Mechanical Engineering Commons^™

Computational Study Of The Effect Of Interparticle Contact In Conductive Properties Of Random Particulate Systems, Dongfang Zhao

Electronic Theses and Dissertations

The effective conductivity of random particulate material system is computationally investigated using the Monte Carlo scheme and finite element method. A cubic system consisting of randomly-dispersed, equal-sized, deformable ellipsoids are modeled in this study. The steady-state conduction analysis along with a finite element analysis are performed to evaluate the electrical or thermal conductivity for the mechanical contact system. To represent more realistic material system, interfacial friction and gap conductance (or contact resistance) are included among the contacting particles. The Monte Carlo simulations are implemented to give a quantitative relationship between the effective conductivity and the inclusion volume fraction. Several parametric …

Venus Lander Design, Garon Morgan, Brian Rodrigues, Dhruv Sachani, Jason Scott

Capstone Design Expo Posters

The students designed an Entry, Descent, and Landing (EDL) system for a lander to reach the surface of Venus. The students used a combination of 3D modelling and programming to design the EDL within given constraints under specific tolerances. An EDL takes into consideration entry flight dynamics, aeroheating, and landing systems. The EDL was divided into three stages (see below). The separation of stages was designed to address unique challenges found at different points throughout the EDL. The primary objective of the first stage was to minimize the heat associated with the entry velocity to the payload. The second stage …

Ergonomic Immobilization Frame For Radiotherapy, Raheel Ahmed, Travis Alford, Talal Almutairi, Kaleem Farooq

Capstone Design Expo Posters

The primary purpose of this project is to demonstrate that patients can be safely immobilized using air in the general torso area so that radiation can be administered to that region. The primary target will be to treat tumors in the lungs and liver. By immobilizing patients during treatment it allows for the radiation to be consistent in targeting the desired region of the body, which would not be the case if the patient was moving. Air was chosen as the desired medium to immobilize the patient because of comfort and it provides an easy medium for radiation to travel …

Dynamic Modeling And Simulation Of A Variable Cycle Turbofan Engine With Controls, Robert W. Buettner

Browse all Theses and Dissertations

Next generation aircraft (especially combat aircraft) will include more technology and capability than ever before. This increase in technology comes at the price of higher electrical power requirements and increased waste heat that must be removed from components to avoid overheating induced shutdowns. To help combat the resulting power and thermal management problem, a vehicle level power and thermal management design and optimization toolset was developed in MATLAB®/Simulink®. A dynamic model of a three-stream variable cycle engine was desired to add to the capabilities of the power and thermal management toolset. As an intermediate step to this goal, the dynamic …

Forming A Metal Matrix Nanocomposite (Mmnc) With Fully Dispersed And Deagglomerated Multiwalled Carbon Nanotubes (Mwcnts), Mahesh Kumar Pallikonda

ETD Archive

Carbon Nanotubes (CNTs) with their exceptional properties will facilitate the Metal matrix composites (MMC) to exhibit good mechanical properties, thermal and electrical conductivities, corrosion resistance, etc. The critical factor that holds the development of the Metal matrix Nanocomposites (MMNC) by using CNTs is the tendency of CNTs to form clusters (agglomerations) due to their high Van der Waals attractions. Due to this factor, low density and other properties of the CNTs, there has been a delay in harnessing their ultimate potential.
Existing literature in contemporary times from the works of few researches in Nanocomposites shows the prevalence of using surfactants …

Investigation Of Extremum Seeking Control For Adaptive Exercise Machines, Brahm T. Powell

ETD Archive

Many muscle rehabilitation regimens are non-adaptive and recommended subjectively by physicians. While there are advantages to having the feedback of a qualified physician, utilizing real-time muscle performance feedback could be beneficial. An extremum seeking control design is proposed to fulfill the need for an automated, load-varying exercise machine that can optimize muscle performance.

Several steps are outlined to contribute to the realization of this goal. First, the extremum seeking control scheme is discussed. Second, the Hill muscle model will be described. Theoretical muscle effort extrema will be derived for selected optimization cases, namely maximizing average squared power by varying load …

Survey Of Lean Management Practices In Pakistani Industrial Sectors, Khurrum Bhutta, Gokhan Egilmez, Kamran Chatha, Faizul Huq

Mechanical and Industrial Engineering Faculty Publications

This research was undertaken to study the implementation and adoption of Lean management practices across several industrial sectors in Pakistan. A total of 100 companies were surveyed across five industries. The objective was to determine if there was disparity in the implementation of Lean practices and to provide a yardstick to measure that disparity. Furthermore, this study identified Lean management best practices across several industries in Pakistan, thus providing benchmarks for other industrial sectors. The data collected was analysed using various descriptive statistical methods. The results indicated robust adoption and implementation of Lean practices in Pakistani industry, though there were …

From Green Buildings To Green Supply Chains: An Integrated Input Output Life Cycle Assessment And Optimization Framework For Carbon Footprint Reduction Policy Making, N. Muhammad Aslaam, Gokhan Egilmez, Murat Kucukvar, M.Khurrum S. Butta

Mechanical and Industrial Engineering Faculty Publications

Purpose: This paper focuses on tracing GHG emissions across the supply chain industries associated with the U.S. residential, commercial and industrial building stock and provides optimized GHG reduction policy plans for sustainable development.

Design/Methodology/Approach: A two-step hierarchical approach is developed. Firstly, Economic Input Output-based Life Cycle Assessment (EIO-LCA) is utilized to quantify the GHG emissions associated with the U.S. residential, commercial and industrial building stock. Secondly, a mixed integer linear programming (MILP) based optimization framework is developed to identify the optimal GHG emissions’ reduction (%) for each industry across the supply chain network of the U.S. economy.

Findings: The results …

Effects Of Roughness On Droplet Apparent Contact Angles On A Fiber, M. M. Amrei, M. Davoudi, G. G. Chase, H. Vahedi Tafreshi

Mechanical and Nuclear Engineering Publications

This paper reports on our investigation of the effects of surface roughness on the equilibrium shape and apparent contact angles of a droplet deposited on a fiber. In particular, the shape of a droplet on a roughened fiber is studied via the energy minimization method implemented in the surface evolver finite element code. Sinusoidal roughness varying in both the longitudinal and radial directions is considered in the simulations to study the effects of surface roughness on the most stable shape of a droplet on a fiber (corresponding a global minimum energy state). It is found that surface roughness delays droplet …

Rolatube Deployment System, Zachary Allin, Zachary Ratliff, Nathaniel Trepatschko, Jeffrey Wilson

Capstone Design Expo Posters

The team has been tasked with designing a compact mechanism capable of deploying and retracting the Rolatube horizontally and vertically at a controlled rate in confined spaces (i.e. tank housing structures). Because workers are confined to tight quarters, a mechanism to aid in common activities is at times required. The mechanism will allow for tool deployment with attachments for easily sending tools and utilizing cameras. It will also be used to assist workers in stringing lights, keeping wires organized, and delivering hoses and tubes. This design will allow workers at Newport News Shipbuilding (NNS) to save time and energy while …

Fabricating Zirconia Parts With Organic Support Material By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Andrew Scherff, Ming Leu, Gregory Hilmas

Faculty Publications, Mechanical Engineering

Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently developed for fabricating dense, functional ceramic components. This paper presents a further development of this process and focuses on fabricating 3 mol% yttria-stabilized zirconia (3YSZ) components that cannot be fabricated without using support structures. The 3YSZ paste is deposited through the main nozzle, and a polycaprolactone (PCL) pellet feedstock is melted and deposited through an auxiliary nozzle to build support structures. After a green part is printed and dried, the support structures are removed by heating the part to ~70°C to melt the PCL. The part is then sintered …

Mechanical And Aerospace Engineering, 2016-2017, College Of Engineering And Applied Sciences

Mechanical and Aerospace Engineering News

• Letter from the Department Chair
• Mechanical and Aerospace Engineering Wins Grant from DENSO North America Foundation
• NSF $452,399 award to bring state-of-the-art instrument to WMU
• Faculty Research
• Faculty Summer Research
• Research in Fluid Mechanics and Aerodynamics
• Auto lab upgrades make it a premier teaching and research facility
• MAE faculty

P2: Construction Of Weather Station For Measuring Wind Using A Hovering Drone Network, Adam Stead, Mark Travis, Rishi Maheshwari

Undergraduate Research Posters 2017

Our research aims to build and test the effectiveness of the Sparkfun® Weather Station in its ability to record meaningful data while streaming to a remote device in real-time. This is motivated by our plans to utilize a hovering-drone system to collect meteorological data, such as wind speed, wind direction, humidity, pressure, and temperature. This data is essential to evaluate the wind profiles of a given area and assess available wind resource. The weather station was first calibrated by comparing measurements of the cup anemometer against a standard pitot tube in the lab. We found that the measured wind speed …

Development And Verification Of A Mechanical Loading Device For Microfluidics, Stefan Habean, Erin Tesny

Undergraduate Research Posters 2017

Establishing the role that mechanics play in nerve cell (e.g. neurons) function requires experimental testing. Microfluidic based experiments are commonly used to study neuron growth and function, and studies have found mechanics to play an important role in neuron health. External loads can be applied to a microfluidic device using a motor, which presumably influences the mechanical environment of the cells. While a motor can easily apply known displacements, a “load cell” is necessary to measure corresponding forces. In an existing prototype microfluidic loading device, a load cell was integrated and verified. The manufacturer's calibration of the load cell was …

Variable Oxidation & Defects In Ti-6al-4v Material In Electron Beam Melting Additive Manufacturing, Edward Patton Clark

Electronic Theses and Dissertations

Powder-based metal in additive manufacturing (AM) is advantageous for rapid prototyping of parts and components, with the benefit of reusing powder to reduce production costs. A common driver in the aerospace industry is free-form complex geometries which can be created using CAD software to optimize specifications with strength-to-weight ratios in components. Weight optimization of aircraft components using additive manufacturing reduces material, which significantly reduces production cost in comparison to cast and wrought metallic products. Large biomedical and aerospace industries heavily invest in feedstock metal powders that have low density under structural stresses and high temperatures, resulting in superior resistance to …

P1: Measuring Wind Using A Hovering Drone Network: Met-Masts On The Go, Mohamad Khattab, Hassan Jaroudi

Undergraduate Research Posters 2017

Renewable energy has grown considerably over the past years, with a projected growth of $460 billion per year by 2030. One of these renewable energies is deploying wind turbines to harvest wind energy. Knowledge of wind speed and direction is critical to determine the appropriate site to place wind turbines. The current method of collecting wind data primarily by installing stationary meteorological towers is expensive and limited, because met masts are fixed once built. This research aims at using a network of hovering drones as a platform to measure wind speed, direction, temperature and humidity at multiple elevations, which could …

Demisting Using An Ultrasonic Standing Wave Field, T. M. Merrell, John Saylor

Publications

Removing drops from an air flow can be challenging, particularly, for small drops. Herein a method for demisting is presented that employs ultrasonics to force small drops to combine. Specifically, a cylindrical ultrasonic standing wave field is established in a tube, forming pressure nodes that take the form of cylinders located within the tube and having the same axis as the tube. Droplets are driven toward these pressure nodes by the acoustic radiation force, forcing smaller drops to combine to form larger drops, which eventually fall due to gravity, thereby demisting the flow. Experiments presented herein show that, for the …

Dynamic Coupling Of Phase-Heat And Mass Transfer In Porous Media And Conjugate Fluid/Porous Domains, Mahmoud Mohamed Mostafa Elhalwagy, Anthony G. Straatman

Mechanical and Materials Engineering Publications

No abstract provided.

Piv Analysis Of Wake Structure Of Real Elephant Seal Whiskers, Joseph Antun Bunjevac

ETD Archive

Seals are able to accurately detect minute disturbances in the ambient flow
environment using their whiskers, which is attributed to the exceptional capability of
their whiskers to suppress vortex-induced vibrations in the wake. To explore potential applications for designing smart flow devices, such as high-sensitivity underwater
flow sensors and drag reduction components, researchers have studied how the role
of some key parameters of whisker-like morphology affect the wake structure. Due to
the naturally presented variation in size and curvature along the length of whiskers,
it is not well understood how a real whisker changes the surrounding flow and the
vortex …

Design And Control Of A Powered Rowing Machine With Programmable Impedance, Jose Humberto De La Casas Zolezzi

ETD Archive

Due to the rise of obesity, diabetes and cardiovascular disease, research in human performance and physical activity has received increased attention. Rowing machines are used for performance improvements through concentric exercises, however a combination of concentric and eccentric actions is known to improve the effectiveness of training. In this work, a conventional rowing machine was modified to include an electric motor and a robust impedance control system, enabling programmable impedance with concentric and eccentric capabilities. Eccentric exercises are known to contribute significantly to the efficacy of training and to diminish the detrimental effects of humans operating in microgravity for long …

Strained Hybrid Perovskite Thin Films And Their Impact On The Intrinsic Stability Of Perovskite Solar Cells, Jingjing Zhao, Yehao Deng, Haotong Wei, Xiaopeng Zheng, Zhenhua Yu, Yuchuan Shao, Jeffrey E. Shield, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

Organic-inorganic hybrid perovskite (OIHP) solar cells have achieved comparable efficiencies to those of commercial solar cells, although their instability hinders their commercialization. Although encapsulation techniques have been developed to protect OIHP solar cells from external stimuli such as moisture, oxygen, and ultraviolet light, understanding of the origin of the intrinsic instability of perovskite films is needed to improve their stability. We show that the OIHP films fabricated by existing methods are strained and that strain is caused by mismatched thermal expansion of perovskite films and substrates during the thermal annealing process. The polycrystalline films have compressive strain in the out-of-plane …

The Effect Of Number Of Corrugation On Crashworthiness Of Aluminum Corrugated Tube Under Lateral Loading, Hozhabr Mozafari, Arameh Eyvazian, Abdel Magid Hamouda

Department of Mechanical and Materials Engineering: Faculty Publications

Thin-walled tubes have been developed and are growing in use as new energy absorber structures. The objective of this study is to investigate the energy absorption and crushing characteristics of corrugated tubes with different number of corrugation in a specific length exposed to lateral loading. At the first step, experimental tests were carried out on a corrugated tube with three con'ugations (two inner and one outer) and a tube without corrugation. After that, a finite element model was developed by means of ABAQUS software in order to study the effect of corrugation number on crushing properties of thin-walled tubes. The …

Methods, Systems, And Devices For Surgical Visualization And Device Manipulation, Shane M. Farritor, Mark Rentschler, Amy Lehman, Nathan A. Wood, Adam Bock, Reed Prior

Department of Mechanical and Materials Engineering: Faculty Publications

A surgical device includes a console having a visual display and a manipulator arm, a robotic device having a camera and a connection component. The robotic device is configured to be positioned completely within a body cavity. The camera is configured to transmit visual images to the visual display. The connection component operably couples the console and the robotic device. The manipulator arm is positioned relative to the visual display so as to appear to be penetrating the visual display.

Local And Segmental Motions Of The Mobile Amorphous Fraction In Semi-Crystalline Polylactide Crystallized Under Quiescent And Flow-Induced Conditions, Xavier Monnier, Laurence Chevalier, Antonello Esposito, Lucia Fernandez-Ballester, Allisson Saiter, Eric Dargent

Department of Mechanical and Materials Engineering: Faculty Publications

The molecular dynamics of the constrained and unconstrained mobile amorphous fractions in semicrystalline polylactide (PLA) was investigated in the presence of both flow-induced crystalline structures and spherulites by fast scanning calorimetry (FSC) through cooperativity and physical aging concepts. First, the shear rate conditions leading to flow-induced crystallization were characterized by examining the relaxation of shear-induced precursors. At a temperature of 150 °C, the critical relaxation time is so long that cooling down the sheared melt to the crystallization temperature does not affect significantly the precursors. Therefore, highly oriented structures develop. The arrangement of the crystalline fraction, either in flow-induced crystalline …

Transcutaneous Electrical Stimulation For The Production Of Functional Motion Of A Human Arm, Kyra Ruby

Undergraduate Research Posters 2017

Persons with tetraplegia experience little to no function in their arms and are therefore unable to perform reaching tasks without assistance. While functional electrical stimulation (FES) has shown promise for restoring motion to paralyzed limbs, it is limited by issues such as muscle fatigue and atrophy. A control strategy robust enough to overcome these issues has yet to be developed and some motions are not feasible even with the most sophisticated FES control strategy. In theory, a powered exoskeleton could be used in concert with an FES system to increase the accuracy of control and assist the arm when motions …

Defect Engineering: A Path Toward Exceeding Perfection, Hamed Attariani, Kasra Momeni, Kyle R. Adkins

Mechanical and Materials Engineering Faculty Publications

Moving to nanoscale is a path to get perfect materials with superior properties. Yet defects, such as stacking faults (SFs), are still forming during the synthesis of nanomaterials and, according to common notion, degrade the properties. Here, we demonstrate the possibility of engineering defects to, surprisingly, achieve mechanical properties beyond those of the corresponding perfect structures. We show that introducing SFs with high density increases the Young’s Modulus and the critical stress under compressive loading of the nanowires above those of a perfect structure. The physics can be explained by the increase in intrinsic strain due to the presence of …

Four-Terminal Square Piezoresistive Sensors For Mems Pressure Sensing, Awlad Hossain, Ahsan Mian

Mechanical and Materials Engineering Faculty Publications

The sensitivity of four-terminal piezoresistive sensors commonly referred to as van der Pauw (VDP) structure is investigated. The VDP sensor is considered to be fabricated on (100) silicon due to its potential application in MEMS (microelectromechanical systems) pressure sensors. The sensitivity of the VDP sensor may be affected by misalignment during the etching/diffusion process, the nonuniformity of piezoresistive coefficients through the sensor thickness, and pad size with respect to the sensor size. For this particular analysis, the effect of VDP stress sensitivity on variations in pad sizes and through-the-thickness -coefficient variation are studied as the effect of misalignment has already …

Design, Modeling, Fabrication, And Testing Of A Multistage Micro Gas Compressor With Piezoelectric Unimorph Diaphragm And Passive Microvalves For Microcooling Applications, Shawn Thanhson Le

Doctoral Dissertations

This dissertation investigates the development of a multistage micro gas compressor utilizing multiple pump stages cascaded in series to increase the pressure rise with passive microvalves and piezoelectric unimorph diaphragms. This research was conducted through modeling, simulation, design, and fabrication of the microcompressor and its components. A single-stage and a two-stage microcompressor were developed to demonstrate and compare the performance and effectiveness of using a cascaded multistage design.

Steady fluid flow through static microvalves structure was studied to gain insight on its gas flow dynamics and characteristics. Transient analysis combined with the structure's interaction was investigated with an analytical model …

Experimental Study Of Corrugated Metal-Composite Tubes Under Axial Loading, Arameh Eyvazian, Hozhabr Mozafari, Abdel Magid Hamouda

Department of Mechanical and Materials Engineering: Faculty Publications

In this study, crushing behavior of corrugated metal-composite tube was examined experimentally under axial loading condition. Six types of specimens, classified into two groups of metal and metal-composite, were tested under quasi static axial loading. The failure mechanism and failure history of the specimens were presented and discussed. The experimental result showed that corrugated metal composite tubes demonstrate perfect energy absorption characteristics in terms of uniformity of load-displacement diagram, reduction of initial peak load and controlling failure mechanism. Moreover, it was also found that adding filament wound layer of composite on the surface of metallic corrugated tube compensated weakness of …

Disturbed Cyclical Stretch Of Endothelial Cells Promotes Nuclear Expression Of The Pro-Atherogenic Transcription Factor Nf-Kb, Ryan M. Pedrigi, Konstantinos I. Papadimitriou, Avinash Kondiboyina, Sukhjinder Sidhu, James Chau, Miten B. Patel, Daniel C. Baeriswyl, Emmanuel M. Drakakis, Rob Krams

Department of Mechanical and Materials Engineering: Faculty Publications

Exposure of endothelial cells to low and multidirectional blood flow is known to promote a pro-atherogenic phenotype. The mechanics of the vessel wall is another important mechano-stimulus within the endothelial cell environment, but no study has examined whether changes in the magnitude and direction of cell stretch can be pro-atherogenic. Herein, we developed a custom cell stretching device to replicate the in vivo stretch environment of the endothelial cell and examined whether low and multidirectional stretch promote nuclear translocation of NF-kB. A fluid–structure interaction model of the device demonstrated a nearly uniform strain within the region of cell attachment and …