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Articles 91 - 120 of 1287
Full-Text Articles in Engineering
Hyperspectral Imaging For Temperature Measurements Of Hot Spots In Shocked Plastic-Bonded Explosives, Dhanalakshmi Sellan, Siva Kumar Valluri, Dana D. Dlott
Hyperspectral Imaging For Temperature Measurements Of Hot Spots In Shocked Plastic-Bonded Explosives, Dhanalakshmi Sellan, Siva Kumar Valluri, Dana D. Dlott
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Hot spots are formed when energetic microstructures are shocked, and they play a critical role in shock sensitivity. It is important to know both the time-dependent size and temperature of the hot spots, in order to generate a kinetic model to describe reaction growth in plastic-bonded explosives (PBX). Here we use a recently developed technique where PBX is fabricated in the form of a thin wafer, embedded within a transparent polymer binder, and shocked with a laser-launched flyer plate that produces pressures of about 30 GPa range. In this method, every crystal of the cyclotetramethylene-tetranitramine (HMX)-based PBX can be observed …
Uncovering Upconversion Photoluminescence In Layered Pbi2 Above Room Temperature, Sharad Ambardar, Xiaodong Yang, Jie Gao
Uncovering Upconversion Photoluminescence In Layered Pbi2 Above Room Temperature, Sharad Ambardar, Xiaodong Yang, Jie Gao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
As a van der Waals (vdW) layered semiconductor material, lead iodide (PbI2) possessing a direct bandgap with strong photoluminescence emission in visible range has gained wide attention in applications of photonic and optoelectronic devices. Here, up conversion photoluminescence (UPL) in exfoliated PbI2 flakes is demonstrated at room temperature and elevated temperatures. The linear power dependence of UPL emission with 532 nm excitation suggests the one-photon involved multiphonon-assisted UPL emission process, which is revealed by the temperature-dependent UPL emission measurement. Meanwhile, the nonlinear power dependence of UPL emission with 561 nm excitation indicates the transition of UPL emission mechanism from linear …
Fpga-Based Sensors For Distributed Digital Manufacturing Systems: A State-Of-The-Art Review, Laraib Khan, Sriram Praneeth Isanaka, Frank Liou
Fpga-Based Sensors For Distributed Digital Manufacturing Systems: A State-Of-The-Art Review, Laraib Khan, Sriram Praneeth Isanaka, Frank Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The combination of distributed digital factories (D2Fs) with sustainable practices has been proposed as a revolutionary technique in modern manufacturing. This review paper explores the convergence of D2F with innovative sensor technology, concentrating on the role of Field Programmable Gate Arrays (FPGAs) in promoting this paradigm. A D2F is defined as an integrated framework where digital twins (DTs), sensors, laser additive manufacturing (laser-AM), and subtractive manufacturing (SM) work in synchronization. Here, DTs serve as a virtual replica of physical machines, allowing accurate monitoring and control of a given manufacturing process. These DTs are supplemented by sensors, providing near-real-time data to …
Thermal Conductivity Characterization Of High Oleic Vegetable Oils Based Hybrid Nanofluids Formulated Using Gnp, Tio2, Mos2, Al2o3 Nanoparticles For Mql Machining, Anthony Chukwujekwu Okafor, Tobechukwu Kingsley Abor, Saidanvar Esanjonovich Valiev, Ignatius Echezona Ekengwu, Abiodun Saka, Monday Uchenna Okoronkwo
Thermal Conductivity Characterization Of High Oleic Vegetable Oils Based Hybrid Nanofluids Formulated Using Gnp, Tio2, Mos2, Al2o3 Nanoparticles For Mql Machining, Anthony Chukwujekwu Okafor, Tobechukwu Kingsley Abor, Saidanvar Esanjonovich Valiev, Ignatius Echezona Ekengwu, Abiodun Saka, Monday Uchenna Okoronkwo
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper presents the results of thermal conductivity characterization of six high oleic soybean oil (HOSO) and four high oleic canola oil (HOCO)-based hybrid nanofluids formulated with four types of nanoparticles (Graphene nanoplatelet (xGnP), TiO2, MoS2, and Al2O3) at nanoparticles wt.% concentration from 1 % to 7 % in 1 % increment using the two-step method for use in MQL machining of difficult-to-cut metals. Thermal conductivity of the formulated hybrid nanofluids were measured using Thermtest Transient Hot Wire Liquid Thermal Conductivity Meter at temperatures from 25 °C to 75 °C in increment of 10 °C. Obtained results showed that thermal …
Biaxial Strain Tuned Upconversion Photoluminescence Of Monolayer Ws2, Shrawan Roy, Xiaodong Yang, Jie Gao
Biaxial Strain Tuned Upconversion Photoluminescence Of Monolayer Ws2, Shrawan Roy, Xiaodong Yang, Jie Gao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Monolayer tungsten disulfide (1L-WS2) is a direct bandgap atomic-layered semiconductor material with strain tunable optical and optoelectronic properties among the monolayer transition metal dichalcogenides (1L-TMDs). Here, we demonstrate biaxial strain tuned up conversion photoluminescence (UPL) from exfoliated 1L-WS2 flakes transferred on a flexible polycarbonate cruciform substrate. When the biaxial strain applied to 1L-WS2 increases from 0 to 0.51%, it is observed that the UPL peak position is redshifted by up to 60 nm% strain, while the UPL intensity exhibits exponential growth with the up-conversion energy difference varying from − 303 to − 120 meV. The measured …
Temperature Effect On The Properties And Response Of Composite Materials And Plates, Victor Birman
Temperature Effect On The Properties And Response Of Composite Materials And Plates, Victor Birman
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The paper illustrates the effect of temperature on composite material properties and its influence on the response of composite plates. Two composites considered include laminae with uniaxially oriented and with in-plane randomly oriented fibers. Analytical solutions are presented for a uniformly heated large-aspect-ratio plate deforming into a cylindrical surface. The solutions are demonstrated for thermal buckling and natural frequencies for the cases of controlled loading and controlled displacements. Micromechanical residual and lifetime thermally induced stresses at the interface of fibers and matrix are assessed to predict a possible onset of local damage after the curing and during lifetime. The material …
Machine Vision To Provide Quantitative Analysis Of Meltpool Stability For A Coaxial Wire Directed Energy Deposition Process, Braden Mclain, Remy Mathenia, Todd Sparks, Frank Liou
Machine Vision To Provide Quantitative Analysis Of Meltpool Stability For A Coaxial Wire Directed Energy Deposition Process, Braden Mclain, Remy Mathenia, Todd Sparks, Frank Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Wire-based additive manufacturing (AM) is at the forefront of complex metal fabrication because of its scalability for large components, potential for high deposition rates, and ease of use. A common goal of wire directed energy deposition (DED) is preserving a stable process throughout deposition. If too little energy is put into the deposition, the wire will stub into the substrate and begin oscillating, creating turbulence within the melt pool. If too much energy exists, the wire will overheat, causing surface tension to take over and create liquid drips as opposed to a solid bead. This paper proposes a computer vision …
Interlaboratory Study Of The Operational Stability Of Automated Sorption Balances, Samuel L. Zelinka, Samuel V. Glass, Eleanor Q. D. Lazarcik, Emil E. Thybring, Michael Altgen, Lauri Rautkari, Simon Curling, Jinzhen Cao, Yujiao Wang, Tina Kunniger, Gustav Nystrom, Christopher Hubert Dreimol, Ingo Burgert, Mohd Khairun Anwar Uyup, Tumirah Khadiran, Mark G. Roper, Darren P. Broom, Matthew Schwarzkopf, Arief Yudhanto, Mohammad Subah, Gilles Lubineau, Maria Fredriksson, Marcin Strojecki, Wieslaw Olek, Jerzy Majka, Nanna Bjerregaard Pedersen, Daniel J. Burnett, Armando R. Garcia, Els Verdonck, Frieder Dreisbach, Louis Waguespack, Jennifer Schott, Luis G. Esteban, Alberto Garcia-Iruela, Thibaut Colinart, Romain Remond, Brahim Mazian, Patrick Perre, Lukas Emmerich, Ling Li
Interlaboratory Study Of The Operational Stability Of Automated Sorption Balances, Samuel L. Zelinka, Samuel V. Glass, Eleanor Q. D. Lazarcik, Emil E. Thybring, Michael Altgen, Lauri Rautkari, Simon Curling, Jinzhen Cao, Yujiao Wang, Tina Kunniger, Gustav Nystrom, Christopher Hubert Dreimol, Ingo Burgert, Mohd Khairun Anwar Uyup, Tumirah Khadiran, Mark G. Roper, Darren P. Broom, Matthew Schwarzkopf, Arief Yudhanto, Mohammad Subah, Gilles Lubineau, Maria Fredriksson, Marcin Strojecki, Wieslaw Olek, Jerzy Majka, Nanna Bjerregaard Pedersen, Daniel J. Burnett, Armando R. Garcia, Els Verdonck, Frieder Dreisbach, Louis Waguespack, Jennifer Schott, Luis G. Esteban, Alberto Garcia-Iruela, Thibaut Colinart, Romain Remond, Brahim Mazian, Patrick Perre, Lukas Emmerich, Ling Li
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Automated sorption balances are widely used for characterizing the interaction of water vapor with hygroscopic materials. These instruments provide an efficient way to collect sorption isotherm data and kinetic data. A typical method for defining equilibrium after a step change in relative humidity (RH) is using a particular threshold value for the rate of change in mass with time. Recent studies indicate that commonly used threshold values yield substantial errors and that further measurements are needed at extended hold times as a basis to assess the accuracy of abbreviated equilibration criteria. However, the mass measurement accuracy at extended times depends …
Iterative Correction Of Robotic Grinding Using Spatial Feedback For Precision Applications, Philip A. Olubodun, Joseph D. Fischer, Douglas A. Bristow
Iterative Correction Of Robotic Grinding Using Spatial Feedback For Precision Applications, Philip A. Olubodun, Joseph D. Fischer, Douglas A. Bristow
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Since the advent of robots, many tasks that were originally performed by humans have now been tasked to industrial robots. From a manufacturing standpoint, robots have primarily been used in pick-and-place or other non-machining operations that require high repeatability. However, with the increasing availability of CAD/CAM software and the development of high-precision metrology, comes the opportunity to integrate robots into a wider variety of manufacturing processes through the use of feedback control. One such machining operation that is being explored is precision grinding of metal parts. Most other work in this area has focused on force regulation to improve grind …
Wind Shear Induced Tornados With Full Thermodynamic Effects, Kakkattukuzhy M. Isaac
Wind Shear Induced Tornados With Full Thermodynamic Effects, Kakkattukuzhy M. Isaac
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Wind shear-induced Tornado behavior under full thermodynamic formulation using the ideal gas equation is investigated. The computational fluid dynamics model that includes the energy equation is used to obtain solutions of a natural-scale tornado under pressure and temperature boundary conditions that account for their variations vs. altitude in the atmosphere. The present results show significant differences from previous isothermal simulations and those using the Boussinesq model for buoyancy under small temperature differences. Results show that the downdraft observed in tornados originating from supercells, often accompanied by rain and hail can be captured using the present model that simulates the genesis, …
Promoting Synergies To Improve Manufacturing Efficiency In Industrial Material Processing: A Systematic Review Of Industry 4.0 And Ai, Md Sazol Ahmmed, Sriram Praneeth Isanaka, Frank Liou
Promoting Synergies To Improve Manufacturing Efficiency In Industrial Material Processing: A Systematic Review Of Industry 4.0 And Ai, Md Sazol Ahmmed, Sriram Praneeth Isanaka, Frank Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The manufacturing industry continues to suffer from inefficiency, excessively high prices, and uncertainty over product quality. This statement remains accurate despite the increasing use of automation and the significant influence of Industry 4.0 and AI on industrial operations. This review details an extensive analysis of a substantial body of literature on artificial intelligence (AI) and Industry 4.0 to improve the efficiency of material processing in manufacturing. This document includes a summary of key information (i.e., various input tools, contributions, and application domains) on the current production system, as well as an in-depth study of relevant achievements made thus far. The …
A Feedforward Kinematic Error Controller With An Angular Positioning Deviations Model For Backlash Compensation Of Industrial Robots, Mitchell R. Woodside, Tian Hao Cui, John Emelko, Soichi Ibaraki, Robert G. Landers, Douglas A. Bristow
A Feedforward Kinematic Error Controller With An Angular Positioning Deviations Model For Backlash Compensation Of Industrial Robots, Mitchell R. Woodside, Tian Hao Cui, John Emelko, Soichi Ibaraki, Robert G. Landers, Douglas A. Bristow
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The accuracy of industrial robots, typically on the order of several millimeters, has inhibited their adoption in advanced aerospace manufacturing applications, such as robotic machining. For this reason, extensive investigations have been conducted to develop solutions to improve their accuracy. These solutions can be categorized into offline and online compensation strategies, both of which have advantages and limitations. Offline compensation has been shown to improve the accuracy of industrial robots by two to three orders of magnitude; however, the sensitivity of these solutions to environmental changes and external disturbances can degrade their performance. In contrast, online compensation, which utilizes real-time …
Impact-Free Gaits For Planar Bipeds: Changing Walking Speed And Gait, Aakash Khandelwal, Nilay Kant, Ranjan Mukherjee
Impact-Free Gaits For Planar Bipeds: Changing Walking Speed And Gait, Aakash Khandelwal, Nilay Kant, Ranjan Mukherjee
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The problems of changing the walking speed and stride length of impact-free gaits for point-foot planar bipeds are addressed. The impact-free gaits are designed using an approach developed in prior work. It is shown that the impulse controlled Poincaré map (ICPM) approach can be modified to transition between orbits defining gaits with different walking speeds, and the continuous controller can be changed during the swing phase to transition between gaits that have distinct stride lengths. The effectiveness of the approaches is demonstrated using simulations carried out on a five-link biped.
Boosting Predictive Accuracy Of Single Particle Models For Lithium-Ion Batteries Using Machine Learning, Emmanuel Olugbade, Jonghyun Park
Boosting Predictive Accuracy Of Single Particle Models For Lithium-Ion Batteries Using Machine Learning, Emmanuel Olugbade, Jonghyun Park
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The accuracy of single particle (SP) models for lithium-ion batteries at high C-rates is constrained by lithium concentration gradients in the electrolyte, which affect ionic conductivity, overpotential, and reaction rates. This study addresses these limitations using extreme gradient boosting machine learning (ML). By training our ML model with data from a comprehensive electrochemical (P2D) model and performing sensitivity analysis on key battery parameters, we enhance predictive accuracy. Compared to conventional SP and P2D models under constant current loading, our ML-based SP model achieves similar predictive accuracy to P2D, with significant improvements in computational efficiency. Additionally, the ML-based SP model demonstrates …
A Robust Recurrent Neural Networks-Based Surrogate Model For Thermal History And Melt Pool Characteristics In Directed Energy Deposition, Sung Heng Wu, Usman Tariq, Ranjit Joy, Muhammad Arif Mahmood, Asad Waqar Malik, Frank Liou
A Robust Recurrent Neural Networks-Based Surrogate Model For Thermal History And Melt Pool Characteristics In Directed Energy Deposition, Sung Heng Wu, Usman Tariq, Ranjit Joy, Muhammad Arif Mahmood, Asad Waqar Malik, Frank Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In directed energy deposition (DED), accurately controlling and predicting melt pool characteristics is essential for ensuring desired material qualities and geometric accuracies. This paper introduces a robust surrogate model based on recurrent neural network (RNN) architectures—Long Short-Term Memory (LSTM), Bidirectional LSTM (Bi-LSTM), and Gated Recurrent Unit (GRU). Leveraging a time series dataset from multi-physics simulations and a three-factor, three-level experimental design, the model accurately predicts melt pool peak temperatures, lengths, widths, and depths under varying conditions. RNN algorithms, particularly Bi-LSTM, demonstrate high predictive accuracy, with an R-square of 0.983 for melt pool peak temperatures. For melt pool geometry, the GRU-based …
Ground Vacuum Facility To Simulate Low Earth Orbit Plasma Environment, Emmanuel Kofi Asuako Wie-Addo, Jacob Ortega, Daoru Han
Ground Vacuum Facility To Simulate Low Earth Orbit Plasma Environment, Emmanuel Kofi Asuako Wie-Addo, Jacob Ortega, Daoru Han
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper presents a large vacuum facility (6-ft-diameter, 10-ft-long chamber) equipped with a magnetic filter-type low Earth orbit plasma source. A recommended operating envelope for the plasma source was established through single-point measurements by varying the discharge currents of the plasma source and the gas flow rates. A three-axis translation stage was fabricated and tested with 2D and 3D scans of the simulated plasma environment. The measured plasma density during this study was between 1:63 x 1012 − 3:1 x 1012 m−3 for the electrons and 7:54 x 1012 − 1:82 x 1013 m−3 for the ions, whereas the electron …
Surrogate-Based Multidisciplinary Optimization For The Takeoff Trajectory Design Of Electric Drones, Samuel Sisk, Xiaosong Du
Surrogate-Based Multidisciplinary Optimization For The Takeoff Trajectory Design Of Electric Drones, Samuel Sisk, Xiaosong Du
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Electric vertical takeoff and landing (eVTOL) aircraft attract attention due to their unique characteristics of reduced noise, moderate pollutant emission, and lowered operating cost. However, the benefits of electric vehicles, including eVTOL aircraft, are critically challenged by the energy density of batteries, which prohibit long-distance tasks and broader applications. Since the takeoff process of eVTOL aircraft demands excessive energy and couples multiple subsystems (such as aerodynamics and propulsion), multidisciplinary analysis and optimization (MDAO) become essential. Conventional MDAO, however, iteratively evaluates high-fidelity simulation models, making the whole process computationally intensive. Surrogates, in lieu of simulation models, empower efficient MDAO with the …
Heat Treatment Post-Processing For The Improved Mechanical Properties Of Scalmalloy® Processed Via Directed Energy Deposition, Rachel Boillat-Newport, Sriram Praneeth Isanaka, Frank Liou
Heat Treatment Post-Processing For The Improved Mechanical Properties Of Scalmalloy® Processed Via Directed Energy Deposition, Rachel Boillat-Newport, Sriram Praneeth Isanaka, Frank Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
As high-strength aluminum alloys present several processability issues with additive manufacturing (AM), Scalmalloy®, an Al-Mg-Sc-Zr-based alloy, has been developed. This alloy is age-hardenable, allowing it to precipitate out a strengthening precipitate phase, Al3(Sc,Zr). The manufacturer recommends a single-stage aging treatment at 325 °C for 4 h; however, the majority of the literature studies utilize a powder bed processing known as selective laser melting (SLM) over powder-fed processing directed energy deposition (DED). This study addresses the lack of information on heat treatments for DED fabrication by exploring the application of artificial aging temperatures of 300–400 °C for 2, 4, and 6 …
Modeling Powder Spreadability In Powder-Based Processes Using The Discrete Element Method, Austin T. Sutton, M. Hossein Sehhat, Ming C. Leu, Joseph W. Newkirk
Modeling Powder Spreadability In Powder-Based Processes Using The Discrete Element Method, Austin T. Sutton, M. Hossein Sehhat, Ming C. Leu, Joseph W. Newkirk
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Powder-bed fusion (PBF) processes refer to a subset of Additive Manufacturing (AM) techniques where powder is spread on the build-plate before melting (by a laser or electron beam). While PBF processes are attractive due to their ability for realizing complex structures that are either difficult or impossible to create through conventional means, the parts fabricated with these techniques can exhibit defects such as pores, inclusions, and excessive surface roughness. To minimize these defects, much research has been dedicated towards process maturation by optimizing laser or electron beam parameters. However, these developmental efforts typically do not address the recoating process where …
A Study Of Directionality Effects In Three-Beam Coaxial Titanium Wire-Based Laser Metal Deposition, Remy Mathenia, Braden Mclain, Todd Sparks, Frank Liou
A Study Of Directionality Effects In Three-Beam Coaxial Titanium Wire-Based Laser Metal Deposition, Remy Mathenia, Braden Mclain, Todd Sparks, Frank Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Coaxial wire-based laser metal deposition is a versatile and efficient additive process that can achieve a high deposition rate in the manufacturing of complex structures. In this paper, a three-beam coaxial wire system is studied, with particular attention given to the effects of the deposition direction and laser beam orientation on the resulting bead geometry symmetry. With the three-beam laser delivery, the laser spot pattern is not always symmetric with respect to the deposition direction. Single titanium beads are deposited in different directions and at varying deposition rates, and the bead profile is quantitatively scored for multiple symmetry measures. Through …
Analytical And Fem Models For Thermal Analysis And Residual Stresses Using Wire Arc-Based Welding And Additive Manufacturing Of Sus304, Muhammad Arif Mahmood, Usman Tariq, Mihai Oane, Frank Liou
Analytical And Fem Models For Thermal Analysis And Residual Stresses Using Wire Arc-Based Welding And Additive Manufacturing Of Sus304, Muhammad Arif Mahmood, Usman Tariq, Mihai Oane, Frank Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Austenitic stainless steel, also known as SUS304, has a wide industrial application. The resultant residual stresses and deformation due to arc welding play a critical role in an in-service SUS04 part failure. Various experimental studies have been presented to predict residual stresses and part deformation. However, these techniques are expensive and time-consuming owing to the trial-and-error approach, limiting their application to industrial applications. Based on the emergent need, this study introduces two simulation models based on analytical and FEM techniques for thermal distribution and residual stress estimation. The experimentally calibrated models results have been implemented for SUS304 multi-pass arc welding. …
Python Tooth–Inspired Fixation Device For Enhanced Rotator Cuff Repair, Iden Kurtaliaj, Ethan D. Hoppe, Yuxuan Huang, David Ju, Jacob A. Sandler, Donghwan Yoon, Lester J. Smith, Silvio Torres Betancur, Linda Effiong, Thomas Gardner, Liana Tedesco, Sohil Desai, Victor Birman, William N. Levine
Python Tooth–Inspired Fixation Device For Enhanced Rotator Cuff Repair, Iden Kurtaliaj, Ethan D. Hoppe, Yuxuan Huang, David Ju, Jacob A. Sandler, Donghwan Yoon, Lester J. Smith, Silvio Torres Betancur, Linda Effiong, Thomas Gardner, Liana Tedesco, Sohil Desai, Victor Birman, William N. Levine
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Rotator cuff repair surgeries fail frequently, with 20 to 94% of the 600,000 repairs performed annually in the United States resulting in retearing of the rotator cuff. The most common cause of failure is sutures tearing through tendons at grasping points. To address this issue, we drew inspiration from the specialized teeth of snakes of the Pythonoidea superfamily, which grasp soft tissues without tearing. To apply this nondamaging gripping approach to the surgical repair of tendon, we developed and optimized a python tooth–inspired device as an adjunct to current rotator cuff suture repair and found that it nearly doubled repair …
Infrared Phase-Change Chiral Metasurfaces With Tunable Circular Dichroism, Haotian Tang, Liliana Stan, David A. Czaplewski, Xiaodong Yang, Jie Gao
Infrared Phase-Change Chiral Metasurfaces With Tunable Circular Dichroism, Haotian Tang, Liliana Stan, David A. Czaplewski, Xiaodong Yang, Jie Gao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Integrating Phase-Change Materials in Meta surfaces Has Emerged as a Powerful Strategy to Realize Optical Devices with Tunable Electromagnetic Responses. Here, Phase-Change Chiral Meta surfaces based on GST-225 Material with the Designed Trapezoid-Shaped Resonators Are Demonstrated to Achieve Tunable Circular Dichroism (CD) Responses in the Infrared Regime. the Asymmetric Trapezoid-Shaped Resonators Are Designed to Support Two Chiral Plasmonic Resonances with OppositeCDresponses for Realizing SwitchableCDbetween Negative and Positive Values using the GST Phase Change from Amorphous to Crystalline. the Electromagnetic Field Distributions of the Chiral Plasmonic Resonant Modes Are Analyzed to Understand the Chiroptical Responses of the Meta surface. Furthermore, the …
Transfer-Learning-Enhanced Regression Generative Adversarial Networks For Optimal Evtol Takeoff Trajectory Prediction, Shuan Tai Yeh, Xiaosong Du
Transfer-Learning-Enhanced Regression Generative Adversarial Networks For Optimal Evtol Takeoff Trajectory Prediction, Shuan Tai Yeh, Xiaosong Du
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Electric vertical takeoff and landing (eVTOL) aircraft represent a crucial aviation technology to transform future transportation systems. The unique characteristics of eVTOL aircraft include reduced noise, low pollutant emission, efficient operating cost, and flexible maneuverability, which in the meantime pose critical challenges to advanced power retention techniques. Thus, optimal takeoff trajectory design is essential due to immense power demands during eVTOL takeoffs. Conventional design optimizations, however, adopt high-fidelity simulation models in an iterative manner resulting in a computationally intensive mechanism. In this work, we implement a surrogate-enabled inverse mapping optimization architecture, i.e., directly predicting optimal designs from design requirements (including …
Effects Of Process-Induced Defects On The Corrosion Of Additively Manufactured Stainless Steel 304l, Leila Saberi, Frank W. Liou, Mehdi Amiri
Effects Of Process-Induced Defects On The Corrosion Of Additively Manufactured Stainless Steel 304l, Leila Saberi, Frank W. Liou, Mehdi Amiri
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This Study Investigates the Impact of Process-Induced Defects Such as Gas Pores, Lack of Fusions, and Surface Roughness on Corrosion Behavior of Stainless Steel 304L (SS304L) Fabricated by Laser Powder Bed Fusion Additive Manufacturing. Specimens Are Printed with Optimized Process Parameters but Selected from Different Locations on the Build Plate. Parallel and Perpendicular Surfaces to the Build Direction Are Investigated and Compared with Corrosion Properties of Wrought SS304L in 5 Wt% NaCl. the Results Reveal Significant Difference in Corrosion Behavior among Specimens Due to Variations in their Defect Features. Pitting Potential, Pit Initiation, and Growth Rates Are Found to Be …
Effect Of Pre-Heating On Residual Stresses And Deformation In Laser-Based Directed Energy Deposition Repair: A Comparative Analysis, Usman Tariq, Sung Heng Wu, Muhammad Arif Mahmood, Michael M. Woodworth, Frank W. Liou
Effect Of Pre-Heating On Residual Stresses And Deformation In Laser-Based Directed Energy Deposition Repair: A Comparative Analysis, Usman Tariq, Sung Heng Wu, Muhammad Arif Mahmood, Michael M. Woodworth, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser-Directed Energy Deposition (DED), a Metal Additive Manufacturing Method, is Renowned for its Role in Repairing Parts, Particularly When Replacement Costs Are Prohibitive. Ensuring that Repaired Parts Avoid Residual Stresses and Deformation is Crucial for Maintaining Functional Integrity. This Study Conducts Experimental and Numerical Analyses on Trapezoidal Shape Repairs, Validating Both the Thermal and Mechanical Models with Experimental Results. Additionally, the Study Presents a Methodology for Creating a Toolpath Applicable to Both the DED Process and Abaqus CAE Software. the Findings Indicate that Employing a Pre-Heating Strategy Can Reduce Residual Stresses by over 70% Compared to No Pre-Heating. However, Pre-Heating …
Experimental, Computational, And Machine Learning Methods For Prediction Of Residual Stresses In Laser Additive Manufacturing: A Critical Review, Sung Heng Wu, Usman Tariq, Ranjit Joy, Todd Sparks, Aaron Flood, Frank W. Liou
Experimental, Computational, And Machine Learning Methods For Prediction Of Residual Stresses In Laser Additive Manufacturing: A Critical Review, Sung Heng Wu, Usman Tariq, Ranjit Joy, Todd Sparks, Aaron Flood, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In recent decades, laser additive manufacturing has seen rapid development and has been applied to various fields, including the aerospace, automotive, and biomedical industries. However, the residual stresses that form during the manufacturing process can lead to defects in the printed parts, such as distortion and cracking. Therefore, accurately predicting residual stresses is crucial for preventing part failure and ensuring product quality. This critical review covers the fundamental aspects and formation mechanisms of residual stresses. It also extensively discusses the prediction of residual stresses utilizing experimental, computational, and machine learning methods. Finally, the review addresses the challenges and future directions …
Insight Into Uniform Filming Of Lif-Rich Interphase Via Synergistic Adsorption For High-Performance Lithium Metal Anode, Yufang He, Li Wang, Aiping Wang, Bo Zhang, Hiep Pham, Jonghyun Park, Xiangming He
Insight Into Uniform Filming Of Lif-Rich Interphase Via Synergistic Adsorption For High-Performance Lithium Metal Anode, Yufang He, Li Wang, Aiping Wang, Bo Zhang, Hiep Pham, Jonghyun Park, Xiangming He
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Multi-scale simulation is an important basis for constructing digital batteries to improve battery design and application. Lif-rich solid electrolyte interphase (sei) is experimentally proven to be crucial for the electrochemical performance of lithium metal batteries. However, the lif-rich sei is sensitive to various electrolyte formulas and the fundamental mechanism is still unclear. Herein, the structure and formation mechanism of lif-rich sei in different electrolyte formulas have been reviewed. On this basis, it further discussed the possible filming mechanism of lif-rich sei determined by the initial adsorption of the electrolyte-derived species on the lithium metal anode (lma). It proposed that individual …
Optimal Abort Guidance And Experimental Verification Based On Feature Learning, Vinay Kenny, Sixiong You, Chaoying Pei, Godfrey Hendrix, Roha Gul, Ran Dai, Jeremy Rea
Optimal Abort Guidance And Experimental Verification Based On Feature Learning, Vinay Kenny, Sixiong You, Chaoying Pei, Godfrey Hendrix, Roha Gul, Ran Dai, Jeremy Rea
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The abort mission refers to the mission where the landing vehicle needs to terminate the landing mission when an anomaly happens and be safely guided to the desired orbit. This paper focuses on solving the time-optimal abort guidance (TOAG) problem in real-time via the feature-based learning method. First, according to the optimal control theory, the features are identified to represent the optimal solutions of TOAG using a few parameters. After that, a sufficiently large data set of time-optimal abort trajectories is generated offline by solving the TOAG problems with different initial conditions. Then, the features are extracted for all generated …
Jet-Driven Mixing Regimes Identified In The Unsteady Isothermal Filling Of Rectangular Municipal Water Storage Tanks, Pramod Narayan Bangalore, K. (Kelly) O. Homan
Jet-Driven Mixing Regimes Identified In The Unsteady Isothermal Filling Of Rectangular Municipal Water Storage Tanks, Pramod Narayan Bangalore, K. (Kelly) O. Homan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Poor mixing of old and new water in municipal water storage vessels is a well-documented basis for potentially harmful water quality degradation in drinking water distribution systems. This numerical study investigates the effects of inflow and operational variables on mixing in the jet-driven filling process, with a particular focus on the transition from inadequate to sufficient mixing levels. An isothermal unsteady reynolds-averaged-navier-stokes volume-of-fluid (RANS-VOF) simulation is used to model the variable-volume filling process, accounting for the moving free surface following a draw-down in the stored water volume. A low diffusivity tracer is used to mark the old-water volume, and a …