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Finite element analysis using elasto-visco-plastic self-consistent polycrystal model for E-form Mg sheet subjected to bending

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Journal of Magnesium and Alloys 2023年第4期11卷 1393-1407页

作者： Bohye Jeon Min-Seong Kim Shi-Hoon Choi Youngung Jeong department of materials Convergence and System engineering Changwon National UniversityChangwon-siGyeongnamRepublic of Korea Center for Energy materials Research Korea Institute of Science and TechnologySeoulRepublic of Korea Department of Advanced Components and Materials Engineering Sunchon National UniversitySuncheon-siJeollanam-doRepublic of Korea School of materials Science and engineering Changwon National UniversityChangwon-siGyeongnamRepublic of Korea

The mechanical behavior of a magnesium alloy E-form under bending was investigated using the elasto-visco-plastic polycrystal model(ΔEVPSC) and its finite element(FE) implementation(ΔEVPSC-FE) developed in Jeong et al. and Jeong and Tomé. The crystallographic orientation distribution(COD) obtained from X-ray diffraction was used to represent the initial texture, and the Voce hardening parameters were calibrated by fitting the uniaxial tension and the compression flow stress curves. A quasi-static FE analysis of a miniaturized V-bending operation was conducted using the ΔEVPSC-FE model. The bending induced an inhomogeneous stress response along the through-thickness and the lateral directions, which was well captured by the model. Moreover, the predictive capability of the model was validated by comparing with various experimental results such as(1) force vs. displacement curves;(2) the through-thickness variations in the twin volume fraction;and(3) the changes in crystallographic texture as a function of displacement. Additional bending simulation was performed using an isotropic texture, the result of which suggests that the potential improvement in bendability of the magnesium alloy is attainable by weakening the initial texture. Moreover, the simulation results imply that the crystallographic texture, which may affect the twin activation across the thickness direction, plays a significant role in the shifting direction of the neutral layer.

关键词： FEM Texture V-bending Polycrystal Magnesium Elasto-visco-plasticity

Discovery of Pb-free hybrid organic-inorganic 2D perovskites using a stepwise optimization strategy

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npj Computational materials 2022年第1期8卷 776-787页

作者： Byung Do Lee Jin-Woong Lee Minseuk Kim Woon Bae Park Kee-Sun Sohn department of Nanotechnology and advanced materials engineering Sejong University209 Neungdong-roGwangjin-guSeoul143-747South Korea Department of Advanced Components and Materials Engineering Sunchon National UniversityChonnam57922Republic of Korea

The current status of 2D organic–inorganic hybrid perovskites for use in photovoltaic(PV)and light-emitting diode(LED)applications lags far behind their 3D counterparts.Here,we propose a computational strategy for discovering novel perovskites with as few computing resources as possible.A tandem optimization algorithm consisting of an elitism-reinforced nondominated sorting genetic algorithm(NSGA-II)and a multiobjective Bayesian optimization(MOBO)algorithm was used for density functional theory(DFT)calculations.The DFT-calculated band gap and effective mass were taken as objective functions to be optimized,and the constituent molecules and elements of a Ruddlesden–Popper(RP)structure(n=2)were taken as decision variables.Fourteen previously unknown RP perovskite candidates for PV and LED applications were discovered as a result of the NSGA-II/MOBO algorithm.Thereafter,more accurate DFT calculations based on the HSE06 exchange correlation functional and ab initio molecular dynamics(AIMD)were conducted for the discovered 2D perovskites to ensure their validity.

关键词： sorting optimization perovskite

Recent advances in the in-plane shear testing of Mg alloy sheets

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Journal of Magnesium and Alloys 2023年第2期11卷 405-424页

作者： Mahesh Panchal Lalit Kaushik Ravi K.R Rajesh Khatirkar Shi-Hoon Choi Jaiveer Singh department of Mechanical engineering Indian Institute of Technology JodhpurKarwarJodhpur 342030RajasthanIndia Department of Advanced Components and Materials Engineering Sunchon National University255 Jungang-roSuncheonJeonnam 57922Republic of Korea department of Metallurgical and materials engineering Indian Institute of Technology JodhpurKarwarJodhpur 342030RajasthanIndia department of Metallurgical and materials engineering Visvesvaraya National Institute of Technology(VNIT)South Ambazari RoadNagpur 440010MaharashtraIndia

Sheet-metal products are integral parts of engineering industries and academia research. Various testing techniques have revealed the deformation behaviors of sheet metals under complex stress states. Information obtained from tensile and compression tests, however, are insufficient for the identification of material parameters relevant to modern constitutive laws, which require experimental setups capable of generating various loading conditions and applying great amounts of strain to sheet metals. In-plane shear testing has emerged as an important method to overcome the challenges associated with tension and compression tests and can provide additional information about deformation behaviors under large plastic strains. materials such as Mg alloys with poor levels of both ductility and formability cannot accommodate large plastic strains. Therefore, tension and compression tests have limitations in explaining the material behaviors that occur during sheet metal forming where large plastic strains are introduced. Many studies have been conducted to explain the deformation behaviors of Mg alloys under shear deformation techniques. These include severe plastic deformation(SPD), especially the equal channel angular pressing(ECAP)and equal channel angular extrusion, rolling combined with shear deformation i.e. differential speed rolling(DSR), and also in-plane shear for sheet metals, particularly under large levels of plastic strain. These in-plane shear technique involves the Miyauchi shear test, ASTM shear test, and twin bridge shear tests. Moreover, many experimental results have revealed that the evolution of microstructure and texture during in-plane shear is closely related to the failure behavior of materials. Therefore, this review is focused on techniques for in-plane shear testing that have been reported thus far, on the effect of in-plane shear on the microstructure development of Mg alloy sheets, and on the usefulness of in-plane shear testing to evaluate the formability of Mg alloy sheets.

关键词： Mg alloys In-plane shear Texture Formability EBSD

Single-phase formation mechanism and dielectric properties of sol-gel-derived Ba(Ti_(0.2)Zr_(0.2)Sn_(0.2)Hf_(0.2)Ce_(0.2))O_(3) high-entropy ceramics

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Journal of materials Science & Technology 2022年第35期130卷 103-111页

作者： Jia Liu Cuiying Ma Lianli Wang Ke Ren Hongpei Ran Danni Feng Huiling Du Yiguang Wang College of materials Science and engineering Xi’an University of Science and TechnologyXi’an 710054China Institute of advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of advanced materials and Electronic components Guangdong Fenghua Advanced Technology Holding Co.Ltd.Zhaoqing 526020China

Single-phase Ba(Ti_(0.2)Zr_(0.2)Sn_(0.2)Hf_(0.2)Ce_(0.2))O_(3)(BTZSHC) high-entropy ceramics(HECs) with the perovskite structure were successfully prepared via the sol-gel method.The results reveal that the as-prepared ceramics exhibit a single cubic phase belonging to the Pm3 m space group.The high entropy is the driving force of the formation of single-phase ceramics.A larger entropy(ΔS_(mix)) and a negative enthalpy(ΔH_(mix)) are conducive to the formation of single-phase compounds.Herein,ΔS_(mix)=0.323 R mole-1andΔH_(mix)=43.88 kJ/mol.The sluggish-diffusion effect ensures the thermal stability of high-entropy systems.Dielectric measurements reveal that the as-prepared BTZSHC high-entropy ceramics are relaxor ferroelectrics,and the degree of relaxor(γ) is 1.9.The relaxor behavior of the as-prepared ceramics can be ascribed to the relaxation and thermal evolution of their polar units(PUs).The findings of this work provide a theoretical basis and technical support for the preparation of single-phase high-entropy ceramics.

关键词： High-entropy ceramics Single-phase formation mechanism Perovskite structure Sol-gel method Dielectric properties

揭示银关联缺陷的双重作用:环保型AgIn0.5Ga0.5S2中发光和载流子动力学的操纵者

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Science China materials 2024年第1期67卷 214-222页

作者：刘高豫徐丽丽胡扬李晓明 Seokwoo Jeon 张胜利曾海波 MIIT Key Laboratory of advanced Display materials and Devices School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China department of materials Science and engineering Korea UniversitySeoul02841Republic of Korea

AgIn_(0.5)Ga_(0.5)S_(2)由于环境友好、合成成本低、成分灵活可调等优点在许多领域受到广泛关注.适当的直接带隙、无禁戒跃迁和高激子结合能使其成为一种有前途的发光材料.多组分体系的演化丰富了光电特性,并使其本征缺陷更加复杂.反过... 详细信息

AgIn_(0.5)Ga_(0.5)S_(2)由于环境友好、合成成本低、成分灵活可调等优点在许多领域受到广泛关注.适当的直接带隙、无禁戒跃迁和高激子结合能使其成为一种有前途的发光材料.多组分体系的演化丰富了光电特性,并使其本征缺陷更加复杂.反过来,这些缺陷对光电性能有重要影响,从而影响其发光性能.然而,对于这类半导体,在实验中观察到的与发光相对应的点缺陷的微观机制大多是未知的或间接推断的.本工作系统地揭示了AgIn_(0.5)Ga_(0.5)S_(2)的微观缺陷与发光之间的机制.热力学稳定性表明AgIn_(0.5)Ga_(0.5)S_(2)是亚稳态的并且与次生相之间存在显著的竞争.此外,计算的缺陷结果表明,与银关联的缺陷是幕后操纵者.两个浅能级缺陷(VAg和Agi)充当载流子提供者,而四个深能级反位缺陷(AgIn,AgGa,InAg和GaAg)充当载流子湮灭者.最后,载流子动力学的研究揭示了四种深能级反位缺陷对载流子辐射过程的不利影响.这些旨在为AgIn_(0.5)Ga_(0.5)S_(2)在发光领域的功能应用提供重要指导.

关键词：深能级反位缺陷发光材料本征缺陷浅能级热力学稳定性禁戒跃迁多组分体系

Stretchable alkaline quasi-solid-state electrolytes created by super-tough, fatigue-resistant and alkali-resistant multi-bond network hydrogels

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Chinese Chemical Letters 2023年第4期34卷 275-278页

作者： Hao Xu Yujun Liu Xu-Ming Xie Key Laboratory of advanced materials(MOE) Department of Chemical EngineeringTsinghua UniversityBeijing 100084China

Hydrogel-based quasi-solid-state electrolytes(Q-SSEs) swollen with electrolyte solutions are important components in stretchable supercapacitors and other wearable devices. This work fabricates a supertough, fatigue-resistant, and alkali-resistant multi-bond network(MBN) hydrogel aiming to be an alkaline Q-SSE. To synthesize the hydrogel, a 2-ureido-4[1H]-pyrimidone(UPy) motif is introduced into a poly(acrylic acid) polymer chain. The obtained MBN hydrogels with 75 wt% water content exhibit tensile strength as high as 2.47 MPa, which is enabled by the large energy dissipation ability originated from the dissociation of UPy dimers due to their high bond association energy. Owing to the high dimerization constant of UPy motifs, the dissociated UPy motifs are able to partially re-associate soon after being released from external forces, resulting in excellent fatigue-resistance. More importantly, the MBN hydrogels exhibit excellent alkali-resistance ability. The UPy Gel-10 swollen with 1 mol/L KOH display a tensile strength as high as ~1.0 MPa with elongation at break of ~550%. At the same time, they show ionic conductivity of ~17 m S/cm, which do not decline even when the hydrogels are stretched to 500% strain.The excellent mechanical property and ionic conductivity of the present hydrogels demonstrate potential application as a stretchable alkaline Q-SSE.

关键词： Alkaline quasi-solid-state electrolyte Super-tough hydrogel Fatigue resistance Alkali resistance Multi-bond network

Synthesis of a novel Al foam with a periodic architecture by introducing hollow Al tubes and Al/Mg powders

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Journal of materials Science & Technology 2023年第17期148卷 105-115页

作者： Zhigang Xu Dayong Shen Kai Wang Peng He Jian Zhang Hao Zhang Peng Cao Shangyu Huang Jian Peng Qiang Shen Chuanbin Wang Lianmeng Zhang Hubei Key Laboratory of advanced Technology for Automotive components Wuhan University of TechnologyWuhan 430070China State Key Lab of advanced Technology for materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China School of materials Science and engineering Wuhan University of TechnologyWuhan 430070China Wuhan Second Ship Design and Research Institute Wuhan 430205China department of Chemical and materials engineering University of AucklandPrivate Bag 92019Auckland 1142New Zealand

In this work,we synthesized a brand-new Al foam with a periodic structure via a simple powder metallurgical route.The periodic architecture consists of both hierarchical porous and bi-directional composition-graded structures.The results show that the hierarchical porous material includes large pores on millimeter scale inheriting from the hollow structure of the Al tubes,and small pores on mi-crometer scale produced by the sintering of Al/Mg powders.The bi-directional Mg concentration-graded structure is formed in the tube walls due to the condensation of Mg vapor in the inner tube wall.The addition of Mg powders achieves excellent metallurgical bonding between the Al powders and the hollow tubes at 550℃.The plateau stress and energy absorption capacity of the Al foam in y-axis compression are significantly higher than that in the x-axis due to their anisotropic structure.In general,the Al foam with Mg addition presents the most superior compression performance,and we believe that our find-ings could open up a unique strategy for developing high-performance metallic foams with the periodic architecture involving both hierarchical porous and bi-directional graded structure.

关键词： Al foam Hollow Al tube Mg evaporation Bi-directional composition-graded structure Compression properties Energy absorbing performance

面向水环境中神经形态计算的聚电解质-受限流体忆阻器

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Science Bulletin 2023年第8期68卷 767-769页

作者：刘越陈培宁彭慧胜 State Key Laboratory of Molecular engineering of Polymers Department of Macromolecular Science and Laboratory of Advanced MaterialsFudan UniversityShanghai 200438China

Artificial synapse devices with co-location memory and logic functions have attracted enormous attention since they are the indispensable components for neuromorphic computing systems[1].Extensive efforts have been made to mimic neural electric pulse patterns through solid-state devices like two-terminal memristors and three-terminal transistors.

关键词： neural 忆阻器聚电解质

Actuator Fault Monitoring and Fault Tolerant Control in Distillation Columns

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International Journal of Automation and computing 2017年第1期14卷 80-92页

作者： Sulaiman Ayobami Lawal Jie Zhang School of Chemical engineering and advanced materials Newcastle University department of Chemical engineering University of Lagos

This paper presents, from a practical viewpoint accommodation in distillation columns. Addressing faults in an investigation of real-time actuator fault detection, propagation and industrial processes, coupled with the growing demand for higher performance, improved safety and reliability necessitates implementation of less complex alternative control strategies in the events of malfunctions in actuators, sensors and or other system components. This work demonstrates frugality in the design and implementation of fault tolerant control system by integrating fault detection and diagnosis techniques with simple active restructurable feedback controllers and with backup feedback signals and switchable reference points to accommodate actuator fault in distillation columns based on a priori assessed control structures. A multivariate statistical process monitoring based fault detection and diagnosis technique through dynamic principal components analysis is integrated with one-point control or alternative control structure for prompt and effective fault detection, isolation and accommodation. The work also investigates effects of disturbances on fault propagation and detection. Specifically, the reflux and vapor boil-up control strategy used for a binary distillation column during normal operation is switched to one point control of the more valued product by utilizing the remaining healthy actuator. The proposed approach was implemented on two distillation processes： a simulated methanol-water separation column and the benchmark Shell standard heavy oil fractionation process to assess its effectiveness.

关键词： Dynamic principal component analysis fault detection and diagnosis distillation column fault tolerant controller inferential control.