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表面机械研磨处理的金属试样扭转疲劳寿命

表面机械研磨处理的金属试样扭转疲劳寿命

Influences of nanotwin volume fraction on the ballistic performance of coarse-grained metals

第十八届全国疲劳与断裂学术会议

作者：郭翔杨涛 g.j.weng 天津大学机械工程学院 Department of Mechanical and Aerospace Engineering Rutgers University

实验研究展示表面机械研磨纳米化能在金属试样表面产生大的残余压应力和提高表面硬度从而增加其疲劳寿命。本文针对表面机械研磨处理的金属管状试样,建立了一个结合内聚力有限元和蒙特卡洛方法的计算框架来研究其扭转疲劳裂纹扩展和疲... 详细信息

实验研究展示表面机械研磨纳米化能在金属试样表面产生大的残余压应力和提高表面硬度从而增加其疲劳寿命。本文针对表面机械研磨处理的金属管状试样,建立了一个结合内聚力有限元和蒙特卡洛方法的计算框架来研究其扭转疲劳裂纹扩展和疲劳寿命。空间随机分布的内聚强度和断裂能被三参数的威布尔分布描述。模拟结果能合理预测裂纹图案和疲劳寿命,同时展示了纳米晶层在疲劳寿命改进方面的重要角色。随着纳米晶层变厚,疲劳裂纹从管状试样的内表面萌生而后朝外表面扩展的概率增加。

关键词：表面机械研磨疲劳寿命内聚力有限元蒙特卡罗

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Theoretical & Applied Mechanics Letters 2017年第5期7卷 265-268页

作者： Q.D.Ouyang g.j.weng A.K.Soh X.guo School of Mechanical Engineering Tianjin UniversityTianfin 300072China Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin 300072China Department of Mechanical and Aerospace Engineering Rutgers UniversityNew BrunswickNJ 08903USA School of Engineering Monash University MalaysiaBandar SunwaySalangorMalaysia

Coarse-grained（Cg） metals strengthened by nanotwinned（NT） regions possess high strength and good ductility. As such, they are very suitable for applications in bullet-proof targets. Here, a numerical model based on the conventional theory of strain gradient plasticity and the johnson–Cook failure criterion is employed to study the influences of volume fraction of NT regions on their ballistic *** results show that in general a relatively small twin spacing（4–10 nm） and a moderate volume fraction（7%–20%） will lead to excellent limit velocity and that the influences of volume fraction on limit displacement change with the category of impact processes.

关键词： Nanotwin Ballistic performance Volume fraction Limit velocity Limit displacement

Resource Allocation to Minimize the Makespan with Multi-Resource Operations

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journal of Systems Science & Complexity 2024年第5期37卷 2054-2070页

作者： weng Wuyan CHU Chengbin WU Peng School of Economics and Management Fuzhou University Univ gustave Eiffel ESIEE Paris&COSYS-GRETTIA

This paper investigates a new resource-allocation problem involving multi-resource operations, where completing an operation requires simultaneous use of multiple(renewable) resources,probably of different types. The goal of the study is to provide a solution method that minimizes the makespan. The authors formulate the problem into a novel mixed-integer linear program(MILP)model. To efficiently solve practical-sized instances, an exact Benders decomposition algorithm is developed. This algorithm divides the original problem into a master problem of allocating resources and a subproblem of calculating the makespan, and both are linked via Benders cuts. The convergence is sped up by improving the mathematical model and embedding the variable neighborhood search algorithm. Compared with CPLEX, a commonly used MILP solver, the computational results demonstrate that the proposed algorithm provides tighter upper and lower bounds in most instances. In particular,compared with CPLEX, the proposed method can on average improve the upper and lower bounds by 4.76% and 4.39%, respectively, in solving practical-sized instances.

关键词： Benders decomposition multi-resources operations resource allocation

Biomineralization of soil with crude soybean urease using different calcium salts

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journal of Rock Mechanics and geotechnical Engineering 2024年第5期16卷 1788-1798页

作者： Yajie weng junjie Zheng Hanjiang Lai Mingjuan Cui Xingzhi Ding School of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan430074China Zijin School of geology and Mining Fuzhou UniversityFuzhou350108China College of Civil Engineering Fuzhou UniversityFuzhou350116China

Calcium salt is an important contributing factor for calcium-based *** study the effect of calcium salt on soil biomineralization using crude soybean urease,the calcium salts,including the calcium chloride (CaCl_(2)),calcium acetate ((CH_(3)COO)_(2)Ca) and calcium nitrate (Ca(NO_(3))_(2)),were used to prepare the biotreatment solution to carry out the biomineralization tests in this *** series of biomineralization tests in solution and sand column,respectively,were *** electron microscopy (SEM) and X-ray diffraction (XRD) were performed to determine the microscopic characteristics of the precipitated calcium carbonate (CaCO_(3)) *** experimental results indicate that the biomineralization effect is the best for the CaCl2 case,followed by (CH_(3)COO)_(2)Ca,and worst for Ca(NO_(3))_(2) under the test conditions of this study (i.e.1 mol/L of calcium salt-urea).The mechanism for the effect of the calcium salt on the biomineralization of crude soybean urease mainly involves: (1) inhibition of urease activity,and (2) influence on the crystal size and morphology of CaCO_(3).Besides Ca^(2+) ,the anions in solution can inhibit the activity of crude soybean urease,and NO_(3)− has a stronger inhibitory effect on the urease activity compared with both CH_(3)COO^(−) and Cl^(−) .The co-inhibition of Ca^(2+) and NO_(3)− on the activity of urease is the key reason for the worst biomineralization of the Ca(NO_(3))_(2) case in this *** difference in biomineralization between the CaCl_(2) and (CH_(3)COO)_(2) Ca cases is strongly correlated with the crystal morphology of the precipitated CaCO_(3).

关键词： Biomineralization Crude soybean urease Calcium salt Influence mechanism

Breaking the Fe_(3)O_(4)-wrapped copper microstructure to enhance copper-slag separation

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International journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2312-2325页

作者： Xiaopeng Chi Haoyu Liu jun Xia Hang Chen Xiangtao Yu Wei weng Shuiping Zhong Zijin School of geology and Mining Fuzhou UniversityFuzhou 350108China Fujian Key Laboratory of green Extraction and High-Value Utilization of New Energy Metals Fuzhou UniversityFuzhou 350108China Zijin Mining group Co. Ltd.Longyan 364200China Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China

The precipitation of Fe_(3)O_(4)particles and the accompanied formation of Fe_(3)O_(4)-wrapped copper structure are the main obstacles to copper recovery from the molten slag during the pyrometallurgical smelting of copper ***,the commercial powdery pyrite or anthracite is replaced with pyrite-anthracite pellets as the reductants to remove a large amount of Fe_(3)O_(4)particles in the molten slag,resulting in a deep fracture in the Fe_(3)O_(4)-wrapped copper microstructure and the full exposure of the copper matte *** 1wt%composite pellet is used as the reductant,the copper matte droplets are enlarged greatly from 25μm to a size observable by the naked eye,with the copper content being enriched remarkably from 1.2wt%to 4.5wt%.Density functional theory calculation results imply that the formation of the Fe_(3)O_(4)-wrapped copper structure is due to the preferential adhesion of Cu_(2)S on the Fe_(3)O_(4)particles.X-ray photoelectron spectroscopy,Fourier transform infrared spectrometer(FTIR),and Raman spectroscopy results all reveal that the high-efficiency conver-sion of Fe_(3)O_(4)to FeO can decrease the volume fraction of the solid phase and promote the depolymerization of silicate network *** a consequence,the settling of copper matte droplets is enhanced due to the lowered slag viscosity,contributing to the high efficiency of copper-slag separation for copper *** results provide new insights into the enhanced in-situ enrichment of copper from mol-ten slag.

关键词： pyrometallurgical smelting process slag cleaning reductants copper matte

Programmable and reconfigurable humidity-driven actuators made with MXene(Ti_(3)C_(2)T_(x))-cellulose nanofiber composites for biomimetic applications

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Nano Research 2024年第7期17卷 6619-6629页

作者： Shaofeng Zeng Yuanji Ye Peidi Zhou Shimin Yi Qiaohang guo Huamin Chen guozhen Shen Mingcen weng School of Mechanical and Automotive Engineering Fujian University of TechnologyFuzhou 350118China School of Materials Science and Engineering Fujian Provincial Key Laboratory of Advanced Materials Processing and ApplicationKey Laboratory of Polymer Materials and Products of Universities in FujianFujian University of TechnologyFuzhou 350118China Institute of Smart Marine and Engineering Fujian University of TechnologyFuzhou 350118China Fujian Key Laboratory of Functional Marine Sensing Materials College of Materials and Chemical EngineeringMinjiang UniversityFuzhou 350108China School of Integrated Circuits and Electronics Beijing Institute of TechnologyBeijing 100081China

Smart actuators have a wide range of applications in bionics and energy *** ability to reconfigure shape is essential for soft actuators to achieve various shapes and deformations,which is a crucial feature for next-generation ***,it is still an enormous challenge to establish a straightforward approach to creating programmable and reconfigurable ***-cellulose nanofiber composite film(MCCF)with a brick-and-mortar hierarchical structure was produced through a vacuum filtration *** demonstrates impressive mechanical properties such as a tensile stress of 68 MPa and a Young’s modulus of 4.65 ***,the MCCF highlights its potential for water-assisted shaping/welding due to the abundance of hydrogen bonds between MXene and cellulose *** also showcases capabilities as a humiditydriven actuator with a rapid response rate of 550°·s^(−1).Using the methods of water-assisted shaping/welding,several bionic actuators(such as flower,butterfly,and muscle)based on MCCF were designed,highlighting their versatility in applications of smart *** research showcases the impressive capabilities of MXene-based actuators and offers beneficial insights for the advancement of future intelligent materials.

关键词： MXene cellulose nanofibers programmable actuators humidity-driven

generation of polarized electron beams through self-injection in the interaction of a laser with a pre-polarized plasma

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High Power Laser Science and Engineering 2024年第3期12卷 62-68页

作者： L.R.Yin X.F.Li Y.j.gu N.Cao Q.Kong M.Büscher S.M.weng M.Chen Z.M.Sheng Key Laboratory of Nuclear Physics and Ion-beam Application(MoE) Institute of Modern PhysicsDepartment of Nuclear Science and TechnologyFudan UniversityShanghaiChina State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghaiChina SANKEN(Institute of Scientific and Industrial Research) Osaka UniversityOsakaJapan Sichuan Research Institute Shanghai Jiao Tong UniversityChengduChina Peter grünberg Institut(PgI-6) Forschungszentrum JülichJülichGermany Institut für Laser-und Plasmaphysik Heinrich-Heine-Universität DüsseldorfDüsseldorfGermany Key Laboratory for Laser Plasmas(MoE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghaiChina Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghaiChina

Polarized electron beam production via laser wakefield acceleration in pre-polarized plasma is investigated by particlein-cell *** evolution of the electron beam polarization is studied based on the Thomas±Bargmann±Michel±Telegdi equation for the transverse and longitudinal self-injection,and the depolarization process is found to be influenced by the injection *** the case of transverse self-injection,as found typically in the bubble regime,the spin precession of the accelerated electrons is mainly influenced by the ***,in the case of longitudinal injection in the quasi-1D regime(for example,*** et al.,***.110,135002(2013)),the direction of electron spin oscillates in the laser *** the electrons move around the laser axis,the net influence of the laser field is nearly zero and the contribution of the wakefield can be ***,an ultra-short electron beam with polarization of 99%can be obtained using longitudinal self-injection.

关键词： laser wakefield acceleration longitudinal self-injection particle-in-cell simulation polarized electron beam

Highly Stretchable and Tunable Thermo-fluorochromic Polymer Elastomer through Eu^(3+)Dynamic Coordination Cross-linking

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Chinese journal of Polymer Science 2024年第10期42卷 1449-1458,I0008页

作者： Qiu-Li Tan Kai gou jing-Zhi Tang Ming-Hui Wei Chong Wang Yi-jing Nie geng-Sheng weng School of Materials Science and Chemical Engineering State Key Laboratory Base of Novel Functional Materials and Preparation ScienceNingbo UniversityNingbo315211China Institute of Polymer Materials School of Materials Science and EngineeringJiangsu UniversityZhenjiang212013China

Thermochromic polymers with tunable thermochromism,high stretchability and mechanical strength are of interests for optical information storage and *** this work,we demonstrate a new design of thermo-fluorochromic carboxylated nitrile butadiene rubber(XNBR)elastomer cross-linked by Eu^(3+)-COOH dynamic coordination with deprotonated imidazole(DPIm)as the ancillary *** presence of DPIm not only improves the mechanical strength and stretchability,but also dramatically intensifies the fluorescence emission and lifetime of the Eu-containing *** elastomer behaves reversible thermo-fluorochromism with easily tunable transition temperature and emission intensity by the simple change of the deprotonation degree of *** facile tunable thermo-fluorochromism,exceptional mechanical strength,and high stretchability(up to about 5000%)enable the Eu-containing XNBR elastomer with potential applications in soft electronics where optical information storage and encryption are required.

关键词： Dynamic coordination Thermochromism Highly stretchable Elastomer Europium

Exfoliation of bulk 2H-MoS_(2)into bilayer 1T-phase nanosheets via ether-induced superlattices

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Nano Research 2024年第6期17卷 5705-5711页

作者： Xiuling Shi Dongmei Lin Zhuorui Xiao Yibo weng Hanxiang Zhou Xiaoying Long Zhiyu Ding Fuyuan Liang Yan Huang guohua Chen Kaikai Li Tong-Yi Zhang School of Materials Science and Engineering Harbin Institute of TechnologyShenzhen 518055China Department of Mechanical Engineering Research Institute for Smart EnergyThe Hong Kong Polytechnic UniversityHong KongChina School of Energy and Environment City University of Hong KongTat Chee AvenueKowloonHong KongChina The Hong Kong University of Science and Technology(guangzhou) Guangzhou Municipal Key Laboratory of Materials InformaticsAdvanced Materials Thrust and Sustainable Energy and Environment ThrustNanshaGuangzhou 511400China

The exfoliation of bulk 2H-molybdenum disulfide(2H-MoS_(2))into few-layer nanosheets with 1T-phase and controlled layers represents a daunting challenge towards the device applications of MoS_(2).Conventional ion intercalation assisted exfoliation needs the use of hazardous n-butyllithium and/or elaborate control of the intercalation potential to avoid the decomposition of the MoS_(2).This work reports a facile strategy by intercalating Li ions electrochemically with ether-based electrolyte into the van der Waals(vdW)channels of MoS_(2),which successfully avoids the decomposition of MoS_(2)at low *** co-intercalation of Li+and the ether solvent into MoS_(2)makes a first-order phase transformation,forming a superlattice phase,which preserves the layered structure and hence enables the exfoliation of bulk 2H-MoS_(2)into bilayer nanosheets with *** with the pristine 2H-MoS_(2),the bilayer 1T-MoS_(2)nanosheets exhibit better electrocatalytic performance for the hydrogen evolution reaction(HER).This facile method should be easily extended to the exfoliation of various transition metal dichalcogenides(TMDs).

关键词： exfoliation of MoS_(2) phase transformations superlattices ether electrolyte hydrogen evolution reaction(HER)