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Numerical Quantification Model and Experiment of External Force on Roller Hemming of Curved Edge Aluminium Alloy with Adhesive

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Chinese Journal of Mechanical Engineering 2022年第1期35卷 144-155页

作者： jianjun li Wenfeng Zhu Shunchao Wang School of Mechanical Engineering Tongji UniversityShanghai 201804China

Accurate quantification of external force is the key to improve the high-precision hemming of autobody closure ***,the mechanism of external force on forming quality of complex contour sheet metal with adhesive is not clear subjected to geometric curvature and *** the present study,taking the curved edge aluminum sheet as the research object,SPH(smooth particle hydrodynamics)is introduced to simulate the viscous adhesive,and the SPH-FEM(Finite element method)coupling model of adhesive and panels considering the viscosity-pressure effect is *** numerical simulation of the roller hemming process is carried out,then the validity and reliability of the proposed method are verified by measuring the external force in real time using triaxial force *** multi-step forming process and the effect of external force on the roll in/out,surface wave and plastic strain of aluminum alloy sheet under the viscosity-pressure effect are studied,and the relationship between process parameters and external force is *** show that the coupling SPH-FEM model can well reflect the hemming process of curved edge *** normal force is about 2–3 times of the tangential force in the pre and final hemming *** with the case without adhesive,the surface wave of flange part of the hemming with adhesive is slightly *** normal force and the tangential force increase about 90 N and 30 N respectively,when the height increases by 1 *** provides an important basis for the accurate control of hemming trajectory and the improvement of manufacturing quality of autobody closure panels.

关键词： External force Forming Adhesive Simulation Aluminum alloy sheet Manufacturing quality

The Probability Analysis for the Many-Versus-One Guerrilla War

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Journal of Systems Science & Complexity 2015年第3期28卷 645-660页

作者： liU liwei li jianjun QIAN linfang School of Science Nanjing University of Science and Technology School of Mechanical Engineering Nanjing University of Science and Technology

This paper discusses a stochastic duel model between two forces. On one side is the guerrilla(or terrorists) which has only one weapon(or person), and on the other an organized force of some sort which has many weapons. The model is called the many-versus-one guerrilla war. The guerrilla side has a number of advantages such as choice of location and time of engagement, concealment by topography, observation of the intended target, and line of fire. The authors present these advantages in what they believe are a realistic scenario of a duel between the guerrilla force and the organized force. By the four suppositions coinciding with the practical duel background, the paper presents the formulas to calculate the satisfying probability, the weak satisfying probability, and the acceptable probability of the attack side.

关键词： Fokker-Planck equation guerrilla war Markov chains military operational research stochastic duel.

SPECIFIC HEAT MEASUREMENTS OF ZrAlNiCuCo ALLOY

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中国有色金属学会会刊：英文版 1999年第1期9卷 50-53页

作者： Zhao, Ming li, jianjun Jiang, Qing Jilin Univ of Technology Changchun China

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｏｅｘａｍｉｎｅｔｈｅｔｈｅｒｍｏｄｙｎａｍｉｃｓａｎｄｄｙｎａｍｉｃｓｏｆｇｌａｓｓｔｒａｎｓｉｔｉｏｎｏｆａｍｏｒｐｈｏｕｓａｌｏｙ，ｉｔｉｓｎｅｃｅｓｓａｒｙｔｏｍｅａｓｕｒｅｓｐ... 详细信息

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｏｅｘａｍｉｎｅｔｈｅｔｈｅｒｍｏｄｙｎａｍｉｃｓａｎｄｄｙｎａｍｉｃｓｏｆｇｌａｓｓｔｒａｎｓｉｔｉｏｎｏｆａｍｏｒｐｈｏｕｓａｌｏｙ，ｉｔｉｓｎｅｃｅｓｓａｒｙｔｏｍｅａｓｕｒｅｓｐｅｃｉｆｉｃｈｅａｔｏｆｔｈｅａｌ...

关键词： ZrAlNiCuCo alloy specific heat amorphous alloy

GLASS TRANSITION AND THERMODYNAMIC FUNCTION OF ZrAlNiCuCo ALLOY

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中国有色金属学会会刊：英文版 1999年第2期9卷 51-55页

作者： Zhao, Ming li, jianjun Jiang, Qing Jilin Univ of Technology Changchun China

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｇｌａｓｔｒａｎｓｉｔｉｏｎａｓａｐｏｌｙｍｏｒｐｈｏｕｓｏｎｅ（ｒｅｑｕｉｒｉｎｇｅｑｕａｌｉｔｙｏｆｃｏｍｐｏｓｉｔｉｏｎｉｎａｌｐｈａｓｅｓ）ｎｅｅｄｓａｖｅｒｙｓｍａｌＥ（ａｃ... 详细信息

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｇｌａｓｔｒａｎｓｉｔｉｏｎａｓａｐｏｌｙｍｏｒｐｈｏｕｓｏｎｅ（ｒｅｑｕｉｒｉｎｇｅｑｕａｌｉｔｙｏｆｃｏｍｐｏｓｉｔｉｏｎｉｎａｌｐｈａｓｅｓ）ｎｅｅｄｓａｖｅｒｙｓｍａｌＥ（ａｃｔｉｖａｔｉｏｎｅｎｅｒｇｙ）ｗｉ...

关键词： ZrAlNiCuCo alloyglass transitionthermodynamic functionKauzmann temperature

Interaction between plasma jet and silicone rubber covered by porous inorganic contaminants:Surface hydrophobicity or hydrophilicity?

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High Voltage 2022年第6期7卷 1023-1033页

作者： Shuang li jianjun li Yongqiang Fu Ruobing Zhang Engineering Laboratory of Power Equipment Reliability in Complicated Coastal Environments Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhenChina

The variation of surface hydrophobicity of silicone rubber materials covered with porous inorganic pollution layer under the action of atmospheric pressure plasma jet presents some new features,which have important engineering applications in the field of outdoor insulation of power *** of the plasma with the polluted silicone rubber is studied and surface hydrophobicity is *** results show that the exposure of plasma greatly accelerates the transfer of low molecular weight siloxanes(LMWs)in the pollution ***,the surface hydrophobicity is determined by the LMWs contents and the exposure *** acceleration effects of plasma during and after plasma exposure are proposed,their influence on surface hydrophobicity is analysed and related mechanisms are *** addition,the competing influence of plasmainduced acceleration of the transfer of LMWs towards the surface and plasmaoxidation of LMWs on surface hydrophobicity is discussed.

关键词： rubber inorganic acceleration

Modelling of dynamic recrystallization kinetics of 300M steel at high strain rates during hot deformation

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Science China(Technological Sciences) 2019年第9期62卷 1534-1544页

作者： GUO Peng DENG Lei WANG XinYun li jianjun State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology

The flow curves of 300M steel exhibit a transition from stress peak presence to stress peak absence as the strain rate increases. It is difficult to establish dynamic recrystallization(DRX) kinetics models suitable for strain rates where there are no stress peaks in the flow curves using the existing Avrami equation, and the optimal processing parameters for forging can be scarcely *** this study, the high-temperature flow and DRX behavior of 300M steel are investigated by performing isothermal compression tests at temperatures between 1173–1423K with strain rates between 0.001–50 s-1. Distinct stress peaks can be found in the flow curves at low strain rates, and the average grain size decreases with the increase in the strain rate at the same temperature. The DRX mechanism is a discontinuous DRX, and the grain boundary migration plays an important role in the DRX process. In contrast, no stress peak is observed in the flow curves at high strain rates, and the average grain size no longer decreases with the strain rate increase at the same temperature. The DRX mechanism in this case is a continuous DRX. The demarcated strain rate is calculated based on the characteristics of the obtained flow curves and grain sizes. The recrystallization volume fraction model and prediction grain size model at high strain rates are established. In combination with the existing DRX kinetics models at low strain rates, the processing parameters can be optimized to produce components with excellent mechanical properties.

关键词： 300M steel flow curves demarcated strain rate dynamic recrystallization grain size

Expert Recommendation in Community Question Answering via Heterogeneous Content Network Embedding

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Computers, Materials & Continua 2023年第4期75卷 1687-1709页

作者： Hong li jianjun li Guohui li Rong Gao lingyu Yan School of Computer Science and Technology Huazhong University of Science and TechnologyWuhan 430074China College of Computer Science and Technology Hubei University of TechnologyWuhan 430068China

ExpertRecommendation(ER)aims to identify domain experts with high expertise and willingness to provide answers to questions in Community Question Answering(CQA)web *** to model questions and users in the heterogeneous content network is critical to this *** traditional methods focus on modeling questions and users based on the textual content left in the community while ignoring the structural properties of heterogeneous CQA networks and always suffering from textual data sparsity *** approaches take advantage of structural proximities between nodes and attempt to fuse the textual content of nodes for ***,they often fail to distinguish the nodes’personalized preferences and only consider the textual content of a part of the nodes in network embedding learning,while ignoring the semantic relevance of *** this paper,we propose a novel framework that jointly considers the structural proximity relations and textual semantic relevance to model users and questions more ***,we learn topology-based embeddings through a hierarchical attentive network learning strategy,in which the proximity information and the personalized preference of nodes are encoded and ***,we utilize the node’s textual content and the text correlation between adjacent nodes to build the content-based embedding through a meta-context-aware skip-gram *** addition,the user’s relative answer quality is incorporated to promote the ranking *** results show that our proposed framework consistently and significantly outperforms the state-of-the-art baselines on three real-world datasets by taking the deep semantic understanding and structural feature learning *** performance of the proposed work is analyzed in terms of MRR,P@K,and MAP and is proven to be more advanced than the existing methodologies.

关键词： Heterogeneous network learning expert recommendation semantic representation community question answering

Promotion effect of Au single-atom support graphene for CO oxidation

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Chinese Chemical Letters 2022年第11期33卷 4822-4827页

作者： Ping Yan Song Shu Xian Shi jianjun li College of Architecture and Environment Sichuan UniversityChengdu 610065China Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 611731China

CO oxidation is a vital catalytic reaction for environmental purification,facing challenges due to the catalysts applied to oxidize CO are mainly rare and expensive noble *** the high atomic availability,catalytic efficiency,and selectivity of single-atom catalysis,it has been widely studied and proven to be brilliant in CO *** single-atom catalysts are regarded as excellent single-atom catalysts in oxidizing CO,whose progress is limited by the indistinct understanding of the reaction mechanism and role of the active ***,DFT calculation was used to investigate CO oxidation processes,active mechanisms,and the role of Au *** involving prominent physical and chemical properties was selected as a model *** single-atom support graphene materials exhibit better CO oxidation activities than pristine graphene,among which CO oxidation property on Au/GP is the highest with a0.38 eV rate-determining barrier following ER *** outstanding performances including excellent electronic structures,adsorption properties,and strong activation of intermediate products contribute to the high CO oxidation activity of Au/GP,and the Au single-atom is the active *** work provides a novel guide for single-atom catalytic CO oxidation,accelerating the development of single-atom catalysis.

关键词： Single-atom Graphene CO oxidation ER mechanism DFT

Shear instability in heterogeneous nanolayered Cu/Zr composites

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Journal of Materials Science & Technology 2022年第10期105卷 81-91页

作者： jianjun li Feng Qin Dingshun Yan Wenjun Lu Jiahao Yao School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China State Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Ultrastrong nanolayered metallic composites are usually subjected to low ductility due to plastic instability during *** we investigated the shear instability of a newly designed heterogeneous nanolayered Cu/Zr composites by *** heterogeneity in size was generated by inserting a few thin Cu-Zr bilayers with an individual layer thickness of 2.5-10 nm into the interface region of the Cu/Zr layered composites with an individual layer thickness of 100 *** microindentation tests showed that multiple shear bands appeared in the heterogeneous composite with one bilayer,whereas only a single shear band was formed in that with two or three *** importantly,the layer strain in the multi-shear band region is much smaller than that in the single-shear band *** example,the strain of the 100 nm layers within the shear band in the composite with one 10 nm bilayer could reach as low as 2.8,which was less than half of that in the composite with three 10 nm bilayers,i.e.,*** fndings demonstrated that strain delocalization can be achieved through shear band multiplication if an appropriate number of thin bilayers were used as interlayers in the 100 nm Cu/Zr ***,compared with the homogeneous composite with an individual layer thickness of 100 nm and the bimodal composite which is composed of alternating one 100 nm Cu-Zr bilayer and two 10 nm CuZr bilayers,the heterogeneous composite with one bilayer displayed a higher strength(2.15 GPa)and a favorable resistance to strain localization.

关键词： Nanolayered metallic composites Sputtering Microindentation Shear band Strain delocalization