Materials Science and Engineering Commons^™

Analysis Of Loading Rate, Fiber Orientation And Material Composition Through Image Processing And Digital Volume Correlation In High Performance Concrete, Aidan R. Carlson

Electronic Theses and Dissertations

Ultra High Performance Concrete (UHPC) and High Performance concrete (HPC) is characterized by high compressive strength and high toughness. This is achieved through maximizing the particle packing density in the matrix and the use of fibers to reinforce the matrix, increasing the materials toughness. The interactions of fibers and the matrix during loading is quite complex and involves several different energy dissipation mechanisms. The goal of this work and this thesis is to investigate these interactions and identify any changes in material response, and hope that these changes may be useful for the design of UHPC moving forward.

In this …

Advances In Cellulose Nanomaterial-Based Foams For Environmental Applications, Md Musfiqur Rahman

Electronic Theses and Dissertations

The use of metal-oxide nanoparticles adsorbents is limited to fixed-bed columns in industrial-scale water treatment applications. This limitation is commonly attributed to the tendency of nanoparticles to aggregate, the use of non-sustainable and inefficient polymeric resins as supporting materials, or a lack of adsorption capacity. Foams and aerogels derived from cellulose nanomaterials have unique characteristics, such as high porosity and low density, which enables their use in a variety of environmental applications, including water treatment. However, the overall use of cellulose nanomaterial-based foams in various environmental sectors is limited due to the high cost of production associated with time- and …

Barriers To Use Of Cross-Laminated Timber In Maine, Shane R. O'Neill

Forest Resources Faculty Scholarship

To increase understanding of both the adoption rate and in-state manufacturing of mass timber In Maine, the 131^st Legislature and Governor Mills passed LD 881, a resolve directing a study of the barriers facing cross-laminated timber In Maine and provide recommendations to promote their use in construction. This study was developed in response to the resolve. The study engaged 108 unique participants to define available training, education, and experiences across the stakeholders throughout the building lifecycle process in the state.

From this information, the following five recommendations are proposed:

1. Understand the policies and initiatives of other states to develop …

Investigating The Effect Of Bead Geometry On Fiber Orientation And Thermomechanical Properties For Large-Format Extrusion-Based Additive Manufacturing, Joanna F. Keaton

Electronic Theses and Dissertations

In large-format extrusion-based additive manufacturing of polymer composites, the relationship between material properties and processing parameters requires further investigation. This thesis focuses on the relationship between fiber orientation and thermomechanical properties for short fiber-filled thermoplastic polymer systems manufactured by extrusion-based additive manufacturing. Fiber orientation is particularly important in determining the thermomechanical properties of the composite material as properties in the direction of deposition are expected to be higher for highly aligned fibers than randomly aligned fibers. Fiber orientation distribution, which is related to processing parameters and deposition conditions, can be efficiently represented by the orientation tensor. The orientation tensor can …

Mechanical Characterization Of Automated Fiber Placement And Additive Manufacturing Hybrid Composites, Lucan Haviland

Electronic Theses and Dissertations

This thesis presents the optimization of processing parameters based on the mechanical properties of Continuous Fiber-Reinforced Thermoplastic (CFRTP) Unidirectional (UD) consolidated tapes. The UD tapes were consolidated using an AFP head and a thermoforming press for comparison. The adhesive strength of hybrid parts consisting of CFRTP UD tape bonded to a 3D-printed substrate with the same matrix system were investigated. Large Area Additive Manufacturing (LAAM) was utilized for the 3D-printed parts. Different types of thermoplastic composite materials were explored, including Glass Fiber reinforced Polyethylene Terephthalate Glycol (GF/PETG), Carbon Fiber reinforced Polyethylene Terephthalate Glycol (CF/PETG), Carbon Fiber reinforced Polycarbonate (CF/PC), and …

Efficient Sintering Of Lunar Soil Using Concentrated Sunlight, Diprajit Biswas

Electronic Theses and Dissertations

Construction material is one crucial need for long-term habitation on the moon. When concentrated for high heat flux, solar radiation can heat lunar soil or regolith until it sinters at temperatures above 900°C. The solid, sintered soil simulant can be used as construction material. This work explores the conditions leading to effective lunar soil sintering for both direct and indirect irradiated sintering. Lunar soil simulants were sintered using concentrated light from a xenon-arc lamp with varying heat flux intensity. During direct sintering of LHS-1, a sintering range of 860°C-1140°C corresponding to a peak heat flux of 105-120 kW/m2 was identified …

Influence Of Platinum Nanoparticles On Ionic Transport And Hydrogen Reactivity Of Yttria-Stabilized Zirconia Thin Films, Firas Mahyob

Electronic Theses and Dissertations

Yttria-stabilized zirconia (YSZ) is a widely used ceramic material in solid oxide fuel cells, oxygen sensors, and sensing applications due to its high ionic conductivity, chemical inertness, and thermal stability. YSZ is promising active coating for use in miniaturized harsh environment wireless surface acoustic sensors to monitor gases such as H₂. Adding catalytic Pt nanoparticles can enhance gas reactivity and lead to associated film conductivity changes.

In this work, thin films with an (8% Y₂O₃ - 92% ZrO₂) composition were deposited onto piezoelectric langasite substrates using RF magnetron sputtering in Ar:O₂ - …

Mechanics And Mechanisms Of Fracture For An Eastern Spruce Subject To Transverse Loading Using Acoustic Emission, Parinaz Belalpour Dastjerdi

Electronic Theses and Dissertations

Due to its excellent structural qualities and accessibility, wood is among the most often utilized structural materials. Despite its ubiquity, wood poses numerous challenges. It is heterogeneous and anisotropic. It has a complex hierarchical ultrastructure, and the properties can have wide variation within a species, and indeed within an individual tree. This work aims to improve our understanding of the strength and fracture behavior of spruce-pine-fir (south) (SPFs), particularly in cross-grain direction. This study’s primary goal is to examine the relationship between crack propagation and cross grain morphology under the following loading configurations: compact tension, compression, and rolling shear. The …

Biobased Packaging Materials From Cellulose Nanofibrils Produced From Virgin Wood Pulp Or Recycled Cardboard Pulp, Md Ikramul Hasan

Electronic Theses and Dissertations

Self-standing cellulose nanofibril (CNF) films are regarded as one of the promising alternatives to current petroleum-based packaging materials. The mechanical and barrier properties of CNF films are not yet up to the mark for certain applications, especially at high relative humidity. Those properties of CNF films can be tuned by the drying methods of films, degree of fibrillation, cross-linking, and controlled shrinkage. A comprehensive understanding of these processes and their influence on the structure and properties of CNF films have been presented in this thesis.

First, we prepared CNF films from CNF suspensions with two different degrees of fibrillation- standard …

Contact Dewatering Of Cellulose Nanofibers For Biopolymer Composite Applications, Alexander Collins

Electronic Theses and Dissertations

Cellulose Nanofibrils (CNFs) are promising materials for reinforcement of polymer matrices attributable to their impressive physical and mechanical properties, as well as their biodegradability. However, the utilization of these materials in composites is made challenging by the water content of CNF slurries, the tendency of CNFs to agglomerate as they dry, and incompatibility between hydrophilic CNFs and hydrophobic polymer matrices. The most commercially viable drying methods to produce small-scale dry CNFs, such as spray drying, are very energy intensive, can only dry the materials down to micron-scale agglomerates, and do not preserve fibrillar aspect ratios. “Contact dewatering,” or the removal …

Numerical Modeling Of Localized Heating In Continuous Fiber Reinforced Thermoplastic Laminates, James T. Gayton

Electronic Theses and Dissertations

The manufacturing of continuous fiber-reinforced thermoplastic (CFRTP) laminates requires the application of heat and pressure. Standard CFRTP manufacturing methods like thermoforming take a global approach to manufacturing, where the whole part is heated and undergoes a forming process. There is an opportunity to develop advanced manufacturing methods based on localized heating and deformations of consolidated stock. This thesis provides a localized heating method via networks of resistive heating elements embedded within the laminate and a means to evaluate that method.

Typical heating methods for CFRTP laminates include infrared and convective ovens or surface contact heaters. They have the same drawbacks …

Continuous, Non-Destructive Detection Of Surface Bacterial Growth With Bioinspired Vascularized Polymers, Brandon Dixon

Electronic Theses and Dissertations

Reducing or eliminating bacteria on surfaces is vital for medical devices, drinking water quality, and industrial processes. Evaluating surface bacterial growth at buried interfaces can be problematic due to the time-consuming disassembly process required for obtaining standard surface samples. In this work, a continuous, non-destructive, and reusable method was developed to detect surface bacterial growth at buried interfaces. Inspired by vascular systems in nature that permit chemical communication between the surface and underlying tissues of an organism, bacterial-specific signals diffusing from cells on the surface were detected in channels filled with an inert carrier fluid embedded in a polymer matrix. …

Comparative Life Cycle Assessment Of Embodied Carbon And Operational Energy Of Different Building Systems, Marilia Hellmeister

Electronic Theses and Dissertations

Due to human activity, the levels of carbon emissions found in the atmosphere have reached its highest concentration and therefore it is necessary to find solutions to reduce, mitigate and adapt to a more sustainable pattern of development. The substitution of fossil fuel-dependent materials with renewable materials which exhibit lower embodied carbon is an option to be considered in the design phase of a building. Engineered wood product innovations over the past twenty years, coupled with design innovation and building code modifications have demonstrated their viability in multi-story construction (18 stories). The goals of this project are to 1) estimate …

Yield And Mechanical Properties Of Veneer From Maine-Grown Eastern Spruce And Balsam Fir, Marshal Bertrand

Electronic Theses and Dissertations

This research focused on the utilization of Maine Eastern spruce and balsam fir for veneer production. Maine currently has no manufacturers of or products using structural veneer. The diversification of markets for Maine’s softwoods has been identified as a route to increase the resilience of the forest-based economy. Veneer production technology has improved significantly since the last look at Maine spruce veneer (1969), justifying the reinvestigation of Maine spruce-fir veneer. The objective of this research was to provide information on the yield of processing veneer and the quality of said veneer. A sample size of 37 Eastern spruce and 38 …

Development And Characterization Of Bound Metal Deposition Including Laser Ablation, Alexander J. Watson

Electronic Theses and Dissertations

Bound Metal Deposition (BMD) is a novel metal additive manufacturing technology in which a metal powder-binder composite paste is layer-wise extruded to form a part, which is then debound and sintered into a solid metal part. Although promising, BMD suffers from shrinkage-induced warpage and an inability to produce fine length scale features. This research addresses these problems by: (1) characterizing warpage of planar parts, and (2) developing a novel laser ablated process to create fine length scale features. First, a 12-factor resolution IV fractional-factorial design of experiments (DOE) was conducted to determine the warpage of planar parts as a function …

Development And Evaluation Of Modeling Approaches For Extrusion-Based Additive Manufacturing Of Thermoplastics, Christopher C. Bock

Electronic Theses and Dissertations

This work focuses on evaluating different modeling approaches and model parameters for thermoplastic AM, with the goal of informing more efficient and effective modeling approaches. First, different modeling approaches were tested and compared to experiments. From this it was found that all three of the modeling approaches provide comparable results and provide similar results to experiments. Then one of the modeling approaches was tested on large scale geometries, and it was found that the model results matched experiments closely. Then the effect of different material properties was evaluated, this was done by performing a fractional factorial design of experiments where …

Non-Destructive Evaluation Of Concrete Using Electrical Resistivity And Ultrasonic Wave Propagation, Justin Harris

Electronic Theses and Dissertations

With the intent to investigate the relationship between concrete physical properties and non-destructive evaluation techniques (NDE), several experiments were performed. Specimens were made at varying geometries using a range of different concrete mixes under several different curing conditions. These specimens were subjected to a combination of electrical resistivity and ultrasonic wave propagation measurements. One part of this study investigated determining the orientation of steel fibers using electrical resistivity. This resulted in the fabrication of a four-probe square device with the potential capabilities of determining fiber orientation. The other part of this research applied ultrasonic wave propagation via through-transmission along with …

Near-Field Thermal Radiation In Graphene-Based Systems, Hua Lin

Honors College

Radiative heat transfer between two media separated by a sub-wavelength distance (the dominant wavelength of thermal radiation at room temperature is around 10 m.) is referred to as near-field radiative heat transfer (NFRHT). Graphene was found to have one of the greatest levels of NFRHT [1]. Additionally, NFRHT of graphene can be modulated externally via application of a bias voltage to the material [1][2], thereby altering its Fermi energy level. As such, graphene is an ideal candidate for several applications such as NFRHT for thermal switching, nano-gap thermophotovoltaic waste heat recovery, and thermal rectification. Modulation ratios as large as 77.7274 …

Life Cycle Analysis And Implications Of 3d Printed Bio-Based Homes, A Preliminary Study, Claire Liedtka

Honors College

The purpose of this study is to evaluate the life cycle, embodied energy, and sustainability potential for large scale additive manufacturing of 3D printed homes. Additive manufacturing is the process of selectively depositing materials using a 3D printing process, which optimizes material usage and reduces waste. I performed a preliminary Cradle to Cradle Life Cycle Analysis for constructing 3D printed homes using a bio-based material, poly-lactic acid (PLA) filled with wood flour. For purposes of this study, I consider the Life Cycle Analysis to be the environmental assessment of each stage of a product’s life cycle, from material sourcing, processing, …

Charged-Particle Interactions To Generate Novel Coatings And Materials, Pradnya D. Rao

Electronic Theses and Dissertations

A typical paper coating formulation contains anionically charged pigments and latex to provide a high-quality surface for printing. However, during application and drying, the latex can migrate to the surface or deep into the paper, resulting in weak coating layers or the need to use a high latex content to obtain the same strength properties. In this thesis, we have explored the introduction of cationically charged particles into the suspension as a way to reduce the amount of binder in the coatings, improve coating strength and reduce binder migration. With these aims in mind, we have generated cationic precipitated calcium …

Thermal And Mechanical Numerical Modeling Of Extrusion-Based 3d Printed Reinforced Polymers For Selecting Manufacturing Process Parameters, Sunil Bhandari

Electronic Theses and Dissertations

Extrusion-based 3D printing of thermoplastic polymer composites manufactures parts that have nonhomogenous, orthotropic, and process-dependent macro-scale material properties. As a part of the dissertation, research works were carried out to: • improve the interlayer mechanical properties and reduce the orthotropy, • use experimentally homogenized orthotropic material properties to numerically model the mechanical behavior of the non-homogenous orthotropic 3D printed parts, • create an efficient numerical thermal model to predict the process-dependent thermal history of the 3D printed part, and • aid the manufacturing process by selecting a suitable set of processing parameters based on a simplified sequentially coupled thermomechanical model. …

Growth Ring Orientation Effects In Transverse Softwood Fracture, Parinaz Belalpour Dastjerdi, Eric N. Landis

Civil Engineering Faculty Scholarship

In this study, the fracture mechanics of eastern spruce were characterized in relation to end-grain orientation. Compact tension-type specimens with small pre-formed cracks were prepared such that grain angle varied relative to the load axis. Specimens were loaded under crack mouth opening displacement (CMOD) control as to maintain stable crack growth. Specimen fracture was characterized using both R-curve and bulk fracture energy approaches. The results showed that under a RT grain orientation, as well as grain deviations up to about 40^∘, cracks will follow a path of least resistance in an earlywood region. As the grain angle exceeds …

Nanostructured Self-Assembled Thin Films Of Cationic Bottlebrush Block Copolymers, Hathaithep Senkum

Electronic Theses and Dissertations

Biofouling which is an accumulation of small species on submerged surfaces that causes detrimental impacts on economic and environmental factors for aquaculture activities and human health. To suppress the fouling, polymeric coatings from amphiphilic block copolymers provide nanostructured surfaces and carry multiple functional groups in a molecular chain. Polymers with quaternary ammonium functional groups enable material coatings to inhibit microbial adhesion by killing bacteria, consequently prolonging the material efficiency of, for example, medical implanted devices. Herein, well-defined architectures with full-arm density of quaternary ammonium bottlebrush polymers were generated from grafting-through ring opening metathesis polymerization (ROMP). Factors such as the halide …

Development Of Hybrid Ultra-High Performance Concrete Thermoplastic Composite Panels For Blast And Ballistic Protection, Alyssa M. Libby

Electronic Theses and Dissertations

In recent years, ultra-high performance concrete (UHPC) has become a material of interest for structures needing resistance to impact and blast loadings. These types of loadings have induced brittle flexural failure in UHPC due to punching shear from the impactor. One way to improve the impact resistance, energy absorption, and ductility of UHPC is by adding fiber-reinforced polymer (FRP) skins to the front and rear faces of the concrete, resulting in a sandwich configuration. In this study, E-glass fiber-reinforced thermoplastic laminates were bonded to UHPC panels using a heated consolidation process known as stamp thermoforming. The bond between the UHPC …

Handling And Manipulation Of Water- And Air- Borne Biological Samples Using Liquid-Infused Surfaces, Daniel P. Regan

Electronic Theses and Dissertations

Research on novel materials to handling water- and airborne samples for biological threats analysis is in great demand due to the COVID-19 pandemic. Work conducted on a new field of material science, called liquid-infused surfaces, demonstrate strong potential for the handling and manipulation of biological samples. As a result of the field’s infancy, only a limited number of studies have explored how liquid-infused surfaces can apply droplet manipulation strategies to address real-world problems. Presented in this dissertation are two platforms that leverage liquid-infused surfaces to address the challenges associated with handling water- and airborne biological samples. When dealing with waterborne …

Fabrication Of Silicon Microneedles For Dermal Interstitial Fluid Extraction In Human Subjects, Caleb A. Berry

Electronic Theses and Dissertations

The goal of this project is to design and develop a fabrication process for silicon microneedle arrays to extract dermal interstitial fluid (ISF) from human skin. ISF is a cell- free, living tissue medium that is known to contain many of the same, clinical biomarkers of general health, stress response and immune status as in blood. However, a significant barrier to adoption of ISF as a diagnostic matrix is the lack of a rapid, minimally invasive method of access and collection for analysis. Microfabricated chips containing arrays of microneedles that can rapidly and painlessly access and collect dermal ISF for …

Impact Resistance Of Fiber-Reinforced Composites Using Computational Simulations, Maitham Alabbad

Electronic Theses and Dissertations

Composite materials are widely used in aerospace, automotive and wind power industries due to their high strength-to-weight and stiffness-to-weight ratios and their improved mechanical properties compared to metals. The damage resistance of composite materials due to low velocity impact depends on fiber breakage, matrix cracking and delamination between the interfaces. In this research, a numerical investigation of low velocity impact response of a multidirectional symmetric carbon-epoxy composite laminate is carried out and presented. Two different finite element models are developed for composite laminates made of non-crimp fabric to investigate their behavior under different levels of impact energy. In the first …

Elucidation Of The Factors Affecting The Production And Properties Of Novel Wood Composites Made Using Renewable Nanomaterials As A Binder, Ezatollah Amini

Electronic Theses and Dissertations

A novel application of cellulose nanofibrils (CNF) as a binding agent is proposed. In this work the utilization of CNF as a complete replacement for the conventional resin-adhesives in the formulation of particleboard (PB) was evaluated. PB panels with varying CNF contents and target densities were produced using a two-step (i.e. cold and hot) pressing process. For initial evaluation, the mechanical and physical properties of the manufactured panels were determined. The need to remove a considerable amount of water from the wood particle (WP)-CNF mixture during cold pressing, motivated the study of the furnish dewatering behavior. Dewatering was assessed through …

Damage Resistance And Tolerance Of 3d Woven Composites, Justin T. Mcdermott

Electronic Theses and Dissertations

Composite materials have been adopted into primary aircraft structures by virtue of their great strength-to-weight and stiffness-to-weight ratios, fatigue insensitivity, and corrosion resistance. These characteristics are leveraged by aircraft designers to deliver improved fuel effciency and reduced scheduled maintenance burdens for their customers. These benefits have been impressively realized in the Boeing 787 and Airbus A350 XWB, with airframes utilizing about 50% composites by weight. Tempering these successes, however, are the inherent vulnerabilities of carbon-fiber reinforced composites. When compared to conventional metallic structure, composite laminates are more sensitive to stress concentrations at mechanical fastenings and damage due to low-velocity impact. …

Influence Of Mechanical Properties Of Paper Coating On The Crack At The Fold Problem, Seyyed Mohammad Hashemi Najafi

Electronic Theses and Dissertations

Paper coating layers are subject to various stresses and deformations in many converting processes such as calendering, printing, slitting, and folding of the paper. In some cases, products may crack during folding to generate a defect called cracking at the fold (CAF). The parameters that influence these defects are not well understood. The overall goal of this thesis is to better understand the CAF behavior as related to material properties of the coating layer.

A method was developed to produce free-standing pigmented coating layers thick enough to be tested in bending as well as tension. The mechanical properties of these …