Mechanical Engineering Commons^™

Composite Suspension For A Mass Market Vehicle, Sarah M. Chapiama, Brian Auyeung, Jose Guerrero, Ethan Lau

Mechanical Engineering

Statement of Confidentiality: The complete senior project report was submitted to the project advisor and sponsor. The results of this project are of a confidential nature and will not be published at this time.

Mass Accretion And Ozone Reactivity Of Idealized Indoor Surfaces In Mechanically Or Naturally Ventilated Indoor Environments, Elliott T. Gall, Donghyun Rim

Mechanical and Materials Engineering Faculty Publications and Presentations

In indoor environments, accretion of mass to materials may provide sites for surface chemistry that differ from those of the original material. Since indoor surfaces are a major sink of oxidant gases, surface mass accretion may impact indoor O₃ chemistry. In this study, the effect of surface mass accretion on O₃ surface deposition was tested by deploying cleaned borosilicate glass plates in two types of indoor environments: a mechanically ventilated ( MV ) office and a naturally ventilated ( NV ) residence located in Singapore. In each environment, seven replicate glass plates and one field blank were deployed …

Analysis Of The Low-Cycle Fatigue Behavior Of Silicone Rubber For Biomedical Balloons, Chase Cooper

Materials Engineering

The development of a medical drug delivery device that allows for the deployment drugs into the adventitial tissue of blood vessels requires the inflation of a silicone elastomer. The inflated silicone must be able to consistently endure multiple loading cycles without failing so that the device can operate reliably. There are multiple methods of processing the silicone for the device and the goal of this study is to examine the effect of the various processing methods on the characteristics of the silicone. The Dynamic Mechanical Analysis Machine (DMA) is used to model the conditions of the device’s application by performing …

Mechanical Characterization Of Selectively Laser Melted 316l Stainless Steel Body Centered Cubic Unit Cells And Lattice Of Varying Node Radii And Strut Angle, Christopher James Hornbeak

Master's Theses

An experimental study of several variants of radius and strut angle of the body centered cubic unit cell was performed to determine the mechanical properties and failure mechanisms of the mesostructure. Quasi static compression tests were performed on an Instron® universal testing machine with a 50kN load cell at 0.2mm/min. The test samples were built using a SLM Solutions 125 selective laser melting machine with 316L stainless steel. Test specimens were based on 5mm cubic unit cells, with a strut diameter 10% of the unit cell size, with skins on top and bottom to provide a cantilever boundary constraint. Specimens …

Perovskite Solar Cells Fabricated Via Scalable Dip Coating Methods, Joseph F. Iannello

Theses and Dissertations

Perovskite solar cells present the possibility for less expensive electricity generation, through the use of low cost materials and fabrication methods relative to current silicon-based technology. Many current methods of fabricating thin film perovskite solar cells focus on spin-coating, which inherently lacks scalability due to particle conglomeration, poor uniformity over a larger area, and safety concerns. Dip-coating, an alternative to spin-coating, which is explored here addresses these issues which limit scalability. Each individual layer can be separately synthesized, deposited, and characterized, which leads towards scalability. Choosing only the best results from each independent layer allowed progress to the creation of …

Three Speed 3d Printed Magnetic Gear, Robert J. Rutherford

Maseeh Summer Undergraduate Research Experience

Power transmission is traditionally achieved with a mechanical gear. Mechanical gears require maintenance, cause vibration, and have no overload protection. Magnetic gears offer an innovative solution to these drawbacks as they do not require regular maintenance, have no need for lubrication, create very little acoustic noise, have built in overload protection and as a result of these advantages, have a longer lifetime of operation. This research focused upon the design, assembly and demonstration of the magnetic gear concept. The research used a solid works design, 3D printed ABS plastic housing, and use of neodymium magnets and ferromagnetic iron segments.

This …

Soft-Microrobotics: The Manipulation Of Alginate Artificial Cells, Samuel Sheckman

Mechanical Engineering Research Theses and Dissertations

In this work, the approach to the manipulation of alginate artificial cell soft-microrobots, both individually and in swarms is shown. Fabrication of these artificial cells were completed through centrifugation, producing large volumes of artificial cells, encapsulated with superparamagnetic iron oxide nanoparticles; these artificial cells can be then externally stimulated by an applied magnetic field. The construction of a Permeant Magnet Stage (PMS) was produced to manipulate the artificial cells individually and in swarms. The stage functionalizes the permanent magnet in the 2D xy-plane. Once the PMS was completed, Parallel self-assembly (Object Particle Computation) using swarms of artificial cells in complex …

Ozone Removal Efficiency And Surface Analysis Of Green And White Roof Hvac Filters, Omed A. Abbass, David Sailor, Elliott T. Gall

Mechanical and Materials Engineering Faculty Publications and Presentations

Heating, ventilation, and air-conditioning ( HVAC ) system filters from a commercial building were tested for their ability to remove ozone from intake air. Filters were taken from rooftop HVAC systems installed for two months: one located on a white membrane roof and the other on a vegetated green roof. One new, unused filter sample was tested as a reference. Samples from these filters were exposed to ozonated air streams at 40 and 120 ppb and relative humidity levels of 30% and 70%. Filter surfaces were analyzed with a scanning electron microscope to observe the structure and composition of the …

Preliminary Investigation Of Tensile Strength And Impact Characterization Of Cementitious Composite Incorporating Carbon Nanotubes, Robabeh Jazaei

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cement has been largely used in the construction industry, specifically as a matrix for concrete. Recently, a new generation of cement-based composite that greatly increases mechanical properties is replacing conventional concrete. With periodic advances in the field, researchers considered particles with high-aspect ratios such as Carbon Nanotubes (CNTs) to reinforce cement matrices. Although there is not much literature to draw upon in research, some research on improving the tensile strength of cementitious composite incorporating with CNTs does exist. However, there had been no evidence of investigation into impact strength until this study.

Most papers presented examined the effect of multi-walled …

Design And Synthesis Of Novel Nanometallic Catalysts And Electrode Materials For Green Fuel Cells, Jing Zhang

Graduate Dissertations and Theses

The United Nations formally adopted 17 sustainable development goals (SDGs) at its 2015 summit. Many of these goals addressed issues such poverty, hunger, health, education, climate-change, gender equality, water, sanitation, energy, urbanization, environment and social justice. The seventh SDG seeks to ensure access to affordable, reliable, sustainable and modern energy for all. So among all renewable forms of energy, fuel cells with high efficiency have attracted a lot of attention recently. In particular, the direct ethanol fuel cells (DEFCs) and microbial fuel cells (MFCs) are significant due to their green fuel, less waste generated and environmental friendliness. Hence the overall …

Aligned Carbon Nanotube Arrays Bonded To Solid Graphite Substrates: Thermal Analysis For Future Device Cooling Applications, Betty T. Quinton, Levi Elston, James D. Scofield, Sharmila M. Mukhopadhyay

Mechanical and Materials Engineering Faculty Publications

Carbon nanotubes (CNTs) are known for high thermal conductivity and have potential use as nano-radiators or heat exchangers. This paper focuses on the thermal performance of carpet-like arrays of vertically aligned CNTs on solid graphite substrates with the idea of investigating their behavior as a function of carpet dimensions and predicting their performance as thermal interface material (TIM) for electronic device cooling. Vertically aligned CNTs were grown on highly oriented pyrolytic graphite (HOPG) substrate, which creates a robust and durable all-carbon hierarchical structure. The multi-layer thermal analysis approach using Netzsch laser flash analysis system was used to evaluate their performance …

Research And Development Of Powder Brazing Filler Metals For Diamond Tools: A Review, Fei Long, Peng He, Dusan P. Sekulic

Mechanical Engineering Faculty Publications

Powder brazing filler metals (PBFMs) feature a number of comparative advantages. Among others, these include a low energy consumption, an accurate dosage, a good brazeability, a short production time, and a high production efficiency. These filler metals have been used in the aerospace, automobile, and electric appliances industries. The PBFMs are especially suitable for diamond tools bonding, which involves complex workpiece shapes and requires accurate dosage. The recent research of PBFMs for diamond tools is reviewed in this paper. The current applications are discussed. The CuSnTi and Ni-Cr-based PBFMs have been the two commonly used monolayer PBFMs. Thus, the bonding …

Analysis Of Surface Integrity In Machining Of Aisi 304 Stainless Steel Under Various Cooling And Cutting Conditions, F. Klocke, B. Döbbeler, S. Lung, S. Seelbach, Ibrahim S. Jawahir

Institute for Sustainable Manufacturing Faculty Publications

Recent studies have shown that machining under specific cooling and cutting conditions can be used to induce a nanocrystalline surface layer in the workspiece. This layer has beneficial properties, such as improved fatigue strength, wear resistance and tribological behavior. In machining, a promising approach for achieving grain refinement in the surface layer is the application of cryogenic cooling. The aim is to use the last step of the machining operation to induce the desired surface quality to save time-consuming and expensive post machining surface treatments. The material used in this study was AISI 304 stainless steel. This austenitic steel suffers …

Effects Of Tension On Resonant Frequencies Of Strings, Blake Burnett

Senior Theses

This project tests and explores resonance of strings. Since all materials and mechanisms are affected by vibrations, it is important to know the frequencies at which resonance occurs. To explore this subject, strings were used as a model material to test the effect tension has on resonance. The fundamental frequencies and the corresponding modes of resonance were used to analyze the data. The results of this experiment show that increasing tension on a string increases its resonance frequency. Understanding the physics behind resonance frequency allows systems to be designed to take advantage of resonance properties, or to avoid resonance where …

Measuring The Double Layer Capacitance Of Electrolyte Solutions Using A Graphene Field Effect Transistor, Agatha Ulibarri

Senior Theses

When operating graphene field effect transistors (GFETs) in fluid, a double layer capacitance (C_dl) is formed at the surface. In the literature, the C_dl is estimated using values obtained using metal electrode experiments. Due to the distinctive electronic and surface properties of graphene, there is reason to believe these estimates are inadequate. This work seeks to directly characterize the double layer capacitance of a GFET. A unique method for determining the C_dl has been implemented, and data has been obtained for three electrolytes and one ionic fluid. The results yield dramatically lower C_dl values than …

Accelerated Creative Problem Solving And Product Improvement Applied To Experimental Devices In A Bloodstain Pattern Interpretation Class--Improving The Role Of Insight Development Tools As A Generator Of New Ideas In Novel Situations, Douglas Ridolfi

Creativity and Change Leadership Graduate Student Master's Projects

This project uses an action research centered study protocol to examine the effects of a problem-based learning exercise related to bloodstain pattern interpretation in a crime scene processing and general criminalistics class taught as part of an upper division forensic chemistry major in a four year college. The goal is to apply design principles and creative problem solving methods directly adapted to a project involving interpreting a set of crime scene photographs depicting blood spatter and with the aid of guided exercises in ideation and design, lead students into the development of alternate theories of how the bloodstains were created …

Understanding The Evolution Of Surface Texture Under Boundary Lubrication, Salil T. Bapat

Graduate Theses and Dissertations

The objective of this research was to understand the evolution of surface texture under boundary/mixed lubrication (BL). Significant material/energy losses occur during BL because of direct contact between the two surfaces. Traditionally, tribofilms have been studied extensively for BL while textures have been used as a static engineering design parameter to enhance lubricant film properties. However, texture is dynamic at the tribological mating interface, where both physical and chemical interactions are continuously modulated. The evolution and the interplay between the tribofilm and texture is least studied in the literature, which is the focus of this research.

MoS2-based lubricants, known for …

Ultrasonic Nondestructive Evaluation Of Metal Additive Manufacturing., Venkata Karthik Nadimpalli

Electronic Theses and Dissertations

Metal Additive Manufacturing (AM) is increasingly being used to make functional components. One of the barriers for AM components to become mainstream is the difficulty to certify them. AM components can have widely different properties based on process parameters. Improving an AM processes requires an understanding of process-structure-property correlations, which can be gathered in-situ and post-process through nondestructive and destructive methods. In this study, two metal AM processes were studied, the first is Ultrasonic Additive Manufacturing (UAM) and the second is Laser Powder Bed Fusion (L-PBF). The typical problems with UAM components are inter-layer and inter-track defects. To improve the …

Phase Field Model Of Thermally Induced Phase Separation (Tips) For The Formation Of Porous Polymer Membranes, Ashley Green, Aria Green

Mechanical Engineering Undergraduate Honors Theses

Most membrane research and development has been done through experimental work, which can be costly and time consuming. An accurate computational model would greatly reduce the need for these experiments. The focus of the research presented in this paper is to create an accurate computational model for membrane formation using thermally induced phase separation (TIPS). A phase field model is employed to create this model including the Cahn Hilliard Equation and Flory Huggins Theory. This model produced computational results that correspond well with theoretical and experimental results. The model was then adapted to correspond to the PVDF/DPC polymer-solvent system by …

Influence Of Impact Conditions On Feedstock Deposition Behavior Of Cold-Sprayed Fe-Based Metallic Glass, Constance Ziemian, Wendelin Wright, David E. Cipoletti

Faculty Journal Articles

Cold spray is a promising method by which to deposit dense Fe-based metallic glass coatings on conventional metal substrates. Relatively low process temperatures offer the potential to prevent the crystallization of amorphous feedstock powders while still providing adequate particle softening for bonding and coating formation. In this study, Fe48 Mo14 Cr15 Y2 C15 B6 powder was sprayed onto a mild steel substrate, using a variety of process conditions, to investigate the feasibility of forming well-bonded amorphous Fe-based coatings. Particle splat adhesion was examined relative to impact conditions, and the limiting values of temperature and velocity associated with successful softening and …

Phase Transitions In Monochalcogenide Monolayers, Mehrshad Mehboudi

Graduate Theses and Dissertations

Since discovery of graphene in 2004 as a truly one-atom-thick material with extraordinary mechanical and electronic properties, researchers successfully predicted and synthesized many other two-dimensional materials such as transition metal dichalcogenides (TMDCs) and monochalcogenide monolayers (MMs). Graphene has a non-degenerate structural ground state that is key to its stability at room temperature. However, group IV monochalcogenides such as monolayers of SnSe, and GeSe have a fourfold degenerate ground state. This degeneracy in ground state can lead to structural instability, disorder, and phase transition in finite temperature. The energy that is required to overcome from one degenerate ground state to another …

Peridynamic Modeling Of Dynamic Fracture In Bio-Inspired Structures For High Velocity Impacts, Sneha Akula

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

Bio-inspired damage resistant models have distinct patterns like brick-mortar, Voronoi, helicoidal etc., which show exceptional damage mitigation against high-velocity impacts. These unique patterns increase damage resistance (in some cases up to 3000 times more than the constituent materials) by effectively dispersing the stress waves produced by the impact. Ability to mimic these structures on a larger scale can be ground-breaking and could be used in numerous applications. Advancements in 3D printing have now made possible fabrication of these patterns with ease and at a low cost. Research on dynamic fracture in bio-inspired structures is very limited but it is …

Evolution Of Mg Az31 Twin Activation With Strain: A Machine Learning Study, Andrew D. Orme

Undergraduate Honors Theses

Machine learning is being adopted in various areas of materials science to both create predictive models and to uncover correlations which reveal underlying physics. However, these two aims are often at odds with each other since the resultant predictive models generally become so complex that they can essentially be described as a black box, making them difficult to understand. In this study, complex relationships between microstructure and twin formation in AZ31 magnesium are investigated as a function of increasing strain. Supervised machine learning is employed, in the form of J-48 decision trees. In one approach, strain is incorporated as an …

Hawai'i Wildlife Fund V. County Of Maui, Lowell J. Chandler

Public Land & Resources Law Review

In Hawai’i Wildlife Fund v. County of Maui, the Ninth Circuit held that the plain language of the Clean Water Act provides jurisdiction over indirect discharges of pollutants from a point source into groundwater that is shown to be connected to navigable waters. The court found that studies confirmed pollutants entering the Pacific Ocean were fairly traceable to the County of Maui’s sewage disposal wells. In affirming the district court’s ruling, the Ninth Circuit held that Maui County violated the Clean Water Act by discharging pollutants into a navigable water without the required permit. The court also concluded the …

Scalable Patterning Using Laser-Induced Shock Waves, Saidjafarzoda Ilhom, Khomidkhodza Kholikov, Peizhen Li, Claire Ottman, Dylan Sanford, Zachary Thomas, Omer San, Haluk E. Karaca, Ali O. Er

Mechanical Engineering Faculty Publications

An advanced direct imprinting method with low cost, quick, and minimal environmental impact to create a thermally controllable surface pattern using the laser pulses is reported. Patterned microindents were generated on Ni₅₀Ti₅₀ shape memory alloys and aluminum using an Nd: YAG laser operating at 1064 nm combined with a suitable transparent overlay, a sacrificial layer of graphite, and copper grid. Laser pulses at different energy densities, which generate pressure pulses up to a few GPa on the surface, were focused through the confinement medium, ablating the copper grid to create plasma and transferring the grid pattern onto …

A Laboratory Kit For Multimeter Design, Seth Percy, Joshua Perry

Thinking Matters Symposium Archive

The multimeter is an important electrical tool and is a combination of many individual instruments. In practice, common multimeter designs are digital and measure voltage, current, resistance, capacitance, etc., using a single set of probes. Before the digital age, the world relied on analog displays. Some argue that analog displays are outdated technology. However, this overlooks one of the most important characteristics provided by the analog display, which is its ability to provide an instantaneous visual perception. Analog displays are currently used for many applications in aviation and automobiles, demonstrating their continuing usefulness in the field. In the multimeter, the …

An Evaluation Of Induction Heating In Healthcare Food Industry, Barrett Alexander Hampton

Masters Theses & Specialist Projects

This thesis addresses the problem healthcare facilities are having in maintaining proper food temperatures while transporting meals to patients after food has left the kitchen area. Induction heat has been a known method for generating heat for many years. The commercial food industry currently uses this technology, which is beginning to appear in the residential sector as well because of developments made by manufacturers. This study focuses on the top commercial brand models of induction heaters and the supporting materials currently used to create heat sources to maintain food temperatures in hospitals and long term care facilities.

The research in …

Structural And Photoluminescence Properties Of Zno Thin Films Deposited By Ultrasonic Spray Pyrolysis, Iwan Sugihartono, Erfan Handoko, Vivi Fauzia, Artoto Arkundato, Lara Permata Sari

Makara Journal of Technology

Zinc oxide (ZnO) thin films on a silicon (Si) (111) substrate were grown herein using ultrasonic spray pyrolysis at 450 °C with different Zn concentrations. The ZnO thin films had X-ray diffraction patterns of a polycrystalline hexagonal wurtzite structure. The (002) and (101) peak intensities changed under different Zn concentrations. Furthermore, according to Scherer's and Stokes–Wilson equations, the crystallite size and the internal strain of the ZnO thin films in the (002) and (101) peaks changed with the Zn concentration. Optically, the photoluminescence spectra indicated that the ratio of the UV/GB emission of the ZnO thin films was the highest …

Materials Design With Polylactic Acid-Polyethylene Glycol Blends Using 3d Printing And For Medical Applications., Jeremiah R. Bauer

Electronic Theses and Dissertations

This thesis is an examination of two material systems derived from polylactic acid (PLA) and polyethylene glycol (PEG). PLA is a polymer commonly sourced from renewable sources such as starches and sugars. It is a relatively strong, biodegradable polymer, making it ideal for use in the body. Even though it has a relative high strength, PLA is also brittle leading to the use of plasticizers to increase flexibility. One such plasticizer is PEG, which is a material that can exist at room temperature as either a thin liquid, or a hard waxy solid depending on the molecular weight. The first …

An Exploratory Study Of Sukuk Utilisation For Transportation Infrastructure Development In Indonesia, Fiona Lamari, Ayomi Dita Rarasati, Meilia Evita

Makara Journal of Technology

Investment in infrastructure is one of the principal drivers of the growth of the economy. For that reason, the Indonesian government has proposed an investment budget in the railway and sea and air transport sectors over the next 10 years. In order to overcome the burden of direct outflows and for the future, a study was conducted to lay down the framework of Shariah-compliant payments for the development of infrastructure in Indonesia in the transport sector. This paper aims to explore the opportunity and implementation of sukuk utilisation to develop transportation infrastructure. Secondary data study and interviews were selected for …