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A microstructure-based analysis of cyclic plasticity of pearlitic steels with Hill's self-consistent scheme incorporating general anisotropic Eshelby tensor

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Acta Mechanica Sinica 2008年第1期24卷 91-99页

作者： Xuesong Long xianghe peng Wenli Pi Department of Engineering Mechanics Chongqing University Chongqing 400044 China

A pearlitic steel is composed of numerous pearlitic colonies with random orientations, and each colony consists of many parallel lamellas of ferrite and cementite. The constitutive behavior of this kind of materials may involve both inherent anisotropy and plastic deformation induced anisotropy. A description of the cyclic plasticity for this kind of dual-phase materials is proposed by use of a microstructure-based constitutive model for a pearlitic colony, and the Hill＇s self-consistent scheme incorporating anisotropic Eshelby tensor for ellipsoidal inclusions. The corresponding numerical algorithm is developed. The responses of pearlitic steel BS 11 and single-phase hard-drawn copper subjected to asymmetrically cyclic loading are analyzed. The analytical results agree very well with experimental ones. Compared with the results using isotropic Eshelby tensor, it is shown that the isotropic approximation can provide acceptable overall responses in a much simpler way.

关键词： Pearlitic steel Hill's self-consistent scheme Eshelby tensor Cyclic plasticity Microstructure-basedanalysis

The first principles investigation of ferrite magnetic response with mismatch stress

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Science China(Physics,Mechanics & Astronomy) 2014年第3期57卷 512-520页

作者： HUANG JunPing peng xianghe HU XianZhi Department of Engineering Mechanics Chongqing University School of Mechanical Engineering Chongqing Vocational Institute of Engineering Faculty of Science Kunming University of Science and Technology

The quasi-ferrite model is proposed and an appropriate PBE exchange functional with the spin density functional theory （SDFT） is selected for the calculation of the relation between magnetic moment and residual stress in ferrite using a quantum mechanics code. The relationship between ferrite magnetism and the carbon content is determined, and then a ferrite interstitial solid solution （ISS） model in a low carbon concentration state is replaced with an a-Fe model in the case of majority magnetic calculation. The band structure of the loaded α-Fe is compared with that of the unloaded a-Fe. The comparison shows that the energy of Fe atomic 3d orbital changes a little, while the energy of electron orbital of iron core below 3d almost keeps un- changed. The relationship between the magnetic moment and the stress appears intermittent due to the Bragg total reflection. The change in the magnetic moment due to lattice mismatch is much larger than that caused by mechanical loading.

关键词： the first-principles calculation SDFT quasi-ferrite lattice mismatch residual stress

EXTENSION OF COMBINED SELF-CONSISTENT AND MORI-TANAKA APPROACH TO EVALUATION OF ELASTOPLASTIC PROPERTY OF PARTICULATE COMPOSITES

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Acta Mechanica Solida Sinica 2013年第1期26卷 71-82页

作者： xianghe peng Ning Hu Xuesong Long Hengwei Zheng Department of Engineering Mechanics Chongqing University State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Department of Mechanical Engineering Chiba University

The combined self-consistent and Mori-Tanaka approach proposed for the evaluation of the effective elastic property of particulate composites is extended to evMuate the effective elastoplastic property of particulate composites. Suppose there are sufficient identical particle inclusions with total volume fraction c in a representative volume element （RVE） of a particulate composite, these inclusions are separated into two groups, with volume fractions （1 -A-1）c and c/A over the RVE, respectively. We assume that the first group of inclusions has already been embedded in the original matrix to form a fictitious matrix, and the RVE of the composite consists of the fictitious matrix and the second group of particle inclusions. The property of the fictitious matrix is determined by the conventional self-consistent scheme, while the effective elastoplastic property of the composite is determined by the conventional Mori-Tanaka scheme. Analysis shows that, the conventional Mori-Tanaka scheme and self-consistent scheme can be obtained as the two limit cases of the extended approach as A = 1 and A = c~, respectively. The constitutive behavior of the inclusions in either Group I or Group II is identical, indicating the consistency in the description of the constitutive behavior in the two steps. ~klrthermore, the effective elastoplastic behavior of some typical particulate composites is analyzed, and the satisfactory agreement between the computational and experimental results demonstrates the validity of the extended approach. The introduced A can serve reasonably as a parameter, which is related to the actual property of composites and can be identified by experiments, for a more accurate evaluation of the effective elastoplastic property of particulate composites.

关键词： particulate composite elastoplasticity effective property combined self-consistent and Mori-Tanaka approach

A MICROSTRUCTURE-BASED ANALYSIS FOR CYCLIC PLASTICITY OF DUAL-PHASE PEARLITIC RAIL STEELS

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Acta Mechanica Solida Sinica 2001年第4期14卷 334-343页

作者： peng xianghe Chang Jian Chongqing Univ Dept Engn Mech Chongqing 400044 Peoples R China

Based on the assumption that a representative element of apearlitic steel is an aggregate of numerous spherical pearliticcolonies with randomly distributed orientations, and that each colonyis com- posed of many parallel fine lamellas of ferrite andcementite, a description for the dual-phase pearlitic steel isobtained by making use of a microstructure-based constitutiveequation for a single dual-phase pearlitic colony and the Hill'sself-consistent scheme. The elastoplastic response of dual-phasepearlitic steel BS11 subjected to asymmetrically cyclic loading isanalyzed, and a comparison with the experimental results showssatisfacto- ry agreement. The non-proportional cyclic plasticity ofBS11 is also analyzed, in which stress develops along a semi-circlein a biaxial tension/compression and shear stress plane, as istypically experienced by the sur- face elements in rolling andsliding contact.

关键词： pearlitic steel lamellar dual-phase material Hill's self-consistent scheme cyclic plasticity

MICROMECHANICAL DAMAGE MODEL FOR ROCKS AND CONCRETES SUBJECTED TO COUPLED TENSILE AND SHEAR STRESSES

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Acta Mechanica Solida Sinica 2008年第3期21卷 232-240页

作者： Zhongjun Ren xianghe peng Chunhe Yang Department of Engineering Mechanics Chongqing University Chongqing 400044 China Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China

Based on the analysis of the deformation in an infinite isotropic elastic matrix with an embedded elliptic crack under far field coupled tensile and shear stresses, the energy release rate and a mixed fracture criterion are obtained using an energy balance approach. The additional compliance tensor induced by a single opening elliptic microcrack in a representative volume element is derived, and the effect of microcracks with random orientations is analyzed with the Taylor＇s scheme by introducing an appropriate probability density function. A micromechanical damage model for rocks and concretes is obtained and is verified with experimental results.

关键词： elliptic microcrack energy release rate Taylor's scheme micromechanical damage model

ANALYSIS OF SHAKEDOWN OF FG BREE PLATE SUBJECTED TO COUPLED THERMAL-MECHANICAL LOADINGS

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Acta Mechanica Solida Sinica 2009年第2期22卷 95-108页

作者： xianghe peng Ning Hu Hengwei Zheng Cuirong Fang Department of Engineering Mechanics Chongqing University Chongqing 400044 China Department of Mechanical Engineering Chiba University 1-33 Yayoi Inage-ku Chiba 263-8522 Japan

The static and kinematic shakedown of a functionally graded （FG） Bree plate is analyzed. The plate is subjected to coupled constant mechanical load and cyclically varying temperature. The material is assumed linearly elastic and nonlinear isotropic hardening with elastic modulus,yield strength and the thermal expansion coeffcient varying exponentially through the thickness of the plate. The boundaries between the shakedown area and the areas of elasticity,incremental collapse and reversed plasticity are determined,respectively. The shakedown of the counterpart made of homogeneous material with average material properties is also analyzed. The comparison between the results obtained in the two cases exhibits distinct qualitative and quantitative difference,indicating the importance of shakedown analysis for FG structures. Since FG structures are usually used in the cases where severe coupled cyclic thermal and mechanical loadings are applied,the approach developed and the results obtained are significant for the analysis and design of such kind of structures.

关键词： functionally graded material the Bree plate coupled thermal-mechanical loading,shakedown

Superior mechanical and thermal properties than diamond:Diamond/lonsdaleite biphasic structure

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Journal of Materials Science & Technology 2020年第13期47卷 114-122页

作者： Bo Yang xianghe peng Yinbo Zhao Deqiang Yin Tao Fu Cheng Huang College of Aerospace Engineering Chongqing UniversityChongqing 400044China State Key Laboratory of Coal Mining Disaster Dynamics and Control Chongqing UniversityChongqing 400044China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China

It has been found recently in experiments that diamond/lonsdaleite biphase could possess excellent thermal-mechanical properties,implying that the properties of carbon materials can be improved by reasonably designing their internal *** mechanism of the excellent performance arising from biphasic structure is still unknown and needs to be *** this paper,we established a series of possible diamond/lonsdaleite biphasic structures and revealed the optimization mechanism of the biphasic structure using first principles *** shows in our ab-initio molecular dynamics simulations that the lonsdaleite cannot exist stably at room temperature,which could explain why pure lonsdaleite can hardly be found or *** analysis shows that partial slip would occur in the lonsdaleite region if the applied strain is sufficiently large,leading to the transition from biphasic phase to cubic ***,further shear strain would be applied along the hard shear direction of the cubic structure,resulting in an ascent of *** results presented could offer an insight into the structural transformation at high temperature and large strain.

关键词： Ultrahard carbon materials Biphasic structure Extreme shear strain Phase transition First principle calculation

A CONSTITUTIVE MODEL FOR TRANSFORMATION, REORIENTATION AND PLASTIC DEFORMATION OF SHAPE MEMORY ALLOYS

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Acta Mechanica Solida Sinica 2012年第3期25卷 285-298页

作者： xianghe peng Bin Chen Xiang Chen Jun Wang Huyi Wang Department of Engineering Mechanics Chongqing UniversityChongqing 400044China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China China Academy of Engineering Physics Mianyang 621900China

A constitutive model is developed for the transformation, reorientation and plastic deformation of shape memory alloys （SMAs）. It is based on the concept that an SMA is a mixture composed of austenite and martensite, the volume fraction of each phase is transformable with the change of applied thermal-mechanical loading, and the constitutive behavior of the SMA is the combination of the individual behavior of its two phases. The deformation of the martensite is separated into elastic, thermal, reorientation and plastic parts, and that of the austenite is separated into elastic, thermal and plastic parts. Making use of the Tanaka＇s transformation rule modified by taking into account the effect of plastic deformation, the constitutive model of the SMA is obtained. The ferroelasticity, pseudoelastieity and shape memory effect of SMA Au-47.5 at.%Cd, and the pseudoelasticity and shape memory effect as well as plastic deformation and its effect of an NiTi SMA, are analyzed and compared with experimental results.

关键词： shape memory alloys two-phase mixture transformation reorientation plasticity,constitutive model

Anisotropic and asymmetric deformation mechanisms of nanolaminated graphene/Cu composites

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Nano Materials Science 2019年第2期1卷 121-130页

作者： Shayuan Weng Huiming Ning Tao Fu Ning Hu Shu Wang Kaiyan Huang xianghe peng H. Jerry Qi Cheng Yan College of Aerospace Engineering Chongqing University Chongqing 400044 PR China Key Laboratory of Optoelectronic Technology and Systems of the Education Ministry of China Chongqing University Chongqing 400044 PR China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Changsha 410082 PR China The George W. Woodruff School of Mechanical Engineering Renewable Bioproduct Institute Georgia Institute of Technology Atlanta GA 30332 United States School of Chemistry Physics and Mechanical Engineering Science and Engineering Faculty Queensland University of Technology (QUT) 2 George Street G.P.O. Box 2434 Brisbane Australia

We conducted molecular dynamics (MD) simulations of tension and compression along the direction and MD simulations of compression along the and directions on nanolaminated graphene/Cu (NGCu) composites to investigate the effects of the incorporated graphene and the deformation mechanisms related to the loading direction. The deformation behavior and the defect structures were found to be strongly dependent on the loading conditions. An asymmetric tension-compression deformation behavior was thus found in graphene/Cu nanolaminates under the loading, which was dominated by stacking faults and deformation twins formed by dislocation slide under tension and compression, respectively. High density and ordered nanotwins were formed at the graphene/Cu interfaces. Two different formation mechanisms of the twins were found under the compression, and the nucleated twins were easy to be thickened with the assistance of the graphene wrinkles. Multiple twins were formed under the compression by the dislocation cross-slip. This study provides a way to introduce graphene reinforcement and twin boundary to Cu matrix composites and design nanotwinned graphene/Cu composites with excellent mechanical performance.

关键词： Deformation Mechanisms Molecular Dynamics Graphene/Cu Composites Interface Twin