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Influence of Water Content on Conductivity and Piezoresistivity of Cement-based Material with both Carbon Fiber and Carbon Black

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Journal of Wuhan university of Technology(Materials Science) 2010年第1期25卷 147-151页

作者：韩宝国欧进萍 school of civil {2. Harbin Institute of Technology school of civil and Hydraulic {2. Dalian University of Technology

The influence of water content on the conductivity and piezoresistivity of cement-based material with carbon fiber （CF） and carbon black （CB） was investigated. The piezoresistivity of cement-based material with both CF and CB was compared with that of cement-based material with CF only, and the changes in electrical resistivity of cement-based material with both CF and CB under static and loading conditions in different drying and soaking time were studied. It is found that the piezoresistivity of cement-based material with both CF and CB has better repeatability and linearity than that of cement-based material with CF only. The conductivity and the sensitivity of piezoresistive cement-based material with both CF and CB are enhanced as the water content in piezoresistive cement-based material increases.

关键词： cement-based material carbon fiber carbon black water content conductivity piezoresistivity

Homogenization-based multi-scale damage theory

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Science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 690-698页

作者： LI Jie 1,2.& REN XiaoDan 1 1 school of civil {2., Tongji university, Shanghai 2.0092. china 2.State Key Laboratory of Disaster Reduction in civil {2., Shanghai 2.0092. china 1. school of civil {2. Tongji University Shanghai 200092 China2. State Key Laboratory of Disaster Reduction in Civil Engineering Shanghai 200092 China

The research of modern mechanics reveals that the damage and failure of structures should be considered on different scales. The present paper is dedicated to establishing the multi-scale damage theory for the nonlinear structural analysis. Starting from the asymptotic expansion based homogenization theory, the multi-scale energy integration is proposed to bridge the gap between the micro and macro scales. By recalling the Helmholtz free energy based damage definition, the damage variable is represented by the multi-scale energy integration. Hence the damage evolution could be numerically simulated on the basis of the unit cell analysis rather than the experimental data identification. Finally the framework of the multi-scale damage theory is established by transforming the multi-scale damage evolution into the conventional continuum damage mechanics. The agree- ment between the simulated results and the benchmark results indicates the validity and effectiveness of the proposed theory.

关键词： Multi-scale damage representation asymptotic method constitutive model numerical simulation

An effective and practical method for solving an unnegligible problem inherent in the current calculation model for multi-support seismic analysis of structures

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Science china(Technological Sciences) 2010年第7期53卷 1774-1784页

作者： LIU GuoHuan2. GUO Wei1 & LI HongNan2.1 National engineering Laboratory for High Speed Railway Construction, school of {2. engineering and architecture, Central South university, Changsha 410075, china 2.Faculty of Infrastructure engineering, Dalian university of Technology, Dalian 11602., china 2. Faculty of Infrastructure engineering Dalian University of Technology Dalian 116024 China1. National Engineering Laboratory for High Speed Railway Construction School of Civil Engineering and Architecture Central South University Changsha 410075 China

In the seismic analysis of extended structures subject to spatially varying motions, the displacement input model instead of acceleration model is usually adopted for accurate results. In this paper, a more detailed and comprehensive analysis of the displacement input model is carried out and the research shows that there exists an unnegligible problem in the current displacement model, which leads to the irrationality and unconvergence of some calculated results such as base shear etc. Based on the situation, an effective method named massless rigid element (MRE) method is presented to solve the problem. Moreover, the rationality and accuracy of the method are further assessed and the method is applied to a transmission tower-line system project using the commercially available structural analysis software SAP2.00. The theoretical and numerical analyses indicate that the MRE approach is not only feasible with sufficient computational accuracy but also practical and can be easily implemented using the commercially available finite element software such as SAP2.00.

关键词： extended structures seismic responses spatially varying motions displacement input model massless rigid element (MRE) transmission tower-line system

Numerical Simulation of Rock Fracturing under Uniaxial Compression Using Virtual Internal Bond Model

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Journal of Shanghai jiaotong university(Science) 2009年第4期14卷 423-428页

作者：柯长仁蒋俊玲葛修润 school of Naval architecture Ocean and Civil Engineering Shanghai Jiaotong University school of civil {2. Hubei University of Technology Institute of Rock and Soil Mechanics The Chinese Academy of Science

A multi-scale virtual internal bond (VIB) model for the isotropic materials has been recently proposed to describe the material deformation and fracturing. During the simulation process of material fracturing using VIB, the fracture criterion is directly built into the constitutive formulation of the material using the cohesive force law. Enlightened by the similarity of the damage constitutive model of rock under uniaxial compression and the cohesive force law of VIB, a VIB density function of rock under uniaxial compression is suggested. The elastic modulus tensor is formulated on the basis of the density function. Thus the complete deformation process of rock under the uniaxial compression is simulated.

关键词： virtual internal bond rock uniaxial compression stress-strain curve

Study on Soil and Water Loss Characteristic of the Railway Construction in Mountain Area

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地球科学进展 2004年第S1期19卷 232-237页

作者： BAI Ming-zhou~1, XU Zhao-yi~1, HUO Yu-hua~1, DONG Yong~2.(1. school of civil {2. and architecture of Beifing jiaotong university, Beijing 100044,china 2. Personnel Division of the First Railway Survey & Design Institute, Lanzhou 730000, china)

The factor of human project activity is often the immediate cause resulting in soil and water loss. The Baoji-Lanzhou second railway in construction is an example. The soil and water loss law caused by earth and stone mountain railway engineering construction in the northwestern china is studied systematically and that caused possibly by the road bed project, the road moat project, the field project, the tunnel project and the service road project in construction is probed. At the same time, the type, t...

关键词： Mountain railway Soil and water loss Characteristic.

Reliability analysis of ship structure system with multi-defects

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Science china(Physics,Mechanics & Astronomy) 2010年第11期53卷 2113-2124页

作者： AN Hai 1,AN WeiGang 1 & ZHAO WeiTao 2.1 school of Aerospace and civil {2.,Harbin {2. university,Harbin 150001,china 2.school of Aeronautics and Astronautics,Shenyang Institute of Aeronautical {2.,Shenyang 110034,china 1. school of Aerospace and civil {2. Harbin Engineering University Harbin 150001 China2. School of Aeronautics and Astronautics Shenyang Institute of Aeronautical Engineering Shenyang 110034 China

This paper analyzes the influence of multi-defects including the initial distortions,welding residual stresses,cracks and local dents on the ultimate strength of the plate element,and has worked out expressions of reliability calculation and sensitivity analysis of the plate *** analysis is made for the system with multi-defects plate *** mechanism,failure paths and the calculating approach to global reliability index are also worked *** plate elements with multi-defects fail,the formula of reverse node forces which affect the residual structure is deduced,so are the sensitivity expressions of the system reliability *** ensures calculating accuracy and rationality for reliability analysis,and makes it convenient to find weakness plate elements which affect the reliability of the structure ***,for the validity of the approach proposed,we take the numerical example of a ship cabin to compare and contrast the reliability and the sensitivity analysis of the structure system with multi-defects with those of the structure system with no *** approach has implications for the structure design,rational maintenance and renewing strategy.

关键词： initial distortions welding residual stresses cracks and local defects ultimate strength reverse node forces sensitivity expression reliability analysis

Research on arc erosion of silver-based alloy contact materials under low voltage,resistive load and small current at 400 Hz and 50 Hz

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Journal of Pharmaceutical Analysis 2009年第3期21卷 149-154页

作者： Jing Li1,2.Zhi-ying Ma11. school of Electrical engineering,Xi’an {2. university,Xi’an 710049 2. school of Electrical Information,Hunan Institute of engineering,Xiangtan 411101,china. school of Electrical engineering Xi'an Jiaotong University Xi'an 710049 China school of Electrical Information Hunan Institute of Engineering Xiangtan 411101 China

By using a self-developed IF power and a ASTM contact material experimental system of small-capacity and variable frequency,the value of arcing characteristics and the welding force of the silver-based contact material are acquired under low voltage,resistive load and small current at 400 Hz and 50 Hz. By means of an electricity-ray analytical balance,SEM and EDAX,the weighing values of the contact materials and the changes of AgCdO,AgNi,AgC and AgW contact material surface profile and micro-area constituent are obtained and analyzed. The arc erosion causes of silver-based alloy contact materials at 400 Hz and 50 Hz are also discussed.

关键词： silver-based alloy low voltage 400 Hz 50 Hz contact material arc erosion

Hydration Kinetics of Phosphorus Slag-cement Paste

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Journal of Wuhan university of Technology(Materials Science) 2011年第1期26卷 142-146页

作者：陈霞 school of civil {2. Wuhan University Department of Mateials and Structure Changjiang River Scientific Research lnstitute

Hydration characteristics of Portland cement paste with phosphorus slag powder incorporated and hydration kinetics was investigated with SEM, X-ray diffraction, DTA-TG and calorimeter Ⅱ80. Results showed that phosphorus slag powder could reduce total amount of hydration products yet had little influence on the type of hydration products. The total amount of heat of hydration was decreased by 49.11% and the final setting was postponed by 2.2. h when phosphorus slag powder substituted 35% Portland cement by mass. The accelerating stage of this composite paste was controlled by catalysis, decreasing stage controlled by both catalysis and diffusion while stabilizing stage by diffusion alone. Hydration resistance and activation energy were reduced and hydration speed was accelerated.

关键词： phosphorus slag hydration kinetics cement micro structure mechanism.

Experiments and sensitivity analyses for heat transfer in a meter-scale regularly fractured granite model with water flow

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Journal of Zhejiang university-Science A(Applied Physics & engineering) 2012年第12期13卷 958-968页

作者： Wei LU1,2.Yan-yong XIANG1 (1school of civil {2.,Beijing jiaotong university,Beijing 100044,china) (2.tate Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,china Institute of Water Resources and Hydropower Research,Beijing 100038,china) 1. school of civil {2. Beijing Jiaotong University Beijing 100044 China 2. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower Research Beijing 100038 China

Experiments of saturated water flow and heat transfer were conducted for a meter-scale model of regularly fractured granite. The fractured rock model （height 1502.5 ram, width 904 mm, and thickness 300 mm）, embedded with two vertical and two horizontal fractures of pre-set apertures, was constructed using 18 pieces of intact granite. The granite was taken from a site currently being investigated for a high-level nuclear waste repository in china. The experiments involved different heat source temperatures and vertical water fluxes in the embedded fractures either open or filled with sand. A finite difference scheme and computer code for calculation of water flow and heat transfer in regularly fractured rocks was developed, verified against both the experimental data and calculations from the TOUGH2.code, and employed for parametric sensitivity analyses. The experiments revealed that, among other things, the temperature distribution was influenced by water flow in the fractures, especially the water flow in the vertical fracture adjacent to the heat source, and that the heat conduction between the neighboring rock blocks in the model with sand-filled fractures was enhanced by the sand, with larger range of influence of the heat source and longer time for approaching asymptotic steady-state than those of the model with open fractures. The temperatures from the experiments were in general slightly smaller than those from the numerical calculations, probably due to the fact that a certain amount of outward heat transfer at the model perimeter was unavoidable in the experiments. The parametric sensitivity analyses indicated that the tem- perature distribution was highly sensitive to water flow in the fractures, and the water temperature in the vertical fracture adjacent to the heat source was rather insensitive to water flow in other fractures.

关键词： Fractured granite Water flow Heat transfer Physical modeling Numerical calculation Sensitivity analysis