Engineering Science and Materials Commons^™

Ultrahigh Strength And Plasticity In Laser Rapid Solidified Al–Si Nanoscale Eutectics, Huai-Hsun Lien, Jyoti Mazumder, Jian Wang, Amit Misra

Department of Mechanical and Materials Engineering: Faculty Publications

As-cast Al–20wt.% Si alloys were processed via laser rapid solidification (LRS) techniques to create eutectic microstructures with nanoscale interconnected, nanotwinned Si fibers. LRS morphologies exhibit higher flow stress, exceeding 800 MPa and uniform plastic deformation above 20% compared to as-cast alloy that fractures at strains below 8% at flow strength of approximately 200 MPa. The strengthening mechanisms of LRS morphologies are interpreted in terms of the interfacial constraints: increase in yield strength as well as strain hardening rate due to nanoscale confined slip in fibrous Al–Si eutectic, and load transfer and eventual plasticity in the nanoscale Si fibers.

Leidenfrost Droplet Microfluidics, Sidy Ndao, George Gogos, Dennis Alexander, Troy Anderson, Craig Zuhlke

Department of Mechanical and Materials Engineering: Faculty Publications

Systems and methods are described for propelling a liquid droplet in a Leidenforst state. A microfluidic device embodiment includes, but is not limited to, a solid structure having a patterned surface, the patterned surface including at least a first patterned region having a first Leidenfrost temperature with respect to a fluid, the first patterned region adjacent to the second patterned region, the first patterned region defining a path over which a droplet of the fluid is configured to travel in a Leidenfrost state.

Iron Pyrite Nanocrystals, Jinsong Huang, Baodong Mao, Christopher L. Exstrom

Department of Mechanical and Materials Engineering: Faculty Publications

An apparatus includes a nanocrystal. The nanocrystal includes a core including FeS2; and a coating including a ligand component capable of chemically interacting with both an iron atom and a sulfur atom on a surface of the core.

Colocalized Sensing And Intelligent Computing In Micro-Sensors, Mohammad H. Hasan, Ali Al-Ramini, Eihab Abdel-Rahman, Roozbeh Jafari, Fadi Alsaleem

Department of Mechanical and Materials Engineering: Faculty Publications

This work presents an approach to delay-based reservoir computing (RC) at the sensor level without input modulation. It employs a time-multiplexed bias to maintain transience while utilizing either an electrical signal or an environmental signal (such as acceleration) as an unmodulated input signal. The proposed approach enables RC carried out by sufficiently nonlinear sensory elements, as we demonstrate using a single electrostatically actuated microelectromechanical system (MEMS) device. The MEMS sensor can perform colocalized sensing and computing with fewer electronics than traditional RC elements at the RC input (such as analog- to-digital and digital-to-analog converters). The performance of the MEMS RC …

Microstructural Evolution Of Nanotwinned Al-Zr Alloy With Significant 9r Phase, N.A. Richter, Y.F. Zhang, D. Y. Xie, R. Su, Q. Li, S. Xue, T. Niu, J. Wang, H. Wang, Xinghang Zhang

Department of Mechanical and Materials Engineering: Faculty Publications

Aluminum (Al) alloys have a multitude of applications, notably in the automotive, aerospace and coating industries, yet they exhibit significantly lower mechanical strength than conventional steels. Nanotwins drastically improve mechanical strength while retaining ductility. However, the high SFE of Al largely prevents twinning. Here, we synthesize Al-Zr alloy films containing an abundance of incoherent twin boundaries and 9R phases. These alloys exhibit an extended solid solubility of Zr, retaining a columnar nanotwinned structure across all compositions. These films reach a hardness up to 4.2 GPa with 10 at% Zr and demonstrate the capacity for producing strong Al alloys with nanotwins.

Attainment Of Rigorous Thermodynamic Consistency And Surface Tension In Single-Component Pseudopotential Lattice Boltzmann Models Via A Customized Equation Of State, Cheng Peng, Luis F. Ayala, Zhicheng Wang, Orlando M. Ayala

Engineering Technology Faculty Publications

The lack of thermodynamic consistency is a well-recognized problem in the single-component pseudopotential lattice Boltzmann models which prevents them from replicating accurate liquid and vapor phase densities; i.e., current models remain unable to exactly match coexisting density values predicted by the associated thermodynamic model. Most of the previous efforts had attempted to solve this problem by introducing tuning parameters, whose determination required empirical trial and error until acceptable thermodynamic consistency was achieved. In this study, we show that the problem can be alternatively solved by properly designing customized equations of state (EOSs) that replace any cubic EOS of choice during …

Lateral Bracing Of Beams Provided By Standing Seam Roof System: Concepts And Case Study, Gengrui Wei, Benjamin Schafer, Michael Seek, Matthew Eatherton

Engineering Technology Faculty Publications

The standing seam roof (SSR) system is the most commonly used roof system for metal buildings due to its superior durability, water tightness, and energy efficiency. In this type of system, SSR panels attach to Z-shaped or C-shaped purlins with clips, and the purlins are in turn connected to rafters (i.e. roof beams). For the design of metal building rafters against lateral torsional buckling, bottom flange braces provide torsional bracing to the rafter and the SSR system provides some lateral bracing. However, the degree to which the SSR system can restrain the rafter against lateral movement has not previously been …

Fabrication, Development, And Characterization Of Hipco Swcnt - Alginate Hydrogel Composites For Cellular Product Applications, Fabian Armando Alvarez-Primo

Open Access Theses & Dissertations

In this study, we designed, synthesized, and characterized ultrahigh purity single-walled carbon nanotube (SWCNT)-alginate hydrogel composites. Among the parameters of importance in the formation of an alginate-based hydrogel composite with single-walled carbon nanotubes, are their varying degrees of purity, their particulate agglomeration and their dose-dependent correlation to cell viability, all of which have an impact on the resultant compositeâ??s efficiency and effectiveness towards biomedical applications. To promote their homogenous dispersion by preventing agglomeration of the SWCNT, at first, we used three different surfactants-sodium dodecyl sulfate (SDS-anionic), cetyltrimethylammonium bromide (CTAB-cationic), and Pluronic F108 (nonionic). After experimentation and corroboration through evidence obtained …

Supercritical Processed Decellularized Extracellualr Matrix As Regeneration Therapeutics Applying 3d Printing, Seungwon Chung

Open Access Theses & Dissertations

Extracellular matrix has been broadly applied and show great promise in medical applications and tissue engineering. Product of extracellular matrix (ECM) should be treated with decellularization and purification process. Supercritical carbon dioxide treatment is of particular interest for purifying ECM because of its medically available and rapid speed of process. However, it is not fully researched in treatment of biomaterials for tissue engineering. Therefore, we investigated optimal conditions of supercritical carbon dioxide processing in different extracting parameters from porcine adipose tissue. The 3-day, dual treatment including enzymatic decellularization and supercritical fluid extraction of pork adipose tissue were performed. Two types …

Atv Dynamics And Pediatric Rider Safety, James T. Auxier Ii

Theses and Dissertations--Biomedical Engineering

It has been observed through numerous academic and governmental agency studies that pediatric all-terrain vehicle ridership carries significant risk of injury and death. While no doubt valuable to safety, the post-hoc approach employed in these studies does little to explain the why and how behind the risk factors. Furthermore, there has been no prolonged, widespread, organized, and concerted effort to reconstruct and catalog the details and causes of the large (20,000+) number of ATV-related injuries that occur each year as has been done for road-based motor vehicle accidents. This dissertation takes the opposite approach from a meta-analysis and instead examines …

Fabrication, Characterization And Applications Of Highly Conductive Wet-Spun Pedot:Pss Fibers, Ruben Sarabia Riquelme

Theses and Dissertations--Chemical and Materials Engineering

Smart electronic textiles cross conventional uses to include functionalities such as light emission, health monitoring, climate control, sensing, storage and conversion of energy, etc. New fibers and yarns that are electrically conductive and mechanically robust are needed as fundamental building blocks for these next generation textiles.

Conjugated polymers are promising candidates in the field of electronic textiles because they are made of earth-abundant, inexpensive elements, have good mechanical properties and flexibility, and can be processed using low-cost large-scale solution processing methods. Currently, the main method to fabricate electrically conductive fibers or yarns from conjugated polymers is the deposition of the …

Influence Of Size Effects On Surface Generation During Finish Machining And Surface Integrity In Ti-6al-4v, Ian S. Brown

Theses and Dissertations--Mechanical and Aerospace Engineering

Finish machining is an essential manufacturing process that is used to enhance the mechanical characteristics of critical components. The deformation that occurs at the tool and workpiece interface in finish machining significantly affects a host of component properties, commonly referred to as “surface integrity” properties. Surface roughness is a machining deformation-affected characteristic that is of high relevance in contemporary manufacturing. However, over recent decades it has been made clear that the material properties of the deformed surface layers are relevant to component performance as well. Predicting the overall surface quality of a machined component is of great relevance to the …

Buckling Load Study On Pop Nut (Rivet) Using Finite Element Analysis, Saurabh Shankar Shegokar

Dissertations, Master's Theses and Master's Reports

This study highlights the material behavior in riveting operation that includes buckling load analysis using ABAQUS. Finite Element Analysis is used to find the buckling load vs. Displacement results and validated with the results obtained in physical testing of rivet (POP Nut). A mesh sensitivity study is performed using ABAQUS to understand the optimum mesh size for this analysis. An axisymmetric model with contact properties is created and simulated to reduce the simulation time using ABAQUS. The results obtained through Finite Element Analysis show a good resemblance with the testing results. Design changes were suggested to achieve better results that …

Multiscale Modeling Of Carbon Fibers/Graphene Nanoplatelets/Epoxy Hybrid Composites For Aerospace Applications, Hashim Al Mahmud

Dissertations, Master's Theses and Master's Reports

Significant research effort has been dedicated for decades to improve the mechanical properties of aerospace polymer-based composite materials. Lightweight epoxy-based composite materials have increasingly replaced the comparatively heavy and expensive metal alloys used in aeronautical and aerospace structural components. In particular, carbon fibers (CF)/graphene nanoplatelets (GNP)/epoxy hybrid composites can be used for this purpose owing to their high specific stiffness and strength. Therefore, this work has been completed to design, predict, and optimize the effective mechanical properties of CF/GNP/epoxy composite materials at different length scales using a multiscale modeling approach. The work-flow of modeling involves a first step of using …

Increasing Access To Pv Technology Through Sustainable Racking: A Review Of Existing Literature And Ground Mounted Fixed Tilt Designs, And What Can Be Done Next, Parijata Prabhakara

Dissertations, Master's Theses and Master's Reports

There is a lack of literature on the structural balance of systems (BOS), also called racking, for ground mount, fixed-tilt solar PV systems. Literature that exists discusses mostly rooftop racking and installations, additional wind loading, and weight considerations imposed on roofs, and little guidance is provided in building codes. The lack of peer-reviewed guidance on design requirements for domestic and large-scale application solar PV racking systems leaves most consumers relying on expensive, patented, off-the-shelf hardware. As PV cell technology and module costs have improved, we can start to focus on PV BOS improvements (particularly racking) and move towards sustainable designs …

Synthesis And Characterization Of Novel Lithium Gallium Phosphate (Ligap2o7) For Extreme Environment Applications, Mohan Raj Rajkumar

Open Access Theses & Dissertations

In this work, we report on the synthesis, characterization, and performance of LiGaP2O7 (LGP), a novel material and fairly new to the scientific & engineering community. LiGaP2O7 materials were was synthesized using the conventional high-temperature, solid-state ceramic reaction. Calcination was done in three steps at the temperatures of 300 °C, 500 °C, and 650 °C for 8 h each to ensure a single phase. Utilizing this, different green pellets were sintered at 800 °C for varying times of 3 h, 6 h, 12 h, and 24 h. The structure, phase, and morphology were analyzed using X-ray diffraction (XRD) and scanning …

Effect Of Flow Velocity And Geometry On The Signal From A Piezoelectric Flow Rate Sensor, Jad Gerges Aboud

Open Access Theses & Dissertations

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Development Of Software Tools And Experimental In Situ Electron Spin Resonance For Characterizing The Magnetic And Electrocatalytic Properties Of Transition Metal Chalcogenide Crystals, Jose Armando Delgado

Open Access Theses & Dissertations

Studying the magnetic properties and crystal defects of transition metal chalcogenide crystals is of paramount importance for utilizing them for next generation spintronics devices and hydrogen evolution reaction catalysts. Hydrothermally grown transition metal chalcogenide nanocrystals (MoS2, Ru2S3, Rh2S3, Co2S8) were chosen as catalysts for the hydrogen evolution reaction due to their low dimensionality and previous utilization as catalysts for hydrodesulfurization. The relationship between crystal defect sites and catalytic activity must be discerned to maximize the efficiency of hydrogen production during the hydrogen evolution reaction. ESR spectroscopy was utilized as a spin sensitive technique to study the defects and local changes …

Bending Behavior And Deflection Prediction Of High-Strength Sfrc Beams Under Fatigue Loading, Dan Ying Gao, Zhi Qiang Gu, Chenglin Wu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The experiments of high-strength steel-fiber-reinforced concrete (SFRC) beams subjected to fatigue bend loading were conducted in this work. A total of 12 beams were tested to failure, including 2 under static loading and 10 under fatigue loading. The main varying parameters of the tested beams included the stress level, fiber volume fraction, and strength of the steel reinforcement. The fatigue life, mid-span deflection, residual deflection, and crack width were measured and evaluated. The stiffness degradation of high-strength SFRC beams was analyzed. The results indicated that both the stress level and fiber volume fraction have significant influences on the fatigue life …

Ab Initio Modeling Of An Electron Transport Layer Interface In Hybrid Perovskite Solar Cells, Krantikumar Subhash Pawar

Browse all Theses and Dissertations

Hybrid organic-inorganic perovskite solar cell is an emerging technology which has shown the fastest advancement in power conversion efficiency within a few years since introduction, thus making it one of the clean energy breakthroughs. These cells are based on thin-film technology which makes them suitable to manufacture using low-cost solution processing methods. As these types of cells are easily tunable with the selection of different materials, interfacial engineering is an important approach to increasing their efficiency. One of the main hurdles in this regard is the loss caused by the recombination of separated charges. An approach to tackle these issues …