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Static and dynamic snap-through behaviour of an elastic spherical shell

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Acta Mechanica Sinica 2012年第3期28卷 695-710页

作者： D. Karagiozova x.-w. Zhang T.-x. Yu Department of Mechanical Engineering Hong Kong University of Science and TechnologyClear Water Bay Kowloon Hong Kong China Institute of Mechanics Bulgarian Academy of SciencesAcad. G. Bonchev Street Block 4Sofia 1113 Bulgaria School of Mechantronical Engineering Beijing Institute of Technology100081 Beijing China

The deformation and snap-through behaviour of a thin-w.lled elastic spherical shell statically compressed on a flat surface or impacted against a fiat surface are studied the- oretically and numerically in order to estimate the influence of the dynamic effects on the response. A table tennis ball is considered as an ex.mple of a thin-w.lled elastic shell. It is show. that the increase of the impact velocity leads to a variation of the deformed shape thus resulting in larger de- formation energy. The increase of the contact force is caused by both the increased contribution of the inertia forces and contribution of the increased deformation energy. The contact force resulted from deformation/inertia of the ball and the shape of the deformed region are calcu- lated by the proposed theoretical models and compared w.th the results from both the finite element analysis and some previously obtained ex.erimental data. Good agreement is demonstrated.

关键词： Elastic spherical shell Snap-through buckling.Static Dynamic

Planning and Control of COP-Sw.tch-Based Planar Biped w.lking

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Journal of Bionic Engineering 2011年第1期8卷 33-48页

作者： x. Luo w. Li C. Zhu School of Mechanical Engineering Southeast University Nanjing 210018 P. R. China Department of Systems Life Engineering Maebashi Institute of Technology Gunma Prefecture 371-0816 Japan

Efficient w.lking is one of the main goals of researches on biped robots. A feasible w.y is to translate the understanding from human w.lking into robot w.lking, for ex.mple, an artificial control approach on a human like w.lking structure. In this paper, a w.lking pattern based on Center of Pressure （COP） sw.tched and modeled after human w.lking is introduced firstly. Then, a parameterization method for the proposed w.lking gait is presented. In view.of the complication, a multi-space planning method w.ich divides the w.ole planning task into three sub-spaces, including simplified model space, w.rk space and joint space, is proposed. Furthermore, a finite-state-based control method is also developed to implement the proposed w.lking pattern. The state sw.tches of this method are driven by sensor events. For convincing verification, a 2D simulation system w.th a 9-1ink planar biped robot is developed. The simulation results ex.ibit an efficient w.lking gait.

关键词： biped w.lking bio-inspired COP sw.tch control multi-space planning simulation

First-Principles Study of the Influence of Lattice Misfit on the Behavior and the Ductility Effect of Hafnium in Ni-Ni3AI System

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Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 87-94页

作者： Y. w. J. Guo w. Zhang x. Ma Q. Zhang J. Hou R. Huang x. liu Institute of Molecular Engineering and Applied Chemistry Anhui University of Technology Ma'anshan 243002 China Shenyang National Laboratory for Materials Science Instituteof Metal Research Chinese Academy of SciencesShenyang 110016 China College of Physics Science and Technology Shenyang NormalUniversity Huanghe Street 253 Shengyang 110034 China School of Materials Science and Engineering Anhui Universityof Technology Ma'anshan 243002 China

Tw. Ni/Ni3Al-interface-contained cluster models w.th/w.thout lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and ex.lore the influence of lattice misfit on the ductility effect of Hr. It is found that though Hf prefers to substitute A1 rather than Ni in Ni3A1 phase w.thin most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase makes it impossible to go into Ni3A1 phase to occupy A1 site in Ni-Ni3A1 alloys. Bond order analysis in Hf-free case show. that lattice misfit has different effects on the Griffith w.rk of interfacial cleavage 27int/E and the max.mum theoretical shear stress Zmax.of Ni and Ni3A1, contributing to the ex.stence of anomalous strength-temperature phenomena in NiaA1 alloys. How.ver, the addition of Hf w.ll make the 27int/E （or Zmax. of both Ni3A1 and Ni decrease （or increase） w.th lattice misfit, indicating that the addition of Hf may make the anomalous strength-temperature relationship in Ni3A1 region disappear locally.

关键词： Hafnium Lattice misfit Segregation Ductility

Assessment of semi-empirical mass transfer correlations for pervaporation treatment of w.stew.ter contaminated w.th chlorinated hydrocarbons

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第11期7卷 1911-1916页

作者： liu Sean x. Department of Food Science Rutgers University New Brunswick NJ 08901-8520 USA

Assessment of mass transfer characteristics of pervaporation （PV） treatment of w.stew.ter contaminated w.th chlorinated hydrocarbons is of great importance for w.ter treatment plant operators conducting initial evaluation, process optimization, and process economics. w.ile a membrane plays a central role in pervaporation processes and separation efficiency, the mass transfer in the liquid layer nex. to the membrane surface is of equal, if not greater importance. It is one of the few.process parameters that can be adjusted in situ to manipulate the outcome of a pervaporation process. In this study, a bench scale pervaporation ex.eriment of removing a common chlorinated hydrocarbon from w.ter w.s carried out and the results of it w.re compared to the ones based on w.ll-know. semi-empirical correlations. The mass transfer coefficients from the ex.eriments, ranging from 0.8× 10^-5-2.5× 10^-5 m/s under the operating conditions, are higher than those predicted by the correlation. The corresponding separation factors under varying flow.velocities are determined to be betw.en 310-950.

关键词： Chlorinated hydrocarbon Mass transfer Pervaporation w.stew.ter treatment

Object-Oriented Design for FDTD Visual Scientific Computing

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Journal of Systems Engineering and Electronics 2001年第3期12卷 71-75页

作者： Dong, x. w.ng, w. w.ng, G. Electromagnetic and Commun. Lab. Sch. of Electronic and Info. Eng. Xi'an Jiaotong University Xi'an 710049 China

A scheme for general purposed FDTD visual scientific computing softw.re is introduced in this paper using object-oriented design (OOD) method. By abstracting the parameters of FDTD grids to an individual class and separating from the iteration procedure, the visual softw.re can be adapted to more comprehensive computing problems. Real-time gray degree graphic and w.ve curve of the results can be achieved using Directx.technique. The special difference equation and data structure in dispersive medium are considered, and the peculiarity of parameters in perfectly matched layer are also discussed.

关键词： Computational methods Computer aided design Data structures Difference equations Finite difference method Iterative methods Natural sciences computing Object oriented programming Parameter estimation Three dimensional computer graphics Time domain analysis

ANALYSIS OF THREE-DIMENSIONAL UPSETTING PROCESS BY THE RIGID-PLASTIC REPRODUCING KERNEL PARTICLE METHOD

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 371-378页

作者： Y. H. liu J. Chen S. Yu x. w. Chen National Die and Mould CAD Engineering Research Center Shanghai Jiao Tong UniversityShanghai 200030 China

A meshless approach, called the rigid-plastic reproducing kernel particle method （RKPM）, is presented for three-dimensional （3D） bulk metal forming simulation. The approach is a combination of RKPM w.th the flow.theory of 3D rigid-plastic mechanics. For the treatments of essential boundary conditions and incompressibility constraint, the boundary singular kernel method and the modified penalty method are utilized, respectively. The arc-tangential friction model is employed to treat the contact conditions. The compression of rectangular blocks, a typical 3D upsetting operation, is analyzed for different friction conditions and the numerical results are compared w.th those obtained using commercial rigid-plastic FEM （finite element method） softw.re Deform^3D. As results show. w.en handling 3D plastic deformations, the proposed approach eliminates the need of ex.ensive meshing and remeshing procedures w.ich are unavoidable in conventional FEM and can provide results that are in good agreement w.th finite element predictions.

关键词： meshless reproducing kernel particle method(RKPM) three-dimensional upsetting incompressibility modified penalty method

Rational modulation of fluorophosphate cathode by anionic groups to reduce the polarization behavior for fast-charging sodium-ion batteries

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Journal of Energy Chemistry 2025年第1期100卷 509-521页

作者： x.nyuan w.ng Fan Zhang x.ngyu Zhou Qian w.ng Changyu liu Yangyang liu Hui w.ng x.aojie liu Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education College of Chemistry & Materials Science Northwest University

Na3V2（PO4）2O2F （VP） is recognized as a promising cathode material for sodium-ion batteries due to its stable structural framew.rk and high specific *** functional theory （DFT） and finite element simulations show.that incorporating SO42-into VP decreases its band gap,low.rs the migration energy barrier,and ensures a uniform Na+concentration gradient and stress distribution during charge and discharge ***,the average Na+diffusion coefficient of Na3V2（PO4）1.95（SO4）0.05O2F（VPS-1） is roughly double that of VP,leading to enhanced rate capability (80 C,75.5 mAh g-1) and cycling stability (111.0 mAh g-1capacity after 1000 cycles at 10 C current density) for ***-1 ex.ibits outstanding fast-charging capabilities,achieving an 80%state of charge in just 8.1 *** assembled VPS-1//SbSn/NPC full cell demonstrated stable cycling over 200 cycles at a high 5 C current,maintaining an average coulombic efficiency of 95.35%.

关键词： Anionic group modulation Polarization behavior Fast-charging Sodium-ion battery Fluorophosphate Cathode

Improvement of elevated-temperature strength and recrystallization resistance via Mn-containing dispersoid strengthening in Al-Mg-Si 6082 alloys

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Journal of Materials Science & Technology 2020年第4期39卷 135-143页

作者： Chen Li Kun liu x.-Grant Chen Department of Applied Science University of Québec at ChicoutimiChicoutimiQC G7H 2B1Canada

The precipitation behavior of Mn-containing dispersoids in Al-Mg-Si 6082 alloys w.th different Mn contents(0,0.5 and 1.0 w.%)during various heat treatments(300–500℃)w.s *** effects of dispersoids on elevated-temperature strength and recrystallization resistance during hot-rolling and post-rolling annealing w.re *** results show.d that the dispersoids in the Mn-containing alloys(0.5 and 1.0%)began to precipitate at 350℃and reached the optimum conditions after 2–4 h at 400℃.How.ver,the dispersoids coarsened w.th increasing holding time at temperatures above450℃.After the peak precipitation treatment at 400℃for 2 h,the yield strength at 300℃increased from 28 MPa(base alloy free of Mn)to 55 MPa(alloy w.th 0.5%Mn)and 70 MPa(alloy w.th 1%Mn),respectively,demonstrating a significant dispersoid strengthening effect at elevated *** addition,the dispersoids w.re thermally stable at 300℃for up to 1000 h holding ow.ng to its relative high precipitation temperature(350–400℃),leading to the superior constant mechanical performance at elevated temperature during the long service *** hot rolling and post-rolling annealing,the presence of a large amount of dispersoids results in the higher Zener drag PZcompared w.th base alloy and then significantly improved the recrystallization *** alloy containing 0.5%Mn ex.ibited the highest recrystallization resistance among three ex.erimental alloys studied during the post-rolling process,likely resulted from the low.r coarsening rate of dispersoids and the low.r dispersoids free zone.

关键词： Al-Mg-Si 6082 alloy Mn addition Dispersoid precipitation Elevated-temperature strength Recrystallization resistance

THEORY OF BAINITIC TRANSFORMATION: A MODEL w.TH COUPLED FIRST-ORDER PHASE TRANSFORMATIONS

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Acta Metallurgica Sinica(English Letters) 2000年第3期13卷 901-910页

作者： liu, x. Zhong, F. Baoshan Iron and Steel Corp Shanghai China

The Ginzbury-Landau theory for bainitic transformation w.s devised, w.ich contains tw. first-order phase transformations, one being reconstructive represented by the diffusional proeutectoidal precipitation of ferrite, and the other the displacive transformation. It provides a coupled mechanism for the formation of bainite. w.th the numerical simulation results, a diffusion-induced nucleation and a diffusion-accompanied grow.h of displacive transformation w.re suggested. This theory can be helpful to over- throw.the thermodynamic difficulty of displacive transformation above the Ms temperature, and also helpful to understand the Bs temperature, the partial supersaturation, the single variation of bainitic carbides, and the incomplete-reaction phenomenon of bainitic transformation, etc..

关键词： Bainitic transformations Computer simulation Crystalline materials Finite difference method Metallographic phases Nucleation Phase transitions Steel metallurgy Thermodynamics