Mechanical Engineering Commons^™

Development Of Scalable And Tunable Super- Hydrophilic And - Hydrophobic Coatings On The Cu Substrate For Phase Change Heat Transfer Applications, Raikan Saad Dawas

Theses and Dissertations

The aim of this study is to enhance and sustain the thin liquid film evaporation (TLFE) as well as dropwise condensation (DWC) on scalable copper substrates. The current dissertation consists of two sections. The objective of the first section is to enhance the dry cooling technology which is widely used in industrial applications such as in the air side of power plants, AC unit, or electronic cooling. However, the thermal dissipation performance is limited with low heat transfer coefficients (HTCs) due to the low thermal conductivity and density of the air. Inspired by the phase change heat transfer during the …

Surface Science And Engineering Of Nano-Structured Cathodes For Intermediate Temperature Solid Oxide Fuel Cells, Yeting Wen

Theses and Dissertations

The bulk-to-surface Sr-segregation can seriously compromise the stability of oxygen electrocatalysis in Sr-doped perovskite oxides such as La1-xSrxCoO3-δ and La1-xSrxCo1- yFeyO3-δ and limit their practical applications as cathode materials in solid oxide fuel cells. Although such chemical instability has been actively studied in recent years, fundamental understanding of Sr-segregation process vs temperature and time, particularly under real-world conditions, as well as the suppression method, are still needed. This PhD dissertation aims to acquire fundamental knowledge of Sr-segregation process under practical conditions in solid oxide fuel cells and develop suppression method to ensure the long-term stability through surface modifications.

To gain …

Acoustoelastic Metamaterial With Simultaneous Noise Filtering And Energy Harvesting Capability From Ambient Vibrations, Fariha Mir

Theses and Dissertations

Harvesting unused and untapped energy from ambient vibration noise and acoustic sound waves is an emerging field of research in the recent years. Utilization of the energy with a wide band of the frequency spectrum from the vibrational sources alone stands as one of the most promising ways to power small electronic devices, smartphones, local structural health monitoring (SHM) sensors and home and workshop appliances. Various sources of ambient vibration and acoustic noise can be found around us in our everyday life. These sources are abundant in almost all the engineering industries and manufacturing facilities for example in aerospace, mechanical …

Friction Stir Additive Manufacturing(Fsam) Of 2050 Al-Cu-Li Alloy, Ilana Lu

Theses and Dissertations

As a solid state process, friction stir welding (FSW) is an advantageous joining method for higher strength aluminum alloys such as 2050 Al-Cu-Li which are not readily fusion welded. This study explores the potential of friction stir lap welding (FSLW) as an additive manufacturing process for this aluminum-lithium alloy. To accomplish this, lap weld joints were performed so that each additional layer would penetrate the preceding weld pass which creates a large, stacked build. Excess material is machined away leaving only weld. Cast AA2050 is explored in this study as a more cost-efficient feedstock for this process as compared to …

Electrochemical Conversion Of Methane To Ethylene In A Solid Oxide Electrolyer, Changli Zhu, Shisheng Hou, Xiuli Hu, Jinhai Lu, Fanglin Chen, Kui Xie

Faculty Publications

Conversion of methane to ethylene with high yield remains a fundamental challenge due to the low ethylene selectivity, severe carbon deposition and instability of catalysts. Here we demonstrate a conceptually different process of in situ electrochemical oxidation of methane to ethylene in a solid oxide electrolyzer under ambient pressure at 850 °C. The porous electrode scaffold with an in situ-grown metal/oxide interface enhances coking resistance and catalyst stability at high temperatures. The highest C2 product selectivity of 81.2% together with the highest C2 product concentration of 16.7% in output gas (12.1% ethylene and 4.6% ethane) is achieved while the methane …

Controlling The Oxygen Electrocatalysis On Perovskite And Layered Oxide Thin Films For Solid Oxide Fuel Cell Cathodes, Gene Yang, Wonsang Jung, Sung-Jin Ahn, Dongkyu Lee

Faculty Publications

Achieving the fast oxygen reduction reaction (ORR) kinetics at the cathode of solid oxide fuel cells (SOFCs) is indispensable to enhance the efficiency of SOFCs at intermediate temperatures. Mixed ionic and electronic conducting (MIEC) oxides such as ABO₃ perovskites and Ruddlesden-Popper (RP) oxides (A₂BO₄) have been widely used as promising cathode materials owing to their attractive physicochemical properties. In particular, oxides in forms of thin films and heterostructures have enabled significant enhancement in the ORR activity. Therefore, we aim to give a comprehensive overview on the recent development of thin film cathodes of SOFCs. We …

High-Throughput 3d Reconstruction Of Stochastic Heterogeneous Microstructures In Energy Storage Materials, Yanxiang Zhang, Mufu Yan, Yanhong Wan, Zhenjun Jiao, Yu Chen, Fanglin Chen, Changrong Xia, Meng Ni

Faculty Publications

Stochastic heterogeneous microstructures are widely applied in structural and functional materials, playing a crucial role in determining their performance. X-ray tomography and focused ion beam serial sectioning are frequently used methods to reconstruct three-dimensional (3D) microstructures, yet are demanding techniques and are resolution-limited. Here, a high-throughput multi-stage 3D reconstruction method via distance correlation functions is developed using a single representatively large-sized 2D micrograph for stochastic microstructures, and verified by X-ray micro-tomography datasets of isotropic and anisotropic solid oxide fuel cell electrodes. This method provides an economic, easy-to-use and high-throughput approach for reconstructing stochastic heterogeneous microstructures for energy conversion and storage …

Use Of Flexible Sensor To Characterize Biomechanics Of Canine Skin, Austin Downey, Jin Yan, Eric M. Zellner, Karl H. Kraus, Iris V. Rivero, Simon Laflamme

Faculty Publications

Background Suture materials and techniques are frequently evaluated in ex vivo studies by comparing tensile strengths. However, the direct measurement techniques to obtain the tensile forces in canine skin are not available, and, therefore, the conditions suture lines undergo is unknown. A soft elastomeric capacitor is used to monitor deformation in the skin over time by sensing strain. This sensor was applied to a sample of canine skin to evaluate its capacity to sense strain in the sample while loaded in a dynamic material testing machine. The measured strain of the sensor was compared with the strain measured by the …

Recent Advances In Piezoelectric Wafer Active Sensors For Structural Health Monitoring Applications, Hanfei Mei, Mohammad Faisal Haider, Roshan Prakash Joseph, Asaad Migot, Victor Giurgiutiu

Faculty Publications

In this paper, some recent piezoelectric wafer active sensors (PWAS) progress achieved in our laboratory for active materials and smart structures (LAMSS) at the University of South Carolina: http: //www.me.sc.edu/research/lamss/ group is presented. First, the characterization of the PWAS materials shows that no significant change in the microstructure after exposure to high temperature and nuclear radiation, and the PWAS transducer can be used in harsh environments for structural health monitoring (SHM) applications. Next, PWAS active sensing of various damage types in aluminum and composite structures are explored. PWAS transducers can successfully detect the simulated crack and corrosion damage in aluminum …

Propagating, Evanescent, And Complex Wavenumber Guided Waves In High-Performance Composites, Victor Giurgiutiu, Mohammad Faisal Haider

Faculty Publications

The study of propagating, evanescent and complex wavenumbers of guided waves (GWs) in high-performance composites using a stable and robust semi-analytical finite element (SAFE) method is presented. To facilitate understanding of the wavenumber trajectories, an incremental material change study is performed moving gradually from isotropic aluminum alloy to carbon fiber reinforced polymer (CFRP) composites. The SAFE results for an isotropic aluminum alloy plate are compared with the exact analytical solutions, which shows that N = 20 SAFE elements across the thickness provides

Propagating, Evanescent, And Complex Wavenumber Guided Waves In High-Performance Composites, Victor Giurgiutiu, Mohammad Faisal Haider

Faculty Publications

The study of propagating, evanescent and complex wavenumbers of guided waves (GWs) in high-performance composites using a stable and robust semi-analytical finite element (SAFE) method is presented. To facilitate understanding of the wavenumber trajectories, an incremental material change study is performed moving gradually from isotropic aluminum alloy to carbon fiber reinforced polymer (CFRP) composites. The SAFE results for an isotropic aluminum alloy plate are compared with the exact analytical solutions, which shows that N = 20 SAFE elements across the thickness provides <0.5% error in the highest evanescent wavenumber for the given frequency-wavenumber range. The material change study reveals that reducing the transverse and shear moduli moves the wavenumber solution towards one similar to composite material. The comparison of the propagating, evanescent and complex wavenumber trajectories between composites and aluminum alloy show that antisymmetric imaginary Lamb wave modes always exist in composites although they may not exist in isotropic aluminum alloy at some frequencies. The wavenumber trajectories for a unidirectional CFRP plate show that the range of real wavenumber is much smaller than in the isotropic aluminum alloy. For laminated CFRP composite plates (e.g., unidirectional, off-axis, transverse, cross-ply and quasi-isotropic laminates), the quasi Lamb wave and shear horizontal (SH) wave trajectories are also identified and discussed. The imaginary SH wave trajectories in laminated composites are distorted due to the presence of ±45 plies. The convergence study of the SAFE method in various CFRP laminates indicates that sufficient accuracy can always be achieved by increasing the number of SAFE elements. Future work will address the stress-continuity between composite layers.

A Bismuth Attack At Grain-Boundaries Of Ceria-Based Electrolytes, Tianrang Yang, Kevin Huang

Faculty Publications

Bismuth is a common additive of commercial silver pastes for enhancing metallization effect; silver paste is also commonly used in high-temperature electrochemical cells as a current collector or contact layer. We here report that the minor amount of bismuth in commercial silver pastes can transport to the interface of electrode/Gd-doped CeO₂ (GDC) electrolyte and seriously corrode grain-boundaries (GBs) of the GDC electrolyte, a commonly used intermediate-temperature electrolyte, causing significant ionic conductivity degradation. A comprehensive electron microscopic analysis reveals that the Bi-corrosion takes place along GBs of GDC electrolyte acting as “washing flux” agent, causing grain separation and thus blocking …

Experimental Investigation Of Two-Phase (Gas/Liquid) Flow In Intermediate Sized, Horizontal And Inclined Pipes, Noble C. Anumbe

Theses and Dissertations

Multiphase flow models and correlations are indispensable tools for the design and operation of vital flow systems that power various industries. The development, validation and tuning of these flow models & correlations depend on the availability of reliable and accurate data. This dissertation reports on an experimental campaign that not only generated crucial two-phase flow data but also evaluated the effect of inclination angle on several flow parameters of interest. The report details the experimental investigation of upward, adiabatic, co-current two-phase (gas/liquid) flow through a 101.6 mm inner diameter (ID) pipe. Experimental data for the investigation were acquired using an …

Topological Conduction And Investigation On Multi Occurrence Of Dirac Cone, Mustahseen Mobashwer Indaleeb

Theses and Dissertations

The unique phenomena in acoustic metamaterial at the Dirac-like cone, and at the exceptional spawning ring could transform the field of engineering with multiple new applications that were never possible before. Localized conical dispersion called Dirac cone at the Brillouin Zone boundaries are the well-known phenomena demonstrated by photonics and phononic metamaterials. However, Dirac cone-like dispersion at the center of the Brillouin zone (where wave number, k = 0) [1] is rare and only happens due to accidental degeneracy at finite frequencies in two-dimensional periodic crystals (PCs), with or without microarchitectures. Accidental degeneracies are generally the ‘sweet spots’ where the …

Ultrasonic Analysis And Tools For Quantitative Material State Awarness Of Engineered Materials, Subir Patra

Theses and Dissertations

The objective of this research is to devise new methods and tools to generate real time awareness of the material state of composite and metallic structures through ultrasonic nondestructive evaluation (NDE) and structural health monitoring (SHM) at its very early stage of failure. To device new methodology it is also important to verify the method through virtual experiments and hence computational NDE is getting popular in the recent years. In this thesis, while experimental methodology is developed to understand the material state at its early stage of failure, a new peridynamic based Peri-Elastodynamic (PED) computational method is also developed for …

Nonlocal Damage Mechanics For Quantification Of Health For Piezoelectric Sensor, Amit Shelke, Anowarul Habib, Umar Amjad, Ullrich Pietsch, Sourav Banerjee

Faculty Publications

In this paper, a novel method to quantify the incubation of damage on piezoelectric crystal is presented. An intrinsic length scale parameter obtained from nonlocal field theory is used as a novel measure for quantification of damage precursor. Features such as amplitude decay, attenuation, frequency shifts and higher harmonics of guided waves are commonly-used damage features. Quantification of the precursors to damage by considering the mentioned features in a single framework is a difficult proposition. Therefore, a nonlocal field theory is formulated and a nonlocal damage index is proposed. The underlying idea of the paper is that inception of the …

Experimental Investigation Of Impact Localization In Composite Plate Using Newly Developed Imaging Method, Mohammad Faisal Haider, Asaad Migot, Md Yeasin Bhuiyan, Victor Giurgiutiu

Faculty Publications

This paper focuses on impact localization of composite structures, which possess more complexity in the guided wave propagation due to the anisotropic behavior of composite materials. In this work, a composite plate was manufactured by using a compression molding process with proper pressure and temperature cycle. Eight layers of woven composite prepreg were used to manufacture the composite plate. A structural health monitoring (SHM) technique was implemented with piezoelectric wafer active sensors (PWAS) to detect and localize the impact on the plate. There were two types of impact event that were considered in this paper (a) low energy impact event …

Multi-Pred: A Software Module For Predictive Modeling Of Coupled Multi-Physics Systems, Dan Gabriel Cacuci, Ruixian Fang, Madalina C. Badea

Faculty Publications

The software module MULTI-PRED implements the methodology for predictive modeling of coupled multi-physics systems (PM-CMPS) formulated by Cacuci [Ann. Nucl. Energy, Vol. 70, p, 266 (2014)]. This methodology fully takes into account the coupling terms between the systems but requires only the computational resources that would be needed to perform predictive modeling on each system separately. The PM-CMPS methodology uses the maximum entropy principle to construct an optimal approximation of the unknown a priori distribution based on a priori known mean values and uncertainties characterizing the experimental and computational parameters and results of interest responses called for the multi-physics models …

The Performance Of Syngas-Fueled Sofcs Predicted By A Reduced Order Model (Rom): Temperature And Fuel Composition Effects, Xinfang Jin, Anthony Ku, Atul Verma, Brandon Ohara, Kevin Huang, Surinder Singh

Faculty Publications

An electrochemical reduced order model (ROM) has been developed in this study to simulate the performance of syngas-fueled anode-supported SOFCs with coupled bulk chemical reactions and multi-species gas diffusion in the electrodes. Experimental V-I curves with syngas fuel were used to validate the model to ensure its high fidelity. The model was used to investigate the effects of fuel composition and temperature on the electrochemical performance of the cell, chemical reaction rate and concentration distributions of gaseous species across the anode. The results show that H₂ electro-oxidation dominates the overall cell performance, and that CO contributes to the performance …

Pedestrian Injury Severity Analysis In Motor Vehicle Crashes In Ohio, Majbah Uddin, Fahim Ahmed

Faculty Publications

According to the National Highway Traffic Safety Administration, 116 pedestrians were killed in motor vehicle crashes in Ohio in 2015. However, no study to date has analyzed crashes in Ohio in order to explore the factors contributing to the pedestrian injury severity resulting from motor vehicle crashes. This study fills this gap by investigating the crashes involving pedestrians exclusively in Ohio. This study uses the crash data from the Highway Safety Information System, from 2009 to 2013. The explanatory factors include the pedestrian, driver, vehicle, crash, and roadway characteristics. Both fixed- and random-parameters ordered probit models of injury severity (where …

Second-Order Sensitivity Analysis Of Uncollided Particle Contributions To Radiation Detector Responses, Dan Gabriel Cacuci, Jeffrey A. Favorite

Faculty Publications

This work presents an application of Cacuci's Second-Order Adjoint Sensitivity Analysis Methodology (2nd-ASAM) to the simplified Boltzmann equation that models the transport of uncollided particles through a medium to compute efficiently and exactly all of the first- and second-order derivatives (sensitivities) of a detector's response with respect to the system's isotopic number densities, microscopic cross sections, source emission rates, and detector response function. The off-the-shelf PARTISN multigroup discrete ordinates code is employed to solve the equations underlying the 2nd-ASAM. The accuracy of the results produced using PARTISN is verified by using the results of three test configurations: (1) a homogeneous …

Uncertainty Evaluation In The Design Of Structural Health Monitoring Systems For Damage Detection, Christine Schubert Kabban, Richard Uber, Kevin Lin, Bin Li, Md Yeasin Bhuiyan, Victor Giurgiutiu

Faculty Publications

The validation of structural health monitoring (SHM) systems for aircraft is complicated by the extent and number of factors that the SHM system must demonstrate for robust performance. Therefore, a time- and cost-efficient method for examining all of the sensitive factors must be conducted. In this paper, we demonstrate the utility of using the simulation modeling environment to determine the SHM sensitive factors that must be considered for subsequent experiments, in order to enable the SHM validation. We demonstrate this concept by examining the effect of SHM system configuration and flaw characteristics on the response of a signal from a …

Optimization Of Microfluidic Chip Fabrication Via Femtosecond Laser Ablation, Kenneth Aycock

Senior Theses

Microfluidic devices have become staple tools in biomedical research and have a promising future as low cost, point-of-care (POC) diagnostic devices. Despite the advancements in microfluidic device technology, the manipulation and fabrication of these systems can be tedious and expensive. Repeatable techniques in which computer-aided designs are translated into microfluidic systems in a matter of minutes are highly desirable both for researchers and manufacturers. Laser ablation of tape substrates has shown promise in producing cost-effective, rapidly manipulable devices, but the work done thus far has utilized continuous wave lasers that perform suboptimally due to the relatively short wavelengths used and …

Highly Efficient Electrochemical Reforming Of Ch4/Co2 In A Solid Oxide Electrolyser, Jinhai Lu, Changli Zhu, Changchang Pan, Wenlie Lin, John P. Lemmon, Fanglin Chen, Chunsen Li, Kui Xie

Faculty Publications

Reforming CH₄ into syngas using CO₂ remains a fundamental challenge due to carbon deposition and nanocatalyst instability. We, for the first time, demonstrate highly efficient electrochemical reforming of CH₄/CO₂ to produce syngas in a solid oxide electrolyser with CO₂ electrolysis in the cathode and CH₄ oxidation in the anode. In situ exsolution of an anchored metal/oxide interface on perovskite electrode delivers remarkably enhanced coking resistance and catalyst stability. In situ Fourier transform infrared characterizations combined with first principle calculations disclose the interface activation of CO₂ at a transition state between a CO …

Atomic Layer Deposition On Porous Materials: Problems With Conventional Approaches To Catalyst And Fuel Cell Electrode Preparation, Tzia Ming Onn, Rainer Küngas, Paolo Fornasiero, Kevin Huang, Raymond J. Gorte

Faculty Publications

Atomic layer deposition (ALD) offers exciting possibilities for controlling the structure and composition of surfaces on the atomic scale in heterogeneous catalysts and solid oxide fuel cell (SOFC) electrodes. However, while ALD procedures and equipment are well developed for applications involving flat surfaces, the conditions required for ALD in porous materials with a large surface area need to be very different. The materials (e.g., rare earths and other functional oxides) that are of interest for catalytic applications will also be different. For flat surfaces, rapid cycling, enabled by high carrier-gas flow rates, is necessary in order to rapidly grow thicker …

An Experimental Study On Static And Dynamic Strain Sensitivity Of Embeddable Smart Concrete Sensors Doped With Carbon Nanotubes For Shm Of Large Structures, Andrea Meoni, Antonella D'Alessandro, Austin Downey, Enrique García-Macías, Marco Rallini, A. Luigi Materazzi, Luigi Torre, Simon Laflamme, Rafael Castro-Triguero, Filippo Ubertini

Faculty Publications

The availability of new self-sensing cement-based strain sensors allows the development of dense sensor networks for Structural Health Monitoring (SHM) of reinforced concrete structures. These sensors are fabricated by doping cement-matrix mterials with conductive fillers, such as Multi Walled Carbon Nanotubes (MWCNTs), and can be embedded into structural elements made of reinforced concrete prior to casting. The strain sensing principle is based on the multifunctional composites outputting a measurable change in their electrical properties when subjected to a deformation. Previous work by the authors was devoted to material fabrication, modeling and applications in SHM. In this paper, we investigate the …

Peri-Elastodynamic Simulations Of Guided Ultrasonic Lamb Waves In Smart Structure With Surface Mounted Pzt, Subir Patra, Hossain Ahmed, Sourav Banerjee

Faculty Publications

Peridynamic based elastodynamic computation tool named Peri-elastodynamics is proposed herein to simulate the three-dimensional (3D) Lamb wave modes in materials for the first time. Peri-elastodynamics is a nonlocal meshless approach which is a scale-independent generalized technique to visualize the acoustic and ultrasonic waves in plate-like structure, micro-electro-mechanical systems (MEMS) and nanodevices for their respective characterization. In this article, the characteristics of the fundamental Lamb wave modes are simulated in a sample plate-like structure. Lamb wave modes are generated using a surface mounted piezoelectric (PZT) transducer which is actuated from the top surface. The proposed generalized Peri-elastodynamics method is not only …

System Optimization And Material Development Of Solid Oxide Cells For Energy Conversion And Storage, Libin Lei

Theses and Dissertations

Solid oxide cells (SOCs) can convert chemical energy to electricity in the fuel cell mode and store electricity to chemicals in the electrolysis mode. However, there are still critical barriers, such as energy efficiency and durability, for the development and commercialization of SOCs. The objective of this dissertation is to apply system optimization and materials design to address the critical barriers for solid oxide cells in energy conversion and energy storage applications. One major focus of the dissertation is related to improve energy efficiency, enhance the cell performance and achieve multifunctionality in solid oxide electrolysis cells (SOECs). In addition, development …

Enhance Flow Boiling In Microchannels By Regulating Two-Phase Transport Patterns, Wenming Li

Theses and Dissertations

Flow boiling in microchannels is one of the most promising cooling techniques for microelectronics. Using latent heat by vaporization can significantly improve heat dissipation of high power density electronic devices. Most of the failure of electronic devices is induced by the occurrence of critical heat flux (CHF), which defines the maximum operating conditions. However, the vigorous rapid generation of vapor through phase change leads to chaotic two-phase flows in microchannels, resulting in flowinstability in terms of severe flow, temperature and pressure drop fluctuations. Particularly, the very well-known bubble confinement exacerbates the two-phase flow instabilities and greatly deteriorates heat transfer performance …

Multiscale Deformation And Failure Behavior Of Polymer Bonded Explosives Subjected To High Rate Loading, Suraj Muthiramalil Ravindran

Theses and Dissertations

Polymer bonded explosives (PBX) are heterogeneous granular composites with a high-volume fraction of solid. Typically, they contain 80-95% explosive crystals and 5- 20% soft polymer binder. These materials are subjected to different loading conditions during their service life. The main function of the soft binder is to reduce shock sensitivity to prevent an accidental explosion. However, there have been inadvertent detonations in these materials during transportation and handling. The reason for such unintentional explosion is not well understood. It is commonly accepted that the formation of local hightemperature regions, called ‘hot spots’, is the primary cause. Hotspot formation is associated …