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A constitutive model for evaluation of mechanical behavior of fiber-reinforced cemented sand

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第2期11卷 349-360页

作者： Hadi Abioghli Amir Hamidi Department of Civil Engineering School of EngineeringKharazmi University

The aim of this study is to present a constitutive model for prediction of the mechanical behavior of fiberreinforced cemented sand. For this purpose, a generalized plasticity constitutive model of sandy soil is selected and the parameters of the model are determined for three types of sandy soils using the results of triaxial tests. Next, the proposed model is developed using the existing models based on the physicomechanical characteristics of fiber-reinforced cemented sand. The elastic parameters, flow rule and hardening law of the base model are modified for fiber-reinforced cemented sand. To verify the proposed model, the predicted results are compared with those of triaxial tests performed on fiber-reinforced cemented sand. Finally, the efficiency of the proposed model is studied at different confining pressures, and cement and fiber contents.

关键词： Fiber-reinforced cemented sand Constitutive model hardening law Flow rule

Asymptotic state behaviour and its modeling for saturated sand

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Science China(Technological Sciences) 2009年第8期52卷 2350-2358页

作者： LUO Ting YAO YangPing CHU Jian Department of Civil Engineering Beihang UniversityBeijing 100083China Department of Civil Engineering Nanyang Technological UniversitySingapore

A new double hardening elasto-plastic model is proposed in this paper based on the existing unified hardening model (UH model). By assuming that there is part coupling effect between the plastic volumetric strain and plastic shear strain, hardening parameters consisting of a coupled and an uncoupled components are adopted in this model. A unique feature of this model is that it can describe not only the conventional drained and undrained behaviors of soil, but also the stress-strain relationships of soil under partially drained conditions which can be volumetric compression or dilation. Adopting the asymptotic state concept, simple equations for estimating the limiting stress ratio under undrained or earth pressure at rest (i.e. K0) conditions are derived. The new model is relatively simple to be adopted in practice for two reasons. First, the same soil parameters as in Cam-clay model are used except the addition of one extra parameter, the stress ratio at the characteristic state. Second, all the parameters can be determined using conventional triaxial compression tests.

关键词： sand asymptotic state double hardening constitutive model partially coupled

Analysis of pile load-transfer under pile-side softening

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Journal of Central South University of Technology 2003年第3期10卷 231-236页

作者：刘杰张可能 School of Geology and Environment Engineering Central South University Changsha 410083 China Department of Civil Engineering Zhuzhou Institute of Technology Zhuzhou 412008 China School of Geology and Environment Engineering Central South University Changsha 410083 China

A set of analytical equations for the variation of the axial force along depth and the pile-top load-settle-ment curve were established, using tri-linear softening model to pile-side soil and bilinear hardening model to pile-end soil . Influences of the pile-side and pile-end soil behavior on the load-settlement curve were discussed, indica-ting that the lowering reason for the variation step degree of the axial force along depth is the softening of the pile-side soil to result in the side friction lowering when the pile-top load is increased. To verify the reliability of thismethod, the parameters used in calculation are obtained from the test in Zhuzhou area. The obtained results are thencompared with the tested results. Contrast shows that the calculated results and the tested values are very close,which illustrates that the proposed method is reliable.

关键词： load-settlement curve tri-linear softening model bilinear hardening model

Property improvement of multilayer TiN/Ti films with C^+ implantation

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Science China(Technological Sciences) 1997年第5期40卷 449-454页

作者：赵志勇张通和梁宏张荟星张孝吉 Institute of Low Energy Nuclear Physics Radiation Beam and Materials Engineering Laboratory Beijing Normal University Beijing 100875 China

Using the MEVVA ion source, carbon ions have been implanted in TiN coatings deposited by multi-arc ion plating The Vickers microhardness of the C+ -implanted TiN films increased with the increase in the ion flux and dose. X-ray diffraction (XRD) analysis showed that the TiC phases had been formed in the films. In addition, the films had the preferred growth orientations of TiN and TiC, both of which were (111) orientation after annealing at 500℃ for 30 min. Auger electron spectra analysis indicated that C+ -implanted profile was in typical Gaussian-like distribution in single films. The distribution with multipeaks of C atoms was obtained in multi-layer TiN/Ti. The possibility of the multilayer films (Ti (C, N)/TiN/Ti(C, N)/TiN and Ti(C, N)/TiC/Ti(C, N)/TiC) forming using the C-implanted TiN/Ti films is presented for the first time.

关键词： MEVVA ion implantation C ion implantation TiN multilayer films phase transition hardening mechanism.

Spatial dependent diffusion of cosmic rays and the excess of primary electrons derived from high precision measurements by AMS-02

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Chinese Physics C 2016年第1期40卷 60-64页

作者：靳超郭义庆胡红波 School of Physical Engineering Zhengzhou University Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of Sciences

The precise spectra of Cosmic Ray （CR） electrons and positrons have been published by the measurement of AMS-02. It is reasonable to regard the difference between the electron and positron spectra （△Ф=Фe- -Фe＋） as being dominated by primary electrons. The resulting electron spectrum shows no sign of spectral softening above 20 GeV, which is in contrast with the prediction of the standard model of CR propagation. In this work, we generalize the analytic one-dimensional two-halo model of diffusion to a three-dimensional realistic calculation by implementing spatial variant diffusion coefficients in the DRAGON package. As a result, we can reproduce the spectral hardening of protons observed by several experiments, and predict an excess of high energy primary electrons which agrees with the measurement reasonably well. Unlike the break spectrum obtained for protons, the model calculation predicts a smooth electron excess and thus slightly over-predicts the flux from tens of GeV to 100 GeV. To understand this issue, further experimental and theoretical studies are necessary.

关键词： cosmic rays primary electron excess diffusion propagation hardening

The Properties of Cement Mortars Modified by Emulsified Epoxy and Micro-fine Slag

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Journal of Wuhan University of Technology(Materials Science) 2003年第3期18卷 83-85页

作者：陈友治 Institute of Materials Science and Technology Wuhan University of Technology

The epoxy resin polymer cement mortars with excellent performances were made up through modifying ordinary Portland cement with emulsified epoxy and micro fine slag.The microstructure of the epoxy resin polymer cement materials was studied and their hydration and hardening characteristics were discussed by means of modern analysis measures such as SEM,XRD and Hg intrusion micromeritics.The experimental results indicate that the series effects of water reducing,density,pozzolanicity,filling and solidification crosslinking through the action together with epoxy organism and micro fine slag endowed cement based materials with perfect performances.The main hydration products in the system are C S H gel and hydrated calcium aluminate.At later age,AFt can be in existence,and no Ca(OH) 2 is found.When epoxy resin is solidified,the organism is in a network structure.In the micro pore structure of hydrated cement with modified epoxy and fine slag,big harmful pores were fewer,more harmless abundant micro pores were and the possible pore radius was smaller than that of ordinary Portland cement.

关键词： emulsified epoxy modification cement mortar hydration hardening

Abnormality of magnetic behavior and core loss of nanocrystalline Fe_(73.5)Cu_1Nb_3Si_(15.5)B_7 alloy

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Science China(Technological Sciences) 2010年第2期53卷 343-347页

作者： DONG BangShao1, ZHI QiZheng2, LI DeRen1, LU ZhiChao1 & ZHOU ShaoXiong1 1 Central Iron & Steel Research Institute, Advanced Technology & Materials Co., Ltd., Beijing 100081, China 2 School of Materials & Metallurgy, Northeastern University, Shenyang 110004, China Central Iron & Steel Research Institute Advanced Technology & Materials Co. Ltd. Beijing China School of Materials & Metallurgy Northeastern University Shenyang China

The correlation between microstructure and magnetic properties of Fe73.5Cu1Nb3Si15.5B7 alloy annealed at 360°C—620°C has been investigated. The best static and dynamic soft magnetic properties have been obtained after annealing at 500°C and 550°C for 1 h, respectively. The dependence of annealing temperature on coercivity has shown three magnetic hardenings for the studied alloys annealed at 460°C, 530°C and 620°C, respectively. And the plot of core loss as a function of annealing temperature manifests a peak at 530℃, and this peak increases with increasing magnetic induction at low frequencies. This effect can probably be attributed to the precipitation of a new phase.

关键词： nanocrystalline coercivity magnetic hardening core loss

INFLUENCE OF AGING ON LOW CYCLE FATIGUE BEHAVIOR IN 8090 Al-Li ALLOY

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中国有色金属学会会刊：英文版 1995年第1期5卷 80-83页

作者： Ai Suohua Wang Zhongguang Zhang Yun(State Key Laboratory of Fatigue and Fracture for Materials ,Institute of Metal Research , Academia Sinica, Shenyang 110015) Han Xinglin Wu Yaqiao (Shenyang Industrial University, Shenyang 110023) ACAD SINICA INST MET RESSTATE KEY LAB FATIGUE & FRACTURE MATSHENYANG 110015PEOPLES R CHINA SHENYANG IND UNIV SHENYANG 110023PEOPLES R CHINA

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关键词： low cycle fatigue cyclic hardening precipilate phase

Acclimatization of in Vitro-derived Dendrobium

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Horticultural Plant Journal 2017年第3期3卷 110-124页

作者： Jaime A.Teixeira da Silva Mohammad Musharof Hossain Madhu Sharma Judit Dobránszki Jean Carlos Cardoso ZENG Songjun Miki-cho post office Department of Botany University of Chittagong Division of Biotechnology CSIR-Institute of Himalayan Bioresource Technology Research Institute of Nyíregyháza University of Debrecen Centro de Ciências Agrárias UFSCar Guangdong Provincial Key Laboratory of Applied Botany South China Botanical GardenChinese Academy of Sciences

The successful ex vitro establishment of Dendrobium plantlets raised in vitro determines the quality of the end product(cut flowers or potted plants) in commercial production for economic gain. When in vitro Dendrobium plantlets are transplanted from the culture room to greenhouse conditions, they may desiccate or wilt rapidly and can die as a result of changes in the environment, unless substantial precautions are taken to adapt plantlets to a new environment. The acclimatization of in vitro-grown Dendrobium plantlets to an ex vitro environment by gradually weaning them towards ambient relative humidity and light levels facilitates better survival of young and physiologically sensitive plantlets.Dendrobium plantlets raised in vitro must thus undergo a period of acclimatization or transitional development to correct anatomical abnormalities and to enhance their physiological performance to ensure survival under ex vitro conditions. The most common approach to improve the survival of Dendrobium plantlets upon transfer to an ex vitro environment is their gradual adaptation to that environment. Under such conditions, plants convert rapidly from a heterotrophic or photomixotrophic state to an autotrophic growth, develop a fully functional root system,and better control their stomatal and cuticular transpiration. Gradual adaptation is carried out in a greenhouse by decreasing relative humidity using fog or mist chambers and by increasing light intensity using shading techniques. This review details the acclimatization and ex vitro survival of Dendrobium plants produced in vitro. This advice is also useful for other orchids.

关键词： Orchidaceae acclimation hardening autotrophic light intensity medicinal orchid relative humidity