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Articles 1 - 30 of 253

Full-Text Articles in Mechanical Engineering

Analysis For Predicting Surface Temperature And Combustion Of Heavy-Duty, Pre-Chamber-Enabled, Hydrogen Engines, Tony Spezia Apr 2026

Analysis For Predicting Surface Temperature And Combustion Of Heavy-Duty, Pre-Chamber-Enabled, Hydrogen Engines, Tony Spezia

Master's Theses (2009 -)

Hydrogen as an alternative fuel shows great promise to help reduce greenhouse gas emissions from heavy duty engines. However, the challenge for hydrogen engines is that hydrogen has very different combustion properties compared to conventional hydrocarbon fuels. Hydrogen has very high flame speeds, very low ignition energy, and very wide flammability limit. These properties result in hydrogen engines being prone to abnormal combustion. Abnormal combustion makes hydrogen engines difficult to control or can cause catastrophic damage to the engine, so it is important to avoid conditions where abnormal combustion occurs. Hot spots along the combustion chamber walls are often the …

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X-Ray Tomography Of Damage Dynamics In Advanced Materials Using A Laser Wakefield Accelerator, Vigneshvar Senthilkumaran, Nicholas F. Beier, Sylvain Fourmaux, Peter Kenesei, Sean Dobson, Joël Maltais, Alvaro R. Arce-Borkent, Tait Richards, Michael G. Lipsett, Le Zhou, John A. Moore, Amina E. Hussein Apr 2026

X-Ray Tomography Of Damage Dynamics In Advanced Materials Using A Laser Wakefield Accelerator, Vigneshvar Senthilkumaran, Nicholas F. Beier, Sylvain Fourmaux, Peter Kenesei, Sean Dobson, Joël Maltais, Alvaro R. Arce-Borkent, Tait Richards, Michael G. Lipsett, Le Zhou, John A. Moore, Amina E. Hussein

Mechanical Engineering Faculty Research and Publications

Additively manufactured (AM) metals offer the potential for customizable, cost-effective components, but qualification and certification are crucial. Key to this process is understanding pore dynamics under stress, typically analyzed using micro-computed tomography. This study introduces laboratory-scale “betatron” x-rays from laser wakefield acceleration as a high-throughput alternative for x-ray tomography of advanced materials, such as AM AlSi10Mg alloys. Coupled with 3D finite element modeling, this method provides detailed insights into stress-porosity interactions. The approach delivers high-resolution scans, revealing that pore shape and local triaxiality significantly influence fracture dynamics, supporting advanced material characterization. This work also demonstrates the potential and versatility of …

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Fundamental Exploration Of Soot Formation And Morphology From A Molecular Modeling Perspective, Khaled Mosharraf Mukut Jul 2025

Fundamental Exploration Of Soot Formation And Morphology From A Molecular Modeling Perspective, Khaled Mosharraf Mukut

Dissertations (1934 -)

Soot formation remains one of the least understood phenomena in combustion science, posing significant challenges due to its complex physicochemical nature and considerable environmental and health impacts. This dissertation presents a comprehensive molecular-level investigation into the fundamental mechanisms governing soot inception, particle growth, and morphological evolution through state-of-the-art reactive molecular dynamics (RMD) simulations of acetylene pyrolysis. A novel computational analysis utility, Molecular Arrangement and Fringe Identification and Analysis from Molecular Dynamics (MAFIA-MD), was developed to accurately characterize soot particle formation, providing detailed insights into chemical composition, internal structure, and surface characteristics. Critical physicochemical markers defining the boundary between gas-phase species …

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Development Of Prechamber Enabled Mixing-Controlled Combustion Strategy For Ultra-Low Methane Emissions From Lean Burn Natural Gas Engines, Osama Nsaif, Adam Dempsey Apr 2025

Development Of Prechamber Enabled Mixing-Controlled Combustion Strategy For Ultra-Low Methane Emissions From Lean Burn Natural Gas Engines, Osama Nsaif, Adam Dempsey

Mechanical Engineering Faculty Research and Publications

This numerical study explores the optimization of Prechamber Enabled Mixing-Controlled Combustion (PC-MCC) using natural gas in heavy-duty engines, aiming to enhance combustion efficiency to minimize methane slip and NOx emissions. The approach involves a prechamber ignition system, distinct from conventional spark ignition (SI) systems, to initiate combustion of direct injected natural gas. By leveraging the robust ignition characteristics of the prechamber, the PC-MCC method demonstrates significant potential in achieving efficient combustion akin to diesel engines but with lower greenhouse gas emissions. The research evaluates the effects of various geometric and operational parameters on the combustion process and emissions, including prechamber …

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Mixing-Controlled Combustion Of Ethanol Enabled By Prechamber Ignition (Pc-Mcc): A Preliminary Experimental Demonstration, Jared Zeman, Ziming Yan, Michael Bunce, Adam Dempsey Jan 2025

Mixing-Controlled Combustion Of Ethanol Enabled By Prechamber Ignition (Pc-Mcc): A Preliminary Experimental Demonstration, Jared Zeman, Ziming Yan, Michael Bunce, Adam Dempsey

Mechanical Engineering Faculty Research and Publications

This numerical study focuses on assessing the key design parameters of interest for use of an active prechamber igniter as an ignition assistance device to enable mixing-controlled combustion (MCC) of ethanol (E100) in a heavy-duty Caterpillar C9.3B engine. Computational fluid dynamic (CFD) simulations of a baseline diesel and prechamber retrofitted C9.3B at a gross indicated mean effective pressure (IMEPg) of 5 bar and 1800 rpm are carried out using CONVERGE. In particular, the sizing of the prechamber volume, sizing of total orifice cross sectional area (orifice diameter), and location of the prechamber relative to a centrally mounted common rail direct …

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Experimental Comparison Of Open Chamber Spark Plug And Passive Prechamber Spark Igniters On The Combustion Of Fumigated Natural Gas For Heavy Duty Engine Applications, John Richard Valla Oct 2024

Experimental Comparison Of Open Chamber Spark Plug And Passive Prechamber Spark Igniters On The Combustion Of Fumigated Natural Gas For Heavy Duty Engine Applications, John Richard Valla

Master's Theses (2009 -)

Methane the primary component of natural gas, has 80 times the global warming potential of CO2. As a result methane emissions regulations have rapidly increased in recent years. This posses a challenge for heavy duty spark ignited (SI) natural gas engine OEMs, in efforts to reduce methane and other criteria pollutant emissions such as NOx. Heavy duty natural gas engine OEMs are pushing engine efficiency and reducing emissions by running higher compression ratios and leaner air fuel ratios. This reduces fuel consumption and combustion temperature which decreases NOx emissions, but tends to increase methane emissions. Unfortunately, lean high compression ratio …

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Investigation Of Emissions Characteristics Of Natural Gas Engines With Prechamber Enabled Mixing Controlled Combustion, Johnathan Michael Ronsman Jul 2024

Investigation Of Emissions Characteristics Of Natural Gas Engines With Prechamber Enabled Mixing Controlled Combustion, Johnathan Michael Ronsman

Master's Theses (2009 -)

Increasingly stringent emissions regulations have motivated the exploration of ways to decarbonize the internal combustion engine (ICE). Alternative fuels are of interest as they can easily be implemented with existing infrastructure. Among these alternative fuels, natural gas stands out due to its large abundance and high hydrogen-to-carbon ratio, which can significantly reduce CO2 emissions. Due to its low reactivity, most natural gas engines today are premixed lean burn spark ignited (SI) engines. These engines produce criteria pollutants, such as nitrogen oxides (NOx) and carbon monoxide (CO), but due to their premixed nature, also produce relatively large amounts of unburned methane …

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Design And Verification Of A Planar, Programmable, Compliant Hand For Use In General Open-Loop Constrained Manipulation, Jacob Frye Jul 2024

Design And Verification Of A Planar, Programmable, Compliant Hand For Use In General Open-Loop Constrained Manipulation, Jacob Frye

Master's Theses (2009 -)

Conventional robots are adept at performing tasks where the desired absolute position of the robot's end effector is well defined. However, these robots will struggle with tasks in which the desired position is poorly defined, subject to variation, or determined by contact with a constraint with positional uncertainty. This problem can be solved by introducing compliance to the system, either active or passive. Active compliance uses force feedback to make corrective motions, but is limited in speed and experiences higher contact forces than passive systems. Passively compliant systems are capable of realizing the necessary compliance for a given task but …

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Material Modeling Of An Ultraviolet Sensitive Resin At High Pressures And Rates, Truman Miller Russell Apr 2024

Material Modeling Of An Ultraviolet Sensitive Resin At High Pressures And Rates, Truman Miller Russell

Master's Theses (2009 -)

A full understanding of the behavior of binder materials under shock loading is required for effective simulation of heterogeneous polymer-binder-explosives (PBX) and polymer-binder-surrogate (PBS) systems. An accurate simulation is critical for the ultimate goal of designing meso-scale heterogeneous PBS systems. The binder materials studied here is an ultraviolet sensitive resin (UV resin). The UV resin is manufactured by AnyCubic. It is a glassy thermoset polymer and is known to be similar to polymethyl methacrylate (PMMA) both in mechanical properties and in chemical makeup. This material was chosen as it can be additively manufactured, and it will present a lower impedance …

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A Study Of The Effect Of Preparation Parameters On The Mechanical Properties Of Freeze-Dried Gelatin-Elastin-Hyaluronate Scaffolds, Mansour Qamash Apr 2024

A Study Of The Effect Of Preparation Parameters On The Mechanical Properties Of Freeze-Dried Gelatin-Elastin-Hyaluronate Scaffolds, Mansour Qamash

Master's Theses (2009 -)

This thesis is dedicated to a detailed study of changes in the properties of Gelatin-Elastin-Hyaluronate (GEH) tissue engineering scaffold resulting from changes in preparation parameters. More specifically, utilizing a combination of foaming and freeze-drying techniques, this research investigates the effects of different parameters, including agitation speed, duration time, and chilling temperature on the scaffold’s structural integrity, porosity, and mechanical properties. The methodology involves a carefully calibrated process in which the scaffold matrix is initially prepared by incorporating 8% gelatin, 2% elastin, and 0.5% hyaluronate (w/v) into a homogenous aqueous solution, followed by controlled agitation and subsequent freezing at designated temperatures. …

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Investigating The Impacts Of Bin Variability On Particle Size Distributions In Multiphase Eulerian-Eulerian Simulations, Wilbert Alexander Cruz Apr 2024

Investigating The Impacts Of Bin Variability On Particle Size Distributions In Multiphase Eulerian-Eulerian Simulations, Wilbert Alexander Cruz

Master's Theses (2009 -)

In this study, a 3D steady-state Eulerian-Eulerian simulation was developed to investigate flow performance in a dilute pneumatic conveying system. The investigation focused on two main objectives: (1) assessing the influence of bin selection on solution accuracy for representing the polydisperse mixture, and (2) exploring methods to simplify the modeling of polydisperse particles in the simulation by utilizing a mean diameter derived from the mixture’s particle size distribution. The system's geometry and initial boundary conditions featured a 10.6 m long, 150 mm diameter horizontal pipe with both gaseous and solid phases initially moving at 27 m/s . The steady-state simulation …

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Automated Combustion Model Classification For Char Particle Distributions Using 3-D Morphology Analysis And Pore-Resolving Cfd Simulations, Dongyu Liang, Simcha L. Singer Mar 2023

Automated Combustion Model Classification For Char Particle Distributions Using 3-D Morphology Analysis And Pore-Resolving Cfd Simulations, Dongyu Liang, Simcha L. Singer

Mechanical Engineering Faculty Research and Publications

Combustion of pulverized coal involves millions of particles with a distribution of morphologies. A workflow is presented to characterize, classify, and model distributions of highly porous coal char particles. To understand the impacts of morphology, 3-D pore-resolving combustion simulations for 150 particles imaged with micro-CT are first performed. To facilitate modeling distributions of morphology in reactor-scale CFD, a machine learning algorithm is then trained to classify particles according to their expected combustion behavior and to select an accurate, computationally efficient 1-D particle-scale combustion model. Whereas existing approaches classify particles solely according to morphology and use 2-D measurements, the present approach …

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Pore-Resolving Simulations Of Biomass Char Particle Combustion, Dongyu Liang, Simcha L. Singer Jan 2023

Pore-Resolving Simulations Of Biomass Char Particle Combustion, Dongyu Liang, Simcha L. Singer

Mechanical Engineering Faculty Research and Publications

Biomass char morphology affects combustion behavior at the particle scale for zone II conditions, in which both heterogeneous reaction and intra-particle diffusion govern the overall rate. Furthermore, particle-scale processes affect reactor-scale outputs, and reactor-scale simulations are sensitive to particle-scale models. However, most char particle combustion models employ coarse-grained, effective-continuum approaches, which treat all porosity at the subgrid-scale. Effective-continuum approaches are not valid or accurate in the presence of large, irregular pores which can approach the size of the particle. A 3-D, pore-resolving CFD simulation approach using real biomass char particle geometries obtained from X-ray micro-computed tomography (micro-CT) is therefore used …

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Modeling Thermal Radiation In Combustion Environments: Progress And Challenges, Sandip Mazumder, Somesh P. Roy Jan 2023

Modeling Thermal Radiation In Combustion Environments: Progress And Challenges, Sandip Mazumder, Somesh P. Roy

Mechanical Engineering Faculty Research and Publications

Modeling thermal radiation in combustion environments can be extremely challenging for two main reasons. First, the radiative transfer equation (RTE), which is the cornerstone of modeling radiation in such environments, is a five-dimensional integro-differential equation. Second, the absorption and scattering coefficients of molecular gases and particulates prevalent in combustion environments oscillate strongly with the wavenumber (or wavelength), i.e., the medium is strongly nongray, requiring the solution of the RTE for a large number of wavenumbers. This article reviews the progress that has been made in this area to date with an emphasis on the work performed over the past three …

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Assessment Of Narrow-Band And Full Spectrum Gas Radiation Methods In A Real Industrial Glass Furnace Configuration, M. Galtier, W. Woelffel, F. André, V. P. Solovjov, B. W. Webb, Somesh Roy Nov 2022

Assessment Of Narrow-Band And Full Spectrum Gas Radiation Methods In A Real Industrial Glass Furnace Configuration, M. Galtier, W. Woelffel, F. André, V. P. Solovjov, B. W. Webb, Somesh Roy

Mechanical Engineering Faculty Research and Publications

This work is dedicated to a comparison of various methods of gaseous flame radiation in a three-dimensional configuration representative of a glass furnace studied at Saint Gobain Research Paris. For this purpose, several narrow band and full spectrum models of flame radiation are assessed against LBL calculations. Among narrow band models, the recently proposed l-distribution method is shown to be more accurate than the k-distribution method. Among global models, the RC-SLW technique provides a high accuracy and can be confidently used for radiative heat transfer calculations in three-dimensional high temperature configurations.

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Planar Compliance Realization With Two 3-Joint Serial Mechanisms, Shuguang Huang, Joseph M. Schimmels Oct 2022

Planar Compliance Realization With Two 3-Joint Serial Mechanisms, Shuguang Huang, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

In this paper, the realization of any specified planar compliance with two 3R serial elastic mechanisms is addressed. Using the concept of dual elastic mechanisms, it is shown that the realization of a compliant behavior with two serial mechanisms connected in parallel is equivalent to its realization with a 6-spring fully parallel mechanism. Since the spring axes of a 6-spring parallel mechanism indicate the geometry of a dual 3R serial mechanism, a new synthesis procedure for the realization of a stiffness matrix with a 6-spring parallel mechanism is first developed. Then, this result is extended to a geometric construction-based synthesis …

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Molecular Arrangement And Fringe Identification And Analysis From Molecular Dynamics (Mafia-Md): A Tool For Analyzing The Molecular Structures Formed During Reactive Molecular Dynamics Simulation Of Hydrocarbons, Khaled Mosharraf Mosharraf Mukut, Somesh Roy, Eirini Goudeli Jul 2022

Molecular Arrangement And Fringe Identification And Analysis From Molecular Dynamics (Mafia-Md): A Tool For Analyzing The Molecular Structures Formed During Reactive Molecular Dynamics Simulation Of Hydrocarbons, Khaled Mosharraf Mosharraf Mukut, Somesh Roy, Eirini Goudeli

Mechanical Engineering Faculty Research and Publications

Reactive molecular dynamics (RMD) simulations are becoming popular, with the recent developments in high-performance and efficient computing architecture, for investigating fundamental physico-chemical behaviors of reacting species. Due to the complexity of hydrocarbon systems, characterization of molecules formed during RMD simulations of hydrocarbons can be very challenging for simulations involving a large number of molecules. The novel post-processing utility “MAFIA-MD” – an acronym for “Molecular Arrangement and Fringe Identification and Analysis from Molecular Dynamics” – presented in this manuscript can analyze and perform molecular characterization of a large number of RMD trajectory files (.XYZ files) simultaneously. The utility will be useful …

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A Porosity-Based Model Of Dynamic Compaction In Under-Dense Materials, John A. Moore, Nathan R. Barton Jun 2022

A Porosity-Based Model Of Dynamic Compaction In Under-Dense Materials, John A. Moore, Nathan R. Barton

Mechanical Engineering Faculty Research and Publications

Under-dense metals including micro-architectured structures and stochastic foams provide a combination of low weight, high strength-to-weight ratio, high permeability, and low stiffness, which make them desirable materials for a variety of applications. Specifically, their energy absorption capabilities under dynamic compressive loads are desirable. However, under high loading rates there are several challenges in performing accurate simulations of under-dense materials—primarily, the responses of materials with high, low, and zero porosity are difficult to accurately predict with a single model. A general model that tracks porosity and pore geometry and is flexible for a variety of matrix material constitutive responses has yet …

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Poly (5-Carboxyindole)–Β-Cyclodextrin Composite Material For Enhanced Formaldehyde Gas Sensing, John N. Hodul, Nikhil F. Carneiro, Allison K. Murray, Wilson Lee, Kelly M. Brayton, Xinping He, Carsten Flores-Hansen, Dimitry Zemlyanov, George T.-C. Chiu, James E. Braun, Bryan W. Boudouris, Jeffrey F. Rhoads Jun 2022

Poly (5-Carboxyindole)–Β-Cyclodextrin Composite Material For Enhanced Formaldehyde Gas Sensing, John N. Hodul, Nikhil F. Carneiro, Allison K. Murray, Wilson Lee, Kelly M. Brayton, Xinping He, Carsten Flores-Hansen, Dimitry Zemlyanov, George T.-C. Chiu, James E. Braun, Bryan W. Boudouris, Jeffrey F. Rhoads

Mechanical Engineering Faculty Research and Publications

Formaldehyde, a compound commonly employed in many construction materials, paints, and plastics, has been linked to deleterious health effects. Thus, monitoring the presence of formaldehyde in interior locations is increasingly important when it comes to public health. Currently, there is a crucial need for a low-cost, small-scale, selective, and sensitive indoor sensor capable of real-time formaldehyde detection. To meet these performance metrics, materials need to be incorporated onto existing gas sensor platforms to act as chemically selective recognition layers. A main challenge when addressing this issue is creating a material that can remain easily processable, can be easily synthesized, and …

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Microstructural Characteristics And Mechanical Properties Of Additively Manufactured Cu–10sn Alloys By Laser Powder Bed Fusion, Abhishek Mehta, Le Zhou, Holden Hyer, Thinh Huynh, Binghao Lu, Erica J. Drobner, Sun Hong Park, Yongho Sohn Mar 2022

Microstructural Characteristics And Mechanical Properties Of Additively Manufactured Cu–10sn Alloys By Laser Powder Bed Fusion, Abhishek Mehta, Le Zhou, Holden Hyer, Thinh Huynh, Binghao Lu, Erica J. Drobner, Sun Hong Park, Yongho Sohn

Mechanical Engineering Faculty Research and Publications

Cu – 10 wt% Sn (Cu–10Sn) alloy specimens were additively manufactured by varying the laser powder bed fusion (LBPF) processing parameters, e.g., laser power (200–350 W) and laser scan speed (100–1400 mm/s) at a fixed hatch spacing (0.12 mm) and slice thickness (0.03 mm), to examine their effects on the density, melt pool structure, and microstructure. Microstructural characteristics of the most dense sample were examined using electron microscopy (SEM, TEM) and X-ray Diffraction. The grains in the top-most melt pool layer showed a fan-like structure, whereas all other areas showed small columnar structure aligned nearly parallel to the build direction …

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Elimination Of Extraordinarily High Cracking Susceptibility Of Aluminum Alloy Fabricated By Laser Powder Bed Fusion, Holden Hyer, Le Zhou, Sharon Park, Thinh Huynh, Abhishek Mehta, Saket Thapliyal, Rajiv S. Mishra, Yongho Sohn Mar 2022

Elimination Of Extraordinarily High Cracking Susceptibility Of Aluminum Alloy Fabricated By Laser Powder Bed Fusion, Holden Hyer, Le Zhou, Sharon Park, Thinh Huynh, Abhishek Mehta, Saket Thapliyal, Rajiv S. Mishra, Yongho Sohn

Mechanical Engineering Faculty Research and Publications

Using the calculation of phase diagrams approach and Scheil solidification modeling, the Al-2.5Mg-1.0Ni-0.4Sc-0.1Zr alloy was designed, intentionally with an extraordinarily high cracking susceptibility, making it prime for solidification cracking during laser powder bed fusion. This study demonstrates the ability to mitigate even the most extreme solidification cracking tendencies in aluminum alloys with only minor alloying additions of Sc and Zr, 0.5 wt.% max. Furthermore, by employing a simple direct ageing heat treatment, good tensile mechanical properties were observed with a yield strength of 308 MPa, an ultimate tensile strength of 390 MPa, and a total elongation of 11%.

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Inverted Reactivity Controlled Compression Ignition (Ircci) With Methanol Fuel & Reactivity Enhancers, Musharrat Chowdhury, Adam Dempsey Mar 2022

Inverted Reactivity Controlled Compression Ignition (Ircci) With Methanol Fuel & Reactivity Enhancers, Musharrat Chowdhury, Adam Dempsey

Mechanical Engineering Faculty Research and Publications

Reactivity Controlled Compression Ignition (RCCI) is a low temperature combustion regime that has demonstrated ultra-low NOx and soot while achieving high thermal efficiency. RCCI uses a low reactivity premixed charge which is ignited via direct injection of a high reactivity fuel. The aim is to create a nearly homogeneous charge but maintain control over the combustion timing via the ratio between the premixed and direct injected fuel, hence controlling global reactivity via reactivity gradients in-cylinder. RCCI combustion with gasoline as the premixed fuel and diesel as the high reactivity fuel has shown good combustion timing controllability. However, RCCI with alcohol …

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A Continuum Damage Approach To Spallation And The Role Of Microinertia, S. B. Qamar, John A. Moore, Nathan R. Barton Feb 2022

A Continuum Damage Approach To Spallation And The Role Of Microinertia, S. B. Qamar, John A. Moore, Nathan R. Barton

Mechanical Engineering Faculty Research and Publications

Spall failure is of interest due to its prevalence in high strain rate problems in which the spallation is driven by the interaction of release waves. In this article, a porosity-based damage model that includes microinertial effects is used to examine spall failure. The model is successfully calibrated to plate impact-driven experiments and then used to evaluate experimental conditions producing more extreme strain rate conditions, such as those in laser-driven experiments. The incorporation of microinertia allows us to better understand the increase in apparent macroscopic spall strength seen at high strain rates. Correspondingly, we conclude that the incorporation of microinertial …

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Microstructural Development In Inconel 718 Nickel-Based Superalloy Additively Manufactured By Laser Powder Bed Fusion, Thinh Huynh, Abhishek Mehta, Kevin Graydon, Jeongmin Woo, Sharon Park, Holden Hyer, Le Zhou, D. Devin Imholte, Nicolas E. Woolstenhulme, Daniel M. Wachs, Yongho Sohn Jan 2022

Microstructural Development In Inconel 718 Nickel-Based Superalloy Additively Manufactured By Laser Powder Bed Fusion, Thinh Huynh, Abhishek Mehta, Kevin Graydon, Jeongmin Woo, Sharon Park, Holden Hyer, Le Zhou, D. Devin Imholte, Nicolas E. Woolstenhulme, Daniel M. Wachs, Yongho Sohn

Mechanical Engineering Faculty Research and Publications

Excellent weldability and high temperature stability make Inconel 718 (IN718) one of the most popular alloys to be produced by additive manufacturing. In this study, we investigated the effects of laser powder bed fusion (LPBF) parameters on the microstructure and relative density of IN718. The samples were fabricated with independently varied laser power (125–350 W), laser scan speed (200–2200 mm/s), and laser scan rotation (0°–90°). Archimedes’ method, optical microscopy, and scanning electron microscopy were employed to assess the influence of LPBF parameters on the relative density and microstructure. Optimal processing windows were identified for a wide range of processing parameters, …

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The Relationship Between Mechanism Geometry And The Centers Of Stiffness And Compliance, Shuguang Huang, Joseph M. Schimmels Jan 2022

The Relationship Between Mechanism Geometry And The Centers Of Stiffness And Compliance, Shuguang Huang, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

A significant amount of research has been directed toward developing a more intuitive appreciation of spatial elastic behavior. Results of these analyses have often been described in terms of the elastic behavior (stiffness or compliance) centers. This paper investigates the properties of centers of stiffness and compliance and provides a fresh view of elastic center locations, specifically, the locus of centers associated with a given mechanism’s topology and geometry. We show that the location of the center of stiffness (compliance) for a set of elastic components connected in parallel (in serial) can be described in terms similar to the …

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Conductive Polymer Spark Gap Igniters, Miranda P. Mcconnell, Allison K. Murray, Bryan W. Boudouris, I. Emre Gunduz, Steven F. Son, George T.-C. Chiu, Jeffrey F. Rhoads Oct 2021

Conductive Polymer Spark Gap Igniters, Miranda P. Mcconnell, Allison K. Murray, Bryan W. Boudouris, I. Emre Gunduz, Steven F. Son, George T.-C. Chiu, Jeffrey F. Rhoads

Mechanical Engineering Faculty Research and Publications

Electrodes fabricated from electronically active polymers offer some benefits over those fabricated with common metals, including an appreciable resistance to corrosion and lower density. These benefits, and potentially others, manifest the advantages of using conductive polymers in lieu of metals for the mass production of ignition systems. In this work, spark gap igniters were fabricated using a potentially low-cost, roll-to-roll compatible process utilizing the doped conductive polymer polyaniline as the electrode material. Subsequently, nanothermite was printed on the spark gap igniters between the organic leads and ignited using a high voltage source to demonstrate the effectiveness of the device. All …

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The Coalescence Of Incipient Soot Clusters, Akaash Sharma, Khaled Mosharraf Mosharraf Mukut, Somesh Roy, Eirini Goudeli Aug 2021

The Coalescence Of Incipient Soot Clusters, Akaash Sharma, Khaled Mosharraf Mosharraf Mukut, Somesh Roy, Eirini Goudeli

Mechanical Engineering Faculty Research and Publications

Reactive molecular dynamics (MD) simulations are employed to investigate the coalescence of incipient soot clusters. Initially, one thousand acetylene molecules collide and react with each other, allowing bond breakage and new bond formation upon collision, leading to various species (e.g., linear hydrocarbons, branched polyaromatic hydrocarbons) up to the formation of nascent soot clusters with diameter of up to 3.5 nm. The structure and composition of the formed soot clusters are quantified by the packing density and carbon-to-hydrogen (C/H) ratio, respectively, during nucleation and up to the formation of large nascent soot nanoparticles. Then, the nucleated incipient soot clusters are isolated …

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Microstructure, Mechanical Performance, And Corrosion Behavior Of Additively Manufactured Aluminum Alloy 5083 With 0.7 And 1.0 Wt% Zr Addition, Le Zhou, Holden Hyer, Jinfa Chang, Abhishek Mehta, Thinh Huynh, Yang Yang, Yongho Sohn Aug 2021

Microstructure, Mechanical Performance, And Corrosion Behavior Of Additively Manufactured Aluminum Alloy 5083 With 0.7 And 1.0 Wt% Zr Addition, Le Zhou, Holden Hyer, Jinfa Chang, Abhishek Mehta, Thinh Huynh, Yang Yang, Yongho Sohn

Mechanical Engineering Faculty Research and Publications

Effect of 0.7 wt% and 1.0 wt% of Zr alloying on the laser powder bed fused (LPBF) printability/buildability of AA5083 alloys was investigated by examination of the microstructure and mechanical property. General corrosion behavior of these Zr-modified AA5083 alloys produced by LPBF in 3.5 wt% NaCl solution was also examined and compared to the LPBF AlSi10Mg alloy and AA5083-H131 alloy. Unmodified AA5083 alloy produced by LPBF exhibited extensive solidification cracks, but alloying it with Zr mitigated the cracking due to the grain refinement from the formation of the primary L12-Al3Zr. Moreover, 1.0 wt% of Zr alloying …

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Pore-Resolving Simulations To Study The Impacts Of Char Morphology On Zone Ii Combustion And Effectiveness Factor Models, Dongyu Liang, Simcha L. Singer Jul 2021

Pore-Resolving Simulations To Study The Impacts Of Char Morphology On Zone Ii Combustion And Effectiveness Factor Models, Dongyu Liang, Simcha L. Singer

Mechanical Engineering Faculty Research and Publications

Combustion and gasification of pulverized char often occur under zone II conditions, in which the rate of conversion depends on both heterogeneous reaction and gas transport within the particle's porous structure. The morphology of porous char has a strong influence on intra-particle diffusion, and thus, on the overall conversion rate. Because pulverized coal and biomass char particles are often irregularly shaped and contain pores and voids which can approach the size of the particles themselves, conventional models based on spherical symmetry and coarse-grained, upscaled, effective continuum conservation equations are not applicable or appropriate. A recent 3-D, pore-resolving CFD simulation approach …

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Design Of Heterogeneous Structured Al Alloys With Wide Processing Window For Laser-Powder Bed Fusion Additive Manufacturing, Saket Thapliyal, Shivakant Shukla, Le Zhou, Holden Hyer, Priyanshi Agrawal, Priyanka Agrawal, Mageshwari Komarasamy, Yongho Sohn, Rajiv S. Mishra Jun 2021

Design Of Heterogeneous Structured Al Alloys With Wide Processing Window For Laser-Powder Bed Fusion Additive Manufacturing, Saket Thapliyal, Shivakant Shukla, Le Zhou, Holden Hyer, Priyanshi Agrawal, Priyanka Agrawal, Mageshwari Komarasamy, Yongho Sohn, Rajiv S. Mishra

Mechanical Engineering Faculty Research and Publications

Required microstructural attributes of an alloy vary with structural applications. The microstructural fine-tuning capability of laser-powder bed fusion (L-PBF) additive manufacturing (AM) enables application specific manufacture of the components. Such manufacture with L-PBF AM requires alloys that exhibit wide processing window and are amenable to multiple deformation mechanisms. However, high hot cracking susceptibility of Al alloys poses a barrier to such printability-performance synergy. In this work we show that an integration of, a) grain refinement through heterogeneous nucleation, and b) eutectic solidification, leads to crack-free parts at wide range of process parameters, microstructural heterogeneity, and hierarchy in the Al-Ni-Ti-Zr …

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