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2020

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Full-Text Articles in Materials Science and Engineering

Characteristics Of Nanosilver Ink (Utdag) Microdroplets And Lines On Polyimide During Inkjet Printing At High Stage Velocity, Aamir Hamad, Adam Archacki, Ahsan Mian Jan 2020

Characteristics Of Nanosilver Ink (Utdag) Microdroplets And Lines On Polyimide During Inkjet Printing At High Stage Velocity, Aamir Hamad, Adam Archacki, Ahsan Mian

Mechanical and Materials Engineering Faculty Publications

The performance of printed electronics strongly depends on printing techniques and printing resolution that enhance their electrical and mechanical properties. In this research paper, a Jetlab 4xl was used to control and dispense microdroplets of highly conductive nanosilver ink (UTDAg) on a polyimide substrate. The waveform effect on the droplet generation is characterized by measuring the size and the speed of the drops. The behavior of ejected drops on the substrate is studied by printing lines at different drop spacing and stage velocity. The jetting parameters that drive the piezoelectric actuator were properly determined and two waveforms (bipolar) were created …


A Numerical Simulation On The Airfoil S833 Equipped With Flapping Trailing Edge Fringes, H. Yu, Zifeng Yang Jan 2020

A Numerical Simulation On The Airfoil S833 Equipped With Flapping Trailing Edge Fringes, H. Yu, Zifeng Yang

Mechanical and Materials Engineering Faculty Publications

Design optimization has been increasingly investigated for an airfoil, aiming to reduce the vorticity in the wake and increase the aerodynamic performance. In the current work, a two-dimensional (2D) S833 airfoil equipped with a flapping fringe at the trailing edge has been studied using computational fluid dynamics (CFD) simulations. The objective is to investigate the influence of the length (Lf) and flapping frequency (f) of the fringe on shedding vortices from the airfoil and the drag and lift coefficients. The validation of the current numerical approach for both static and dynamic motions of the airfoil was conducted. First, four different …


Evaluation Of Cyclo Olefin Polymer As Sabot Material For High-Density Projectiles, Estebanne Tarango Jan 2020

Evaluation Of Cyclo Olefin Polymer As Sabot Material For High-Density Projectiles, Estebanne Tarango

Open Access Theses & Dissertations

Assuring the integrity of spacecraft and its occupants are a priority in the field of space exploration. Micrometeoroids and orbital debris are one of the primary threats that affect spacecraft materials due to the high kinetic energies involved with hypervelocity impacts. Improvement of projectile launching capabilities prompts the investigation of adequate materials for the manufacturing of sabots able to carry high-density projectiles without catastrophic failure. Polycarbonate (PC) has been the chosen material by the Hypervelocity Team at White Sands Test Facility for sabots on the 0.50 caliber launcher; however, there is a material constraint when the projectile becomes significantly dense …


The Study Of Non-Permanent Tattoo Ink Using Nano Silver Compounds And Untact 3d Printing Technology, Jisu Lee Jan 2020

The Study Of Non-Permanent Tattoo Ink Using Nano Silver Compounds And Untact 3d Printing Technology, Jisu Lee

Open Access Theses & Dissertations

Due to a recent epidemic of COVID 19, the possibility of 3D tattoo printing technology using the Internet of Things (IoT) control system developed in a non-face-to-face contact process was identified. A non-surgical tattoo process and hygiene safety differentiated with silver tattoo ink was used to solve the health problems arising from the surgical tattoo process and to identify 3D tattoo printing techniques through a non-personal contact concept. During the tattoo processing, the image selected by the customer is sent to a designated printer via an IoT control system in a separate location. A piston-type extruder (PTE) printing technique was …


Enhancement Of Absorptance By Ultrafast Laser Pulse Shaping For Efficient Laser Processing Of Thin Polymers, Arifur Rahaman Jan 2020

Enhancement Of Absorptance By Ultrafast Laser Pulse Shaping For Efficient Laser Processing Of Thin Polymers, Arifur Rahaman

Electronic Theses and Dissertations, 2020-2023

Ultrashort-pulsed lasers have been used for high precision processing of a wide range of materials including dielectrics, semiconductors, metals, and polymers/polymer composites, enabling numerous applications ranging from micromachining, photonics to life sciences. However, there are challenges when applying this technology in the industry, which requires scale and throughput different from lab use. The goal of this research is to understand how ultrafast laser pulses interact with thin polymers/polymer composite materials and develop a method that is efficient for ultrafast laser processing of these materials. It is a common practice in industrial applications to run the laser at a high repetition …


Characterization Of Directed Energy Deposition Additively Manufactured Grcop-42 Alloy, Scott Landes Jan 2020

Characterization Of Directed Energy Deposition Additively Manufactured Grcop-42 Alloy, Scott Landes

Electronic Theses and Dissertations

GRCop is an alloy family constructed of copper, chromium, and niobium and was developed by NASA for high heat flux applications. The first of its kind, GRCop-84, was specifically designed for the environments seen by channel cooled main combustion chamber liners. To further increase thermal conductivity while maintaining material strength characteristics, the percentage of alloying elements were cut in half and GRCop- 42 was developed. In recent years, NASA has successfully additively manufactured GRCop with comparable material characteristics to wrought GRCop using a Laser Powder Bed Fusion (L-PBF) process. Benefits of this process include fabrication of intricate cooling channels as …


Data-Driven Modeling Of The Wake Behind A Wind Turbine Array, Naseem Ali, Raul Bayoan Cal Jan 2020

Data-Driven Modeling Of The Wake Behind A Wind Turbine Array, Naseem Ali, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

The wake flow in a wind turbine array boundary layer is described using the Koopman operator. Dynamics of the flow are decomposed into the linear and forcing terms, and the low-energy delay coordinates are revealed. The rare events show the non-Gaussian long tails that capture the switching and bursting phenomena. The near-wake region shows the incoherent phase space region, where the dynamics are strongly nonlinear. The far-wake region is marked with the small non-Gaussian forcing term, and the dynamics are largely governed by linear dynamics. The data-driven predictive model is built based on the Hankel-based dynamic mode decomposition and treats …


Utility-Scale Solar Pv Performance Enhancements Through System-Level Modifications, Andrew D. S. Glick, Naseem Ali, Juliaan Bossuyt, Marc Calaf, Raul Bayoan Cal Jan 2020

Utility-Scale Solar Pv Performance Enhancements Through System-Level Modifications, Andrew D. S. Glick, Naseem Ali, Juliaan Bossuyt, Marc Calaf, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Performance of solar PV diminishes with the increase in temperature of the solar modules. Therefore, to further facilitate the reduction in cost of photovoltaic energy, new approaches to limit module temperature increase in natural ambient conditions should be explored. Thus far only approaches based at the individual panel level have been investigated, while the more complex, systems approach remains unexplored. Here, we perform the first wind tunnel scaled solar farm experiments to investigate the potential for temperature reduction through system-level flow enhancement. The percentage of solar irradiance converted into electric power depends upon module efficiency, typically less than 20%. The …


A Review Of Open Source Ventilators For Covid-19 And Future Pandemics., Joshua M. Pearce Jan 2020

A Review Of Open Source Ventilators For Covid-19 And Future Pandemics., Joshua M. Pearce

Michigan Tech Publications, Part 1

Coronavirus Disease 2019 (COVID-19) threatens to overwhelm our medical infrastructure at the regional level causing spikes in mortality rates because of shortages of critical equipment, like ventilators. Fortunately, with the recent development and widespread deployment of small-scale manufacturing technologies like RepRap-class 3-D printers and open source microcontrollers, mass distributed manufacturing of ventilators has the potential to overcome medical supply shortages. In this study, after providing a background on ventilators, the academic literature is reviewed to find the existing and already openly-published, vetted designs for ventilators systems. These articles are analyzed to determine if the designs are open source both in …


Densification Of Ultra-Refractory Transition Metal Diboride Ceramics, William Fahrenholtz, Greg Hilmas, Ruixing Li Jan 2020

Densification Of Ultra-Refractory Transition Metal Diboride Ceramics, William Fahrenholtz, Greg Hilmas, Ruixing Li

Materials Science and Engineering Faculty Research & Creative Works

The densification behavior of transition metal diboride compounds was reviewed with emphasis on ZrB2 and HfB2. These compounds are considered ultra-high temperature ceramics because they have melting temperatures above 3000°C. Densification of transition metal diborides is difficult due to their strong covalent bonding, which results in extremely high melting temperatures and low self-diffusion coefficients. In addition, oxide impurities present on the surface of powder particles promotes coarsening, which further inhibits densification. Studies prior to the 1990s predominantly used hot pressing for densification. Those reports revealed densification mechanisms and identified that oxygen impurity contents below about 0.5 wt% …


Development Of An Anatomically And Electrically Conductive Brain Phantom For Transcranial Magnetic Stimulation, Hamzah A. Magsood Jan 2020

Development Of An Anatomically And Electrically Conductive Brain Phantom For Transcranial Magnetic Stimulation, Hamzah A. Magsood

Theses and Dissertations

Transcranial Magnetic Stimulation (TMS) is a non-invasive technique for diagnostics, prognostic, and treatments of various neurological diseases. However, the lack of anatomically realistic brain phantoms has made the experimental verification of stimulation strength in the form of induced electric fields/voltages in the brain tissues an impediment to developing new TMS coils, stimulators, and treatment protocols. There are significant technological, safety, and ethical limitations to test the potential TMS treatment procedures or develop enhancements and refine them on humans or animals. This work aims to bridge the gap by introducing and developing an innovative manufacturing and fabrications process to produce a …


Examination Of The Adhesiveness Of The Nanotube Layer On Anodized Commercially Pure Titanium Samples Using The Micro-Limiting Dome Height Test And The Tensile Test., Joshua Manohar Chinthapalli Jan 2020

Examination Of The Adhesiveness Of The Nanotube Layer On Anodized Commercially Pure Titanium Samples Using The Micro-Limiting Dome Height Test And The Tensile Test., Joshua Manohar Chinthapalli

Graduate Research Theses & Dissertations

Titanium oxide (TiO2) nanotube is one of the most extensively studied nanotubes due to its wide applications in electronics and medical fields. In this study, we used electrochemical anodization to create nanotubes on commercially pure titanium (Cp-Ti) samples and examined the adhesiveness of the nanotube layer on the sample surface. Particularly we conducted micro-limiting dome height (µLDH) tests on anodized Cp-Ti foils of 38 µm thickness and 4 mm diameter at room temperature, 100℃, and 200℃. We also conducted tensile tests on standard tensile specimens of anodized Cp-Ti plate at room temperature, and 200℃. The Hitachi S-4500 Field Emission Scanning …


Confinement Of Monolithic Stationary Phases In Targeted Regions Of 3d-Printed Titanium Devices Using Thermal Polymerization, Marta Passamonti, Ischa L. Bremer, Suhas H. Nawada, Sinead A. Currivan, Andrea F.G. Gargano, Peter J. Schoenmakers Jan 2020

Confinement Of Monolithic Stationary Phases In Targeted Regions Of 3d-Printed Titanium Devices Using Thermal Polymerization, Marta Passamonti, Ischa L. Bremer, Suhas H. Nawada, Sinead A. Currivan, Andrea F.G. Gargano, Peter J. Schoenmakers

Articles

Abstract

In this study, we have prepared thermally initiated polymeric monolithic stationary phases within discrete regions of 3D-printed titanium devices. The devices were created with controllable hot and cold regions. The monolithic stationary phases were first locally created in capillaries inserted into the channels of the titanium devices. The homogeneity of the monolith structure and the interface length were studied by scanning a capacitively coupled conductivity contactless detector (C4D) along the length of the capillary. Homogeneous monolithic structures could be obtained within a titanium device equipped with a hot and cold jacket connected to two water baths. The confinement method …


Surface And Structure Engineering For Next Generation Lithium Metal Batteries, Ke Chen Jan 2020

Surface And Structure Engineering For Next Generation Lithium Metal Batteries, Ke Chen

Electronic Theses and Dissertations

Lithium (Li) metal has been considered as one of the most promising anode materials to replace conventional graphite for Li-ion battery due to its high theoretical capacity (3860 mAh g-1) and low electrochemical potential (-3.04 V vs standard hydrogen electrode). However, it still faces some problems such as unstable solid electrolyte interphase (SEI), uncontrolled Li dendrites growth, and infinite volume change during battery charging/discharging. To develop a stable and low-cost Li metal anode for next-generation Li metal battery, in this dissertation, we have made efforts to understand and solve these problems in two aspects, by introducing an artificial SEI and …


Characterization, Modeling, And Thermal Management Of High-Performance Lithium Batteries, Minjun Bae Jan 2020

Characterization, Modeling, And Thermal Management Of High-Performance Lithium Batteries, Minjun Bae

Wayne State University Theses

Lithium-ion (Li-ion) batteries, as one of the most advanced commercial rechargeable batteries, play a crucial role in modern society as they are extensively used in portable electronic devices. Nevertheless, the limited electrochemical performance and poor thermal management systems of Li-ion batteries have hindered the expansion of their future applications. In search of alternative electrode materials to develop a battery with higher electrochemical performance, lithium (Li) metal has attracted much attention as an ideal alternative anode material due to its high specific capacity and lowest redox potential. However, needle-like Li dendritic growth causes severe safety concerns and thus prohibits practical applications …


Enhanced Gas Barrier Properties Of Graphene Oxide/Rubber Composites With Strong Interfaces Constructed By Graphene Oxide And Sulfur, Long Zheng, Stephen Jerrams, Zongchao Xu, Liqun Zhang, Li Liu, Shipeng Wen Jan 2020

Enhanced Gas Barrier Properties Of Graphene Oxide/Rubber Composites With Strong Interfaces Constructed By Graphene Oxide And Sulfur, Long Zheng, Stephen Jerrams, Zongchao Xu, Liqun Zhang, Li Liu, Shipeng Wen

Articles

Constructing strong interfacial interactions and complex filler networks is crucial to establishing high gas barrier properties in rubber composites. In this research, sulfur-graphene oxide (S-GO) hybrids were prepared by in situ growth of sulfur on the surfaces of GO sheets. The S-GO hybrids were also introduced into butadiene styrene rubber (SBR) using a green method of latex compounding. Results showed that sulfur could melt and spread on the surface of the GO during the crosslinking process at high temperatures. This process prevented the aggregation of GO and resulted in a fine dispersion of GO and complex filler networks in S-GO/SBR …


Lateral Bracing Of Beams Provided By Standing Seam Roof System: Concepts And Case Study, Gengrui Wei, Benjamin Schafer, Michael Seek, Matthew Eatherton Jan 2020

Lateral Bracing Of Beams Provided By Standing Seam Roof System: Concepts And Case Study, Gengrui Wei, Benjamin Schafer, Michael Seek, Matthew Eatherton

Engineering Technology Faculty Publications

The standing seam roof (SSR) system is the most commonly used roof system for metal buildings due to its superior durability, water tightness, and energy efficiency. In this type of system, SSR panels attach to Z-shaped or C-shaped purlins with clips, and the purlins are in turn connected to rafters (i.e. roof beams). For the design of metal building rafters against lateral torsional buckling, bottom flange braces provide torsional bracing to the rafter and the SSR system provides some lateral bracing. However, the degree to which the SSR system can restrain the rafter against lateral movement has not previously been …


Tensile-Strained Self-Assembly: Tunable Nanomaterials For Infrared Optoelectronics And Quantum Optics, Paul Simmonds Jan 2020

Tensile-Strained Self-Assembly: Tunable Nanomaterials For Infrared Optoelectronics And Quantum Optics, Paul Simmonds

Materials Science and Engineering Faculty Publications and Presentations

Discovered recently, tensile-strained quantum dots are optically active, defect-free nanostructures. Large tensile strains allow us to tailor band structures for applications from tunable infrared emitters to entangled photon sources. I will discuss the history, current state-of-the-art, and future directions of this rapidly expanding research field.


Two-Dimensional Nanomaterials And Their Composites For Electrochemical Detection Of Toxic Mercury Ions In Water, Md Tawabur Rahman Jan 2020

Two-Dimensional Nanomaterials And Their Composites For Electrochemical Detection Of Toxic Mercury Ions In Water, Md Tawabur Rahman

Electronic Theses and Dissertations

The presence of trace amounts of mercury ion (Hg2+) in drinking water has a detrimental effect on human health. The development of an electrochemical sensor for Hg2+ detection is still challenging to obtain ultra-trace sensitivity, excellent selectivity, wide Linear Detection Ranges (LDRs), and ultra-low detection limit. This work presents an electrochemical sensor based on two-dimensional nanomaterials and their composites for the enhanced sensing of Hg2+ in water. Graphene oxide (GO)-silver nanowires (AgNWs) composite and metallic 1T phase tungsten disulfide (WS2) microflowers were utilized for the fabrication of electrochemical sensors using drop-casting. Under the optimized experimental conditions, …


On Geometric Design Rules And In-Process Build Quality Monitoring Of Thin-Wall Features Made Using Laser Powder Bed Fusion Additive Manufacturing Process, Aniruddha Gaikwad Jan 2020

On Geometric Design Rules And In-Process Build Quality Monitoring Of Thin-Wall Features Made Using Laser Powder Bed Fusion Additive Manufacturing Process, Aniruddha Gaikwad

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The goal of this thesis is to quantify the link between the design features (geometry), in-process signatures, and build quality of parts made using the laser powder bed fusion (LPBF) additive manufacturing (AM) process. This knowledge is the foundational basis for proposing design rules in AM, as well as for detecting the impending build failures using in-process sensor data.

As a step towards this goal, the objectives of this work are two-fold:

1) Quantify the effect of the geometry and orientation on the build quality of thin-wall features. To explain further, the geometry related factor is the ratio of the …


Integrating Graphene Into Polymer Derived Ceramics Towards The Development Of New Thermoelectric Materials, Elizabeth Barrios Jan 2020

Integrating Graphene Into Polymer Derived Ceramics Towards The Development Of New Thermoelectric Materials, Elizabeth Barrios

Electronic Theses and Dissertations, 2020-2023

Radioisotope thermoelectric generators (RTGs) have been an enabling technology for the exploration of deep space since the dawn of the Space Age. Since its first deployment in a meteorological satellite in the late 1960's, RTGs have been used to provide solid-state, maintenance-free power to 27 American spacecraft and scientific instruments. While showing great success in the past, the future usage of thermoelectric devices is limited by the low operating efficiencies and the use of hazardous or expensive materials, limiting the use of thermoelectric technologies to niche applications such as space exploration. Current research efforts that address these disadvantages have focused …


Development Of 3d Porous Chitosan-Based Platform For In Vitro Culture, Kailei Xu Jan 2020

Development Of 3d Porous Chitosan-Based Platform For In Vitro Culture, Kailei Xu

Electronic Theses and Dissertations, 2020-2023

Three-dimensional (3D) cell cultures have been widely used in biological research since two-dimensional (2D) cultures have many limitations including alteration of cell morphology, metabolic pathways and gene expression. Therefore, the application of 2D cell cultures in pharmaceutical companies for drug screening causes reproducibility issues in animal studies, which strongly influences the efficiency of drug development. The aim of my studies is to develop 3D cell culture models to better mimic the extracellular matrix (ECM) in tumor microenvironment, not only for deeper understanding of interaction between cells and ECM, but also for the application in drug screening. Three different compositions of …


The Effect Of Thermal History On The Atomic Structure Andmechanical Properties Of Amorphous Alloys, Nikolai V. Priezjev Jan 2020

The Effect Of Thermal History On The Atomic Structure Andmechanical Properties Of Amorphous Alloys, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The influence of thermal processing on the potential energy, atomic structure, and mechanical properties of metallic glasses is examined using molecular dynamics simulations. We study the three-dimensional binary mixture, which was first relaxed near the glass transition temperature and zero pressure, and then rapidly cooled deep into the glass phase. It was found that glasses annealed at higher temperatures are relocated to higher energy states and their average glass structure remains more disordered, as reflected in the height of the first two peaks in the pair distribution function. The results of mechanical testing demonstrate that both the shear modulus and …


Modeling Of Scrap Dissolution In Molten Iron For The Case Of Heat Transfer-Controlled Process By Different Approaches And Comparison Of Their Accuracies, Ajay Kumar Shukla, Brahma Deo, D. G.C. Robertson Jan 2020

Modeling Of Scrap Dissolution In Molten Iron For The Case Of Heat Transfer-Controlled Process By Different Approaches And Comparison Of Their Accuracies, Ajay Kumar Shukla, Brahma Deo, D. G.C. Robertson

Materials Science and Engineering Faculty Research & Creative Works

Dissolution of steel scrap in molten iron is studied by using analytical as well as numerical approaches for the case of a heat transfer-controlled process. The approaches used are Green's function approach, quasi-static approach, integral profile method (IPM) (with parabolic profile), and finite difference methods (FDM). Application of FDM explicit and FDM implicit with fixed grid and variable grid is described. Accuracy of all the approaches is compared in terms of total dissolution time evaluated from overall heat balance criterion. The selection rule of time step and deciding the suitable approach for achieving minimum error for different operating conditions, represented …


Characterization Of Contact Resistance Properties Of Different Tlm Structure Designs, Nicole A. Karam Pannaci Jan 2020

Characterization Of Contact Resistance Properties Of Different Tlm Structure Designs, Nicole A. Karam Pannaci

Digital Repository: Showcase of Undergraduate Research Excellence

No abstract provided.


Performance Enhancement And Prediction Of Composite Materials With Embedded Electrospun Piezoelectric Sensors, Rahman Jani Mazed, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Md Riaz Uddin Ahmed, Rassel Raihan, Kenneth Reifsnider Jan 2020

Performance Enhancement And Prediction Of Composite Materials With Embedded Electrospun Piezoelectric Sensors, Rahman Jani Mazed, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Md Riaz Uddin Ahmed, Rassel Raihan, Kenneth Reifsnider

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

In today’s world, continuous fiber reinforced composite materials are extensively used in the aerospace, automotive and other structural industries. Since the applications of such fibers demand for a high safety rating, it is of utmost importance for engineers who design such materials to analyze its safety. When cracks are developed in such materials, the mechanical, electrical, and thermal properties also get altered as a function of the cracks. Previous studies have shown that changes in electrical properties can be directly correlated with the development of cracks in the material which can then be used to predict the remaining life of …


Fabrication, Characterization And Applications Of Highly Conductive Wet-Spun Pedot:Pss Fibers, Ruben Sarabia Riquelme Jan 2020

Fabrication, Characterization And Applications Of Highly Conductive Wet-Spun Pedot:Pss Fibers, Ruben Sarabia Riquelme

Theses and Dissertations--Chemical and Materials Engineering

Smart electronic textiles cross conventional uses to include functionalities such as light emission, health monitoring, climate control, sensing, storage and conversion of energy, etc. New fibers and yarns that are electrically conductive and mechanically robust are needed as fundamental building blocks for these next generation textiles.

Conjugated polymers are promising candidates in the field of electronic textiles because they are made of earth-abundant, inexpensive elements, have good mechanical properties and flexibility, and can be processed using low-cost large-scale solution processing methods. Currently, the main method to fabricate electrically conductive fibers or yarns from conjugated polymers is the deposition of the …


Ab Initio Investigation On The Surface Chemistry Of Functionalized Titania Membranes, Evan Hyde Jan 2020

Ab Initio Investigation On The Surface Chemistry Of Functionalized Titania Membranes, Evan Hyde

Theses and Dissertations--Chemical and Materials Engineering

Titania (titanium dioxide) is a metal oxide which has recently been investigated as a photocatalyst, most commonly for use in hydrolysis, which absorbs mostly in the UV range. However, the range of absorption can be shifted to fall within the visible light range either by doping or by functionalizing the surface with atomic or molecular adsorbates. Over the course of this research, a series of Density Functional Theory (DFT) calculations are performed to ascertain the effects of these different methods on the photocatalytic performance of titania. While the effects of nitrogen doping and oxygen vacancies are well known, more recent …


Electrophoresis In Heterogeneous Hydrogels And Applications In Surface Patterning, Ning Ge Jan 2020

Electrophoresis In Heterogeneous Hydrogels And Applications In Surface Patterning, Ning Ge

Theses and Dissertations--Mechanical and Aerospace Engineering

The creation of chemical micropatterns on surfaces makes it possible to add unique chemical functionality to surfaces, modifying properties such as wettability, or even adding the ability to selectively bind other molecules. The creation of biochemical surface patterning in particular is useful in a variety of fields including tissue engineering and highthroughput drug screening. There are many existing surface patterning techniques which focus on precise control over the patterned geometry, even down to submicron scale features, but they do not allow local control over chemical concentration. So the results are high resolution patterns with binary concentration. There are also existing …


Stress Generation In Ni50.3Ti29.7Hf20 Shape Memory Alloys, Utsav Shah Jan 2020

Stress Generation In Ni50.3Ti29.7Hf20 Shape Memory Alloys, Utsav Shah

Theses and Dissertations--Mechanical and Aerospace Engineering

Shape memory alloys such as NiTiHf and NiTi have the ability to generate large recovery stresses when they are constrained after pre-straining and then heated above their Austenite Finish Temperature (Af). In this work Ni49.9Ti50.1 (at.%), the most well-known SMA with impressive shape memory properties but limited temperature range and Ni50.3Ti29.7Hf20, a promising high temperature shape memory alloy, were characterized to reveal their stress generation capabilities. The effects of pre-straining on stress generation were investigated via martensite reorientation method of NiTi and NiTiHf alloys by loading the samples till …