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Experimental and numerical studies on the sluggish diffusion in face centered cubic Co-Cr-Cu-Fe-Ni high-entropy alloys

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Journal of Materials Science & Technology 2018年第10期34卷 1791-1798页

作者： Rui Wang weimin chen Jing Zhong Lijun Zhang State Key Laboratory of Powder Metallurgy Central South University Institute of Advanced Wear & Corrosion Resistant and Functional Materials Jinan University

On purpose of studying the sluggish diffusion of high-entropy alloys, three different face centered cubic Co-Cr-Cu-Fe-Ni high-entropy alloys were prepared, and assembled into three groups of sandwich- type diffusion multiple annealed at 1273, 1323, and 1373 K respectively. By means of the electron probe microanalyzer technique and recently developed numerical inverse method, the composition- dependent interdiffusivities at different temperatures were effectively evaluated by minimizing the residual between the model-predicted compositions/interdiffusion fluxes and the respectively experi- mental ones. After that, the tracer diffusivities were predicted based on the assessed mobility parameters and thermodynamic descriptions with the simplified ideal solution model. The comprehensive compari- son between the interdiffusivities/tracer diffusivities in the Co-Cr-Cu-Fe-Ni high-entropy alloys and those in sub-binary, ternary, quaternary and other quinary alloys indicates that the sluggish diffusion exists in interdiffusion instead of tracer diffusion for the present Co-Cr-Cu-Fe-Ni high-entropy alloys.

关键词： High-entropy alloys Co-Cr-Cu-Fe-Ni Sluggish diffusion Numerical inverse method Diffusion multiple

Fuzzy Hybrid Control of Vibration Attitude of Full Car via Magneto-rheological Suspensions

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Chinese Journal of Mechanical Engineering 2010年第1期23卷 72-79页

作者： LI Rui chen weimin LIAO Changrong DONG Xiaomin Key Laboratory of Optoelectronic Technology and Systems of Ministry of Education Chongqing University Chongqing 400030 China Key Laboratory of Network Control and Intelligent Instrument of Ministry of Education Chongqing University of Posts and Telecommunications Chongqing 400065 China

A magneto-rheological（MR） semi-active suspension system with the controllable damping forces has received more attention in reducing the vibration of a vehicle. However, many control strategies only discussed one or two vibration states of the vehicle based on a quarter-car model or a half vehicle model via MR suspensions. They cannot provide a satisfying whole-vehicle performance on a road test. Hence, a full car vibration model via an MR suspension system is proposed. To reduce the heave, pitch and roll motion of the vehicle body and the vertical vibration of four wheels, a fuzzy hybrid controller for vibration attitude of full car via MR suspensions is proposed. First, a skyhook-fuzzy control scheme is designed to reduce the heave, roll and pitch motion of the vehicle body. Second, a revised ground hook control strategy is adopted to decrease the vertical vibration of the wheels. Finally, a hybrid control scheme based on a fuzzy reasoning method is proposed to tune the hybrid damping parameter, which is suitable for coordination the attitude of the vehicle body and the wheels. A test and control system for the vibration attitude of full car is set up. It is implemented on a car equipped with four MR suspensions. The results on random highway and rough road indicate that the fuzzy hybrid controller can decrease the vibration accelerations of the vehicle body and the wheels to 65%-80% and 80%-90%, respectively. It reduces the automotive vibrations of heave, roll and pitch more effectively than a passive suspension and an MR suspension with a traditional hybrid control scheme so that it achieves better ride comfort and road holding concurrently. This paper proposes a new fuzzy hybrid control（FHC） method for reducing vibration attitude of full car via MR suspensions and develops a road test to evaluate the FHC.

关键词： car magneto-rheological suspension vibration attitude fuzzy control hybrid damping control road test

Measurement and Simulation of Grain Size in Strong Textured and Coarse-Grained Metal Sheets

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Journal of Materials Science & Technology 2003年第Z1期19卷 115-116页

作者： Leng chen weimin MAO Yongning YU Huiping FENG Department of Materials University of Science and Technology Beijing Beijing 100083 China Department of Materials University of Science and Technology Beijing Beijing 100083 China Department of Materials University of Science and Technology Beijing Beijing 100083 China Department of Materials University of Science and Technology Beijing Beijing 100083 China

An X-ray diffractometer that equipped with a two-dimensional detector is used for developing the technique of grainsize measurement for strong textured and coarse-grained Si steel sheet. The method is based on the concept thatthe position of diffraction spots depends on the orientation of individual grains. The two-dimensional detector hasthe ability to collect abundant diffraction information in seconds, thus it can be determined rapidly and accuratelywhether a series of diffraction spots come from the same grain. The experimental results show that this method canbe used for measuring grain size and its distribution in strong textured and coarse-grained metal sheets.

关键词： Grain size, Texture, Two-dimensional detectorLeng

Cracking Propagation of Hardening Concrete Based on the Extended Finite Element Method

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Journal of Wuhan University of Technology(Materials Science) 2017年第5期32卷 1132-1139页

作者：朱振泱 chen weimin ZHANG Guoxin China Institute of Water Resources and Hydropower Research Beifing 100038 China Hydrochina Huadong Engineering Corporation Hangzhou 310014 China

Self-deformation cracking is the cracking caused by thermal deformation, autogenous volume deformation or shrinkage deformation. In this paper, an extended finite element calculation method was deduced for concrete crack propagation under a constant hydration and hardening condition during the construction period, and a corresponding programming code was developed. The experimental investigation shows that initial crack propagation caused by self-deformation loads can be analyzed by this program. This improved algorithm was a preliminary application of the XFEM to the problem of the concrete self-deformation cracking during the hydration and hardening period. However, room for improvement exists for this algorithm in terms of matching calculation programs with mass concrete temperature fields containing cooling pipes and the influence of creep or damage on crack propagation.

关键词： concrete crack self-deformation loads extended finite element method

A Model for Temperature Infl uence on Concrete Hydration Exothermic Rate (Part one: Theory and Experiment)

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Journal of Wuhan University of Technology(Materials Science) 2014年第3期29卷 540-545页

作者：朱振泱 QIANG Sheng chen weimin Hydrochina Huadong Engineering Corporation College of Water Conservancy and Hydropower Engineering Hohai University

Recent achievements in concrete hydration exothermic models based on Arrhenius equation have improved computation accuracy for mass concrete temperature field. But the properties of the activation energy and the gas constant （Ea/R） have not been well studied yet. From the latest experiments it is shown that Ea/R obviously changes with the hydration degree without fixed form. In this paper, the relationship between hydration degree and Ea/R is studied and a new hydration exothermic model is proposed. With those achievements, the mass concrete temperature field with arbitrary boundary condition can be calculated more precisely.

关键词： hydration exothermic model Arrhenius equation activation energy hydration degree temperature rise model

DESIGN METHOD OF MAGNETORHEOLOGICAL FLUID SHOCK ABSORBER FOR CAR SUSPENSION

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Chinese Journal of Mechanical Engineering 2008年第5期21卷 19-22页

作者： LIAO Changrong ZHANG Honghui YU Miao chen weimin Center for Intelligent Structures Chongqing University Chongqing 400044 China Key Laboratory for Optoelectronic Technology and Systems of Ministry of Education Chongqing 400044 China

The Bingham constitutive model, which is previously used in depiction of magnetorheological （MR） fluids rheological behaviors for design devices, exhibits discontinuous characteristics in representation of pre-yield behaviors and post-yield behaviors. A Biviscous constitutive model is presented to depict rheological behaviors of MR fluids and design automotive shock absorber. Quasi-static flow equations of MR fluids in annular channels are set theoretically up based on Navier-Stokes equations and several rational simplifications are made. And both flow boundary conditions and flow compatibilities conditions are established. Meantime, analytical velocity profiles of MR fluids though annular channels are obtained via solution of the quasi-static flow equations using Biviscous constitutive model. The prediction methodology of damping force offered by MR fluid shock absorber is formulated and damping performances are predicated in order to determine design parameters. MR fluid shock absorber for Mazda 323 car suspension is designed and fabricated in Chongqing University, China. Measurements from sinusoidal displacement cycle by Shanchuan Shock Absorber Ltd. of China North Industry Corporation reveal that the analytical methodology and design theory are reasonable.

关键词： Magnetorheological fluid shock absorber Biviscous constitutive model Bingham constitutive model

Moment-tensor inversion and decomposition for cracks in thin plates

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Chinese Journal of Aeronautics 2021年第4期34卷 352-359页

作者： Yue KONG Min LI weimin chen Ning LIU Boqi KANG School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China Key Laboratory of Space Utilization Technology and Engineering Center for Space UtilizationChinese Academy of SciencesBeijing 100094China

The knowledge of crack type and dislocation orientation is helpful for the lifetime prediction of thin plates on *** moment-tensor inversion utilizes the Acoustic Emission(AE)signals to detect cracks and the source mechanisms can be interpreted by the decomposition of moment *** the traditional moment-tensor inversion is implemented for the AE sources inside infinite elastic bodies,the inversion needs to be modified for the cracks in thin *** this study,the moment tensors of cracks in thin plates are derived and the inversion equation is provided based on the Green's function of second kind.A method of modifying the moment tensors to adapt to the existing decomposition processes and source-type plots is *** employing the Finite Element Method(FEM),the wave fields generated by the AE sources are *** AE sources continuously changing from pure tensile type(Model I)to shear type(Model II)are achieved in the FE models and the moment tensors are *** the comparison between the reference values and recovered solutions,the source type can be accurately identified in the source-type plot and the applicability of the moment-tensor inversion for cracks in thin plates is confirmed.

关键词： Acoustic emission Fatigue Moment tensor Source mechanism Structural health monitoring Thin plate

A non-probabilistic reliability topology optimization method based on aggregation function and matrix multiplication considering buckling response constraints

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 321-336页

作者： Lei WANG Yingge LIU Juxi HU weimin chen Bing HAN Institute of Solid Mechanics School of Aeronautic Science and EngineeringBeihang UniversityBeijing 100191China Aircraft and Propulsion Laboratory Ningbo Institute of TechnologyBeihang UniversityNingbo 315100Zhejiang ProvinceChina State Key Laboratory of Navigation and Safety Technology Shanghai Ship and Shipping Research InstituteShanghai 200135China National Engineering Research Center of Ship&Shipping Control System Shanghai Ship and Shipping Research InstituteShanghai 200135China

A non-probabilistic reliability topology optimization method is proposed based on the aggregation function and matrix *** expression of the geometric stiffness matrix is derived,the finite element linear buckling analysis is conducted,and the sensitivity solution of the linear buckling factor is *** a specific problem in linear buckling topology optimization,a Heaviside projection function based on the exponential smooth growth is developed to eliminate the gray *** aggregation function method is used to consider the high-order eigenvalues,so as to obtain continuous sensitivity information and refined structural *** cyclic matrix programming,a fast topology optimization method that can be used to efficiently obtain the unit assembly and sensitivity solution is *** maximize the buckling load,under the constraint of the given buckling load,two types of topological optimization columns are *** variable density method is used to achieve the topology optimization solution along with the moving asymptote optimization *** vertex method and the matching point method are used to carry out an uncertainty propagation analysis,and the non-probability reliability topology optimization method considering buckling responses is developed based on the transformation of non-probability reliability indices based on the characteristic ***,the differences in the structural topology optimization under different reliability degrees are illustrated by examples.

关键词： buckling topology optimization aggregation function uncertainty propagation analysis non-probabilistic reliability

Hydroelastic dynamic characteristics of a slender axis-symmetric body

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Science China(Physics,Mechanics & Astronomy) 2010年第7期53卷 1339-1347页

作者： chen weimin LI Min ZHENG ZhongQin ZHANG LiWu Laboratory of Environmental Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Aeronautics Sciences and Technology Beijing University of Aeronautics and AstronauticsBeijing 100191China

The slender axis-symmetric submarine body moving in the vertical plane is the object of our investigation.A coupling model is developed where displacements of a solid body as a Euler beam(consisting of rigid motions and elastic deformations) and fluid pressures are employed as basic independent variables,including the interaction between hydrodynamic forces and structure dynamic *** the hydrodynamic forces,depending on and conversely influencing body motions,are taken into account as the governing *** expressions of fluid pressure are derived based on the potential *** characteristics of fluid pressure,including its components,distribution and effect on structure dynamics,are *** the coupling model is solved numerically by means of a finite element method(FEM).This avoids the complicacy,combining CFD(fluid) and FEM(structure),of direct numerical simulation,and allows the body with a non-strict ideal shape so as to be more suitable for practical *** illustrative example is given in which the hydroelastic dynamic characteristics,natural frequencies and modes of a submarine body are analyzed and compared with experimental *** agreement is observed and the model presented in this paper is shown to be valid.

关键词： hydroelasticity added mass vibration frequency mode