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Articles 1 - 18 of 18
Full-Text Articles in Engineering
Liquid Phase Stability Under An Extreme Temperature Gradient, Zhi Liang, Kiran Sasikumar, Pawel Keblinski
Liquid Phase Stability Under An Extreme Temperature Gradient, Zhi Liang, Kiran Sasikumar, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using Nonequilibrium Molecular Dynamics Simulations, We Subject Bulk Liquid to a Very High-Temperature Gradient and Observe a Stable Liquid Phase with a Local Temperature Well above the Boiling Point. Also, under This High-Temperature Gradient, the Vapor Phase Exhibits Condensation into a Liquid at a Temperature Higher Than the Saturation Temperature, Indicating that the Observed Liquid Stability is Not Caused by Nucleation Barrier Kinetics. We Show that, Assuming Local Thermal Equilibrium, the Phase Change Can Be Understood from the Thermodynamic Analysis. the Observed Elevation of the Boiling Point is Associated with the Interplay between the "Bulk" Driving Force for the Phase …
Development Of An Experimental Testbed For Research In Lithium-Ion Battery Management Systems, Nima Lotfi, Poria Fajri, Samuel Novosad, Jack Savage, Robert G. Landers, Mehdi Ferdowsi
Development Of An Experimental Testbed For Research In Lithium-Ion Battery Management Systems, Nima Lotfi, Poria Fajri, Samuel Novosad, Jack Savage, Robert G. Landers, Mehdi Ferdowsi
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Advanced electrochemical batteries are becoming an integral part of a wide range of applications from household and commercial to smart grid, transportation, and aerospace applications. Among different battery technologies, lithium-ion (Li-ion) batteries are growing more and more popular due to their high energy density, high galvanic potential, low self-discharge, low weight, and the fact that they have almost no memory effect. However, one of the main obstacles facing the widespread commercialization of Li-ion batteries is the design of reliable battery management systems (BMSs). An efficient BMS ensures electrical safety during operation, while increasing battery lifetime, capacity and thermal stability. Despite …
Multi-Axis Planning Of A Hybrid Material Deposition And Removal Combined Process, J. Zhang, Frank W. Liou
Multi-Axis Planning Of A Hybrid Material Deposition And Removal Combined Process, J. Zhang, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Development Of Freeze-Form Extrusion Fabrication With Use Of Sacrificial Material, Ming-Chuan Leu, Diego A. Garcia
Development Of Freeze-Form Extrusion Fabrication With Use Of Sacrificial Material, Ming-Chuan Leu, Diego A. Garcia
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The development of Freeze-form Extrusion Fabrication (FEF) process to fabricate three-dimensional (3D) ceramic parts with use of sacrificial material to build support sections during the fabrication process is presented in this paper. FEF is an environmentally friendly, additive manufacturing process that builds 3D parts in a freezing environment layer-by-layer by computer controlled extrusion and deposition of aqueous colloidal pastes based on computer-aided design (CAD) models. Methyl cellulose was identified as the support material, and alumina was used as the main material in this study. After characterizing the dynamics of extruding alumina and methyl cellulose pastes, a general tracking controller was …
Probabilistic Simulation Of Solidification Microstructure Evolution During Laser-Based Metal Deposition, Jingwei Zhang, Frank W. Liou, William Seufzer, Joseph William Newkirk, Zhiqiang Fan, Heng Liu, Todd E. Sparks
Probabilistic Simulation Of Solidification Microstructure Evolution During Laser-Based Metal Deposition, Jingwei Zhang, Frank W. Liou, William Seufzer, Joseph William Newkirk, Zhiqiang Fan, Heng Liu, Todd E. Sparks
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A predictive model, based on a Cellular Automaton (CA) - Finite Element (FE) method, has been developed to simulate microstructure evolution during metal solidification for a laser based additive manufacturing process. The macroscopic FE calculation was designed to update the temperature field and simulate a high cooling rate. In the microscopic CA model, heterogeneous nucleation sites, preferential growth orientation and dendritic grain growth kinetics were simulated. The CA model was able to show the entrapment of neighboring cells and the relationship between undercooling and the grain growth rate. The model predicted the dendritic grain size, structure, and morphological evolution during …
Numerical Analysis Of Thermal Stress And Deformation In Multi-Layer Laser Metal Deposition Processes, Heng Liu, Todd E. Sparks, Frank W. Liou, David M. Dietrich
Numerical Analysis Of Thermal Stress And Deformation In Multi-Layer Laser Metal Deposition Processes, Heng Liu, Todd E. Sparks, Frank W. Liou, David M. Dietrich
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Direct metal deposition (DMD) has gained increasing attention in the area of rapid manucooling rate, resulting in residual stresses and distortion. This paper presents a 3D sequentially coupled thermo-mechanical finite element model to predict residual stresses and deformations. The temperature distribution, thermal stress field and geometry deformation across domain are illustrated. The effect of deposition parameters on residual stress and deflections are also explored. A set of validation experiments for mechanical effects were conducted using laser displacement sensor. The comparisons between the simulated and experimental results show good agreement
Vision-Based Process Monitoring For Laser Metal Deposition Processes, Sreekar Karnati, Niroop Matta, Todd E. Sparks, Frank W. Liou
Vision-Based Process Monitoring For Laser Metal Deposition Processes, Sreekar Karnati, Niroop Matta, Todd E. Sparks, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser Metal deposition is a process with immense scope and promise for becoming a robust manufacturing technology in the near future. Monitoring process variables is very instrumental in process planning and output monitoring. The current work deals with realizing the effect of power modulation on size of the high temperature region during deposition with varying powder feed. A thermal camera was used to visualize and analyze the deposition process. The area of the high temperature region through the deposition was identified and compared to realize the effect of each variable parameter during deposition. The power modulation was fruitful in modulating …
Effect Of Architecture And Porosity On Mechanical Properties Of Borate Glass Scaffolds Made By Selective Laser Sintering, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Taylor Comte
Effect Of Architecture And Porosity On Mechanical Properties Of Borate Glass Scaffolds Made By Selective Laser Sintering, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Taylor Comte
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The porosity and architecture of bone scaffolds, intended for use in bone repair or replacement, are two of the most important parameters in the field of bone tissue engineering. The two parameters not only affect the mechanical properties of the scaffolds but also aid in determining the amount of bone regeneration after implantation. Scaffolds with five different architectures and four porosity levels were fabricated using borate bioactive glass (13-93B3) using the selective laser sintering (SLS) process. The pore size of the scaffolds varied from 400 to 1300 μm. The compressive strength of the scaffolds varied from 1.7 to 15.5 MPa …
Additive Manufacturing Laser Deposition Of Ti‐6al‐4v For Aerospace Repair Applications, Nanda Kumar Dey, Frank W. Liou, C. Nedic
Additive Manufacturing Laser Deposition Of Ti‐6al‐4v For Aerospace Repair Applications, Nanda Kumar Dey, Frank W. Liou, C. Nedic
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Parts or products from high performance metal are very expensive, partly due to the processing complexities during manufacturing. The purpose of this project is to use additive laser deposition and machining processes to repair titanium parts, thus extending the service life of these parts. The study broadly included preparing the defects, laser deposition, machining, sample preparation and mechanical tests. Comparative study of mechanical properties (UTS, YS, percentage elongation) of the repaired samples to the ideal conditions was undertaken. The research throws up interesting facts where the data from the test sample shows enhancement of properties of the repaired part.
Experimental Investigation Of Different Cellular Lattice Structures Manufactured By Fused Deposition Modeling, Osman Iyibilgin, Cemil Yigit, Ming-Chuan Leu
Experimental Investigation Of Different Cellular Lattice Structures Manufactured By Fused Deposition Modeling, Osman Iyibilgin, Cemil Yigit, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Experimental tests were conducted to evaluate the compressive properties (yield strength and compressive modulus) and build time for five different cellular lattice structures fabricated by the Fused Deposition Modeling (FDM) process. The lattice structures had repeating unit cells, and the shapes of the unit cell under study included honeycomb, square, diamond, triangle, and circle. Test specimens were manufactured by a Stratasys Fortus 400mc machine using ABS (Acrylonitrile Butadiene Styrene) as the part material. The five different lattice structures were compared with each other and also with the sparse and sparse-double dense build styles that are directly available from the Fortus …
Hybrid System For Enhancing Algal Growth Using Vertical Membranes, David J. Bayless, Ben J. Stuart
Hybrid System For Enhancing Algal Growth Using Vertical Membranes, David J. Bayless, Ben J. Stuart
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A method for enhancing gas-to-liquid transfer rate and algal growth using vertical membranes suspended over a pond, wherein the membranes are formed of fibers. An aqueous solution is applied to the top edges of the membranes through a series of headers. The membranes are exposed to a stream of gas containing soluble gas species as the aqueous solution migrates downwardly through the membranes by virtue of gravity-assisted capillary action. The aqueous solution collects the soluble gases from the gas stream, thus promoting the growth of photosynthetic organisms on the membranes and in the pond. The membranes facilitate a gradual introduction …
Near- And Far-Field Spectroscopic Imaging Investigation Of Resonant Square-Loop Infrared Metasurfaces, J. D'Achangel, E. Tucker, Edward C. Kinzel, E. A. Muller, H. A. Bechtel, M. B. Martin, G. Boreman
Near- And Far-Field Spectroscopic Imaging Investigation Of Resonant Square-Loop Infrared Metasurfaces, J. D'Achangel, E. Tucker, Edward C. Kinzel, E. A. Muller, H. A. Bechtel, M. B. Martin, G. Boreman
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Apparatus And Method For Growing Biological Organisms For Fuel And Other Purposes, David J. Bayless, Morgan Lefay Vis-Chiasson, Ben J. Stuart, Gregory G. Kremer
Apparatus And Method For Growing Biological Organisms For Fuel And Other Purposes, David J. Bayless, Morgan Lefay Vis-Chiasson, Ben J. Stuart, Gregory G. Kremer
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A bioreactor apparatus in which a container has sidewalls, a floor and a ceiling defining a chamber that contains a slurry of water, nutrients and photosynthetic microorganisms. A plurality of optical fibers, each of which has a first end disposed outside the chamber and a second end in the mixture. A light collector spaced from the container has light incident on it and focuses the light onto the first ends of the plurality of optical fibers, thereby permitting the light to be conveyed into the mixture to promote photosynthesis. At least one nozzle is in fluid communication with a source …
Structural Health Monitoring Data Transmission For Composite Hydrokinetic Turbine Blades, A. Heckman, Joshua L. Rovey, K. Chandrashekhara, Steve Eugene Watkins, Daniel S. Stutts, Arindam Banerjee, Rajiv S. Mishra
Structural Health Monitoring Data Transmission For Composite Hydrokinetic Turbine Blades, A. Heckman, Joshua L. Rovey, K. Chandrashekhara, Steve Eugene Watkins, Daniel S. Stutts, Arindam Banerjee, Rajiv S. Mishra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Numerical Investigation Of Plasma Actuator Configurations For Flow Separation Control At Multiple Angles Of Attack, Thomas Kelsey Iv, West, Serhat Hosder
Numerical Investigation Of Plasma Actuator Configurations For Flow Separation Control At Multiple Angles Of Attack, Thomas Kelsey Iv, West, Serhat Hosder
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Equilibrium And Nonequilibrium Molecular Dynamics Simulations Of Thermal Conductance At Solid-Gas Interfaces, Zhi Liang, William Evans, Pawel Keblinski
Equilibrium And Nonequilibrium Molecular Dynamics Simulations Of Thermal Conductance At Solid-Gas Interfaces, Zhi Liang, William Evans, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Thermal Conductance at Solid-Gas Interfaces with Different Interfacial Bonding Strengths is Calculated through Green-Kubo Equilibrium Molecular Dynamics (EMD) Simulations. Due to the Finite Size of the Simulation System, the Long-Time Integral of the Time Correlation Function of Heat Power Across the Solid-Gas Interface Exhibits an Exponential Decay, Which Contains the Information on Interfacial Thermal Conductance. If an Adsorbed Gas Layer is Formed on the Solid Surface, It is Found that the Solid-Gas Interface Needs to Be Defined at a Plane Outside the Adsorbed Layer So as to Obtain the Correct Result from the Green-Kubo Formula. the EMD Simulation Result …
Improvement Of Heat Transfer Efficiency At Solid-Gas Interfaces By Self-Assembled Monolayers, Zhi Liang, William Evans, Tapan Desai, Pawel Keblinski
Improvement Of Heat Transfer Efficiency At Solid-Gas Interfaces By Self-Assembled Monolayers, Zhi Liang, William Evans, Tapan Desai, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using Molecular Dynamics Simulations, We Demonstrate that the Efficiency of Heat Exchange between a Solid and a Gas Can Be Maximized by Functionalizing Solid Surface with Organic Self-Assembled Monolayers (SAMs). We Observe that for Bare Metal Surfaces, the Thermal Accommodation Coefficient (TAC) Strongly Depends on the Solid-Gas Interaction Strength. for Metal Surfaces Modified with Organic SAMs, the TAC is Close to its Theoretical Maximum and is Essentially Independent from the SAM-Gas Interaction Strength. the Analysis of the Simulation Results Indicates that Softer and Lighter SAMs, Compared to the Bare Metal Surfaces, Are Responsible for the Greatly Enhanced TAC. © 2013 …
Numerical Study Of Pressure Fluctuations Due To A Mach 6 Turbulent Boundary Layer, Lian Duan, Meelan M. Choudhari
Numerical Study Of Pressure Fluctuations Due To A Mach 6 Turbulent Boundary Layer, Lian Duan, Meelan M. Choudhari
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Reτ ≈ 464. The emphasis is on comparing the primarily vortical pressure signal at the wall with the acoustic freestream signal under higher Mach number conditions. Moreover, the Mach-number dependence of pressure signals is demonstrated by comparing the current results with those of a supersonic boundary layer at Mach 2.5 and Reτ ≈ 510. It is found that the freestream pressure intensity exhibits a strong Mach number dependence, irrespective of …