceptible to processing anomalies owing to the novelty of the process. Ensuring the quality and reliability of composite manufacturing is essential to fully capitalize on the advantages offered by both techniques. Artificial …

In-Situ Characterization And Machine Learning Applications For Composite Processing, Pragathi Agraharam Chan

Doctoral Dissertations and Master's Theses

Numerous aircraft and spacecrafts utilize carbon fiber-reinforced polymer structures to significantly enhance their operational efficiency and overall performance. Autoclave composite processing offers a solution for the intricate design of complex structures. However, the rapid temperature and strain fluctuations experienced during the processing gives rise to a multitude of defects and residual stresses in the composite. In this study, we have devised an in-situ methodology that leverages Digital Image Correlation (DIC) and Machine Learning Applications to effectively observe and track defect deformations occurring throughout the process. This process presents a dataset derived from the curing process of 40 carbon fiber-reinforced polymer …

Ridds: Removal Of Irregular Debris Using Double Nets, Kayann Coote

Doctoral Dissertations and Master's Theses

The quantity of debris in Earth’s orbit is increasing at an alarming rate, and without a sustainable solution, this will detriment the space environment, impacting the future of space travel and space traffic management. While numerous debris removal concepts and designs have been proposed, very few have made it to actual flight tests, and none can remove debris at a fast enough rate to stop debris growth. For debris currently in orbit, most proposed systems are costly on a large scale and cannot adapt to the wide variety of debris shape and geometry and tumbling. The purpose of the proposed …

Space Radiation Assessment And Mitigation: Meeting The Growing Demand For Shielding Solutions By Enhancing Models And Exploring Novel Shielding Opportunities, M. Laura Sorgi Johann

Doctoral Dissertations and Master's Theses

The rapid growth of satellite technology and the increasing presence of vulnerable technology and human life in space have highlighted the need for improved shielding materials. Industry standard protocols for shielding are being pushed to their limits as we gain a deeper understanding of the harsh space environment and as chip sizes approach the scale of radiation wavelengths. Furthermore, the commercialization of space is attracting interest from industries such as pharmaceuticals and semiconductor crystal growing, as they explore the potential benefits of zero-gravity production environments. However, the eagerness to develop lighter shielding and the lack of consideration for existing tools …

Optimization Of A Plate Beam System For Energy Harvesting Using A Piezoelectric Material, Jose Manuel Almendros Espantaleon

Doctoral Dissertations and Master's Theses

With a continuously growing demand for power, driven by the need to reduce our environmental footprint, this research provides an examination of the potential of energy harvesting with smart materials technology and its practical applications. The energy harvesting system considered here works on generating energy through vibrations of a piezoelectric material beam which will undergo sustained vibrations due to flow of air over its surface. It is assumed that sustained limit cycle oscillations of this system will occur at the flutter velocity. This research creates an optimization framework to obtain the best values of parameters that will result in the …

Additively Manufactured Flexible Piezoelectric Wave-Based Multifunctional Sensor, Rishikesh Srinivasaraghavan Govindarajan

Doctoral Dissertations and Master's Theses

The demand for acoustic wave-based sensors has rapidly increased in the aerospace, chemical, gas, and biological fields due to their versatility in sensing measurands. This study aims to develop a flexible piezoelectric sensor exhibiting enhanced piezoelectric properties using additive manufacturing techniques that can detect mechanical strains and gas or volatile organic compounds (VOCs) by incorporating functional material into the sensing layer. This research explores piezoelectric substrate fabrication through diverse additive manufacturing techniques, including new material development made of polymer/nano-fillers with electrodes that are filled using different printing techniques. Notably, the design of the interdigital transducer (IDT) in the piezoelectric sensor …

Damage Control Measures In Composites: Focus On Damage Tolerance Of Aerospace Structures, Kais Jribi

Doctoral Dissertations and Master's Theses

Barely Visible Impact Damage (BVID) in composite materials presents a stealthy yet significant risk to structural integrity, particularly challenging due to its elusive nature. The approach adopted here diverges from traditional methodologies, focusing on the novel application of Digital Image Correlation (DIC) to map surface area changes during in-situ Compression After Impact (CAI) tests. This technique allows for an in-depth analysis of planar strains along the x and y axes, shedding light on the material's behavior under stress.

A pivotal advancement lies in developing a method for precisely identifying when BVID-induced delamination recommences. By meticulously analyzing strain pattern deviations along …

Ti Nano Powder Speckle Pattern Creation And Use In Dic Of Zno Modified Single Carbon Fibers, James Matthew Harris

Doctoral Dissertations and Master's Theses

As the use of composites continues to grow across aerospace, naval, automotive, construction, 3D printing, and other countless industries, so does the desire to continuously improve their mechanical properties. Improving the adherence of the fiber-matrix interface is one important step for amplifying the capabilities of composites. Work has been performed in modifying carbon fibers by growing zinc oxide (ZnO) nanorods in the fiber surface using a hydrothermal approach, increasing interfacial area and fiber-matrix friction. Macroscale evaluation has shown that the interfacial modification decreases the inter-ply movement and reduces the processing strains and residual stresses. To fully understand the mechanism taking …

Indentation Protection Of Lithium-Ion Batteries Using Woven Fiber Metal Laminates, Sida Xu

Doctoral Dissertations and Master's Theses

Lithium-ion batteries are widely used as electric power sources for smartphones, tablets, laptops, e-scooters, unmanned aerial vehicles, aircraft, electric vehicles, airport equipment, and numerous other transportable electronic devices. When these types of batteries get excessively loaded, damage can occur. To study the effects of excessive damage, lithium-ion battery modules with prismatic cells were subjected to destructive quasi-static indentation using a V-shaped stainless steel wedge indenter at different loading orientations, directions, and rates. The modules were discharged to a very low state of charge prior to testing. Force and voltage were measured as a function of displacement to monitor the damaging …

Starfish: A Compact, Biomimetic, And Adaptive Shape Memory Alloy Orbital Debris Remover, Katelyn Branaman

Doctoral Dissertations and Master's Theses

This thesis aims to turn the tides on the orbital debris issue through the fabrication and demonstration of a compact, biomimetic, and adaptive shape memory alloy actuated orbital debris remover. The design, referred to as Starfish, is discussed in detail along with its fabrication process and object capture ability. A hard skeleton crafted from PETG was combined with shape memory alloy wires and extension springs to create a biomimetic structure that operates similar to the human hand, capable of gripping a wide range of objects. Relevant simulations were performed and discussed, the iterative fabrication process used to create each component …

Adaptive Control Of An Aeroelastic System For Active Flutter Suppression And Disturbance Rejection, Patrick Sterling Downs

Doctoral Dissertations and Master's Theses

The future of aircraft design strives for lighter weight, more aerodynamically efficient structures. These improvements may come with the drawback of increased structural flexibility and elevated aeroelastic effects, often resulting in a lower flutter speed. This motivates the implementation of advanced control methods to control aeroelastic systems over a range of flight conditions, suppress and delay the onset of flutter, and compensate for disturbances, actuator dynamics, and unmodeled nonlinear dynamics.

This dissertation first develops a novel method for constructing time-domain simulation models of two and three-dimensional aeroelastic systems, resulting in models that are suitable for the implementation of state-space control …

A Comparison Of Beamforming Characteristics In Isotropic And Composite Plate Structures For Use In Structural Health Monitoring, Sarah Ketchersid

Doctoral Dissertations and Master's Theses

Structural health monitoring in plate-like simple structures using phased array beamsteering of guided Lamb waves is useful in damage detection and evaluation efforts. Lamb waves can be effectively used for beamsteering using a linear array. The experimentation primarily focuses on beamsteering in the aluminum panel, which involves developing a simulation based on extracted data to visualize the dispersion of waves across the panel. By evaluating parameters such as slowness, velocity, and amplitude direction and variation for a specific metallic plate, the wavefront generated by a single wave source can be represented as a function of propagation angle and distance from …

Stochastic Point Process Modeling For Engineering Applications, Samarth Motagi

Doctoral Dissertations and Master's Theses

Hawkes model or self-exciting point process model is a branching point process model. The model classifies the dataset of discrete events to background and offspring events. It has been used to study interconnected events in many fields, but relatively little work exists in applying these concepts to engineering problems. In our research, we use a self-exciting point process model for two engineering applications: (a) To identify secondary crashes from a given traffic data and (b) To quantify the agglomeration state and size of nanoparticles from computationally generated carbon nanotube microstructure using stochastic percolation model and experimentally generated titanium nanoparticle microstructures. …

Interfacial Thermomechanical Behavior Of Hybrid Carbon Fibers, Sriraj Srihari

Doctoral Dissertations and Master's Theses

The carbon fiber/epoxy interface is of great importance in composite design due to its load transfer mechanisms from the weak epoxy to the stronger fiber. Improving the strength of the interface reduces the risk of failure at the interface and improves the load transfer to the fiber. In this study, two types of nano-species ZnO nanowires and nickel-based metal organic frameworks were grown on carbon fibers to improve the interfaces. The interfacial mechanics of the enhanced fibers are evaluated using nanoindentation studies. Composite samples with Aeropoxy matrix and vertically aligned fibers are fabricated for this purpose. A Bruker TI-980 TriboIndenter …

In-Situ Thermal And Deformation Characterization Of Additive Manufacturing Processes, Nicholas Phillips

Doctoral Dissertations and Master's Theses

Additive manufacturing (AM) is a rapidly growing industry with numerous applications in the aerospace industry such as aircraft parts and emergency tools on the International Space Station. Defects in additively manufactured structures, however, can waste a lot of time and money. Being able to monitor the manufacturing process for defects is one of the first steps which can be taken to mitigate these losses. This study focuses on the use of thermography in conjunction with deep learning to identify flaws during 3D printing of composite structures made using Onyx, a mixture of chopped carbon fiber and nylon, composite prints. In …