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Missouri University of Science and Technology

Mechanical Engineering

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Articles 31 - 60 of 969

Full-Text Articles in Engineering

Oxidation Layer Formation On Aluminum Substrates With Surface Defects Using Molecular Dynamics Simulation, Emmanuel Olugbade, Hiep Pham, Yuchu He, Haicheng Zhou, Chulsoon Hwang, Jonghyun Park Jan 2023

Oxidation Layer Formation On Aluminum Substrates With Surface Defects Using Molecular Dynamics Simulation, Emmanuel Olugbade, Hiep Pham, Yuchu He, Haicheng Zhou, Chulsoon Hwang, Jonghyun Park

Electrical and Computer Engineering Faculty Research & Creative Works

Aluminum Oxide Layer Affects the Integrity of Electrical Contact and Can Contribute Adversely to Passive Intermodulation (PIM) Behavior in Radio Frequency (RF) Devices, necessitating a Need for Understanding its Formation Mechanism and Realistic Estimation of its Thickness. using ReaxFF Molecular Dynamics Simulation Technique, This Study Investigated the Impact of Surface Defects on Aluminum Oxide Layer Formation. Results Reveal that Crystallographic Orientation Did Not Affect the Kinetics of Oxidation Process of Aluminum. However, the Reaction Kinetics Increased Significantly with Surface Inhomogeneities Such as Cracks, Scratches, and Grain Boundaries. a Non-Uniform Oxide Layer with Thickness Variation in the Range of 72-77% Was …

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Experimental Approach For Development Of A Powder Spreading Metric In Additive Manufacturing, M. Hossein Sehhat, Austin T. Sutton, Zane Yates, Ming-Chuan Leu Jan 2023

Experimental Approach For Development Of A Powder Spreading Metric In Additive Manufacturing, M. Hossein Sehhat, Austin T. Sutton, Zane Yates, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Powder Spreading is a Vital Step of Powder-Based Additive Manufacturing (AM) Processes. the Quality of Spread Powder Can Considerably Influence the Properties of Fabricated Parts. Poorly Packed Powder Beds with High Surface Roughness Result in Printed Part Layers with Large Porosity and Low Dimensional Accuracy, Leading to Poor Mechanical Properties. Therefore, the Powder Spread ability and its Dependence on Process Parameters and Powder Characteristics Should Be Quantified to Improve the Efficiency of Powder-Based AM Methods. This Study Proposes a Novel Dimensionless Powder Spread Ability Metric that Can Be Commonly Used in Different Powder-Based AM Processes. the Quality of Spread …

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Experimental Study For Improving The Productivity Of Laser Foil Printing, Tunay Turk, Ming-Chuan Leu Jan 2023

Experimental Study For Improving The Productivity Of Laser Foil Printing, Tunay Turk, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This Study Aims to Improve the Productivity of Laser Foil Printing (LFP), Which is a Foil-Based Metal Additive Manufacturing (AM) Process. LFP Uses a Dual-Laser System to Fabricate a 3-Dimensional Part in a Layered Fashion by Performing Four Steps in Each Layer: Spot Welding, Pattern Welding, Contour Cutting, and Edge Polishing, All of Which Performed by Use of Lasers. We Experimentally Examined the Welding and Polishing Steps in This Study to Enhance LFP Productivity. the Jump Speed, Dwelling Duration, and Weld Path of Spot Welding and the Line Welding Speed and Wait Time between Weld Lines of Pattern Welding Are …

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Comparison Of The Thermal Stability In Equal-Channel-Angular-Pressed And High-Pressure-Torsion-Processed Fe–21cr–5al Alloy, Maalavan Arivu, Andrew Hoffman, Jiaqi Duan, Jonathan Poplawsky, Xinchang Zhang, Frank W. Liou, Rinat Islamgaliev, Ruslan Valiev, Haiming Wen Jan 2023

Comparison Of The Thermal Stability In Equal-Channel-Angular-Pressed And High-Pressure-Torsion-Processed Fe–21cr–5al Alloy, Maalavan Arivu, Andrew Hoffman, Jiaqi Duan, Jonathan Poplawsky, Xinchang Zhang, Frank W. Liou, Rinat Islamgaliev, Ruslan Valiev, Haiming Wen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nanostructured Steels Are Expected to Have Enhanced Irradiation Tolerance and Improved Strength. However, They Suffer from Poor Microstructural Stability at Elevated Temperatures. in This Study, Fe–21Cr–5Al–0.026C (Wt%) Kanthal D (KD) Alloy Belonging to a Class of (FeCrAl) Alloys Considered for Accident-Tolerant Fuel Cladding in Light-Water Reactors is Nanostructured using Two Severe Plastic Deformation Techniques of Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT), and their Thermal Stability between 500–700 °C is Studied and Compared. ECAP KD is Found to Be Thermally Stable Up to 500 °C, Whereas HPT KD is Unstable at 500 °C. Microstructural Characterization Reveals that ECAP KD …

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Microstructure, Mechanical Properties And Oxidation Behavior Of Refractory Multi-Principal Element Alloys By Laser Remelting And Conventional Manufacturing, Visharad Jalan, Seth Crawford, Sung Heng Wu, Frank W. Liou, Haiming Wen Jan 2023

Microstructure, Mechanical Properties And Oxidation Behavior Of Refractory Multi-Principal Element Alloys By Laser Remelting And Conventional Manufacturing, Visharad Jalan, Seth Crawford, Sung Heng Wu, Frank W. Liou, Haiming Wen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Refractory Multi-Principal Element Alloys (RMPEAs), HfNbTaTiZr, (HfNbTaTiZr)9Cr, and (HfNbTaTiZr)9Al, Were Manufactured using Vacuum Arc Melting Followed by Laser Remelting to Mimic Additive Manufacturing. the Microhardness of the As-Cast HfNbTaTiZr, (HfNbTaTiZr)9Cr, and (HfNbTaTiZr)9Al Samples after Arc Melting Was Measured as 6.20, 7.63, and 6.89 Gpa, respectively. after Laser Remelting and Re-Solidification, the Hardness Increased by ~ 30% for Each Composition; the Hardest Was (HfNbTaTiZr)9Cr Measured at 9.60 GPa, While the Softest Was HfNbTaTiZr with a Hardness of 8.42 GPa, Which Was Still Harder Compared to All the Other Samples. the Addition …

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Application Of A Variable Path Length Repetitive Process Control For Direct Energy Deposition Of Thin-Walled Structures, Elias B. Snider, Douglas A. Bristow Jan 2023

Application Of A Variable Path Length Repetitive Process Control For Direct Energy Deposition Of Thin-Walled Structures, Elias B. Snider, Douglas A. Bristow

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct Energy Deposition (DED) Additive Manufacturing is Well Suited to Fabricating Large Thin-Walled Metal Structures Such as Rocket Nozzles but Suffers from Layer-To-Layer Defect Propagation. Propagating Defects May Exhibit as Slumping or a Ripple in Bead Geometry. Recent Works Have Used Repetitive Process Control (RPC) Methods for Additive Manufacturing to Stabilize the Layer-Wise Defect Propagation, But These Methods Require Repetition of the Same Path. However, Typical Thin-Wall DED Applications, Sometimes Referred to as Vase Structures, Have Changing Paths with Each Layer Such as Expanding or Contracting Diameters and Changing Profiles. This Paper Presents an Extension to Optimal RPC that Uses …

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Microstructure And Residual Stress In Functionally Graded 316l Stainless Steel/Inconel 625 Alloys Fabricated By Direct Energy Deposition, Xinchang Zhang, Liang Wang, Frank W. Liou, Yang Ren, Cheng Sun Jan 2023

Microstructure And Residual Stress In Functionally Graded 316l Stainless Steel/Inconel 625 Alloys Fabricated By Direct Energy Deposition, Xinchang Zhang, Liang Wang, Frank W. Liou, Yang Ren, Cheng Sun

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Functionally graded materials (FGMs) provide a unique solution to combine distinct properties within a single component to enhance its overall performance. Understanding the microstructure and residual stress distribution is particularly important as the material dissimilarity in FGMs can result in high residual stress that affects the mechanical integrity of structural components. This work aims to study the microstructure and residual stress of additively manufactured FGMs and the effects of isothermal annealing. In this study, 316L stainless steel/Inconel 625 FGMs were built by direct energy deposition and characterized by optical and electron microscopy as well as synchrotron-based X-ray diffraction. Our study …

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3d-Printed Hydrogels Dressings With Bioactive Borate Glass For Continuous Hydration And Treatment Of Second-Degree Burns, Fateme Fayyazbakhsh, Michael J. Khayat, Candy Sadler, Delbert Day, Yue-Wern Huang, Ming-Chuan Leu Jan 2023

3d-Printed Hydrogels Dressings With Bioactive Borate Glass For Continuous Hydration And Treatment Of Second-Degree Burns, Fateme Fayyazbakhsh, Michael J. Khayat, Candy Sadler, Delbert Day, Yue-Wern Huang, Ming-Chuan Leu

Biological Sciences Faculty Research & Creative Works

Recent advances in additive manufacturing have led to the development of innovative solutions for tissue regeneration. Hydrogel materials have gained significant attention for burn wound treatment in clinical practice among various advanced dressings due to their soothing and moisturizing activity. However, prolonged healing, pain, and traumatic removal due to the lack of long-term wound hydration are some of the challenges in the treatment of second-degree burn wounds. In this study, 3D-printed dressings were fabricated using gelatin, alginate, and bioactive borate glass (BBG) using an extrusion-based bioprinter. After ionic crosslinking, the 3D-printed dressings were characterized for mechanical properties, degradation rate, hydration …

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Fine-Grained Activity Classification In Assembly Based On Multi-Visual Modalities, Haodong Chen, Niloofar Zendehdel, Ming-Chuan Leu, Zhaozheng Yin Jan 2023

Fine-Grained Activity Classification In Assembly Based On Multi-Visual Modalities, Haodong Chen, Niloofar Zendehdel, Ming-Chuan Leu, Zhaozheng Yin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Assembly activity recognition and prediction help to improve productivity, quality control, and safety measures in smart factories. This study aims to sense, recognize, and predict a worker's continuous fine-grained assembly activities in a manufacturing platform. We propose a two-stage network for workers' fine-grained activity classification by leveraging scene-level and temporal-level activity features. The first stage is a feature awareness block that extracts scene-level features from multi-visual modalities, including red, green blue (RGB) and hand skeleton frames. We use the transfer learning method in the first stage and compare three different pre-trained feature extraction models. Then, we transmit the feature information …

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Nanobubble-Induced Aggregation Of Ultrafine Particles: A Molecular Dynamics Study, Eric Bird, Zhi Liang Jan 2023

Nanobubble-Induced Aggregation Of Ultrafine Particles: A Molecular Dynamics Study, Eric Bird, Zhi Liang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nanobubble-induced aggregation (NBIA) of fine and ultrafine particles in liquid is a promising method for enhancing floatation rates in mineral processing, cleaning contaminants from water, and reviving marine ecosystems. Although the current experimental techniques can measure the nanobubble capillary force between two surfaces with controlled approach speed, they are not capable of imaging NBIA dynamics of fine/ultrafine particles by real-time observation with nanoscale spatial resolution. In this work, we use molecular dynamics (MD) simulations to study dynamics of NBIA of Ag particles in a Lennard-Jones fluid system. The molecular-level modeling allows us to study microscopic details of NBIA dynamics that …

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Additively Manufactured Carbon Fiber- Reinforced Thermoplastic Composite Mold Plates For Injection Molding Process, C. Bivens, A. Wood, D. Ruble, M. Rangapuram, S. K. Dasari, K. Chandrashekhara, J. Degrange Jan 2023

Additively Manufactured Carbon Fiber- Reinforced Thermoplastic Composite Mold Plates For Injection Molding Process, C. Bivens, A. Wood, D. Ruble, M. Rangapuram, S. K. Dasari, K. Chandrashekhara, J. Degrange

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Polymer injection molding processes have been used to create high-volume parts quickly and efficiently. Injection molding uses mold plates that are traditionally made of very hard tool steels, such as P20 steel, which is extremely heavy and has very long lead times to build new molds. In this study, composite-based additive manufacturing (CBAM) was used to create mold plates using long-fiber carbon fiber and polyether ether ketone (PEEK). These mold plates were installed in an injection molding machine, and rectangular flat plates were produced using Lustran 348 acrylonitrile butadiene styrene (ABS). Tensile and flexural testing was performed on these parts …

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Static I-V Based Pim Evaluation For Spring And Fabric-Over-Foam Contacts, Kalkidan W. Anjajo, Yang Xu, Shengxuan Xia, Yuchu He, Haicheng Zhou, Hanfeng Wang, Jonghyun Park, Chulsoon Hwang Jan 2023

Static I-V Based Pim Evaluation For Spring And Fabric-Over-Foam Contacts, Kalkidan W. Anjajo, Yang Xu, Shengxuan Xia, Yuchu He, Haicheng Zhou, Hanfeng Wang, Jonghyun Park, Chulsoon Hwang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Spring Clips and Fabric-Over-Foams (FOFs) Are Widely Used in Mobile Devices for Electrical Connection Purposes. However, the Imperfect Metallic Connections Tend to Induce Passive Intermodulation (PIM), Resulting in a Receiver Sensitivity Degradation, Known as RP Desensitization. Due to the Complexity of the PIM Characterization, there is Not Yet a Way to Evaluate PIM Performance using a Simple Setup for Environments Like Factories. in This Paper, a Current-Voltage (I-V) Behavior-Based PIM Evaluation Method is Proposed and Validated with Various Metallic Contacts and Contact Forces. the Test Results Demonstrated the Feasibility of the PIM Performance Evaluation based on the Measured Static I-V …

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Additive Manufacturing Of Complexly Shaped Sic With High Density Via Extrusion-Based Technique – Effects Of Slurry Thixotropic Behavior And 3d Printing Parameters, Ruoyu Chen, Adam Bratten, Joshua Rittenhouse, Tian Huang, Wenbao Jia, Ming-Chuan Leu, Haiming Wen Oct 2022

Additive Manufacturing Of Complexly Shaped Sic With High Density Via Extrusion-Based Technique – Effects Of Slurry Thixotropic Behavior And 3d Printing Parameters, Ruoyu Chen, Adam Bratten, Joshua Rittenhouse, Tian Huang, Wenbao Jia, Ming-Chuan Leu, Haiming Wen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive manufacturing of dense SiC parts was achieved via an extrusion-based process followed by electrical-field assisted pressure-less sintering. The aim of this research was to study the effect of the rheological behavior of SiC slurry on the printing process and quality, as well as the influence of 3D printing parameters on the dimensions of the extruded filament, which are directly related to the printing precision and quality. Different solid contents and dispersant- Darvan 821A concentrations were studied to optimize the viscosity, thixotropy and sedimentation rate of the slurry. The optimal slurry was composed of 77.5 wt% SiC, Y2O3 and Al2O3 …

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Predicting Defects In Laser Powder Bed Fusion Using In-Situ Thermal Imaging Data And Machine Learning, Sina Malakpour Estalaki, Cody S. Lough, Robert G. Landers, Edward C. Kinzel, Tengfei Luo Oct 2022

Predicting Defects In Laser Powder Bed Fusion Using In-Situ Thermal Imaging Data And Machine Learning, Sina Malakpour Estalaki, Cody S. Lough, Robert G. Landers, Edward C. Kinzel, Tengfei Luo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Variation in the local thermal history during the Laser Powder Bed Fusion (LPBF) process in Additive Manufacturing (AM) can cause micropore defects, which add to the uncertainty of the mechanical properties (e.g., fatigue life, tensile strength) of the built materials. In-situ sensing has been proposed for monitoring the AM process to minimize defects, but successful minimization requires establishing a quantitative relationship between the sensing data and the porosity, which is particularly challenging with a large number of variables (e.g., laser speed, power, scan path, powder property). Physics-based modeling can simulate such an in-situ sensing-porosity relationship, but it is computationally costly. …

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Aircraft Engine Particulate Matter Emissions From Sustainable Aviation Fuels: Results From Ground-Based Measurements During The Nasa/Dlr Campaign Eclif2/Nd-Max, Tobias Schripp, Bruce E. Anderson, Uwe Bauder, Bastian Rauch, Joel C. Corbin, Greg J. Smallwood, Prem Lobo, Ewan C. Crosbie, Michael A. Shook, Richard C. Miake-Lye, Zhenhong Yu, Andrew Freedman, Philip D. Whitefield, Claire E. Robinson Oct 2022

Aircraft Engine Particulate Matter Emissions From Sustainable Aviation Fuels: Results From Ground-Based Measurements During The Nasa/Dlr Campaign Eclif2/Nd-Max, Tobias Schripp, Bruce E. Anderson, Uwe Bauder, Bastian Rauch, Joel C. Corbin, Greg J. Smallwood, Prem Lobo, Ewan C. Crosbie, Michael A. Shook, Richard C. Miake-Lye, Zhenhong Yu, Andrew Freedman, Philip D. Whitefield, Claire E. Robinson

Chemistry Faculty Research & Creative Works

The use of alternative jet fuels by commercial aviation has increased substantially in recent years. Beside the reduction of carbon dioxide emission, the use of sustainable aviation fuels (SAF) may have a positive impact on the reduction of particulate emissions. This study summarizes the results from a ground-based measurement activity conducted in January 2018 as part of the ECLIF2/ND-MAX campaign in Ramstein, Germany. Two fossil reference kerosenes and three different blends with the renewable fuel component HEFA-SPK (Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosene) were burned in an A320 with V2527-A5 engines to investigate the effect of fuel naphthalene/aromatic …

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Enabling Ultrathick Electrodes Via A Microcasting Process For High Energy And Power Density Lithium-Ion Batteries, Tazdik Patwary Plateau, Hiep Pham, Yaqi Zhu, Ming-Chuan Leu, Jonghyun Park Oct 2022

Enabling Ultrathick Electrodes Via A Microcasting Process For High Energy And Power Density Lithium-Ion Batteries, Tazdik Patwary Plateau, Hiep Pham, Yaqi Zhu, Ming-Chuan Leu, Jonghyun Park

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Thickening electrodes is one effective approach to increase active material content for higher energy and low-cost lithium-ion batteries, but limits in charge transport and huge mechanical stress generation result in poor performance and eventual cell failure. This paper reports a new electrode fabrication process, referred to as µ-casting, enabling ultrathick electrodes that address the trade-off between specific capacity and areal/volumetric capacity. The proposed µ-casting is based on a patterned blade, enabling facile fabrication of 3D electrode structures. The study reveals the governing properties of µ-casted ultrathick electrodes and how this simultaneously improves battery energy/power performance. The process facilitates a short …

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Effects Of Radiation Reabsorption On The Laminar Flame Speed And No Emission During Aviation Kerosene Combustion At Elevated Pressures, Shu Zheng, Hao Liu, Qing Li, Jiajian Zhu, Mingbo Sun, Bo Zhou, Ran Sui, Qiang Lu Sep 2022

Effects Of Radiation Reabsorption On The Laminar Flame Speed And No Emission During Aviation Kerosene Combustion At Elevated Pressures, Shu Zheng, Hao Liu, Qing Li, Jiajian Zhu, Mingbo Sun, Bo Zhou, Ran Sui, Qiang Lu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Increasing attention has been paid on combustion stability and pollution emission of aviation kerosene due to the emerging interests on supersonic combustion scramjets. Whereas the vitiation component H2O introduced by hydrogen-fueled heaters in high-enthalpy vitiated air during ground experiments has a considerable influence on kerosene combustion, especially through its radiation effect, which needs to be further investigated. In this paper, the radiation reabsorption effects on laminar flame speeds and NO emissions during RP-3/H2O/O2/N2 combustion was assessed numerically over a wide range of equivalence ratio and pressure (ϕ = 0.7–1.4 and P = 1–15 atm) using detailed chemical and radiation models. …

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Improved Additive Manufacturing Of Silicon Carbide Parts Via Pressureless Electric Field-Assisted Sintering, Adam Bratten, Ruoyu Chen, Joshua Rittenhouse, Ming-Chuan Leu, Haiming Wen Sep 2022

Improved Additive Manufacturing Of Silicon Carbide Parts Via Pressureless Electric Field-Assisted Sintering, Adam Bratten, Ruoyu Chen, Joshua Rittenhouse, Ming-Chuan Leu, Haiming Wen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

High solids loading silicon carbide (SiC)-based aqueous slurries containing only.5 wt. % organic additives were utilized to create specimens of various geometries via an extrusion-based additive manufacturing (AM) technique. Pressure less electric field-assisted sintering was performed to densify each specimen without deformation. The combination of these techniques produced parts with >98% relative density despite containing only 5 wt.% oxide sintering additives. After sintering, specimens contained only the α-SiC and yttrium aluminum perovskite phases. This suggests the evolution of a nonequilibrium yttrium aluminate phase, as well as transformation from β-SiC to α-SiC. The fabrication method presented in this work has advantages …

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In-Situ Measurements Of Temperature And Emissivity During Msw Combustion Using Spectral Analysis And Multispectral Imaging Processing, Shu Zheng, Weiguang Cai, Ran Sui, Zixue Luo, Qiang Lu Sep 2022

In-Situ Measurements Of Temperature And Emissivity During Msw Combustion Using Spectral Analysis And Multispectral Imaging Processing, Shu Zheng, Weiguang Cai, Ran Sui, Zixue Luo, Qiang Lu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

By using a novel multispectral imaging technology, the 2-D distributions of flame temperature and emissivity were measured in a 16 MW incinerator to co-fire municipal solid waste (MSW) and municipal sludge. A way to establish the relationship between the multispectral flame images and the temperature was proposed by combing the Newton iteration method and Hottel emissivity model. The results showed that the measured temperatures at different locations varied by 31.25% with a fixed steam evaporation rate, and 11.76% with different steam evaporation rates at a given port. The temperatures and emissivities decreased at upper locations due to the lower local …

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Impact Of Ultrathin Coating Layer On Lithium-Ion Intercalation Into Particles For Lithium-Ion Batteries, Yufang He, Hiep Pham, Xinhua Liang, Jonghyun Park Jul 2022

Impact Of Ultrathin Coating Layer On Lithium-Ion Intercalation Into Particles For Lithium-Ion Batteries, Yufang He, Hiep Pham, Xinhua Liang, Jonghyun Park

Chemical and Biochemical Engineering Faculty Research & Creative Works

Ultrathin film coatings on battery materials via atomic layer deposition (ALD) have been demonstrated as an efficient technology for battery performance enhancement. However, the fundamental understanding on lithium intercalation into active materials through the interface between the coating and active materials is unclear, which makes it difficult to optimize ALD coating strategies. Further, like most active materials, a coating layer can undergo volume change during the intercalation process, which can produce detrimental structural changes and mechanical failure of the layer. In this work, first-principles calculations are conducted to reveal the behavior of a coating layer on an active material particle …

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A Comparative Study On Representativeness And Stochastic Efficacy Of Miniature Tensile Specimen Testing, Sreekar Karnati, Sriram Praneeth Isanaka, Yunlu Zhang, Frank W. Liou, Jason L. Schulthess Jul 2022

A Comparative Study On Representativeness And Stochastic Efficacy Of Miniature Tensile Specimen Testing, Sreekar Karnati, Sriram Praneeth Isanaka, Yunlu Zhang, Frank W. Liou, Jason L. Schulthess

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this article, a miniature dog bone tensile coupon design was tested against the existing ASTM standard specimen design. Specimens were prepared from commercially sourced austenitic stainless steel 304 alloy, and a defect-ridden additively manufactured 304L alloy was studied. By utilizing a tensile specimen design that is 1/230th volume of the smallest ASTM E8-04 (2016), Standard Test Methods for Tension Testing of Metallic Materials, dog bone specimen, coupled to a digital image correlation (DIC) setup, case studies were performed to compare tensile property measurements and strain field evolution. Whereas yield strength measurements were observed to be similar, post-yield, the ultimate …

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In-Situ Infrared Thermographic Inspection For Local Powder Layer Thickness Measurement In Laser Powder Bed Fusion, Tao Liu, Cody S. Lough, Hossein Sehhat, Yi Ming Ren, Panagiotis D. Christofides, Edward C. Kinzel, Ming-Chuan Leu Jul 2022

In-Situ Infrared Thermographic Inspection For Local Powder Layer Thickness Measurement In Laser Powder Bed Fusion, Tao Liu, Cody S. Lough, Hossein Sehhat, Yi Ming Ren, Panagiotis D. Christofides, Edward C. Kinzel, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The laser powder bed fusion (LPBF) process is strongly influenced by the characteristics of the powder layer, including its thickness and thermal transport properties. This paper investigates in-situ characterization of the powder layer using thermographic inspection. A thermal camera monitors the temperature history of the powder surface immediately after a layer of new powder is deposited by the recoating system. During this process, thermal energy diffuses from the underlying solid part, eventually raising the temperature of the above powder layer. Guided by 1D modeling of this heat-up process, experiments show how the parameterized thermal history can be correlated with powder …

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Error Estimate Of A Decoupled Numerical Scheme For The Cahn-Hilliard-Stokes-Darcy System, Wenbin Chen, Shufen Wang, Yichao Zhang, Daozhi Han, Cheng Wang, Xiaoming Wang Jul 2022

Error Estimate Of A Decoupled Numerical Scheme For The Cahn-Hilliard-Stokes-Darcy System, Wenbin Chen, Shufen Wang, Yichao Zhang, Daozhi Han, Cheng Wang, Xiaoming Wang

Mathematics and Statistics Faculty Research & Creative Works

We analyze a fully discrete finite element numerical scheme for the Cahn-Hilliard-Stokes-Darcy system that models two-phase flows in coupled free flow and porous media. To avoid a well-known difficulty associated with the coupling between the Cahn-Hilliard equation and the fluid motion, we make use of the operator-splitting in the numerical scheme, so that these two solvers are decoupled, which in turn would greatly improve the computational efficiency. The unique solvability and the energy stability have been proved in Chen et al. (2017, Uniquely solvable and energy stable decoupled numerical schemes for the Cahn-Hilliard-Stokes-Darcy system for two-phase flows in karstic geometry. …

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Internal Energy Balance And Aerodynamic Heating Predictions For Hypersonic Turbulent Boundary Layers, Matthew Barone, Gary L. Nicholson, Lian Duan Jul 2022

Internal Energy Balance And Aerodynamic Heating Predictions For Hypersonic Turbulent Boundary Layers, Matthew Barone, Gary L. Nicholson, Lian Duan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The elemental equation governing heat transfer in aerodynamic flows is the internal energy equation. For a boundary layer flow, a double integration of the Reynolds-averaged form of this equation provides an expression of the wall heat flux in terms of the integrated effects, over the boundary layer, of various physical processes: turbulent dissipation, mean dissipation, turbulent heat flux, etc. Recently available direct numerical simulation data for a Mach 11 cold-wall turbulent boundary layer allows a comparison of the exact contributions of these terms in the energy equation to the wall heat flux with their counterparts modeled in the Reynolds-averaged Navier-Stokes …

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Anisotropic Third-Harmonic Generation Of Exfoliated As2s3 Thin Flakes, Ravi P.N. Tripathi, Xiaodong Yang, Jie Gao Jun 2022

Anisotropic Third-Harmonic Generation Of Exfoliated As2s3 Thin Flakes, Ravi P.N. Tripathi, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Van der Waals (vdW) materials have recently attracted significant interest in the context of orientation-dependent linear and nonlinear optical properties. Recently, arsenic trisulfide (As2S3) or orpiment is identified as a new vdW layered material having anisotropic vibrational and optomechanical responses due to the reduced in-plane crystal symmetry, but its nonlinear optical response is still not well understood yet. Herein, the anisotropic third-harmonic generation (THG) response of mechanically exfoliated As2S3 thin flakes is reported. The polarization-dependent evolution of THG emission from butterfly-shaped pattern to four-lobe pattern is comprehensively explored. Moreover, the third-order nonlinear susceptibility of As2S3 crystal is extracted by analyzing …

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Tini-Based Bi-Metallic Shape-Memory Alloy By Laser-Directed Energy Deposition, Yitao Chen, Cesar Ortiz Rios, Braden Mclain, Joseph William Newkirk, Frank W. Liou Jun 2022

Tini-Based Bi-Metallic Shape-Memory Alloy By Laser-Directed Energy Deposition, Yitao Chen, Cesar Ortiz Rios, Braden Mclain, Joseph William Newkirk, Frank W. Liou

Materials Science and Engineering Faculty Research & Creative Works

In this study, laser-directed energy deposition was applied to build a Ti-rich ternary Ti–Ni–Cu shape-memory alloy onto a TiNi shape-memory alloy substrate to realize the joining of the multifunctional bi-metallic shape-memory alloy structure. The cost-effective Ti, Ni, and Cu elemental powder blend was used for raw materials. Various material characterization approaches were applied to reveal different material properties in two sections. The as-fabricated Ti–Ni–Cu alloy microstructure has the TiNi phase as the matrix with Ti2Ni secondary precipitates. The hardness shows no high values indicating that the major phase is not hard intermetallic. A bonding strength of 569.1 MPa was obtained …

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Laser-Scribed Conductive, Photoactive Transition Metal Oxide On Soft Elastomers For Janus On-Skin Electronics And Soft Actuators, Ganggang Zhao, Yun Ling, Yajuan Su, Zanyu Chen, Cherian J. Mathai, Ogheneobarome Emeje, Alexander Brown, Dinesh Reddy Alla, Jie Huang, Chansong Kim, Qian Chen, Xiaoqing He, David Stalla, Yadong Xu Jun 2022

Laser-Scribed Conductive, Photoactive Transition Metal Oxide On Soft Elastomers For Janus On-Skin Electronics And Soft Actuators, Ganggang Zhao, Yun Ling, Yajuan Su, Zanyu Chen, Cherian J. Mathai, Ogheneobarome Emeje, Alexander Brown, Dinesh Reddy Alla, Jie Huang, Chansong Kim, Qian Chen, Xiaoqing He, David Stalla, Yadong Xu

Electrical and Computer Engineering Faculty Research & Creative Works

Laser-assisted fabrication of conductive materials on flexible substrates has attracted intense interests because of its simplicity, easy customization, and broad applications. However, it remains challenging to achieve laser scribing of conductive materials on tissue-like soft elastomers, which can serve as the basis to construct bioelectronics and soft actuators. Here, we report laser scribing of metallic conductive, photoactive transition metal oxide (molybdenum dioxide) on soft elastomers, coated with molybdenum chloride precursors, under ambient conditions. Laser-scribed molybdenum dioxide (LSM) exhibits high electrical conductivity, biocompatibility, chemical stability, and compatibility with magnetic resonance imaging. In addition, LSM can be made on various substrates (polyimide, …

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Natural Layered Mercury Antimony Sulfosalt Livingstonite With Anisotropic Optical Properties, Ravi P.N. Tripathi, Jie Gao, Xiaodong Yang May 2022

Natural Layered Mercury Antimony Sulfosalt Livingstonite With Anisotropic Optical Properties, Ravi P.N. Tripathi, Jie Gao, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Naturally occurring layered mineral livingstonite is identified as a new type of van der Waals (vdW) heterostructure based 2D material, consisting of two commensurately modulated alternating layers of HgSb2S4 and Sb2S4. The heterostructures of livingstonite crystal are prepared as thin flakes via mechanical exfoliation method. The prepared livingstonite crystals are further investigated in the context of vibrational, linear, and nonlinear optical properties, including anisotropic Raman scattering, wavelength-dependent linear dichroism (LD) transition effect, birefringence, and anisotropic third-harmonic generation (THG). Owing to the monoclinic crystal structure, livingstonite crystals exhibit strong anisotropic vibrational and optical responses. In contrast to conventional vdW heterostructures, the …

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Dual-Band Selective Circular Dichroism In Mid-Infrared Chiral Metasurfaces, Haotian Tang, Daniel Rosenmann, David A. Czaplewski, Xiaodong Yang, Jie Gao May 2022

Dual-Band Selective Circular Dichroism In Mid-Infrared Chiral Metasurfaces, Haotian Tang, Daniel Rosenmann, David A. Czaplewski, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Most chiral metamaterials and meta surfaces are designed to operate in a single wavelength band and with a certain circular dichroism (CD) value. Here, mid-infrared chiral meta surface absorbers with selective CD in dual-wavelength bands are designed and demonstrated. The dual-band CD selectivity and tunability in the chiral meta surface absorbers are enabled by the unique design of a unit cell with two coupled rectangular bars. It is shown that the sign of CD in each wavelength band can be independently controlled and flipped by simply adjusting the geometric parameters, the width and the length, of the vertical rectangular bars. …

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Updates And Improvements To The Satellite Drag Coefficient Response Surface Modeling Toolkit, Phillip Logan Sheridan, Smriti Nandan Paul, Guillermo Avendaño-Franco, Piyush M. Mehta May 2022

Updates And Improvements To The Satellite Drag Coefficient Response Surface Modeling Toolkit, Phillip Logan Sheridan, Smriti Nandan Paul, Guillermo Avendaño-Franco, Piyush M. Mehta

Mechanical and Aerospace Engineering Faculty Research & Creative Works

For satellites in the Low Earth Orbit (LEO) region, the drag coefficient is a primary source of uncertainty for orbit determination and prediction. Researchers at the Los Alamos National Laboratory (LANL) have created the so-called Response Surface Modeling (RSM) toolkit to provide the community with a resource for simulating and modeling satellite drag coefficients for satellites with complex geometries (modeled using triangulated facets) in the free molecular flow (FMF) regime. The toolkit fits an interpolation surface using non-parametric Gaussian Process Regression (GPR) over drag coefficient data computed using the numerical Test Particle Monte Carlo (TPMC) method. The fitted response surface …

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