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Articles 1 - 15 of 15
Full-Text Articles in Mechanical Engineering
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
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 …
The Coalescence Of Incipient Soot Clusters, Akaash Sharma, Khaled Mosharraf Mosharraf Mukut, Somesh Roy, Eirini Goudeli
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 …
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
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 …
Pore-Resolving Simulations To Study The Impacts Of Char Morphology On Zone Ii Combustion And Effectiveness Factor Models, Dongyu Liang, Simcha L. Singer
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 …
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
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 …
High Throughput Mechanical Testing Platform And Application In Metal Additive Manufacturing And Process Optimization, Ke Huang, Chris Kain, Nathalia Diaz-Vallejo, Yongho Sohn, Le Zhou
High Throughput Mechanical Testing Platform And Application In Metal Additive Manufacturing And Process Optimization, Ke Huang, Chris Kain, Nathalia Diaz-Vallejo, Yongho Sohn, Le Zhou
Mechanical Engineering Faculty Research and Publications
Agility of additive manufacturing (AM) warrants a development of an equally agile, high-throughput properties evaluation technique that can efficiently assess properties of AM specimens as functions of materials and process variables. High throughput (HTP) tensile testing rig has been developed, enabled by miniature sample design and Python based control codes for a full automation of testing and data processing. The rig is capable of testing 60 specimens per hour, much faster than conventional tensile testing. To luminate the merit of its use, an efficient process optimization workflow based on HTP testing is proposed and demonstrated on laser powder bed fusion …
High Strength We43 Microlattice Structures Additively Manufactured By Laser Powder Bed Fusion, Holden Hyer, Le Zhou, Qingyang Liu, Dazhong Wu, Shutao Song, Yuanli Bai, Brandon Mcwilliams, Kyu Cho, Yongho Sohn
High Strength We43 Microlattice Structures Additively Manufactured By Laser Powder Bed Fusion, Holden Hyer, Le Zhou, Qingyang Liu, Dazhong Wu, Shutao Song, Yuanli Bai, Brandon Mcwilliams, Kyu Cho, Yongho Sohn
Mechanical Engineering Faculty Research and Publications
WE43 is a high strength, high creep resistant Mg-alloy containing Y, Nd, and Zr, and has potential for many lightweight structural applications in the automotive, aerospace, and biomedical industries. Additive manufacturing technology such as laser powder bed fusion (LPBF) brings an opportunity to produce complex geometries such as lattice structures. In this study, fabrication, compressive behavior, and fracture modes of 24 different microlattice structures were investigated by varying unit cell type, strut diameter, and number of unit cells. These complex lattice structures were produced by LPBF using the parameter set: laser power = 200 W, scan speed = 1100 mm/sec, …
Additive Manufacturing And Mechanical Properties Of The Dense And Crack Free Zr-Modified Aluminum Alloy 6061 Fabricated By The Laser-Powder Bed Fusion, Abhishek Mehta, Le Zhou, Thinh Huynh, Sharon Park, Holden Hyer, Shutao Song, Yunali Bai, D. Devin Imholte, Nicolas E. Woolstenhulme, Daniel M. Wachs, Yongho Sohn
Additive Manufacturing And Mechanical Properties Of The Dense And Crack Free Zr-Modified Aluminum Alloy 6061 Fabricated By The Laser-Powder Bed Fusion, Abhishek Mehta, Le Zhou, Thinh Huynh, Sharon Park, Holden Hyer, Shutao Song, Yunali Bai, D. Devin Imholte, Nicolas E. Woolstenhulme, Daniel M. Wachs, Yongho Sohn
Mechanical Engineering Faculty Research and Publications
For additive manufacturing such as laser powder bed fusion (LPBF), commercial aluminum alloy (AA) 6061 is typically considered unsuitable due to formation of solidification cracking and/or excessive porosity. In this study, to improve buildability/printability of AA6061, 1 wt% of Zr was alloyed to produce Zr-modified AA6061 by LPBF. Powders of unmodified and Zr-modified AA6061 were produced by gas atomization, and utilized as a feed-stock for the LPBF to fabricate specimens for microstructural examination and mechanical testing. The as-built unmodified AA6061 exhibited poor printability due to formation of cracks and porosity in the microstructure regardless of LPBF parameters. However, the Zr-modified …
In Situ Tem Characterization Of Microstructure Evolution And Mechanical Behavior Of The 3d-Printed Inconel 718 Exposed To High Temperature, Supriya Koul, Le Zhou, Omar Ahmed, Yongho Sohn, Tengfei Jiang, Akihiro Kushima
In Situ Tem Characterization Of Microstructure Evolution And Mechanical Behavior Of The 3d-Printed Inconel 718 Exposed To High Temperature, Supriya Koul, Le Zhou, Omar Ahmed, Yongho Sohn, Tengfei Jiang, Akihiro Kushima
Mechanical Engineering Faculty Research and Publications
This in situ transmission electron microscopy work presents a nanoscale characterization of the microstructural evolution in 3D-printed Inconel 718 (IN718) while exposed to elevated temperature and an associated change in the mechanical property under tensile loading. Here, we utilized a specially designed specimen shape that enables tensile testing of nano-sized thin films without off-plane deformations. Additionally, it allows a seamless transition from the in situ heating to tensile experiment using the same specimen, which enables a direct correlation of the microstructure and the mechanical property of the sample. The method was successfully used to observe the residual stress relaxation and …
Composition-Dependent Solidification Cracking Of Aluminum-Silicon Alloys During Laser Powder Bed Fusion, Holden Hyer, Le Zhou, Abhishek Mehta, Sharon Park, Thinh Huynh, Shutao Song, Yuanli Bai, Kyu Cho, Brandon Mcwilliams, Yongho Sohn
Composition-Dependent Solidification Cracking Of Aluminum-Silicon Alloys During Laser Powder Bed Fusion, Holden Hyer, Le Zhou, Abhishek Mehta, Sharon Park, Thinh Huynh, Shutao Song, Yuanli Bai, Kyu Cho, Brandon Mcwilliams, Yongho Sohn
Mechanical Engineering Faculty Research and Publications
Consistent manufacturing of volumetrically dense engineering components, free of solidification cracks by laser powder bed fusion (LPBF), has been demonstrated for Al-Si alloys such as AlSi10Mg and Al12Si. The success in LPBF of these alloys is attributed to the near eutectic composition with a small freezing range. To illuminate this observation, cracking susceptibility was examined from Scheil-Gulliver solidification modeling by calculating the hot cracking susceptibility, |dT/dfS1/2|. To validate the findings from hot cracking susceptibility calculations, six binary Al-Si alloys, whose compositions were strategically chosen at hypo-, near-, and hyper-eutectic compositions, were gas atomized into alloy powders, and …
A Hybrid Droplet Vaporization-Adaptive Surrogate Model Using An Optimized Continuous Thermodynamics Distribution, Simcha L. Singer, Michael Hayes, Alanna Y. Cooney
A Hybrid Droplet Vaporization-Adaptive Surrogate Model Using An Optimized Continuous Thermodynamics Distribution, Simcha L. Singer, Michael Hayes, Alanna Y. Cooney
Mechanical Engineering Faculty Research and Publications
Liquid transportation fuels are composed of hundreds of species, necessitating the use of surrogates in CFD simulations. Surrogates composed of a few species are often formulated to emulate the combustion properties targets (CPTs) of pre-vaporized fuels but fail to reproduce their vaporization behavior, implying that such surrogates cannot replicate the CPTs in the presence of preferential vaporization. The prevailing approach to this problem proposes a physical–chemical surrogate formulated to match the fuel’s distillation curve in addition to its CPTs. However, the physical–chemical surrogate approach requires more species, may not reproduce the instantaneous (distillation-resolved) CPTs, and is not well-suited to conditions …
Microstructural Development In As Built And Heat Treated In625 Component Additively Manufactured By Laser Powder Bed Fusion, Holden Hyer, Ryan Newell, Dan Matejczyk, Sinsar Hsie, Mason Anthony, Le Zhou, Cathy Kammerer, Yongho Sohn
Microstructural Development In As Built And Heat Treated In625 Component Additively Manufactured By Laser Powder Bed Fusion, Holden Hyer, Ryan Newell, Dan Matejczyk, Sinsar Hsie, Mason Anthony, Le Zhou, Cathy Kammerer, Yongho Sohn
Mechanical Engineering Faculty Research and Publications
The RL10 engine program is exploring the use of IN625 Ni-base superalloy components that are additively manufactured using laser powder bed fusion (LPBF). IN625 alloy powders are commercially available for LPBF to produce dense, complex parts/components. In this study, IN625 components, with both simple and complex geometries with overhangs, were manufactured via LPBF, and subjected to a heat-treatment consisting of a stress relief, hot isostatic pressing (HIP), and a solution anneal. The microstructure was examined with optical, scanning electron, and transmission electron microscopy. Changes in phase constituents and microstructure were documented as a function of heat treatment and component geometry …
Effects Of Alloy Composition And Solid-State Diffusion Kinetics On Powder Bed Fusion Cracking Susceptibility, Holden Hyer, Le Zhou, Abhishek Mehta, Yongho Sohn
Effects Of Alloy Composition And Solid-State Diffusion Kinetics On Powder Bed Fusion Cracking Susceptibility, Holden Hyer, Le Zhou, Abhishek Mehta, Yongho Sohn
Mechanical Engineering Faculty Research and Publications
Laser powder bed fusion (LPBF) has demonstrated its unique ability to produce customized, complex engineering components. However, processing of many commercial Al-alloys by LPBF remains challenging due to the formation of solidification cracking, although they are labelled castable or weldable. In order to elucidate this divergence, solidification cracking susceptibility from the steepness of the solidification curves, specifically |dT⁄dfs1⁄2|, as the fraction solidified nears 1 towards complete solidification, was calculated via Scheil–Gulliver model as a function of solute concentration in simple binary Al-Si, Al-Mg, and Al-Cu systems. Introduction of “diffusion in solid” into Scheil–Gulliver model resulted in a …
Addressing The Practical Limitations Of Volatile Organic Compound Sensors Through An Oscillator-Based Sensing Array, Allison K. Murray, Joseph R. Meseke, Nikhil Bajaj, Jeffrey F. Rhoads
Addressing The Practical Limitations Of Volatile Organic Compound Sensors Through An Oscillator-Based Sensing Array, Allison K. Murray, Joseph R. Meseke, Nikhil Bajaj, Jeffrey F. Rhoads
Mechanical Engineering Faculty Research and Publications
This work demonstrated the development of an array of oscillator-based sensors for the detection of volatile organic compounds (VOCs). A field-programmable gate array (FPGA) was leveraged to monitor the oscillation frequency of 16 sensing elements in parallel. It was shown that three functional chemistries can be deposited via inkjet printing to detect several analytes selectively. These unique response characteristics allowed for the creation of a linear regression model that relates the shifts in oscillation frequencies to the concentration of specific analytes. This approach utilized a single array with sufficient elements to incorporate intentional redundancies. Ultimately, this work demonstrated a low-cost …
A New Line-By-Line Methodology Based On The Spectral Contributions Of The Bands, Felipe R. Coelho, Aline Ziemniczak, Somesh Roy, Francis H.R. França
A New Line-By-Line Methodology Based On The Spectral Contributions Of The Bands, Felipe R. Coelho, Aline Ziemniczak, Somesh Roy, Francis H.R. França
Mechanical Engineering Faculty Research and Publications
This study presents a new methodology to solve thermal radiation in participating gases, the spectrally reduced integration (SRI), which employs a non-uniform spectral discretization to considerably reduce the computational cost of the line-by-line (LBL) solution while still maintaining good levels of accuracy. This non-uniform spectral mesh is generated from discretization schemes based on the spectral contributions of the bands, which apply less or more refined spectral resolution depending on the importance of the bands to the radiative transfer. Based on this methodology, several schemes were initially proposed and evaluated for a homogeneous H2O-CO2 mixture test case. Results …