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arXiv 2023年

作者： margha, Lubna Hamada, Ahmed A. Eltaweel, Ahmed Department of Ocean Engineering Texas A&M University College StationTX77843 United States Department of Aeronautical and Aerospace Engineering Cairo University Giza12613 Egypt Aerospace Engineering Program University of Science and Technology - Zewail City Giza12578 Egypt

The design of supersonic and hypersonic air-breathing vehicles is influenced by the transition between the mach Reflection (mR) and Regular Reflection (RR) phenomena. The purpose of this study is to investigate the dynamic transition of unsteady supersonic flow from mR to RR over a two-dimensional wedge numerically. The trailing edge of the wedge moves downstream along the x-direction with a velocity, V(t) at a free-stream mach number of 3. An unsteady compressible inviscid flow solver is used to simulate the phenomenon. Further, the Arbitrary Lagrangian-Eulerian (ALE) technique is applied to deform the mesh during the wedge motion. The dynamic transition from mR to RR is defined by two criteria, the sonic and the Von-Neumann. moreover, the lag in the dynamic transition from the steady-state condition is studied using various non-dimensional angular velocities, κ, in the range of [0.1-2]. The lag effect in the shock system is remarkable at the high values of the non-dimensional angular velocity, κ = 1.5 and 2.0. Furthermore, because the shock is bent upstream during the fast motion of the wedge, the transition from mR to RR happens below the Dual Solution Domain (DSD). © 2023, CC BY.

关键词： Shock waves

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Cracking Prediction at Solid-Tooth Support Interface During Laser Powder Bed Fusion Additive manufacturing

SSRN

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SSRN 2023年

作者： To, Albert C. Tran, Hai T. J. Mike Walker’66 Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Department of Mechanical Engineering and Materials Science University of Pittsburgh PittsburghPA15261 United States

Cracking resulted from residual stress at the solid-tooth support interface frequently occurs in laser powder bed fusion (LPBF) metallic additive manufacturing, and thus it is critical to predict possible cracking and design the support to prevent it. This study employs a combination of computational methods and experiments to predict cracking at the interface and, for the first time, determine the relationship between the critical J-integral and the contact area of the solid-tooth support interface. In particular, the finite element method-based global-local approach is used to perform the modified inherent strain analysis with homogenized material for the entire part (global), which is followed by the fracture mechanics-based J-integral analysis at conjectured vulnerable locations (local). Both numerical and experimental validations are conducted showing that the local-global approach is both accurate and efficient in crack prediction at the interface between the solid and the tooth support in as-built LPBF printed metals. It is found that given the same basic tooth unit design in the support structure, the critical J-integral increases at an approximate linear slope of 2 with local contact area percentage (~20-40%) at the solid-support interface. These results will enable support designers the flexibility to design the support contact area to prevent solid-tooth support cracking while ensuring the ease of support removal. © 2023, The Authors. All rights reserved.

关键词： 3D printing

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High-Throughput Exploration of the WmoVTaNbAl Refractory multi-Principal Element Alloys Under multiple-Property Constraints

SSRN

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SSRN 2023年

作者： Vela, Brent Acemi, Cafer Singh, Prashant Kirk, Tanner Trehern, William Norris, Eli Johnson, Duane D. Karaman, Ibrahim Arroyave, Raymundo Department of Materials Science and Engineering Texas A&M University College StationTX77843 United States Ames National Laboratory U.S. Department of Energy AmesIA50011 United States Department of Materials Science & Engineering Iowa State University AmesIA50011 United States

The development of next-generation gas turbines requires the design and fabrication of novel high-temperature structural materials capable of operating beyond 1300°C. Here we propose a computational high-throughput alloy design framework under multiple-property constraints to discover new refractory mPEAs for high-temperature applications. The framework treats the development of mPEAs as a composition-agnostic constraint satisfaction problem, i.e., no prescriptions are made concerning the design space before performing investigatory calculations. With this framework, we target alloys in the WmoVTaNbAl chemistry space that are predicted to meet constraints on the following properties simultaneously: single-phase stability, density, solidus temperature, yield strength at 1300°C, and ductile-to-brittle-transition temperature. These properties are relevant to both applications in gas turbines and manufacturability. A set of 214 moNbV-rich alloys meet these relevant constraints. These feasible alloys are investigated with density functional theory (DFT) to provide a fundamental electronic basis for their superior properties. Three compositionally representative alloys from the feasible design space (mo45Nb35Ta5V15, mo25Nb50V20W5, and mo30Nb35Ta5V25W5) are selected with a k-medoids-based design scheme for detailed DFT analysis and experimental characterization. The DFT analysis predicted a single-phase BCC at high temperatures with a high yield strength for all three mPEAs, in agreement with CALPHAD and experiments, respectively. These three alloys are benchmarked against a public database of 1546 mPEAs. Concerning the aforementioned constraints, the mo30Nb35Ta5V25W5 alloy outperforms these 1546 mPEAs. The present work demonstrates the ability of the proposed design methodology to identify candidate alloys for a given application under multiple property constraints in a combinatorically vast design space. © 2023, The Authors. All rights reserved.

关键词： Niobium alloys

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Assessment of ATH-Filled Silicone Rubber Under DC Dry Band Arcing

Assessment of ATH-Filled Silicone Rubber Under DC Dry Band A...

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International middle-East Power System Conference, mEPCON

作者： Basharat mehmood Refat Ghunem Ayman El-Hag mohammad K. Hassan Leena Al-Sulaiti Ahmed Abdala Electrical & Computer Engineering Department University of Waterloo 200 University Avenue W Waterloo ON Metrology Research Center National Research Council of Canada (NRC) Ottawa ON Center for Advanced Materials Qatar University Chemical Engineering Program Texas A&M University at Qatar Doha Qatar

This paper investigates the tracking and erosion performance of silicone rubber filled with alumina trihydrate under DC dry band arcing in the inclined plane tracking and erosion test (IPT). Alumina trihydrate is incorporated into silicone rubber at 50 wt.% loading level for preparing silicone rubber composites, which are exposed to DC dry band arcing under mild and severe voltage levels in the inclined plane tracking and erosion test. Test outcomes indicate that the mechanism of silicone rubber deterioration changes with respect to the severity of the DC dry band arcing. It is found that dry band arcing tends to stimulate surface tracking under mild voltage levels and erosion due to thermal degradation under relatively higher voltage levels (critical). moreover, test results indicate that silicone rubber erosion is not solely influenced by the dry band arcing power derived from the leakage current, but also dependent on additional contributing mechanisms leading to elevated surface temperatures and severe erosion.

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Restoration of Gas Dynamics on Laser Filamentation at High Repetition Rates

Restoration of Gas Dynamics on Laser Filamentation at High R...

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CLEO: QELS_Fundamental science, QELS 2022

作者： Koulouklidis, Anastasios D. Lanara, Christina Fedorov, Vladimir Yu. Tzortzakis, Stelios Institute of Electronic Structure and Laser FORTH Crete Heraklion70013 Greece Department of Materials Science and Technology University of Crete Crete Heraklion70013 Greece Science Program Texas A&M University at Qatar P.O. Box 23874 Doha Qatar P.N. Lebedev Physical Institute The Russian Academy of Sciences 53 Leninskiy Prospekt Moscow119991 Russia

We demonstrate that thermal effects limiting femtosecond laser filamentation in gases can be addressed using a simple gas replenishment method. This enables high average power filamentation applications like THz sourc... 详细信息

ISBN: (纸本)9781557528209

关键词： Gas dynamics

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Efficient machine-learning model for fast assessment of elastic properties of high-entropy alloys

arXiv

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arXiv 2022年

作者： Vazquez, Guillermo Singh, Prashant Sauceda, Daniel Couperthwaite, Richard Britt, Nicholas Youssef, Khaled Johnson, Duane D. Arróyave, Raymundo Department of Materials Science and Engineering Texas A&M University College StationTX77843 United States Ames Laboratory U.S. Department of Energy Iowa State University AmesIA50011 United States Materials Science & Technology Qatar University Doha Qatar Department of Materials Science & Engineering Iowa State University AmesIA50011 United States Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Department of Industrial and Systems Engineering Texas A&M University College StationTX77843 United States

We combined descriptor-based analytical models for stiffness-matrix and elastic-moduli with mean-field methods to accelerate assessment of technologically useful properties of high-entropy alloys, such as strength and ductility. model training for elastic properties uses Sure-Independence Screening (SIS) and Sparsifying Operator (SO) method yielding an optimal analytical model, constructed with meaningful atomic features to predict target properties. Computationally inexpensive analytical descriptors were trained using a database of the elastic properties determined from density functional theory for binary and ternary subsets of Nb-mo-Ta-W-V refractory alloys. The optimal Elastic-SISSO models, extracted from an exponentially large feature space, give an extremely accurate prediction of target properties, similar to or better than other models, with some verified from existing experiments. We also show that electronegativity variance and elastic-moduli can directly predict trends in ductility and yield strength of refractory HEAs, and reveals promising alloy concentration regions. Copyright © 2022, The Authors. All rights reserved.

关键词： High-entropy alloys

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Two-Fold Anisotropic Superconductivity in Bilayer Td-moTe2

arXiv

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arXiv 2024年

作者： Li, Zizhong Jindal, Apoorv Strasser, Alex He, Yangchen Zheng, Wenkai Graf, David Taniguchi, Takashi Watanabe, Kenji Balicas, Luis Dean, Cory R. Qian, Xiaofeng Pasupathy, Abhay N. Rhodes, Daniel A. Department of Materials Science and Engineering University of Wisconsin-Madison MadisonWI53706 United States Department of Physics Columbia University New YorkNY10027 United States Department of Materials Science and Engineering Texas A&M University College StationTX77843 United States National High Magnetic Field Laboratory TallahasseeFL32310 United States National Institute for Materials Science Tsukuba Japan Department of Physics Florida State University TallahasseeFL32306 United States

Noncentrosymmetric 2D superconductors with large spin-orbit coupling offer an opportunity to explore superconducting behaviors far beyond the Pauli limit. One such superconductor, few-layer Td-moTe2, has large upper critical fields that can exceed the Pauli limit by up to 600%. However, the mechanisms governing this enhancement are still under debate, with theory pointing towards either spin-orbit parity coupling or tilted Ising spin-orbit coupling. moreover, ferroelectricity concomitant with superconductivity has been recently observed in the bilayer, where strong changes to superconductivity can be observed throughout the ferroelectric transition pathway. Here, we report the superconducting behavior of bilayer Td-moTe2 under an in-plane magnetic field, while systematically varying magnetic field angle and out-of-plane electric field strength. We find that superconductivity in bilayer moTe2 exhibits a two-fold symmetry with an upper critical field maxima occurring along the b-axis and minima along the a-axis. The two-fold rotational symmetry remains robust throughout the entire superconducting region and ferroelectric hysteresis loop. Our experimental observations of the spin-orbit coupling strength (up to 16.4 meV) agree with the spin texture and spin splitting from first-principles calculations, indicating that tilted Ising spin-orbit coupling is the dominant underlying mechanism. Copyright © 2024, The Authors. All rights reserved.

关键词： Ferroelectricity

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Deep Eutectic Solvents: A New Class of Versatile Liquids

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JOURNAL OF PHYSICAL CHEmISTRY B 2020年第50期124卷 11313-11315页

作者： Gurkan, Burcu E. maginn, Edward J. Pentzer, Emily B. Department of Chemical and Biomolecular Engineering Case Western Reserve University Department of Chemical and Biomolecular Engineering University of Notre Dame Department of Chemistry and Department of Materials Science and Engineering Texas A&M University

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NGenE 2022: Electrochemistry for Decarbonization

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ACS ENERGY LETTERS 2023年第1期8卷 740-747页

作者： Cabana, Jordi Alaan, Thomas Crabtree, George W. Huang, Po-Wei Jain, Akash murphy, megan N'Diaye, Jeanne Ojha, Kasinath Agbeworvi, George Bergstrom, Helen Gersib, Simon Harb, Hassan Stejer, Adrien Quiles-Galarza, Genesis Rodriguez, Oliver Caruso, Isabella Goncalves, Josue m. Chen, Grace Y. Fernandez, Carlos A. Pan, Hanqing Ritter, Kabian Yang, Yingjie Zhang, Haozhe Garcia-Alvarez, Ana Cristina Ilic, Stefan Kumar, Khagesh Silcox, Rachel Yao, Yu Song, Hakhyeon Stoyanov, Stoyan Saraf, mohit Chen, Celine H. Subasinghe, S. m. Supundrika Gomes, Reginaldo Lang, Shuangyan murphy, Eamonn Thind, Arashdeep Singh Zheng, Yu Department of Chemistry University of Illinois at Chicago Chicago Illinois 60607 United States Department of Physics University of Illinois at Chicago Chicago Illinois 60607 United States Joint Center for Energy Storage Research Argonne National Laboratory Lemont Illinois 60439 United States School of Chemical & Biomolecular Engineering Georgia Institute of Technology Atlanta Georgia 30332 United States Materials Science Division Argonne National Laboratory Lemont Illinois 60439 United States Department of Chemistry Beckman Institute for Advanced Science University of Illinois at Urbana−Champaign Urbana−Champaign Urbana Illinois 61801 United States Department of Chemistry and Biochemistry University of Oregon Eugene Oregon 97403-1253 United States Department of Chemistry Texas A&M University College Station Texas 77843-3255 United States Department of Chemical and Biomolecular Engineering University of California Berkeley California 94720 United States Department of Chemical and Biomolecular Engineering University of California Irvine California 92697 United States Department of Chemical and Biomolecular Engineering University of Pennsylvania Philadelphia Pennsylvania 19104 United States Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 United States Department of Mechanical and Industrial Engineering University of Illinois at Chicago Chicago Illinois 60607 United States Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena California 91125 United States George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 United States Department of Chemistry University of Nevada Reno Nevada 89557 United States Department of Chemistry University of California Davis Davis California 95616 United States Pritzker School of Molecular Engineering The University of Chicago Chicago Illinois 60637 United State

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The Origin and Control of Interstitial Impurities in Refractory Complex Concentrated Alloys

SSRN

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SSRN 2024年

作者： Belcher, Calvin Harris Kamp, Daisy To, Sydney Lu, Yemao Chassaing, Delphine Boll, Torben macDonald, Benjamin E. Lee, Elizabeth m.Y. Apelian, Diran Lavernia, Enrique J. Department of Materials Science and Engineering University of California Irvine IrvineCA92617 United States Karlsruhe Nano Micro Facilities Karlsruhe Institute for Technology Karlsruhe76131 Germany Department of Materials Science and Engineering J. Mike Walker’66 Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Department of Chemical and Biomolecular Engineering University of California Irvine IrvineCA92617 United States

Interstitial impurities, primarily O and N, inadvertently introduced during processing of refractory complex concentrated alloys (RCCAs) significantly limit the mechanical properties of the alloys at room temperature. Plasma arc melting (PAm) has facilitated the quest for RCCAs showcasing remarkable combinations of strength and ductility. In this work, the composition and chemistry of residual gases in the PAm chamber environment during arc melting and the interstitial impurities in elemental feedstocks were analyzed to quantify the origin of O and N during synthesis. moreover, the thermodynamic mechanisms governing the absorption of interstitial impurities were investigated in arc-melted moNbTaW RCCAs. To control the thermodynamic drive for the absorption of interstitial impurities during PAm, an H2-rich reducing environment was also studied. The arc-melted moNbTaW RCCAs were then characterized using electron microscopy and atom probe tomography to establish the compositional architecture of grain boundaries and thereby elucidate the thermodynamic drive for segregation and oxide formation in moNbTaW. Additionally, density functional theory calculations of a moNbTaW grain boundary were employed to analyze the effect of local chemical fluctuations on the O segregation and oxide formation at the grain boundary. This quantification of the thermodynamics of absorption and grain boundary embrittlement in moNbTaW RCCAs provides a fundamental understanding of O interactions in RCCAs, which is key for the successful development of refractory alloys with unique combinations of strength and ductility. © 2024, The Authors. All rights reserved.

关键词： Density functional theory

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