Mechanical Engineering Commons^™

Time- And Space-Dependent Uncertainty Analysis And Its Application In Lunar Plasma Environment Modeling, Xinpeng Wei

Doctoral Dissertations

”During an engineering system design, engineers usually encounter uncertainties that ubiquitously exist, such as material properties, dimensions of components, and random loads. Some of these parameters do not change with time or space and hence are time- and space-independent. However, in many engineering applications, the more general time- and space-dependent uncertainty is frequently encountered. Consequently, the system exhibits random time- and space-dependent behaviors, which may result in a higher probability of failure, lower average lifetime, and/or worse robustness. Therefore, it is critical to quantify uncertainty and predict how the system behaves under time- and space- dependent uncertainty. The objective of …

Study On Ductile Fracture With Anisotropic And Strain Rate Effects In Manufacturing Processes, Hao Pan

Electronic Theses and Dissertations, 2020-2023

Ductile fracture is a topic of great importance in automotive and aerospace industries. Prediction of ductile fracture in engineering structures relies on developing robust material models under complex loading conditions. This dissertation addresses the anisotropic and strain rate effects in constitutive and ductile fracture models of lightweight metals. In the present modeling framework, the anisotropic plasticity behavior is modeled by combination of an initial anisotropic yield function and an isotropic hardening correction by Lode dependence. A new all-strain based anisotropic fracture model is proposed based on the approach of linear transformation on plastic strain rate tensor. The strain rate effects …

Multi-Species Measurements At High Temperatures Using Advanced Mid-Infrared Laser Schemes, Zachary Loparo

Electronic Theses and Dissertations, 2020-2023

High-temperature reacting systems are central to many fields including propulsion, power generation, and transportation. Studying such systems requires the use of experimental facilities such as shock tubes to obtain the relevant high temperature conditions, and non-intrusive diagnostic tools for monitoring parameters of interest in the reaction zone, including temperature and species concentration time-histories. Laser absorption spectroscopy offers high-speed, in-situ measurements of the reacting flow field and provides direct measurements of species concentrations and temperature. Applying absorption spectroscopy via different diagnostic strategies enables tailored measurements of these parameters across a variety of combustion systems for chemical kinetic model refinement and enhancing …

Interfacial Properties Modulate Water Entry Dynamics For Spherical Projectiles, Daren Watson

Electronic Theses and Dissertations, 2020-2023

Rigid bodies impacting liquid pools incite splashing and air-entraining cavities that depend on impactor shape, entry speed, surface texture, and free surface conditions. In this body of work, we investigate the influence of interfacial properties on water entry dynamics for free-falling spherical projectiles. Our investigations translate to everyday fluid-structure interactions that are complex and generally conclude beyond the temporal acuity of the naked eye. High-speed videography between 1000 -- 3200 fps is used to digitize the water entry process and measure salient splash features under different initial conditions. We assess splashes arising from the impacts of free-falling hydrophilic spheres with …

Pathological Tremor As A Mechanical System: Modeling And Control Of Artificial Muscle-Based Tremor Suppression, Christopher Kelley

Electronic Theses and Dissertations, 2020-2023

Central nervous system disorders produce the undesired, approximately rhythmic movement of body parts known as pathological tremor. This undesired motion inhibits the patient's ability to perform tasks of daily living and participate in society. Typical treatments are medications and deep brain stimulation surgery, both of which include risks, side effects, and varying efficacy. Since the pathophysiology of tremor is not well understood, empirical investigation drives tremor treatment development. This dissertation explores tremor from a mechanical systems perspective to work towards theory-driven treatment design. The primary negative outcome of pathological tremor is the undesired movement of body parts: mechanically suppressing this …

Heat Transfer And Correlations Of Jet Array Impingement With Flat And Pimple-Dimpled Plate, Husam Nizar Ahmad Zawati

Electronic Theses and Dissertations, 2020-2023

This study compares and analyses the heat transfer between a novel jet array impingement configuration (designated as NPR) and a baseline jet orifice plate (flat) in a maximum crossflow scheme. Both jet plates feature inline arrays of 20 x 26 circular air jets that orthogonally impinge on a flat target surface consisting of 20 segments, parallel to the jet plates. The NPR plate consists of staggered semi-spherical pimples (protrusions) and dimples (imprints) with a jet-to-pimple diameter ratio (Dj,p/Dp) of 0.07 and jet length-to-pimple diameter ratio (L/Dj,p) of ~ 1 with a protrusion ratio (tp/Dj,p) of 2.78. The dimples (imprints) have …

Evaluating The Effectiveness Of Aerospace Materials, Vehicle Shape And Astronaut Position At Lowering The Whole Body Effective Dose Equivalent In Deep Space, Daniel K. Bond

Theses and Dissertations

As future crewed, deep space missions are being planned, it is important to assess how spacecraft design can be used to minimize radiation exposure. Collectively with shielding material, vehicle shape and astronaut position must be used to protect astronauts from the two primary sources of space radiation: Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE). GCRs, which are composed of low intensity, highly energetic, and fully ionized stable and meta-stable isotopes, are considered a chronic source of radiation risk to the astronauts. SPEs, which originate from solar coronal mass ejections, are composed mostly of high intensity protons that can …

A Reduced Model For Microbial Fuel Cell, Dina Aboelela, Moustafa A. Soliman, Ibrahim Ashour

Chemical Engineering

Microbial fuel cells (MFCs) are a group of microbial electrochemical cells (bioreactors) that are used to generate energy from organic waste found in wastewater. MFCs represent a promising method of waste disposal and production of electricity. Scaling up the use of MFCs requires extensive analysis and detailed grasp of the required processes. The current work aimed to study a model of an MFC, and find the optimum parameters needed for maximum energy production. The process was simulated and validated on continuous-flow MFCs with a Columbic efficiency of 162% and 35% COD removal. Sensitivity analysis of the model was performed. The …

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

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 …

Perfusion Cell Seeding And Expansion In Dual Mechanical Stimulation Bioreactor For In Vitro Tissue Development, Sarah Saunders, Sam Coles, Joao S. Soares

Graduate Research Posters

BACKGROUND: Engineered tissues are an exciting potential source of small diameter vascular grafts due to limited supply and patency of available alternatives. Engineered tissue vascular grafts (ETVGs) will provide physiological function that resembles native arteries and maintain the required mechanical properties as they integrate with host tissue. Mechanical stimulation during incubation encourages proper cell alignment and increases extracellular matrix deposition. The enhanced organization of the engineered tissue leads to improved compliance over synthetic alternatives without sacrificing strength and may lead to better integration in vivo.

METHODS: We have developed a bioreactor that mechanically trains grafts during incubation. To test the …

Molecular Dynamics Simulation Study On Thermal Conduction Of Cnt-Cu/Al Composites With New Meam Potentials Between C And Cu/Al, Luyang Ren

Electronic Theses and Dissertations, 2020-2023

Carbon nanotubes (CNTs) have been a promising material for thermal management applications including micro/nano-electromechanical system (MEMS/NEMS) due to their extremely high thermal conductivity values. CNTs-reinforced Cu/Al (CNT-Cu/Al) composites are attractive to meet all-around requirements on high thermal performance materials to be applied in many areas, such as aerospace, automotive and electronic packaging. However, the experimental results on resultant thermal conductivity of these composites are far from expectation due to the law of mixture. In this research, molecular dynamics (MD) simulation is used to study the thermal conduction of CNT-Cu/Al composites. Before the simulation is conducted, new inter-atomic potentials for the …

Production And Elastomer Compatibility Of Renewable Fuels, Alan Felix

Electronic Theses and Dissertations, 2020-2023

Hydrocarbon fuel plays an essential role in modern day society and significant research effort is put forth for fuel characterization, performance optimization, and new procedures for synthesis. Despite the eventual and inevitable shift away from hydrocarbon fossil fuels to more renewable energies, investigations into liquid hydrocarbons remain useful while governments slowly adopt and integrate alternative energies. Many hydrocarbon fuel alternatives can potentially bridge the gap between today's heavy reliance on fossil fuels and future complete adaptation of clean energy. One such alternative is biofuel, which is still hydrocarbon based but is made from bio-materials, most notably plants. Widespread use of …

Experimental, Analytical And Computational Analyses Of Linear And Radial Shape Memory Alloy Helical Actuators, Ryan Puchaty

Electronic Theses and Dissertations, 2020-2023

As access to Shape Memory Alloys (SMAs) has expanded beyond their use as linear wires, the need for characterizing more complex forms that account for the effects of multi-axial stress, strain, and displacement has become increasingly important in actuator design. The novel uses of SMA actuators have also moved the devices into previously unexplored loading conditions, where established theory does not adequately model the real behavior. This work seeks to alleviate some of these issues by addressing problems with the most common multi-axial stress devices: helical springs. New applications are requiring high forces in small spaces, where SMAs' high work …

Thermal Performance Of Sierpinski Carpet Fractal Fins At Various Angles Of Inclination In A Natural Convection Environment, Haidar Jamil Khalil

College of Graduate Studies: Theses & Dissertations

As technology advances, higher performance cooling systems are desired to meet numerous thermal management challenges. Extended surfaces, also known as heat sinks or fins, are commonly used to passively dissipate unwanted heat from mechanical and electrical systems. Fractal fins in accordance with the first four iterations (including a base iteration) of the Sierpinski carpet, manufactured from AL-5052, were studied along seven different inclinations from 0° (orientated perpendicular to the direction of gravity) to 90° (orientated parallel to the direction of gravity), in iterations of 15°. The purpose of study was to investigate the thermal performance of the first four fractal …

Microstructure And Mechanical Behavior Of Metastable Beta Type Titanium Alloys, Chirag Dhirajlal Rabadia

Theses: Doctorates and Masters

Current biomaterials such as stainless steel, Co-Cr alloys, commercially pure titanium and Ti-6Al- 4V either possess poor mechanical compatibility and/or produce toxic effects in the human body after several years of usage. Consequently, there is an enormous demand for long-lasting biomaterials which provide a better combination of mechanical, corrosion and biological properties. In addition to this, alloys used in high-strength applications possess either high-strength or large plasticity. However, a high-strength alloy should possess a better blend of both strength and plasticity when used in high-strength applications. Metastable β-titanium alloys are the best suited alloys for biomedical and high-strength applications because …

Using Computational Fluid Dynamics To Accurately Model Agricultural Spray Nozzles, Zachary Chapman

Electronic Theses and Dissertations

Computational fluid dynamics (CFD) is a tool used by engineers in many industries to study fluid flow. A relatively new industry to adopt the use of CFD is the agricultural industry. The present work seeks to understand whether CFD can be used to accurately model spray nozzles. A spray nozzle commonly used in agricultural spraying was simulated. First, the impact of factors such as mesh size, mesh type, and physics models have on the solution were investigated. Next, a method to pulse the spray was determined. This was required to compare simulation results with experimental data. A user-defined function was …

A Series-Elastic Robot For Back-Pain Rehabilitation, Elhussein Shata

Electronic Theses and Dissertations

Robotics research has been broadly expanding into various fields during the past decades. It is widely spread and best known for solving many technical necessities in different fields. With the rise of the industrial revolution, it upgraded many factories to use industrial robots to prevent the human operator from dangerous and hazardous tasks. The rapid development of application fields and their complexity have inspired researchers in the robotics community to find innovative solutions to meet the new desired requirements of the field. Currently, the creation of new needs outside the traditional industrial robots are demanding robots to attend to the …

Strain-Based Mechanical Failure Analysis Of Buried Steel Pipeline Subjected To Landslide Displacement Using Finite Element Method, Sean Goodluck Mamuzo Edeki

Electronic Theses and Dissertations

Landslide displacement is one of the major threats to the structural integrity of buried oil and natural gas pipelines that are often located far from major markets with terrains prone to permanent ground deformations. These pipelines can experience large longitudinal strains and circumferential deformation resulting from the differential ground movements thereby potentially impacting pipeline safety by adversely affecting structural capacity and leak tight integrity. In order to proffer theoretical basis for the design, safety evaluation and maintenance of pipelines, the failure analysis and mechanical behavior of buried API X65 steel pipeline perpendicularly crossing landslide area was investigated with the Finite …

Impartial Sensor Tasking Via Forecasted Information Content Quantification, Matthew J. Gualdoni, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The consistently increasing population of space debris in orbit about the Earth is becoming an increasingly unavoidable problem, necessitating a proper handling of the problem of sensor tasking to effectively and efficiently obtain observations of space objects to maintain catalogs of their positions and velocities. A variety of approaches have been explored to achieve this in an autonomous fashion, assisting with space traffic management. This work presents new statistical analysis of the Kullback–Leibler divergence justifying the use of its expected value in generating sensor schedules. This divergence's use as an objective measure is extended to simultaneously consider, in an impartial …

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 …

Optimization Strategies For Myopic And Forecasted Divergence-Based Sensor Tasking Objectives, Matthew J. Gualdoni, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In light of the ever-increasing value of space assets operating in the presence of a continuously growing population of space objects in orbit about Earth, space situational awareness is becoming more crucial than ever. The process of tracking and maintaining estimates for the numerous assets and space objects is a complex and highly demanding problem, as it requires robust state estimates in the presence of sparse data. As the number of space objects greatly outweighs the number of available sensors, a sensor tasking policy is necessary to properly utilize the available sensor resources in a way that ensures targets are …

Impact Of Considering And Neglecting States On Descent-To-Landing Navigation, Kyle J. Demars, Kari C. Ward

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper develops a novel square-root formulation of the consider/neglect Kalman filter for navigation applications. The proposed filter partitions system parameters into three distinct categories: those to be estimated by the filter, those whose contribution to the system can be considered without explicitly estimating them, and those with sufficiently low effect on the system such that their contribution can be neglected altogether. Discussion on appropriate selection of consider and neglect parameters is provided with specific attention given to descent-to-landing navigation. Monte Carlo simulations and analysis are performed to assess the performance of the square-root consider/neglect filter.

Robustness Metric For Robust Design Optimization Under Time-And Space-Dependent Uncertainty Through Metamodeling, Xinpeng Wei, Xiaoping Du

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Product performance varies with respect to time and space in many engineering applications. This paper discusses how to measure and evaluate the robustness of a product or component when its quality characteristics (QCs) are functions of random variables, random fields, temporal variables, and spatial variables. At first, the existing time-dependent robustness metric is extended to the present time-and space-dependent problem. The robustness metric is derived using the extreme value of the quality characteristics with respect to temporal and spatial variables for the nominal-the-better type quality characteristics. Then, a metamodel-based numerical procedure is developed to evaluate the new robustness metric. The …

Design And Analysis Of Descent-To-Landing Navigation Incorporating Terrain Effects, Kari C. Ward, Gunner S. Fritsch, J. Cameron Helmuth, Kyle J. Demars, James S. Mccabe

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This study investigated the ability of a navigation filter to process multiple terrain-based sensors, such as slant-range, slant-speed, and terrain relative navigation sensors, during a descent-to-landing scenario to estimate the state of a landing vehicle. The filtering technique leveraged was based upon a factorized form of the multiplicative extended Kalman filter, and terrain-based measurements were fused with star camera and inertial measurement unit sensor returns to estimate the position, velocity, and attitude of the landing vehicle. Monte Carlo simulations were carried out to assess the performance of the navigation filter along a lunar descent trajectory, as well as the consistency …

A Brief Review On 3d Bioprinted Skin Substitutes, Fateme Fayyazbakhsh, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Global Escalating Cases of Skin Donor Shortage for Patients with Severe Wounds Warn the Vital Need for Alternatives to Skin Allografts. over the Last Three Decades, Research in the Skin Regeneration Area Has Addressed the Unmet Need for Artificial Skin Substitutes. 3D Bioprinting is a Promising Innovative Technology to Accurately Fabricate Skin Constructs based on Natural or Synthetic Bioinks, Whether Loaded or Not Loaded with Native Skin Cells (I.e., Keratinocytes and Fibroblasts) or Stem Cells in the Prescribed 3D Hierarchal Structure to Create Artificial Multilayer and Single Cell-Laden Construct. in This Paper, the Recent Developments in 3D Bioprinting for …

Design Of An Annular Disc-Shaped Heat Pipe For Air-Cooled Steam Condensers, Ahmad Saleh

Electronic Theses and Dissertations, 2020-2023

Limitations on water utilization are turning into an expanding issue for the power and electricity generation industry. As a contribution to the solution of water consumption problems, utility companies are shifting toward using air-cooled condensers (ACC) in replace to the typical water-cooling methods of once-through cooling and the surface condenser/wet-cooling tower combination. Although the ACC is a dry cooling method, the industry is quite hesitant to switch over to ACC mainly for three reasons: (a) lower power output, (b) higher capital cost, and (c) larger physical footprint. All these drawbacks are because of the high overall thermal resistance of condensing …

Engineering The Surface Chemistry And Surface Conditions To Optimize The Heat Removal Rate Of Various Surfaces, Thomas Germain

Electronic Theses and Dissertations, 2020-2023

As the demand for more powerful and smaller electronics rise, the need for creative cooling solutions to prevent burnout becomes increasingly paramount. In response to recent cooling needs, new cooling techniques, such as jet impingement cooling, spray cooling, and heat pipes, have risen in popularity for their simple design and efficiency in thermal transport. This interest has risen in both industry and academia, where research has been conducted to optimize the heat transfer performance for these systems and how these systems can be implemented in new technologies. One method that has risen in interest is affecting the surface, through physical …

Multi-Well Plate Channel Device With Reversible Seals, Haipeng Zhang, Timothy Wei, Sangjin Ryu

Department of Mechanical and Materials Engineering: Faculty Publications

Atherosclerosis is a cardiovascular disease which causes over 26,000 yearly deaths in the United States. This disease involves accumulation of substances in arterial walls (or plaques) that occurs frequently to arterial regions experiencing low shear stress, such as bends and bifurcations. A possible reason of plaque growth in arterial walls is the change of endothelial cell (EC)’s shape, which is related to fluid shear stresses tangentially acting on intimal layer (the EC surface) of the arterial wall. Lambert et al. studied the relationship between EC shape and shear stress (Lambert et al., 2019) using a BioFlux system (Fluxion Bioscienes) and …

Universal Mechanical Exfoliation Of Large-Area 2d Crystals, Yuan Huang, Yu-Hao Pan, Rong Yang, Li-Hong Bao, Lei Meng, Hai-Lan Luo, Yong-Qing Cai, Guo-Dong Liu, Wen-Juan Zhao, Zhang Zhou, Liang-Mei Wu, Zhi-Li- Zhu, Ming Huang, Li-Wei Liu, Lei Liu, Peng Cheng, Ke-Hui Wu, Shi-Bing Tian, Chang-Zhi Gu, You-Guo Shi, Yan-Feng Guo, Zhi Gang Cheng, Jiang-Ping Hu, Lin Zhao, Guan-Hua Yang, Eli Sutter, Peter Sutter, Ye-Liang Wang, Wei Ji, Xing-Jiang Zhou, Hong-Jun Gao

Department of Mechanical and Materials Engineering: Faculty Publications

Two-dimensional materials provide extraordinary opportunities for exploring phenomena arising in atomically thin crystals. Beginning with the first isolation of graphene, mechanical exfoliation has been a key to provide high-quality two-dimensional materials, but despite improvements it is still limited in yield, lateral size and contamination. Here we introduce a contamination-free, one-step and universal Au-assisted mechanical exfoliation method and demonstrate its effectiveness by isolating 40 types of single-crystalline monolayers, including elemental two-dimensional crystals, metal-dichalcogenides, magnets and superconductors. Most of them are of millimeter-size and high-quality, as shown by transfer-free measure- ments of electron microscopy, photo spectroscopies and electrical transport. Large sus- pended …