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FInITE ElEMEnT nUMERICAl SIMUlATIOn OF TEMPERATURE FIElD In METAl PATTERn CASTInG SySTEM AnD "REVERSE METHOD" OF DEFInInG THE THERMAl PHySICAl COEFFICIEnT

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Acta Metallurgica Sinica(English letters) 2007年第3期20卷 217-224页

作者： l. Chen P.l. Wang P.n. Song j.y. Zhang Mechanical Engineering College Tianjin University of Technology Tianjin 300191China

With the technology support of virtual reality and AnSyS software, an example on the simulation of temperature distribution of casting system during the solidification process was provided, which took the latent heat of phase change, the conditions for convection, and the interface heat transfer coefficient into consideration. The result of AnSyS was found to agree well with the test data. This research offers an unorthodox way or ＂reverse method＂ of defining the relevant thermal physical coefficient.

关键词： solidification process reverse method AnSyS software

Atomic-scale roles of Zn element in age-hardened AlMgSiZn alloys

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journal of Materials Science & Technology 2021年第11期70卷 105-112页

作者： n.n.jiao y.X.lai S.l.Chen P.Gao j.H.Chen Center for High-Resolution Electron Microscopy College of Materials Science&EngineeringHunan UniversityChangsha410082China Electron Microscopy laboratory and International Center for Quantum Materials School of PhysicsPeking UniversityBeijing100871China

Adding alloying elements to improve the performances or the manufacturing processes of Al-Mg-Si alloys has l.ng been a serious issue in developing advanced automotive aluminum *** Zn element,among those promising ones,has demonstrated positive alloying effects on Al-Mg-Si ***,the atomic-scale roles of Zn in an age-hardened Al-Mg-Si-Zn alloy have not been adequately *** atomic-resolution electron microscopy,here we report the precise locations of Zn elements in all hardening precipitates involved and their alloying mechanism at the atomic scale when alloying the *** results show that Zn atoms enter all the major hardening phases to occupy specific featured atomic sites of the original elements,*** Si1 and Mg2 sites in theβ’-2 phase,and modify their crystal structures,interfacial structures and morphologies in characteristic *** is revealed that for theβ’-phase,Zn atoms occupy unique atomic sites,whereas for other phases,they demonstrate similar behaviors as other additive alloying elements such as Ag and Cu do.

关键词： Al-Mg-Si alloy Zn addition Precipitate Electron microscopy

Timoshenko beam model for chiral materials

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Acta Mechanica Sinica 2018年第3期34卷 549-560页

作者： T.y.Ma y.n.Wang l.yuan j.S.Wang Q.H.Qin Department of Mechanics Tianjin University School of Engineering Deakin University Research School of Engineering Australian National University

natural and artificial chiral materials such as deoxyribonucleic acid （DnA）, chromatin fibers, flagellar filaments, chiral.nanotubes, and chiral lattice materials widely exist. Due to the chirality of intricately helical or twisted microstructures, such materials hold great promise for use in diverse applications in smart sensors and actuators, force probes in biomedical engineering, structural elements for absorption of microwaves and elastic waves, etc. In this paper, a Timoshenko beam model for chiral materials is developed based on noncentrosymmetric micropolar elasticity theory. The governing equations and boundary conditions for a chiral beam problem are derived using the variational method and Hamilton＇s principle. The static bending and free vibration problem of a chiral beam are investigated using the proposed model. It is found that chirality can significantly affect the mechanical behavior of beams, making materials more flexible compared with nonchiral counterparts, inducing coupled twisting deformation, relatively larger deflection, and lower natural frequency. This study is helpful.not only for understanding the mechanical behavior of chiral materials such as DnA and chromatin fibers and characterizing their mechanical properties, but also for the design of hierarchically structured chiral materials.

关键词： Timoshenko beam model Chiral material Chirality Deflection Microrotation

EFFECT OF QUEnCHInG TEMPERATURE On SHAPE MEMORy EFFECT OF Fe-18Mn -5Si-8Cr-4ni AllOy

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Acta Metallurgica Sinica(English letters) 1999年第5期12卷 739-742页

作者： Wen, y.H. li, n. Xu, y.G. Tu, M.j. li, y.l. Ma, y.l. Sichuan Univ Chengdu China

The effects of quenching temperature on shape memory effect and microstructure of Fe 18Mn 5Si 8Cr 4ni shape memory alloy have been studied. The results show that both the shape recovery ratio and the recovery strain increased as quenching temperature increased, the amount of stress induced ε martensite in the process of cold work decreased with the increase of quenching temperature, the shape recovery ratio and the recovery strain reached maximum at 650℃, and then decreased rapidly with the further increase of quenching temperature,the stress induced ε martensite wholly disappeared at 1023K. But when the quenching temperature is higher than 1023K, the further increase of quenching temperature had little effect on shape recovery ratio, the amount and size of thermal induced ε martensite would increased with the further increase in quenching temperature. The shape memory effect can be improved by the moderate amount of pre exist ε martensite in the matrix before deforming.

关键词： shape memory alloy shape recovery ratio ,martensite transformation

Universality of quenching-partitioning-tempering local equilibrium model

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journal of Materials Science & Technology 2022年第29期124卷 116-120页

作者： j.Z.Zhang l.y.Zeng X.W.Zuo j.F.Wan y.H.Rong n.Min j.lu n.l.Chen Department of Mechanical Engineering City University of Hong KongGreater Bay Joint DivisionShenyang National Laboratory for Materials ScienceTat Chee AvenueKowloonHong KongChina Shanghai Key laboratory of Materials laser Processing and Modification School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China laboratory for Microstructures Shanghai UniversityShanghai 201900China CityU-Shenzhen Futian Research Institute Shenzhen 518045China

*** As typical 3rd generation advanced high strength steels(AHSSs),quenching and partitioning(Q&P)steel has attracted lots of attention for excell.nt performance in strength-ductility[1–5].With absorbing carbon partitioning as the core idea of Q&P process,quenching-partitioning-tempering(Q-P-T)process was proposed with emphasis on precipitation strengthening for better combination of strength and ductility[6–10].

关键词： tempering strength ductility

Mathematical modell.ng of axonal microtubule bundles under dynamic torsion

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Applied Mathematics and Mechanics(English Edition) 2018年第6期39卷 829-844页

作者： j.y.WU Hong yUAn l.y.lI MOE Key laboratory of Disaster Forecast and Control in Engineering Institute of Applied MechanicsJinan University School of Engineering University of Plymouth

Owing to its viscoelastic nature, axon exhibits a stress rate-dependent me- chanical behavior. An extended tension-shear chain model with Kelvin-Voigt viscoelas- ticity is developed to illustrate the micromechanical behavior of the axon under dynamic torsional conditions. Theoretical closed-form expressions are derived to predict the de- formation, stress transfer, and failure mechanism between microtubule （MT） and tau protein while the axon is sheared dynamically. The results obtained from the present an- alytical solutions demonstrate how the MT-tau interface l.ngth, spacing between the tau proteins, and loading rate affect the mechanical properties of axon. Moreover, it is found that the MTs are more prone to rupture due to the contributions from the viscoelastic effects. Under the torsional force, the MTs are so l.ng that the stress concentrates at the loaded end where axonal MTs will break. This MT-tau protein dynamics model can help to understand the underlying pathology and molecular mechanisms of axonal injury. Additionally, the emphasis of this paper is on the micromechanical behavior of axon, whereas this theoretical model can be equally applicable to other soft or hard tissues, owning the similar fibrous structure.

关键词： torsion biocomposite diffuse axonal injury (DAI) Kelvin-Voigt viscoelas-tic model dynamic response tension-shear chain model

numerical study of the circular opening effect on mechanical behaviour of rock under confinement

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journal of Rock Mechanics and Geotechnical Engineering 2019年第6期11卷 1201-1210页

作者： y.l.Gui j.l.Shang j.j.Ma Z.y.Zhao school of engineering newcastle universitynewcastle upon tynene17ruunited kingdom school of civil and environmental engineering nanyang technological university639798singapore school of civil engineering sun yat-sen universityguangzhou510275china

Opening holes in rock including their size and distribution can affect the performance of rock-related structures.A good understanding on this will contribute to,for example,rock cavern design,and construction,tunnell.ng,and mining *** improve the understanding,a comprehensive investigation of the opening hole effect on the rock mechanical behaviour under biaxial loading condition is carried out by virtue of a hybrid continuum-discrete element *** specimens with both single hole and multi-hole of various radii are investigated and compared with the cases subjected to uniaxial *** is demonstrated that the confining pressure can increase both the stiffness and strength due to delaying the crack initiation and *** increase due to the confining pressure is more evident for the compressive *** single hole specimens with 0.75 mm radius hole,the increase ratio of the compressive strength is a l.near increasing function with width and the increase ratio ranges from 2.15 for the specimen with 3.5 mm width to 2.45 for 10 mm *** the single hole specimen with 10 mm width,the increase ratio starts at 2.13 for the specimen with 0.75 mm radius hole,ascending to the peak of 2.37 for the specimen with 1 mm radius hole,followed by a decl.ne to 2.2 for the specimen with 1.25 mm radius ***,for the multi-hole specimens,the increase ratio varies from 1.66 to *** addition,to verify the influence of confining pressure magnitude on the performance of the rock specimens,totall.ng 10 confining pressure levels are applied and *** simulation results show that even though there are opening holes in the specimens,the simulated compressive strength generally follows the generalised Hoek-Brown model.

关键词： Rock with opening Simulation Biaxial loading Strength Stiffness

PHySICAl SIMUlATIOn BASED InTEllIGEnT SySTEM FOR THE PREDICTIOn OF SHEET METAl DRAWInG CAPABIlITy

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Acta Metallurgica Sinica(English letters) 2000年第2期13卷 451-458页

作者： D.lv D.n.He X.j.Bao y.Q.Zhang X.y.Ruan j.l.Cheng j.y.jiang national Die&Mold CAD Engineering Research Center Shanghai Jiaotong UniversityShanghai 200030China Shanghai Volkswagen Automotive Company limited Shanghai 201805China

With the combination of a new theoretical formula, physical simulation experiments, the technology of artificial.neural.network and database, an intelligent system for the prediction of sheet metal drawing capability is constructed for the first time. A modified criterion for sheet metal drawing capability is proposed in this paper, namely, the Technological limiting Drawing Ratio, TlDR = f(R, n, s, t, F, μ,r_d,r_p…). Based on the studies of other scholars, a new formula is derived to predict the TlDR in this paper. Then a series of orthogonal physical simulation experiments are designed to investigate the effect of technological parameters on the TlDR, and the results are analyzed in the paper. Then the predicting system is constructed with the combination of the theoretical formula, orthogonal experiments, the technology of artifocial.neural.network and database. The predicted results show good agreements with experimental data, so it can be used to avoid the bl.ndness in the selection of sheet metal before stamping. The system operates under the Windows operating system, and it supports the mechanism of Client/Server as well as Intranet, so the system has high engineering value.

关键词： TlDR theoretical analysis physical simulation orthogonal experiments neural.network database predicting system

Dislocation ordering and texture strengthening of naturally aged Al-Cu-Mg alloy

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journal of Materials Science & Technology 2022年第23期118卷 1-14页

作者： F.liu Z.y.liu G.y.He l.n.Ou School of Materials Science and Engineering Central South UniversityChangsha 410083China Key laboratory of nonferrous Metal Materials Science and Engineering Ministry of EducationCentral South UniversityChangsha 410083China national Key laboratory of Science and Technology on High-Strength Structural Materials Central South UniversityChangsha 410083China

Stability of grain structure,dislocation ordering and strengthening mechanisms of the naturally aged AlCu-Mg alloy after solution treatment are investigated by using optical microscope(OM),scanning electron microscope(SEM),electron back-scattered diffraction(EBSD),X-ray diffraction(XRD) and transmission electron microscope(TEM).Results show that {100},{100},{110} and {110}slip systems can be activated after solution treatment,which can promote the formation of {110}Goss *** combination effect of T-Al_(20)Cu_(2) Mn_(3) phase and Goss-oriented grains with large Taylor factor makes the solution-treated alloys display excell.nt stability of grain *** enhanced yield strength of the alloy is ascribed to grain-refine strengthening,dispersed particles strengthening,dislocation strengthening and texture *** coarsening of the second phase is responsible for softening of the alloy after anneal.ng at 400 ℃+solution treatment at 475 ℃.

关键词： Al-Cu-Mg alloy Dislocation ordering Goss texture Grain structure stability Texture strengthening