Structural Materials Commons^™

Mechanical Interfacial Locking And Multiscale Modeling Of Reinforced Thermoplastic Composites For Structural Applications, Anmol Kothari

All Dissertations

The ever-growing pressure of reducing the adverse impact of transportation systems on environment has pushed industries towards fuel-efficient and sustainable solutions. While several approaches have been used to improve fuel efficiency, the light-weighting of structural components has proven broadly effective. In this regard, reinforced thermoplastic composites (RTPC), owing to their high recyclability, higher impact strength and fast cycle times, have become competitive candidates at an industrial scale. However, to implement RTPC toward large scale structural applications several challenges pertaining to material design and manufacturing effects need to be addressed. To this end, a computational study is carried out to address …

Development Of Lambda Factors For Masonry Design With Lightweight Grout, Rumi Shrestha

All Theses

Reduction in structural mass, improvement in thermal performance, and reduction in shrinkage cracking through internal curing are some of the reasons that lightweight (LW) aggregates have been used in structures and pavements for decades. However, lightweight grout is still not permitted for use in reinforced masonry construction by the TMS 402/602-16 code. In order to realize the benefits of lightweight grout in U.S. reinforced masonry construction, a codified procedure for its use is required which must be informed by experimental testing.

This research is a pilot project directed to characterize the performance of LW grout in comparison to normal weight …

Impact Of Exposure On Thin Epoxy Overlay Performance, Abul Fazal Mazumder

Dissertations

Thin epoxy overlays are used for improving the condition and extending the service life of bridge decks. The tensile bond pull-off strength, evaluated as per the ASTM C1583, is used as the performance indicator. A failure in the substrate with a tensile strength of 250 psi or greater is considered acceptable. However, the performance evaluated on in-service bridge decks shows inconsistent results. Laboratory studies by several researchers documented a distinct performance difference when the overlays are exposed to room temperatures in comparison to elevated temperatures. However, the most influential parameters such as concrete surface profile, thermal compatibility between overlay and …

Advanced Materials Design Using Application-Based Processing Techniques, Daniel S. Camarda

Doctoral Dissertations

This dissertation pertains to generating advanced materials using application-based processing techniques. First, billets consisting of PTFE sintering powders are evaluated using Thermomechancal Analysis. It was found that both shape change and volume change are associated with enthalpic and entropic recoil, respectively. These phenomena, due to melting and stored energy during the powder compaction process, were found to be molecular weight dependent. Additionally, kinetics of the recovery and sintering process were found to be slower in blended specimens than pure samples. Next, the creation of graft copolymers by selectively grafting a second polymer to the amorphous fraction of a semi-crystalline polymer …

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 …

Seaweed Polysaccharide In Food Contact Materials (Active Packaging, Intelligent Packaging, Edible Films, And Coatings), Kalpani Y. Perera, Shubham Sharma, Amit K. Jaiswal, Swarna Jaiswal

Articles

Food contact materials (FCMs) are materials that come in contact with food products such as food packaging which play a significant role in the food quality and safety. Plastic, which is a major food packaging material, harms the eco-system, wildlife, and the environment. As a result, numerous researches have been in progress on alternative polymers, which has similar properties as plastic but is also environmentally friendly (biodegradable). In recent years, the utilization of seaweed polysaccharides has piqued interest due to its biodegradability, non-toxicity, antioxidant capabilities, and excellent film formation ability. However, it has a number of drawbacks such as low …

Tools And Strategies For The Patterning Of Bioactive Molecules And Macromolecules, Daniel J. Valles

Dissertations, Theses, and Capstone Projects

Hypersurface Photolithography (HP) is a printing method for fabricating structures and patterns composed of soft materials bound to solid surfaces and with ~1 micrometer resolution in the x, y, and z dimensions. This platform leverages benign, low intensity light to perform photochemical surface reactions with spatial and temporal control of irradiation, and, as a result, is particularly useful for patterning delicate organic and biological material. In particular, surface- initiated controlled radical polymerizations can be leveraged to create arbitrary polymer and block- copolymer brush patterns. Chapter 1 will review the advances in instrumentation architectures from our group that have made these …

Development Of Density-Functional Tight-Binding Methods For Chemical Energy Science, Quan Vuong

Doctoral Dissertations

Density-functional tight-binding (DFTB) method is an approximation to the popular first-principles density functional theory (DFT) method. Recently, DFTB has gained considerable visibility due to its inexpensive computational requirements that confer it the capability of sustaining long-timescale reactive molecular dynamics (MD) simulations while providing an explicit description of electronic structure at all time steps. This capability allows the description of bond formation and breaking processes, as well as charge polarization and charge transfer phenomena, with accuracy and transferability beyond comparable classical reactive force fields. It has thus been employed successfully in the simulation of many complex chemical processes. However, its applications …

Rapid Annealing Of Perovskite Solar Cell Thin Film Materials Through Intense Pulse Light., Amir Hossein Ghahremani

Electronic Theses and Dissertations

Perovskite solar cells (PSCs) have garnered a great attention due to their rapid efficiency improvement using cheap and solution processable materials that can be adapted for scalable high-speed automated manufacturing. Thin film perovskite photovoltaics (PVs) are typically fabricated in an inert environment, such as nitrogen glovebox, through a set of deposition and annealing steps, each playing a significant role on the power conversion efficiency (PCE), reproducibility, and stability of devices. However, atmospheric processing of PSCs would achieve lucrative commercialization. Therefore, it is necessary to utilize materials and methods that enable successful fabrication of efficient PSCs in the ambient environment. The …

Development Of A Wireless Telemetry Load And Displacement Sensor For Orthopaedic Applications, William Anderson

Electronic Thesis and Dissertation Repository

Due to sensor size and supporting circuitry, in vivo load and deformation measurements are currently restricted to applications within larger orthopaedic implants. The objective of this thesis is to repurpose a commercially available low-power, miniature, wireless, telemetric, tire-pressure sensor (FXTH87) to measure load and deformation for future use in biomechanical applications. The capacitive transducer membrane of the FXTH87 was modified, and a relationship was reported between applied compressive deformation and sensor signal value. The sensor package was embedded within a deformable enclosure to illustrate potential applications of the sensor for monitoring load. Finite element analysis was an effective tool to …

Phase-Field Modeling Of The Polymer Membrane Formation Process For Micro- And Ultra-Filtration, Michael Rosario Cervellere

Graduate Theses and Dissertations

Porous polymer membrane filters are widely used in separation and filtration process. Micro- and ultra-filtration membranes are commonly used in biopharmaceutical applications such as filtering viruses and separating proteins from a carrier solution. The formation of these membrane filters via phase inversion is a complex and interconnected process where varying casting conditions can have a wide variety of effects on the final membrane morphol- ogy. Tailoring membrane filters for specific performance characteristics is a tedious and time consuming process. The time and length scales of membrane formation make it extremely difficult to experimentally observe membrane formation. Modeling the membrane formation …

Frequency Effect On Peak Pressure Coefficients Using The Narrowband Synthesis Random Flow Generator (Nsrfg) Method, Zayuris Del Carmen Atencio Mojica

Graduate Theses and Dissertations

The collapse of the Tacoma Narrows Bridge in Washington state in 1940 due to high wind forces gave structural engineers notice of the importance of understanding the behavior of wind forces on infrastructure. Wind forces play an important role in the design of buildings and other structures. ASCE 7-16 is the manual used for the design of these buildings and other structures throughout the country. These design criteria have been approved based on research projects involving experimental procedures. For the design of wind loads, ASCE 7-16 uses criteria based on wind tunnel (WT) tests. However, since the development of computing …

Investigation Of Membrane Based Processes For Biomedical Applications, Efecan Pakkaner

Graduate Theses and Dissertations

As substantial developments were achieved in nanotechnology and polymer engineering, especially in the last few decades, the use of membranes and membrane-based procedures was found to be expanding into more and more research and development areas; including biological engineering, life sciences and biomedical engineering. Not only have they been the main focus of meaningful research, but they have also been the main pieces of the solutions to very thorny problems encountered within a wide range of applications from microfluidics to water treatment, thanks to their versatility, cost-effectiveness and biocompatibility, when compared to conventional separation techniques. To celebrate and embrace these …

Review: Factors Affecting Composite Laminates Against Lightning Strikes, Aaryan Manoj Nair

Publications and Research

Lightning strike protection (LSP) have recently been a newly developing field particularly with the emergence of graphene thin film integration into carbon fiber composite structures. This technology has a widespread application in airplanes, wind turbines, and other instruments which are susceptible to frequent lightning strikes. Electrical discharge of the instrument in a safe manner is vital for the safety of the passengers (in the case of flights) as well as the integrity of the aircraft structures because of their specific mechanical and structural properties, which are essential for their functioning. The purpose of the study is to fabricate graphene thin …

Material Property Heterogeneity In Dimensional Lumber And Its Relationship To Mass Timber Performance, Fiona O'Donnell

Doctoral Dissertations

According to the Environmental Protection Agency, buildings account for 38% of the United States' carbon dioxide emissions, providing architects and structural engineers a unique opportunity to mitigate a significant factor driving climate change by implementing innovative and sustainable technology in infrastructure design. Wood and mass timber products are becoming an increasingly popular alternative building material due to their economic and environmental benefits. The natural growth of wood leads to highly heterogeneous material properties. Defects such as checks, knots, and localized slope of grain contribute to some of this variation; however, wood properties vary significantly even in clear wood. Using mass …

Harnessing The Mechanics Of Thin-Walled Metallic Structures: From Plate-Lattice Materials To Cold-Formed Steel Shear Walls, Fani Derveni

Doctoral Dissertations

Thin-walled structures have received a lot of interest during the last years due to their light weight, cost efficiency, and ease in fabrication and transportation, along with their high strength and stiffness. This dissertation focuses on the mechanical performance of thin-walled metallic structures from cold-formed steel shear walls and connections (PART I) to plate-lattice architected materials (PART II) via computational, experimental, and probabilistic methods.

Cold-formed steel (CFS) shear walls subjected to seismic loads is the focus of PART I of this dissertation. An innovative three-dimensional shell finite element model of oriented strand board (OSB) sheathed CFS shear walls is introduced …

Assessment Of Carbon Dioxide Emission And Its Impact On High-Rise Mixed-Use Buildings In Egypt, Ahmed Salah Hamza

Theses and Dissertations

With Egypt's vision of 2030 focusing on sustainable development with a true emphasis on Carbon Dioxide (CO₂) emission reduction in the newly built cities and high-rise buildings, efforts are exerted on various levels towards accomplishing the vision’s goals. This is achieved through multiple tools and models associated with aiding the reduction of carbon emissions, yet not a clear one was introduced for the mixed-use buildings in Egypt.

Through this work, a significant gap was identified with respect to high-rise buildings carbon emission assessment in Egypt. This was a main driving force for this work in an attempt to …

Strengthening Of 7175 Aluminum Alloy Through Multi-Step Aging Process, Colin E. Masterson, Ryland W. Jolliffe

Materials Engineering

7175 is a heat-treatable aluminum alloy commonly used in aerospace forgings. This alloy is aged with a multi-step heat treatment. This treatment must balance strength with stress corrosion cracking resistance through a degree of overaging. The team was tasked by Weber Metals to increase the strength of this treatment without sacrificing stress corrosion cracking resistance. Both two-step and retrogression and reaging treatments were tested in experiments to find a heat treatment that could increase the yield and tensile strength by 1-2 ksi while maintaining a minimum electrochemical conductivity equivalence of 38% relative to copper. Two-step aging is the more conventional …

Enhancement Of Asphalt Performance By Graphene-Based Bitumen Nanocomposites, Sara Moghtadernejad, Ehsan Barjasteh, Ren Nagata, Haia Malabeh

Mineta Transportation Institute Publications

As the State of California continues to grow, demand for enhanced infrastructure such as roadways and highways escalates. In view of the current average highway lifespan of 15–20 years, the improvement of asphalt binders leads to material sustainability by decreasing required maintenance and increasing the lifespan of roadways. In the present investigation, enhancement of asphalt binder properties was achieved by different methods of mixing varying compositions of graphene nanoparticles with an SBS polymer and asphalt binder. Additionally, experimental evaluation and comparison of the rheological and mechanical properties of each specimen is presented. Graphene nanoparticles have attracted great curiosity in the …

Use Of Biomimicry Design Approach In Constructing Sustainable Resilient Structures (Case Study: Port Of Beirut), Farouk Bader, Marwan Halabi, Hiba Mohsen, Maged Youssef

BAU Journal - Creative Sustainable Development

Resiliency is not the same as sustainability, nor its substitute, but definitely the two concepts complement each other’s. Sustainability is the avoidance of depletion of natural resources to maintain ecological balance whereas resiliency is to recover, adapt and keep going in the face of setbacks. While designing with green approach is important but what will happen to leed points if the building becomes uninhabitable due to disasters, that’s where resiliency comes into play. The 2019 statistics showed that natural disasters accounted for 133 billion dollars losses and manmade ones accounted for other 7 billion in addition to 11,755 people worldwide …