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Scalable and shapable nacre-like ceramic-metal composites based on deformable microspheres

National science Review 2025年第3期12卷 338-346页

作者： Yu-Jie Lu Xiang-Sen Meng Qiu-An Sun Jie Wang Jun-Jie Song Peng-Fei Wang Guo-Rui Wang Cheng-Xin Yu Yong-Sheng Zhang Li-Bo Mao Shu-Hong Yu Department of Chemistry New Cornerstone Science Laboratory Institute of Biomimetic Materials & Chemistry Anhui Engineering Laboratory of Biomimetic Materials Division of Nanomaterials & Chemistry Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Department of Modern Mechanics CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Institute of Innovative Materials Department of Materials Science and Engineering Department of Chemistry Southern University of Science and Technology

Natural nacre that consists of brittle minerals and weak organics exhibits a high fracture toughness while retaining a high strength. The exceptional mechanical performance of nacre is attributed to its hierarchical structure like a ‘brick-and-mortar' structure, which has inspired the development of tough ceramic-based composites. However, the practical applications of biomimetic structural ceramics are hindered by limited material size, fabrication efficiency and flexibility of being molded into various shapes. We herein report the fabrication of nacre-like ceramic-metal composites based on deformable alumina microspheres coated with nickel salt. Green bodies are produced by assembling the composite microspheres in molds with different shapes. During the hot-pressing sintering of the green bodies, the microspheres are flattened into platelets under pressure and fill up the entire space without visible voids. The aligned platelets are separated by nickel that is reduced from the nickel salt on their surface, constituting a typical ‘brick-and-mortar' structure. By tuning the microsphere sizes, the microstructures of the composites can be optimized to obtain a high flexural strength（386 MPa at room temperature and 286.86 MPa at 600°C） and a high fracture toughness(12.76 MPa·m1/2at room temperature and 12.99 MPa·m1/2at 600°C) simultaneously. This strategy opens a promising avenue for the feasible mass production and all-in-one molding of nacre-like ceramic-metal composites with various shapes, sizes and raw materials.

关键词： ceramic-metal composites biomimetic materials nacre-like structures scalable and shapable properties tough and strong

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Strengthening mechanism and forming control of linear friction welded GH4169 alloy joints

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Chinese Journal of Aeronautics 2024年第4期37卷 609-626页

作者： Yu SU Xiawei YANG Tingxi MENG Xinyuan HE Dong WU Wenya LI Shuo YIN State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Friction Welding Technologies School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Department of Mechanical Manufacturing and Biomedical EngineeringParsons BuildingTrinity College DublinThe University of DublinDublin 2Ireland

Numerical simulation and experimental research on Linear Friction Welding(LFW) for GH4169 superalloy were carried out. Based on the joint microstructure and mechanical properties,a suitable welding process was determined, which provided an important theoretical basis for the manufacture and repair of aeroengine components such as the superalloy blisk. The results show that the joint strain rate gradually increases with the increase of welding frequency, and the deformation resistance of the thermoplastic metal increases in the welding process, resulting in the interface thermoplastic metal not being extruded in time to form a flash, so the joint shortening amount gradually decreases. The thermoplastic metal in the center of the welding surface is kept at high welding temperature for a long time, resulting in the decrease of the joint strength. The microhardness of the joint shows a “W” distribution perpendicular to the weld, and most of the joints break in the Thermo-mechanically Affected Zone(TMAZ) with high tensile strength and low *** the welding area is increased without changing the aspect ratio of the welding surface, the interface peak temperature increases gradually, and the joint shortening amount decreases with the increase of the welding interface size.

关键词： Linear Friction Welding(LFW) Microstructure mechanical properties Numerical simulation Joint shortening amount

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Numerical simulations of ship collision with offshore UHPC structures 9th

Numerical simulations of ship collision with offshore UHPC s...

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9th International Conference on Collision and Grounding of Ships and Offshore Structures, ICCGS 2023

作者： Sha, Yanyan Department of Mechanical and Structural Engineering and Materials Science University of Stavanger Stavanger Norway

ISBN: (纸本)9781032611303

Reinforce concrete (RC) structures have been used to construct various types of offshore structures in the past decades. Reinforce concrete has many advantages such as high strength, relatively low cost, and easy maintenance. Therefore, reinforced concrete has been used to construct the supporting structures of offshore platforms, wind turbines, and floating bridges. Nonetheless, offshore reinforced concrete structures are under the threat of collision loads from service and passing ships. Since offshore reinforced concrete structures are typically thin-walled structures, one major issue is the punching shear damage of such structures under ship collision loads. Recently, ultra-high-performance concrete (UHPC) has been increasingly used for onshore structures. UHPC has demonstrated higher impact resistance than ordinary reinforced concrete. However, research on UHPC structures under ship collision loads has seldom been conducted. In this paper, numerical simulations of ship collision with thin-walled UHPC structures are conducted using detailed finite element models. The application of different UHPC material models on ship collision simulations is discussed. The response of UHPC and normal RC structures are also compared. It is found that with calibrated parameters, the CSCM material model in LS-DYNA can be used for modelling UHPC in ship collision simulations. The results show that using UHPC material can effectively increase the ship collision resistance of offshore structures compared with ordinary reinforced concrete. © 2024 The Author(s).

关键词： Reinforced concrete

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Accelerating the prediction of stacking fault energy by combining ab initio calculations and machine learning

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Physical Review B 2024年第21期109卷 214102-214102页

作者： Albert Linda Md. Faiz Akhtar Shaswat Pathak Somnath Bhowmick Department of Materials Science and Engineering Department of Mechanical Engineering

Stacking fault energies (SFEs) are key parameters to understand the deformation mechanisms in metals and alloys, and prior knowledge of SFEs from ab initio calculations is crucial for alloy design. Machine learning (ML) algorithms used in the present work show a ∼ 80 times acceleration of generalized stacking fault energy predictions, which are otherwise computationally very expensive to get directly from density functional theory calculations, particularly for alloys. The origin of the features used for training the ML algorithms lies in the physics-based Friedel model, and the present work uncovers the connection between the physics of d electrons and the deformation behavior of transition metals and alloys. Predictions based on the ML model agree with the experimental data. Our model can be helpful in accelerated alloy design by providing a fast method of screening materials in terms of stacking fault energies.

关键词： Stacking faults Density functional calculations Machine learning

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Ultrafast relaxation dynamics of excited carriers in metals: Simplifying the intertwined dependencies upon scattering strengths, phonon temperature, photon energy, and excitation level

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Physical Review B 2024年第18期109卷 184310-184310页

作者： D. M. Riffe Richard B. Wilson Mechanical Engineering Department and Materials Science and Engineering Department

Using the Boltzmann transport equation (BTE), we study the evolution of nonequilibrium carrier distributions in simple (sp) metals, assumed to have been instantaneously excited by an ultrafast laser pulse with photon energy hν. The mathematical structure of the BTE scattering integrals reveals that hν is a natural energy scale for describing the dynamics. Normalizing all energy quantities by hν leads to a set of three unitless parameters β/δ, γ, and α that control the relaxation dynamics: β/δ is the normalized ratio of electron-phonon to electron-electron scattering strengths, γ is the normalized phonon (lattice) temperature, and α is the normalized absorbed energy density. Using this theory, we systematically investigate relaxation times for the high-energy part of the distribution (τH), energy transfer to the phonon subsystem (τE), and intracarrier thermalization (τth). In the linear region of response (valid when α is sufficiently small), we offer heuristic descriptions of each of these relaxation times as functions of β/δ and γ. Our results as a function of excitation level α show that many ultrafast experimental investigations lie in a transition region between low excitation (where the relaxation times are independent of α) and high excitation (where the two-temperature model of carrier dynamics is valid). Approximate boundaries that separate these three regions are described by simple expressions involving the normalized parameters of our model.

关键词： Carrier dynamics Electron relaxation Lifetimes & widths

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Amorphous Iridium Oxide-Integrated Anode Electrodes with Ultrahigh Material Utilization for Hydrogen Production at Industrial Current Densities

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Nano-Micro Letters 2024年第10期16卷 225-239页

作者： Lei Ding Kui Li Weitian Wang Zhiqiang Xie Shule Yu Haoran Yu David ACullen Alex Keane Kathy Ayers Christopher BCapuano Fangyuan Liu Pu-Xian Gao Feng-Yuan Zhang Department of Mechanical Aerospace and Biomedical EngineeringUniversity of TennesseeKnoxvilleTN 37996USA Oak Ridge National Lab Center for Nanophase Materials SciencesOak RidgeTN 37831USA Nel Hydrogen WallingfordCT 06492USA Institute of Materials Science University of ConnecticutStorrsCT 06269USA Department of Materials Science and Engineering University of ConnecticutStorrsCT 06269USA

Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin electrodes are first developed as highly active anodes for proton exchange membrane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily scalable electrodeposition at room *** with a Nafion 117 membrane,the IrO_(x)-integrated electrode with an ultralow loading of 0.075 mg cm^(-2)delivers a high cell efficiency of about 90%,achieving more than 96%catalyst savings and 42-fold higher catalyst utilization compared to commercial catalyst-coated membrane(2 mg cm^(-2)).Additionally,the IrO_(x)electrode demonstrates superior performance,higher catalyst utilization and significantly simplified fabrication with easy scalability compared with the most previously reported ***,the remarkable performance could be mainly due to the amorphous phase property,sufficient Ir^(3+)content,and rich surface hydroxide groups in ***,due to the high activity,high cell efficiency,an economical,greatly simplified and easily scalable fabrication process,and ultrahigh material utilization,the IrO_(x)electrode shows great potential to be applied in industry and accelerates the commercialization of PEMECs and renewable energy evolution.

关键词： Ionomer-free Amorphous IrOx electrodes Ultrahigh material utilization Scalable electrodeposition Hydrogen production

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Ultimate and residual strength assessments of intact and collision damaged columns of the Bjørnafjorden floating bridge 9th

Ultimate and residual strength assessments of intact and col...

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9th International Conference on Collision and Grounding of Ships and Offshore Structures, ICCGS 2023

作者： Yu, Zhaolong Wang, Xintong Moan, Torgeir Amdahl, Jørgen Sha, Yanyan Norway Department of Mechanical and Structural Engineering and Materials Science University of Stavanger Norway

ISBN: (纸本)9781032611303

The Norwegian Public Road Administration (NPRA) has initiated an ambitious project to replace the current ferry crossing solutions with floating bridges over the wide and deep Norwegian fjords. This will substantially reduce the travelling time among major cities in Norway. It is found that ship collisions represent major critical loads to the safety and integrity of floating bridges that governs the structural design. This paper investigates the ultimate and residual strength of columns in an initial design of the Bjørnafjorden floating bridge before and after ship collisions with an initial kinetic energy of 125 MJ and 150 MJ respectively corresponding to a 10,000-year event as estimated from risk assessment. The ultimate bending and torsional capacities are assessed. Three different approaches are adopted, (1) the nonlinear finite element method using LS-DYNA;(2) A semi-analytical code PULS based on energy methods;(3) DNV rules-based formulations. The results are compared and discussed. © 2024 The Author(s).

关键词： Structural design

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Dealloying of an amorphous TiCuRu alloy results in a nanostructured electrocatalyst for hydrogen evolution reaction

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Carbon Energy 2023年第8期5卷 87-97页

作者： Jinsen Tian Yuanchao Hu Wenfei Lu Jiahua Zhu Xiaodi Liu Jun Shen Gang Wang Jan Schroers College of Mechatronics and Controlling Engineering Shenzhen UniversityShenzhenChina Shenzhen Key Laboratory of High Performance Nontraditional Manufacturing College of Mechatronics and Control EngineeringShenzhen UniversityShenzhenChina Department of Mechanical Engineering&Materials Science Yale UniversityNew HavenConnecticutUSA Department of Inorganic Materials School of Materials Science and EngineeringTongji UniversityShanghaiChina Laboratory for Microstructures Institute of MaterialsShanghai UniversityShanghaiChina

Development of an electrocatalyst that is cheap and has good properties to replace conventional noble metals is important for H_(2) *** this study,dealloying of an amorphous Ti_(37)Cu_(60)Ru_(3) alloy was performed to prepare a freestanding nanostructured hydrogen evolution reaction(HER)*** effect of dealloying and addition of Ru to TiCu alloys on the microstructure and HER properties under alkaline conditions was investigated.3 at.%Ru addition in Ti_(40)Cu_(60) decreases the overpotential to reach a current density of 10mA cm^(-2) and Tafel slope of the dealloyed samples to 35 and 34mV dec−*** improvement of electrocatalytic properties was attributed to the formation of a nanostructure and the modification of the electronic structure of the ***-principles calculations based on density function theory indicate that Ru decreases the Gibbs free energy of water *** work presents a method to prepare an efficient electrocatalyst via dealloying of amorphous alloys.

关键词： amorphous alloy dealloying first-principles calculations HER TiCuRu

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Sensitivity study of resolution and convergence requirements for the extended overlap region in wall-bounded turbulence

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Physical Review Fluids 2024年第8期9卷 L082601-L082601页

作者： Sergio Hoyas Ricardo Vinuesa Peter Schmid Hassan Nagib Instituto Universitario de Matemática Pura y Aplicada Universitat Politècnica de València FLOW Engineering Mechanics KTH Royal Institute of Technology Department of Mechanical Engineering Division of Physical Sciences and Engineering (PSE) King Abdullah University of Science and Technology (KAUST) Mechanical Materials and Aerospace Engineering Armour College of Engineering ILLINOIS TECH

Direct numerical simulations (DNSs) are among the most powerful tools for studying turbulent flows. Even though the achievable Reynolds numbers are lower than those obtained through experimental means, DNS offers a clear advantage: The entire velocity field is known, allowing for the evaluation of any desired quantity. This capability includes the computation of derivatives of all relevant terms. One such derivative provides the indicator function, which is the product of the wall distance and the wall-normal derivative of the mean streamwise velocity. This derivative may depend on mesh spacing and distribution, but it is extremely affected by the convergence of the simulation. The indicator function is crucial for understanding inner and outer interactions in wall-bounded flows and describing the overlap region between them. We find a clear dependence of this indicator function on the mesh distributions we examine, raising questions about classical mesh and convergence requirements for DNS and achievable accuracy. Within the framework of the logarithmic plus linear overlap region, coupled with a parametric study of channel flows and some pipe flows, sensitivities of extracted overlap parameters are examined. This study reveals a path to establishing their high-Reτ or nearly asymptotic values at modest Reynolds numbers, but larger than the ones used in this work, accessible by high-quality DNS with reasonable cost.

关键词： Boundary layers Complex fluids Three-dimensional turbulence Turbulence Turbulent boundary layers

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Eggshell nanoparticle reinforced recycled low-density polyethylene: A new material for automobile application

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Journal of King Saud University - engineering sciences 2023年第6期35卷 406-414页

作者： Bello, Sefiu Adekunle Raji, Nasirudeen Kolawole Kolawole, Maruf Yinka Adebayo, Mohammed Kayode Adebisi, Jeleel Adekunle Okunola, Kehinde Adekunle AbdulSalaam, Mustekeem Olanrewaju Department of Materials Science and Engineering Kwara State University Malete Nigeria Department of Metallurgical Engineering Yaba College of Technology Lagos Nigeria Department of Mechanical Engineering Kwara State University Malete Nigeria Department of Materials and Metallurgical Engineering University of Ilorin Ilorin Nigeria

Waste from low-density polyethylene products after lifespan accounts for 70% of solid waste in most dumpsites, contributing to environmental impacts. Eggshell foul smells are a threat to human and animal health. Before this study, there was no research documentation on transforming both wastes into green composites for engineering applications. This work developed composites using recycled low-density polyethylene (RLDPE) and eggshell Nanoparticles. They were evaluated structurally and mechanically. Straining, which affirms an improvement in the load-bearing capacity of the RLDPE due to the incorporation of eggshell Nanoparticles, was established by the composite XRD peak broadness. Structural integrities of the composites were confirmed with SEM. Maximum tensile strength was noted at 10% eggshell Nanoparticle additions to the RLDPE, equal to a 68% increase. About 52 and 19% enhancements in respective flexural strength and hardness value with a 0.85% reduction in impact energy were noted at 12% eggshell Nanoparticle additions. The probability value, 0.0481 −2 tensile strength, 21.964 Nmm−2 flexural strength, 21.69 J impact energy, and 59 VHN hardness value using sheet forming technique. Therefore, future usage of the developed RLDPE/10% eggshell Nanoparticle composite is established. © 2021 The Authors

关键词： Nanoparticles

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