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Creep-recovery deformation of 304 stainless-steel springs under low forces

Mechanics of materials 2024年 193卷

作者： Tsai, Ming-Yen Chang, Shou-Yi Zhang, Yulin Yang, Fuqian Lee, Sanboh Department of Materials Science and Engineering National Tsing Hua University Hsinchu300 Taiwan Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing400714 China Materials Program Department of Chemical and Materials Engineering University of Kentucky LexingtonKY40506 United States

The deformation behavior of materials at high temperatures determines the structural stability of mechanical structures under high-temperature service conditions. In this work, we prepare helical springs from 304 stainless-steel wires and study creep-recovery deformation of the helical springs under small forces at temperatures of 475–575 °C. In contrast to most methods reported in the literature, we use Kelvin representation of the Burgers model with a nonlinear dashpot in series connection to analyze the creep-recovery deformation of the helical springs and suggest the deformation mechanisms of the diffusion of interstitial atoms and dislocation generation/annihilation in transient creep and recovery of the helical springs under small forces. For the creep deformation, the stress exponent and activation energy for the plastic flow of the nonlinear dashpot are 2 and 57.8 kJ/mol, respectively, and the activation energy for the deformation flow of the linear dashpot is 41.8 kJ/mol. The nonlinear dashpot does not play any role in the recovery deformation, and the formation energy of defects for the recovery deformation of the helical springs is 51.4 kJ/mol. The approach used in this work provides a simple method to use a phenomenological model with a nonlinear dashpot to capture the power-law creep deformation of metallic materials. © 2024

关键词： Activation energy

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Wave propagation in meta-sandwich beams 16

Wave propagation in meta-sandwich beams

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Health Monitoring of Structural and Biological Systems XVI 2022

作者： Joubaneh, Eshagh Farzaneh Ma, Jihong Department of Mechanical Engineering University of Vermont BurlingtonVT05405 United States Materials Science Program University of Vermont BurlingtonVT05405 United States

ISBN: (数字)9781510649729

ISBN: (纸本)9781510649712

Acoustoelastic metamaterials are widely used as composite cores in sandwich beams. However, discussions on the application of metamaterials in face sheets have been sporadic. In this work, we parametrically explore the dynamic behaviors of sandwich beams with metamaterials as face sheets. In addition to the capability of phonon dispersion modulation using periodic face sheets, the relative positions of top and bottom face sheets can further break their spatial symmetry and thus opens more bandgaps that are not achievable with one-dimensional periodic beams. Our study has implications for the design of sandwich beams to mitigate damages induced by vibrations in various engineering and industrial applications. © 2022 SPIE

关键词： Metamaterials

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Insights into the Structural and Thermodynamic Instability of Ni-Rich NMC Cathode

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ACS Sustainable Chemistry and engineering 2023年第18期11卷 6978-6987页

作者： Tran, Ngoc Thanh Thuy Lin, Che-An Lin, Shih-Kang Research Center National Cheng Kung University Tainan701 Taiwan Department of Materials Science and Engineering National Cheng Kung University Tainan701 Taiwan Program on Smart and Sustainable Manufacturing Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan70101 Taiwan

The Ni-rich LiNi1-x-yMnxCoyO2 (NMC) layered oxides have been promising materials to replace the LiCoO2 commercial cathode due to their high operation voltages, low cost, and enhanced capacity. However, structural instability is the main drawback of the Ni-rich NMC system, leading to capacity fading, which prevents its commerce application. While numerous efforts have been made to comprehend and overcome this issue, there remains a lack of systematic phase stability analysis which is an essential factor to be addressed. Herein, systematic first-principles calculations were performed in this study to reveal the structural, oxidation, and phase stability of Ni-rich NMC during delithiation. This is the first report on competing phases of Ni-rich NMC at various states of charge (SoCs). The compounds with the spinel and rock salt structures formed during delithiation and oxygen evolution takes place at highly delithiation cases, which are likely the origins of capacity fading and crack formation at the surface. This work also outlined the thermodynamic foundation of doping and oxidation state gradient-based core-shell strategies for resolving the instability and enhancing the capacity retention of Ni-rich NMC layered oxides as cathode materials in Li-ion batteries. © 2023 American Chemical Society.

关键词： Cathodes

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Correlation between the Morphology of Carbon Nanofibers and the Transport Characteristics of Li-Ions in a Lib Anode Under Fast Charging Conditions

SSRN

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SSRN 2023年

作者： Cho, Hang In Lee, Sung Hoon Park, Chong Rae WCU Hybrid Materials Program Department of Materials Science and Engineering Research Institute of Advanced Materials Seoul National University Seoul08826 Korea Republic of

Energy storage materials for electric vehicles and energy storage systems must be able to supply high capacity quickly, which requires efficient Li-ion transport within the anode active material. The transport of Li ions through a battery system can lead to concentration polarization and subsequent overpotential, which can limit the electrochemical performance, especially under fast charging conditions. To overcome these limitations, it is important to control solvated Li-ion transport and design an anode material with a rational approach. One way to achieve this is by controlling the morphology of carbon nanofibers (CNFs) to create ion transport channels. A facile method for this was investigated using an immiscible polymer blend electrospinning system and interpreting a ternary phase diagram. The effects of the morphology and space characteristics of each CNF on the electrochemical performance were studied, particularly the rate capability and cycle stability under fast charging conditions. These characteristics were analyzed in terms of the transport properties of the electrochemical species in different types of ion channels. © 2023, The Authors. All rights reserved.

关键词： Electrospinning

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Optimising degradation and mechanical performance of additively manufactured biodegradable Fe–Mn scaffolds using design strategies based on triply periodic minimal surfaces

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Smart materials in Medicine 2024年第1期5卷 127-139页

作者： Dargusch, Matthew S. Soro, Nicolas Demir, Ali Gokhan Venezuela, Jeffrey Sun, Qiang Wang, Yuan Abdal-hay, Abdalla Alali, Aya Q. Ivanovski, Saso Previtali, Barbara Kent, Damon School of Mechanical and Mining Engineering The University of Queensland Advanced Engineering Building Bld 49 Staff House Rd St LuciaQLD4072 Australia Department of Mechanical Engineering Politecnico di Milano Via La Masa 1 Milan20156 Italy School of Dentistry The University of Queensland Herston Campus 4072 Australia Department of Engineering Materials and Mechanical Design Faculty of Engineering South Valley University Qena83523 Egypt Faculty of Industry and Energy Technology Mechatronics Technology Program New Cairo Technological University New Cairo - Fifth Settlement Cairo11835 Egypt School of Science Technology and Engineering University of the Sunshine Coast Maroochydore BCQLD4558 Australia

Additively manufactured lattices based on triply periodic minimal surfaces (TPMS) have attracted significant research interest from the medical industry due to their good mechanical and biomorphic properties. However, most studies have focussed on permanent metallic implants, while very little work has been undertaken on manufacturing biodegradable metal lattices. In this study, the mechanical properties and in vitro corrosion of selective laser melted Fe–35%Mn lattices based on gyroid, diamond and Schwarz primitive unit-cells were comprehensively evaluated to investigate the relationships between lattice type and implant performance. The gyroid-based lattices were the most readily processable scaffold design for controllable porosity and matching the CAD design. Mechanical properties were influenced by lattice geometry and pore volume. The Schwarz lattices were stronger and stiffer than other designs with the 42% porosity scaffold exhibiting the highest combination of strength and ductility, while diamond and gyroid based scaffolds had lower strength and stiffness and were more plastically compliant. The corrosion behaviour was strongly influenced by porosity, and moderately influenced by geometry and geometry-porosity interaction. At 60% porosity, the diamond lattice displayed the highest degradation rate due to an inherently high surface area-to-volume ratio. The biodegradable Fe–35Mn porous scaffolds showed a good cytocompatibility to primary human osteoblasts cells. Additive manufacturing of biodegradable Fe–Mn alloys employing TPMS lattice designs is a viable approach to optimise and customise the mechanical properties and degradation response of resorbable implants toward specific clinical applications for hard tissue orthopaedic repair. © 2023 The Authors

关键词： Porosity

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Oscillatory Hall effect from magnetoelectronic coupling in flexoelectronic silicon

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Physical Review B 2024年第8期109卷 L081113-L081113页

作者： Paul C. Lou Ravindra G. Bhardwaj Anand Katailiha W. P. Beyermann Sandeep Kumar Department of Mechanical Engineering University of California Riverside California 92521 USA Department of Physics and Astronomy University of California Riverside California 92521 USA Materials Science and Engineering Program University of California Riverside California 92521 USA

Magnetoelectronic coupling can be defined as cross-domain coupling between electronic and magnetic properties, where modulation in magnetic properties changes the electronic properties. In this Letter, explicit experimental evidence of magnetoelectronic coupling is presented, which is uncovered from the oscillatory Hall effect response in Hall measurement. The strain gradient in a MgO (1.8 nm)/p-Si (∼400 nm) freestanding sample leads to transfer of electrons (∼5×1018cm−3) from valence to conduction band due to flexoelectronic charge separation in the p-Si layer. The resulting flexoelectronic polarization gives rise to the temporal magnetic moment from dynamical multiferroicity. The external magnetic field changes the net temporal magnetic moment, which causes modulations in charge carrier concentration and oscillatory Hall effect. The period of oscillatory Hall response is 1.12 T, which is attributed to the magnitude of the temporal magnetic moment. The discovery of the oscillatory Hall effect adds another member to the family of Hall effects.

关键词： Hall effect Doped semiconductors Electronically polarized systems Flexoelectrics Multiferroics Hall bar

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The growing memristor industry

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Nature 2025年第8059期640卷 613-622页

作者： Lanza, Mario Pazos, Sebastian Aguirre, Fernando Sebastian, Abu Le Gallo, Manuel Alam, Syed M. Ikegawa, Sumio Yang, J. Joshua Vianello, Elisa Chang, Meng-Fan Molas, Gabriel Naveh, Ishai Ielmini, Daniele Liu, Ming Roldan, Juan B. Department of Materials Science and Engineering National University of Singapore Singapore Singapore Institute for Functional Intelligent Materials National University of Singapore Singapore Singapore Centre for Advanced 2D Materials (CA2DM) National University of Singapore Singapore Singapore Materials Science and Engineering Program Physical Science and Engineering Division King Abdullah University of Science and Technology (KAUST) Thuwal Saudi Arabia Intrinsic Semiconductor Technologies London United Kingdom IBM Research – Zurich Rüschlikon Switzerland Everspin Technologies Chandler AZ United States Department of Electrical and Computer Engineering University of Southern California Los Angeles CA United States CEA-Leti Université Grenoble Alpes Grenoble France Department of Electrical Engineering National Tsing Hua University Hsinchu Taiwan Weebit Nano Hod Hasharon Israel Dipartimento di Elettronica Informazione e Bioingegneria (DEIB) Politecnico di Milano and *** Milano Italy Key Laboratory of Microelectronic Devices and Integrated Technology Institute of Microelectronics Chinese Academy of Sciences Beijing China Departamento de Electrónica y Tecnología de Computadores Universidad de Granada Facultad de Ciencias Granada Spain

The semiconductor industry is experiencing an accelerated transformation to overcome the scaling limits of the transistor and to adapt to new requirements in terms of data storage and computation, especially driven by artificial intelligence applications and the Internet of Things. In this process, new materials, devices, integration strategies and system architectures are being developed and optimized. Among them, memristive devices and circuits—memristors are two-terminal memory devices that can also mimic some basic bioelectronic functions—offer a potential approach to create more compact, energy-efficient or better-performing systems. The memristor industry is growing quickly, raising abundant capital investment, creating new jobs and placing advanced products in the market. Here we analyse the status and prospects of the memristor industry, focusing on memristor-based products that are already commercially available, prototypes with a high technological readiness level that might affect the market in the near future, and discuss obstacles and pathways to their implementation. © Springer Nature Limited 2025.

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Autonomous Burrowing and Retrieval of Soft Robotic Anchors in Granular Media

Autonomous Burrowing and Retrieval of Soft Robotic Anchors i...

引用

IEEE International Conference on Soft Robotics (RoboSoft)

作者： Dongting Li Michael T. Tolley Nick Gravish Department of Mechanical and Aerospace Engineering University of California San Diego (UCSD) CA USA Materials Science and Engineering Program University of California San Diego CA USA

ISBN: (数字)9798331520205

ISBN: (纸本)9798331520212

Vertical digging into and out of granular media is a challenging task for autonomous systems. Granular media present considerable resistance to vertical penetration due to the high friction forces and large pressure at depths. In this paper, we present a soft robot that is capable of digging into and out of granular media to depths over 10× its body length. Our robot incorporates a vibration motor to locally fluidize the granular media for burrowing, and a soft pneumatic actuator to adjust the volume and hence the density of the robot, allowing it to transition from digging down to digging up. To analyze the performance of the robot, we measure its weight and density, track its location using a motion capture system, and investigate the effect of local fluidization. When the robot is buried and inflated with vibration turned off, it can increase its passive anchoring force by 5.22× (up to 35 N) relative to when the robot is deflated with vibration on. By contrast, by inflating the soft pneumatic bladder and providing vibration the robot is able to actively unburrow.

关键词： Vibrations Weight measurement Pneumatic actuators Tracking Pneumatic systems Media Soft robotics Motors Motion capture Immune system

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Fabrication of Zn-Ni Alloy Columns with Low Hydrogen Evolution Overpotential as Efficient Electrocatalyst for H2 Production

Fabrication of Zn-Ni Alloy Columns with Low Hydrogen Evoluti...

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IEEE Conference on Nanotechnology

作者： Yao-Tien Tseng Russell Clemente Jing-Chie Lin Institute of Materials Science and Engineering National Central University Taoyuan Taiwan International Master Program in Applied Materials Science National Central University Taoyuan Taiwan

In this study, steric Zn-Ni alloy columns were fabricated via microanode-guided electroplating (MAGE), which had a very small electrode gap (90 µm) and a very high deposition rate (> 2 µm/min). These microcolumns were used to produce hydrogen by the electrocatalytic decomposition of water in alkaline aqueous solutions of 1 M KOH. The surface morphology study was acquired via the SEM, and after numerous electrocatalytic reactions, the porous structure of the Zn-Ni alloy progressively developed on the surface. The amount of zinc present in the alloy fell from 91 at. % to 52 at. %, which resulted in the column diameter of Zn-Ni increasing from 248 to 300 µm. After conducting an XRD investigation, the primary structure of the Zn-Ni alloy microcolumn was determined to be that of an intermetallic compound belonging to the Zn-Ni series. The phases shifted from Ni 3 Zn 22 to Ni 2 Zn 11 and NiZn 3 when the percentage of zinc in the alloy decreased from 91 to 52 at. %. The results of the linear sweep voltammetry showed that the Zn-Ni alloy microcolumns exhibited good hydrogen production efficiency at 13–24 at.% Ni, the lowest Tafel slope of 45 mV/dec, and only 36 mV overpotential when operating at 10 mA/cm 2 current density. Because of the enormous number of nano-networked nickel hydroxide on the surface that was investigated by TEM, the excellent efficiency with which hydrogen was produced can be attributed to the fact that this resulted in a significant increase in the amount of electrochemical surface area available.

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Vibrational entropies of oxygen vacancy formation in metal oxides

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Physical Review materials 2024年第5期8卷 055407-055407页

作者： Bianca Baldassarri Jiangang He Christopher Wolverton Graduate Program in Applied Physics Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA

Oxygen vacancies play a key role in many energy-related applications, and the investigation of the thermodynamic forces driving their formation across different materials can be tackled through the use of ab initio methods. In this context, however, computational studies targeting finite-temperature properties such as entropy remain scarce. Wider-ranging studies are of interest to deepen the understanding of the role of the entropy of oxygen vacancy formation and its different components in processes like the ones involved in solar thermochemical hydrogen (STCH) production, and to investigate the existence of common trends and differences between materials. In this work, we use density functional theory and harmonic phonon calculations to compute the vibrational entropy of oxygen vacancy formation (ΔSvib) for 10 different metal oxide compounds. The computation is carried out by taking the difference between the vibrational entropy of a vacancy-containing and a pristine structure, while the entropic contribution from the final gaseous state of the oxygen lost from the material is accounted for separately with a gas entropy term. We first examine the temperature dependence of ΔSvib and highlight the presence of an initial peak around room temperature, followed by a steady decrease resulting from the presence of an additional O atom (the one becoming vacant) in the defect-free structure. We then inspect the atomic contributions to ΔSvib, and highlight similarities and differences between compounds. Finally, we consider other significant sources of entropy, and find ΔSvib to provide a smaller, yet non-negligible, contribution to the total entropy of vacancy formation. We also compare the temperature dependence of ΔSvib to that of the gas entropy, and show that the two largely counterbalance each other at high temperatures.

关键词： Entropy Hydrogen production Density functional theory

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