Mechanical Engineering Commons^™

Frontal Crash Analysis Of A Conformable Cng Tank Using Finite Element Analysis, Datta Sandesh Manjunath

Dissertations, Master's Theses and Master's Reports

The purpose of this study is to computationally model and analyze a Conformable Compressed Natural Gas (CNG) fuel tank for frontal crashes using Finite Element Analysis. Researchers have developed a CNG fuel tank, which is conformable, non-conventional and non-cylindrical. This tank increases cost efficiency, volumetric efficiency and cargo efficiency in CNG vehicle applications. A lightweight pickup truck (2015 Chevrolet Silverado) has been used to integrate the CNG tanks and field-testing has been conducted to demonstrate the application.

The report mainly focuses on the effective finite element modeling of the chassis, brackets and tanks using HYPERMESH and RADIOSS. The frontal crash …

Simulation Of Human Ankle Trajectory During Stance Phase Of Gait, Leslie Castelino

Dissertations, Master's Theses and Master's Reports

A simulation was developed which mimics the human gait characteristics based on the input of an individual’s gait trajectory. This simulation also estimates the impedance of the human ankle based on the ground reaction forces measured by the force plate. This simulation will accept alterations of the following parameters: total body weight, weight of the shank, weight of the foot, trajectories of the shank and foot of the individual and orientation of the force plate, which would generate a new gait trajectory for the ankle during the stance phase of gait. The goal of this simulation was to validate the …

Performance Of Hard Disk Drives In High Noise Environments, Trinoy Dutta

Dissertations, Master's Theses and Master's Reports

Digital information stored in rotational media, such as Hard Disk Drives (HDD) needs to be reliable and readily accessible. Various studies have been performed on the modal analysis of HDDs and the noise emitted during operation. Analysis performed by Siemens Corporation, IBM and Tyco Fire Protection Products show that HDDs are sensitive to noise. This report initially focusses on identifying the critical frequency ranges and the levels of noise where the performance of the drives reduces. A series of tests have been performed using pink noise at one-third octave frequency bands at sound pressure levels ranging from 80 dB to …

Research Area 3: Advanced Materials Joining, Vlsj Lab, Mechanical Engineering Department, Georgia Southern University

VLSJ Lab: Research Areas (Archived)

No abstract provided.

Mech 350: Introduction To Dynamics And Controls Of Engineering Systems—A Peer Review Of Teaching Project Benchmark Portfolio, Benjamin S. Terry

UNL Faculty Course Portfolios

There are two purposes of this portfolio. The first purpose is to outline and explain my approach to teaching this classic and fundamental course. I highlight in detail the purpose and curricula, the desired outcomes, and the goals and objectives. I also describe how the course activities and my teaching methodology support the course objectives. The second purpose of this portfolio is to describe a simple course modification—the introduction of a recitation session—and to test in a preliminary way the effect of this change on students’ attitudes towards the examples worked out in class. The results show that in the …

Meng 3250: Mechanics Of Elastic Bodies—A Peer Review Of Teaching Project Benchmark Portfolio, Jinying Zhu

UNL Faculty Course Portfolios

This portfolio focuses on mechanics of materials (course title: Mechanics of Elastic Bodies), a sophomore level course taken primarily by civil engineering and architectural engineering majors on Omaha campus. It is a prerequisite for broad range of courses in mechanical, civil and agricultural engineering majors. This course studies the mechanics of solids with applications to science and engineering, including stress, strains and deformation in structural elements (axial, torsional and bending), shear and moment diagram for beams, and a brief introduction to material failure mechanisms.

This portfolio describes the teaching methods used to help students understand the fundamental knowledge about material …

Exploiting Modern Image Processing In Surface Flow Visualisation, Tarek Ihab Abdelsalam, Richard Williams, Grant Ingram

Mechanical Engineering

Surface flow visualisation is an experimental technique where the surface of interest is painted with an oil and dye mixture before a flow is applied to the object. In regions of high shear stress the oil/dye mixture is then removed and in regions of low shear stress the oil/dye mixture stays or builds up. The resulting pattern can be analysed to determine the structure near the surface under test, this is normally done in a qualitative manner with flow structures being identified based on the expertise of the experimentalist. Modern image processing tools can identify shapes and lines in pictures …

The Effects Of Fiber Orientation And Volume Fraction Of Fiber On Mechanical Properties Of Additively Manufactured Composite Material, Suresh Chandra Kuchipudi

All Graduate Theses, Dissertations, and Other Capstone Projects

Additive manufacturing (AM) also known as 3D printing has tremendous advancements in recent days with a vast number of applications in industrial, automotive, architecture, consumer projects, fashion, toys, food, art, etc. Composite materials are widely used in structures with weight as a critical factor especially in aerospace industry. Recently, additive manufacturing technology, a rapidly growing innovative technology, has gained lot of importance in making composite materials. The properties of composite materials depend upon the properties of constituent’s matrix and fiber. There is lot of research on effect of fiber orientation on mechanical properties of composite materials made using conventional manufacturing …

Transitioning Students With Autism Spectrum Disorder From School To Society, Charla Brenta Spurlin Deleo

Walden Dissertations and Doctoral Studies

High school administrators in a rural school district were providing transition planning to students with autism spectrum disorder (ASD) in order to meet postschool transition goals. Despite these efforts, few students with ASD were employed or enrolled in postsecondary training, and parents reported that they were dissatisfied with the postschool transition process. The purpose of this collective case study was to explore parental and staff perceptions of the postschool transition processes of students with ASD to increase the understanding of the practice related to postschool transitions. Guided by Tinto and Pusser's institutional framework, research questions were focused on the experiences …

Processing, Microstructure, And Mechanical Properties Of Zirconium Diboride-Molybdenum Disilicide Ceramics And Dual Composite Architectures, Ryan Joseph Grohsmeyer

Doctoral Dissertations

"This research had two objectives: characterization of processing-microstructure-mechanical property relationships of conventional ZrB₂-MoSi₂ ceramics at room temperature (RT) and 1500⁰C in air, and fabrication of ZrB₂-MoSi₂ dual composite architectures (DCAs) for use near 1500⁰C. Elastic moduli, fracture toughness, and flexure strength were measured at RT and 1500⁰C for 15 ZrB₂-MoSi₂ ceramics hot pressed using fine, medium, or coarse ZrB₂ starting powder with 5-70 vol.% MoSi₂, referred to as FX, MX, and CX respectively where X is the nominal MoSi₂ content. MoSi₂ decomposed during sintering, resulting in …

Additive Manufacturing Of Glass Using A Filament Fed Process, Junjie Luo

Doctoral Dissertations

"There are many scientific and engineering applications of glass including optics, communications, electronics, and hermetic seals, there has been minimal research towards the Additive Manufacturing (AM) of transparent glass parts. The special thermal and optical properties of glasses make them hard to be printed using conventional AM techniques. In this dissertation, two different AM techniques for glass AM were developed, Selective Laser Melting (SLM) and filament fed process.

Semi-transparent parts were printed with SLM process. However, the filament fed process was found to be more robust and promising for printing optically transparent glass parts. Therefore, this dissertation is focused on …

Reliability Prediction In Early Design Stages, Yao Cheng

Doctoral Dissertations

"In the past, reliability is usually quantified with sufficient information available. This is not only time-consuming and cost-expensive, but also too late for occurred failures and losses. For solving this problem, the objective of this dissertation is to predict product reliability in early design stages with limited information. The current research of early reliability prediction is far from mature. Inspired by methodologies for the detail design stage, this research uses statistics-based and physics-based methodologies by providing general models with quantitative results, which could help design for reliability and decision making during the early design stage. New methodologies which accommodate component …

Optimal Design And Freeform Extrusion Fabrication Of Functionally Gradient Smart Parts, Amir Ghazanfari

Doctoral Dissertations

"An extrusion-based additive manufacturing process, called the Ceramic On-Demand Extrusion (CODE) process, for producing three-dimensional ceramic components with near theoretical density was developed. In this process, an aqueous paste of ceramic particles with a very low binder content (<1 vol%) is extruded through a moving nozzle at room temperature. After a layer is deposited, it is surrounded by oil (to a level just below the top surface of most recent layer) to preclude non-uniform evaporation from the sides. Infrared radiation is then used to partially, and uniformly, dry the just-deposited layer so that the yield stress of the paste increases and the part maintains its shape. The same procedure is repeated for every layer until part fabrication is completed. Sample parts made of alumina and fully stabilized zirconia were produced using this process and their mechanical properties including density, strength, Young's modulus, Weibull modulus, toughness, and hardness were examined. Microstructural evaluation was also performed to measure the grain size, and critical flaw sizes were obtained. The results indicate that the proposed method enables fabrication of geometrically complex parts with superior mechanical properties. Furthermore, several methods were developed to increase the productivity of the CODE process and enable manufacturing of functionally graded materials with an optimum distribution of material composition. As an application of the CODE process, advanced ceramic components with embedded sapphire optical fiber sensors were fabricated and properties of parts and sensors were evaluated using standard test methods"--Abstract, page iv.

Thermomechanical Fatigue Life Investigation Of An Ultra-Large Mining Dump Truck Tire, Wedam Nyaaba

Doctoral Dissertations

The cost benefits associated with the use of heavy mining machinery in the surface mining industry has led to a surge in the production of ultra-large radial tires with rim diameters in excess of 35 in. These tires experience fatigue failures in operation. The use of reinforcing fillers and processing aids in tire compounds results in the formation of microstructural inhomogeneity in the compounds and may serve as sources of crack initiation in the tire. Abrasive material cutting is another source of cracks in tires used in mining applications. It suffices, then, to assume that every material plane in the …

Event-Triggering Architectures For Adaptive Control Of Uncertain Dynamical Systems, Ali Talib Oudah Albattat

Doctoral Dissertations

"In this dissertation, new approaches are presented for the design and implementation of networked adaptive control systems to reduce the wireless network utilization while guaranteeing system stability in the presence of system uncertainties. Specifically, the design and analysis of state feedback adaptive control systems over wireless networks using event-triggering control theory is first presented. The state feedback adaptive control results are then generalized to the output feedback case for dynamical systems with unmeasurable state vectors. This event-triggering approach is then adopted for large-scale uncertain dynamical systems. In particular, decentralized and distributed adaptive control methodologies are proposed with reduced wireless network …

Characterization And Numerical Simulation Of The Microstructural And Micromechanical Viscoelastic Behavior Of Oil Sands Using The Discrete Element Method, Eric Kofi Gbadam

Doctoral Dissertations

"Oil sands are naturally geologic formations of predominantly quartz sand grains whose void spaces are filled with bitumen, water, and dissolved gases. The electric rope shovel is the primary equipment used for excavating the Athabasca oil sand formations. The equipment's static and dynamic loads are transferred to the formation during excavation and propel. These loads cause ground instability leading to sinkage or rutting, crawler wear, and fracture failures. These problems result in unplanned downtimes, production losses, and high maintenance costs. In order to address these problems, there is a need to develop valid models that capture the behavior and performance …

Continuous Focusing And Separation Of Microparticles With Acoustic And Magnetic Fields, Ran Zhou

Doctoral Dissertations

"Microfluidics enables a diverse range of manipulations (e.g., focusing, separating, trapping, and enriching) of micrometer-sized objects, and has played an increasingly important role for applications that involve single cell biology and the detection and diagnosis of diseases. In microfluidic devices, methods that are commonly used to manipulate cells or particles include the utilization of hydrodynamic effects and externally applied field gradients that induce forces on cells/particles, such as electrical fields, optical fields, magnetic fields, and acoustic fields.

However, these conventional methods often involve complex designs or strongly depend on the properties of the flow medium or the interaction between the …

Numerical And Experimental Study Of New Designs Of All-Vanadium Redox Flow Batteries For Performance Improvement, Mohammed Abdulkhabeer Ali Al-Yasiri

Doctoral Dissertations

"Energy storage is envisioned as a key part of a renewable energy solution incorporated in a grid that overcomes two critical limits of renewable energy: intermittency and uncertainty. Among various technologies, a vanadium redox flow battery (VRFB) offers a promise because of its unique features such as long cycle life, separation of energy and power ratings, and capability of a deep discharge. The remaining challenges, however, include the limited application due to low energy density and complicated geometries. The complex geometry makes it difficult to optimize the performance and can cause a serious concern about leakage of the liquid. The …

Repair Of Metallic Components Using Hybrid Manufacturing, Renwei Liu

Doctoral Dissertations

"Many high-performance metal parts users extend the service of these damaged parts by employing repair technology. Hybrid manufacturing, which includes additive manufacturing (AM) and subtractive manufacturing, provides greater build capability, better accuracy, and surface finish for component repair. However, most repair processes still rely on manual operations, which are not satisfactory in terms of time, cost, reliability, and accuracy. This dissertation aims to improve the application of hybrid manufacturing for repairing metallic components by addressing the following three research topics. The first research topic is to investigate and develop an efficient best-fit and shape adaption algorithm for automating 3D models' …

Manufacturing Of Advanced Continuous Fiber Reinforced Composites For High Temperature Applications, James Robert Nicholas

Doctoral Dissertations

"New resin systems have enabled composites to be considered as attractive alternatives in structural applications that require material to be stronger, lighter and/or more resilient to environmental effects. The current work is on the development of processes to produce continuous fiber reinforced materials from two state of the art resin systems. Two processes were developed to produce continuous fiber reinforced ceramic materials from a preceramic polymer. The first was a vacuum forming process developed using the out-of-autoclave polymer composite manufacturing technique in conjunction with the polymer infiltration and pyrolysis process to produce ceramic composite material of zirconium diboride-silicon carbide reinforced …

Volumetric Error Compensation For 5-Axis Machine Tools, Jennifer Ruth Creamer

Doctoral Dissertations

"This work presents a geometric error compensation method for large 5-axis machine tools. The compensation method presented here uses tool tip measurements recorded throughout the axis space to construct a position-dependent geometric error model that can easily be used for error compensation. The measurements are taken using a laser tracker, permitting rapid error data gathering at most locations in the axis space. First two model types are compared for generating table-based error compensation and experimental results are presented. Table-based compensation is then extended to machine tool controller types with restrictions on the number or combination of compensation tables using an …

Control Of Single- And Dual-Probe Atomic Force Microscopy, Muthukumaran Loganathan

Doctoral Dissertations

“Atomic force microscope (AFM) is one of the important and versatile tools available in the field of nanotechnology. It is a type of probe-based microscopy wherein an atomically sharp tip, mounted on the free end of a microcantilever, probes the surface of interest to generate 3D topographical images with nanoscale resolution. An integral part of the AFM is the feedback controller that regulates the probe deflection in the presence of surface height changes, enabling the control action to be used for generating topographical image of the sample. Besides sensing, the probe can also be used as a mechanical actuator to …

Cryogenic Rf Test Of The First Srf Cavity Etched In An Rf Ar/Cl2 Plasma, J. Upadhyay, A. Palczewski, S. Popovic, A.-M. Valente-Feliciano, Do Im, H. L. Phillips, L. Vuskovic

Physics Faculty Publications

An apparatus and a method for etching of the inner surfaces of superconducting radio frequency (SRF) accelerator cavities are described. The apparatus is based on the reactive ion etching performed in an Ar/Cl₂ cylindrical capacitive discharge with reversed asymmetry. To test the effect of the plasma etching on the cavity rf performance, a 1497 MHz single cell SRF cavity was used. The single cell cavity was mechanically polished and buffer chemically etched and then rf tested at cryogenic temperatures to provide a baseline characterization. The cavity's inner wall was then exposed to the capacitive discharge in a mixture of …

Osteogenic Potential Of Poly (L-Lactic Acid) Scaffolds Prepared By Thermally Controlled Methods On Human Adipose Derived Stem Cells, Harish Chinnasami Shanmugam

LSU Doctoral Dissertations

Thermally Induced Phase Separation (TIPS) method was used to make porous three-dimensional PLLA scaffolds. The effect of imposed thermal profile during freezing of the PLLA in dioxane solution on the scaffold was characterized by their micro-structure, porosity (%), pore-sizes distribution and mechanical strength. The porosity (%) decreased considerably with increasing concentrations of PLLA in the solution, while a decreasing trend was observed with increasing cooling rates. The mechanical strength increases with increase in PLLA concentration and also with increase in the cooling rate for both types of solvents. Therefore, mechanical strength was increased by higher cooling rates while the porosity …

Onboard Load Sensor For Use In Freight Railcar Applications, Constantine Tarawneh, Jazmin Ley, Dylan Blackwell, Stephen Crown, Brent Wilson

Mechanical Engineering Faculty Publications

Approximately 40% of intercity freight transportation occurs by rail, making it the most widely used method of transporting large commodities. This trend is expected to persist over the next thirty years as our highway systems are strained and experiencing increased congestion and costly delays. Currently, the load of freight railcars is typically measured by weighbridges or retrofitted tracks at isolated locations. This practice is not efficient and limited by the fact that the load of the railcar cannot be monitored continuously, not to mention the inherent inaccuracies of such systems. Hence, there is great merit for an onboard load sensor …

Finite Element Modeling Of The Plantar Fascia: A Viscohyperelastic Approach, Alexander Knapp

UNF Graduate Theses and Dissertations

The present work details the creation and analysis of a finite element model of the foot, wherein the plantar fascia was modeled as a viscohyperelastic solid. The objective of this work was to develop a fully functional CAD and Finite Element Model of the foot and plantar fascia for analysis by examining the transient stresses on the plantar fascia through the use of a viscohyperelastic material model. The model’s geometry was developed through the use of image processing techniques with anatomical images provided by the National Institutes of Health. The finite element method was used to analyze the transient response …

Degradation Resistant Surface Enhanced Raman Spectroscopy Substrates, Ryan D. Scherzer

UNF Graduate Theses and Dissertations

Raman spectroscopy is employed by NASA, and many others, to detect trace amounts of substances. Unfortunately, the Raman signal is generally too weak to detect when very small, but non-trivial, amounts of molecules are present. One way around this weak signal is to use surface enhanced Raman spectroscopy (SERS).

When used as substrates for SERS, metallic nanorods grown using physical vapor deposition (PVD) provide a large enhancement factor to the Raman signal, as much as 10¹². However, Silver (Ag) nanorods that give high enhancement suffer from rapid degradation as a function of time and exposure to harsh environment. …

Pore Formation In Aluminum Castings: Theoretical Calculations And The Extrinsic Effect Of Entrained Surface Oxide Films, Pedram Yousefian

UNF Graduate Theses and Dissertations

Aluminum alloy castings are being integrated increasingly into automotive and aerospace assemblies due to their extraordinary properties, especially high strength-to-density ratio. To produce high quality castings, it is necessary to understand the mechanisms of the formation of defects, specifically pores and inclusion, in aluminum. There have been numerous studies on pore formation during solidification which lead to hot tearing and/or reduction in mechanical properties. However, a comprehensive study that correlates pore formation theory with in situ observations and modeling assumptions from the literature as well as experimental observations in not available. The present study is motivated to fill this gap. …

Performance Analysis On Free-Piston Linear Expander, Furkan Kodakoglu

UNF Graduate Theses and Dissertations

The growing global demand for energy and environmental implications have created a need to further develop the current energy generation technologies (solar, wind, geothermal, etc.). Recovering energy from low grade energy sources such as waste heat is one of the methods for improving the performance of thermodynamic cycles. The objective of this work was to achieve long-term steady state operation of a Free-Piston Linear Expander (FPLE) and to compare the FPLE with the currently existing expander types for use in low temperature energy recovery systems. A previously designed FPLE with a single piston, two chambers, and linear alternator was studied …

The Effect Of Corrosion Defects On The Failure Of Oil And Gas Transmission Pipelines: A Finite Element Modeling Study, Jennet Orasheva

UNF Graduate Theses and Dissertations

The transportation of oil and gas and their products through the pipelines is a safe and economically efficient way, when compared with other methods of transportation, such as tankers, railroad, trucks, etc. Although pipelines are usually well-designed, during construction and later in service, pipelines are subjected to a variety of risks. Eventually, some sections may experience corrosion which can affect the integrity of pipeline, which poses a risk in high-pressure operations. Specifically, in pipelines with long history of operation, the size and location of the corrosion defects need to be determined so that pressure levels can be kept at safe …