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The 18th International Symposium on Computational Mechanics of materials

作者： Zhang Hongmei~1 zhao guoqun~2 1.school of material science and engineering Beijing Institute of Technology Beijing 100081 China 2.engineering Research Center for Mould & Die Technologies Shandong University Jinan Shandong 250061 China

＜正＞The quality of finite element mesh is one of the important factors which determine the precision and accuracy of finite element analysis,especially in the large metal *** is crucial for the generated meshes to exactly describe all the features of the analyzed solid *** a method for the adaptive generation of hexahedral element mesh based on the geometric features of solid model is *** is based on the conventional grid-based method and geometry-adaptive technique to generate uniformly sized or locally refined hexahedral *** first step is to construct the refinement information fields of source points and the corresponding ones of elements according to the surface curvature of the analyzed solid model.A thickness refinement criterion is then used to construct the thickness-based refinement information field of elements from digital ***, the element refinement fields are integrated and modified according to the conformal refinement templates proposed in this paper, and used as a metric to generate an initial grid structure enveloping the solid model *** order to ensure the conformity of the generated mesh,a set of new refinement templates are proposed,and the corresponding modes for converting arbitrary refinement field to the templates is *** third step is to generate a core mesh through removing all the undesired elements using even and odd parity *** the core mesh is magnified in an inside-out manner through a surface node projection process using the closest position *** match the mesh to the characteristic boundary of the solid model,a minimal Scaled Jacobian criterion is ***,in order to handle the degenerated elements and improve the quality of the resulting mesh,two comprehensive techniques are employed:the insertion technique and collapsing *** present method was applied in the mesh construction of different engineering problems. Scaled Jacobian and Skew m

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Strategy for suppressing abnormal grain growth of ZK60 Mg alloy during solution by pre-compression:A quasi-in-situ study

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Journal of materials science & Technology 2024年第4期171卷 115-128页

作者： Zhenxu Wang Liang Chen Jianwei Tang Cunsheng Zhang guoqun zhao Key Laboratory for Liquid-Solid Structural Evolution and Processing of materials(Ministry of Education) Shandong UniversityJinanShandong 250061China Department of Mechanical engineering Kyushu UniversityFukuoka 819-0395Japan

Abnormal grain growth(AGG)easily takes place in Mg alloys during high-temperature solutions,result-ing in deterioration of mechanical ***,the compression prior to solution(pre-compression)was conducted to suppress AGG,and the microstructure evolution as well as suppressing mechanisms was investigated based on quasi-in-situ *** compression along the transverse direction,11-20>//ED grains preferentially nucleated and rapidly grew up,and the initial10-10>//ED texture was *** grain growth modes of heat-induced and strain-induced grain boundary migrations were *** former was attributed to the high interfacial energy of grain boundaries with large *** latter consumed the adjacent grains with high storage energy,forming abnormal grains with irregular *** compression with a reduction>6%could obviously suppress *** suppressing effects were mainly attributed to weakening the size advantage of11-20>//ED grains,increasing nucleation,reducing grain boundary character distribution,and redistributing storage energy *** 12%compression along the transverse direction,30°misorientation of11-20>//ED grains and high energy grain boundaries were ***{10-12}tensile twins and{10-15}high index twins induced by com-pression increased the nucleation of static ***,compression introduces high-density dislocations,which also contributed to suppressing AGG behavior during solution.

关键词： Quasi-in-situ analysis Mg alloy Abnormal grain growth Compression Microstructure

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Robust, breathable, and chemical-resistant polytetrafluoroethylene (PTFE) films achieved by novel in-situ fibrillation strategy for highperformance triboelectric nanogenerators

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Nano Research 2024年第3期17卷 1942-1951页

作者： Jialong Chai Guilong Wang Jinchuan zhao Guizhen Wang Chao Wei Aimin Zhang guoqun zhao Laboratory for Liquid-Solid Structural Evolution and Processing of materials(Ministry of Education) Shandong UniversityJinan 250061China Key Laboratory of Chinese Education Ministry for Tropical Biological Resources Hainan UniversityHaikou 570228China

In the era of advanced wearable electronic devices,the triboelectric nanogenerators(TENGs)as energy harvesting and self-powered sensing units hold great *** appropriate triboelectric material is the crucial factor to optimize the performance of TENG,while polytetrafluoroethylene(PTFE)stands out as a highly versatile option among the various *** this study,we present an ultrafine nanofibrous PTFE(NF-PTFE)films prepared by novel in-situ fibrillation strategy as the triboelectric material in TENG *** innovative processing methodology facilely addresses the dilemma between high porosity and fine pore size of traditional porous PTFE films,meanwhile achieves exceptional mechanical strength,hydrophobicity,air permeability,and chemical resistance of the *** the integration of nanofibrous PTFE films into contact-separation mode TENG and droplet-based TENG,these devices realize the peak electrical output of 131 V/10.8μA and 54 V/14μA with great durability,which surpass the performance of TENGs using traditional expanded PTFE ***,a smart glove capable of recognizing hand gestures is proposed,which demonstrates the versatility,flexibility,and practicality of this material for potential use in smart *** reported NF-PTFE film provides insights for the design of high-performance TENG device for advanced wearable electrical applications.

关键词： polytetrafluoroethylene(PTFE) nanofibrous film hydrophobic triboelectric nanogenerator self-powered sensor

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A novel micro-rolling&incremental sheet forming hybrid process:Deformation behavior and microstructure evolution

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Chinese Journal of Aeronautics 2024年第5期37卷 603-622页

作者： Yanle LI Feifei LIU Hao YUAN Xiaoqiang LI Jianfeng LI guoqun zhao Key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of EducationShandong UniversityJi'nan 250061China school of Mechanical engineering and Automation Beihang UniversityBeijing 100191China Key Laboratory for Liquid-Solid Structural Evolution and Processing of materials Ministry of EducationShandong UniversityJi'nan 250061China

Thin-walled metal parts with functional micro-featured surface have broad application prospects in the fields of resistance reduction,noise reduction,*** this study,a novel micro-rolling&incremental sheet forming hybrid process(μR-ISF)is proposed to fabricate thin-walled metal parts with microgroove *** analytical model which relates the rolling force and microgroove depth in the micro-rolling stage was first ***,the formation mechanism of microgroove morphology during both micro-rolling stage and macro-shape forming stage are *** the micro-grooved sheet being incrementally formed,a significant reduction(between 21%to nearly 60%)is occurred in the depth of both transverse and longitudinal grooves compared to the flat ***,the width of transverse grooves decreases slightly by about 10%on average,while the width of longitudinal microgrooves increases significantly by more than 30%on *** micro-rolling,85°{102}tensile twins appear on the micro-grooved sheet and the percentage of 65°{112}compressive twins *** incremental forming,the percentage of low-angle grain boundaries and the density of geometrically necessary dislocations in the formed part increase significantly,and the grain size distribution becomes more *** present work provides a new strategy for the fabrication of 3D metal thin-walled components with surface micro-features.

关键词： Incremental sheet forming Microgrooves rolling Surface micromachining Groove size Microstructural evolution

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Effect of solution treatment on the microstructure,phase transformation behavior and functional properties of NiTiNb ternary shape memory alloys fabricated via laser powder bed fusion in-situ alloying

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International Journal of Extreme Manufacturing 2024年第4期6卷 202-223页

作者： Rui Xi Hao Jiang Guichuan Li Zhihui Zhang Huiliang Wei guoqun zhao Jan Van Humbeeck Xiebin Wang Key Laboratory for Liquid-Solid Structural Evolution and Processing of materials(Ministry of Education) Shandong UniversityJingshi Road 17923Jinan 250061People's Republic of China Department of materials engineering University of Leuven(KU Leuven)Kasteelpark Arenberg 44 bus 2450Heverlee B3001Belgium Key Laboratory of Bionic engineering(Ministry of Education) Jilin UniversityRenmin Street 5988Changchun 130025People's Republic of China school of Mechanical engineering Nanjing University of Science and TechnologyXiaolingwei Street 200Nanjing 210094People's Republic of China

Post-heat treatment is commonly employed to improve the microstructural homogeneity and enhance the mechanical performances of the additively manufactured metallic *** this work,a ternary(NiTi)91Nb9(at.%)shape memory alloy was produced by laser powder bed fusion(L-PBF)using pre-alloyed NiTi and elemental Nb *** effect of solution treatment on the microstructure,phase transformation behavior and mechanical/functional performances was *** in-situ alloyed(NiTi)91Nb9 alloy exhibits a submicron cellular-dendritic structure surrounding the supersaturated B2-NiTi *** high-temperature(1273 K)solution treatment,Nb-rich precipitates were precipitated from the supersaturated *** fragmentation and spheroidization of the NiTi/Nb eutectics occurred during solution treatment,leading to a morphological transition from mesh-like into rod-like and *** of theβ-Nb phases occurred with increasing holding *** martensite transformation temperature increases after solution treatment,mainly attributed to:(i)reduced lattice distortion due to the Nb expulsion from the supersaturated B2-NiTi,and(ii)the Ti expulsion from theβ-Nb phases that lowers the ratio Ni/Ti in the B2-NiTi matrix,which resulted from the microstructure changes from non-equilibrium to equilibrium *** thermal hysteresis of the solutionized alloys is around 145 K after 20%pre-deformation,which is comparable to the conventional NiTiNb alloys.A short-term solution treatment(*** 1273 K for 30 min)enhances the ductility and strength of the as-printed specimen,with the increase of fracture stress from(613±19)MPa to(781±20)MPa and the increase of fracture strain from(7.6±0.1)%to(9.5±0.4)%.Both the as-printed and solutionized samples exhibit good tensile shape memory effects with recovery rates>90%.This work suggests that post-process heat treatment is essential to optimize the microstructure and improve the mechanical performances of the L-PBF in-situ allo

关键词： shape memory alloy NiTiNb laser powder bed fusion in-situ alloying heat treatment

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Research on semi-solid slurry of a hypoeutectic Al-Si alloy prepared by low superheat pouring and weak electromagnetic stirring

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Rare Metals 2006年第2期25卷 177-183页

作者： LIU Zheng MAO Weiming zhao Zhengduo material of science and engineering school University of Science and Technology Beijing Beijing 100083 China Faculty of material and Chemical engineering Jiangxi University of Science and Technology Ganzhou 341000 China

The semi-solid slurry of a hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouting temperature and stirring power on the semi-solid slurry were investigated. The results indicated that the semi-solid slurry to satisfy rheocasting can be manufactured by low superheat pouring and weak electromagnetic stirring. The pouring temperature （or superheat） and the stirring power remarkably affected the morphology of primary α-Al and the size of primary α-Al, and there is no obvious effect of stirring time on primary α-Al. Compared with the samples made by low superheat pouring with no stirring, the nucleation rate, particle morphology and grain size of primary α-Al in A356 were markedly improved by low superheat pouring and weak electromagnetic stirring. On the condition of weak electromagnetic stirring, the pouring temperature with low superheat can be suitably raised to reach the effectiveness obtained from the lower pouring temperature without stirring.

关键词： semi-solid low superheat pouring weak electromagnetic stirring hypoeutectic Al-Si alloy A356 Al alloy

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Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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science China(Technological sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1,2, CAI Hongnian1, ZHANG Xinming2, WANG Fuchi1 & TAN Chengwen1,3 1. school of material science and engineering, Beijing Institute of Technology, Beijing 100081, China 2. school of material science and engineering, Central South University, Changsha 410083, China 3. school of material science and engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China 1. school of material science and engineering Beijing Institute of Technology Beijing 100081 China 2. school of material science and engineering Central South University Changsha 410083 China 3. school of material science and engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

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Effect of the silicon powder content on the properties of Al_2O_3-SiC-Me composites

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science China(Technological sciences) 2009年第1期52卷 193-197页

作者： ZHANG ZhiHui1, RUAN GuoZhi1 & CHEN YunBo1,2 1.school of material science and engineering, Shandong University of science and Technology, Qingdao 266510, China 2 Institute of material engineering, China Academy of Machinery science and Technology, Beijing 100083, China school of material science and engineering Shandong University of Science and Technology Qingdao 266510 China Institute of material engineering China Academy of Machinery Science and Technology Beijing 100083 China

By means of transient plastic phase process, the Al2O3-SiC-Me composites were produced throungh adding metal aluminium and silicon-powder to Al2O3-SiC materials. Under the condition of the same content of silicon and aluminium mixed-powder, the effect of silicon powder addition on properties of Al2O3-SiC-Me composites was studied by means of XRD and EPMA analyses in the temperature range of 300℃―1600℃. The results indicated that the content of metal phase in the sample at 1600℃ increases with increasing silicon powder content. At the same time, when the temperature is lower than 1100℃, the strength of samples gradually increases with increasing temperature. However when the temperature is higher than 1100℃, the strength of samples gradually decreases with increasing temperature, and this change is very small. The results also indicated that at the same sintering temperature, the sample with 6% silicon powder has the maximum strength.

关键词： composites strength ceramic

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Preparation of Al_2O_3-SiO_2-TiO_2-ZrO_2 Composite Ceramic Membranes by Sol-Gel Method

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Journal of Wuhan University of Technology(materials science) 2005年第1期20卷 42-45页

作者：吴建锋 school of material science and engineering Wuhan University of TechnologyWu han 430070China

Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a natase), Al 2SiO 5, and ZrO 2 in these membranes. Changing the molar ratio of Al∶Si∶Ti∶Zr,the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nanoscale topography and microstructure of membranes were investiga ted by XRD,SEM,AFM,EPMA. The effects of additives and heat treatments on the sur face nanoscale topography and microstructure of composite ceramic membranes were also analyzed.

关键词： sol-gel method Al 2O 3-SiO 2-TiO 2-ZrO 2 composite ceramic membranes surface nanoscale topography microstructure

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Synthesis of a novel centipede-like copolymer of styrene and methyl methacrylate

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science China Chemistry 2007年第2期50卷 253-257页

作者： LI AiXiang1 & LU ZaiJun2 1.school of material science and engineering,Shandong University of Technology,Zibo 255049,China 2 school of Chemistry and Chemical engineering,Shandong University,Jinan 250100,China 1. school of material science and engineering Shandong University of Technology Zibo 255049 China 2. school of Chemistry and Chemical engineering Shandong University Jinan 250100 China

A well-defined,A2B-type,centipede-like copolymer of styrene and methyl methacrylate(PS-PS-PMMA) was synthesized by the combination of living anionic polymerization and atom transfer radical polym-erization(ATRP) . The synthetic approach involves the coupling reaction of polystyrene(PS) backbone bearing 1,1-diphenylethene(DPE) pendant groups,produced by ATRP and Wittig reaction,with living polystyryllithium(PSLi) ,and subsequent polymerization of the resulting 1,1-diphenylmethyl anions with methy methacrylate. The centipede-like copolymer was characterized by 1H NMR,IR,SEC,SLS,and DSC measurements.

关键词： architecture atom transfer radical polymerization centipede-like copolymer coupling reaction living anionic polymerization

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