Table of Content

25 April 2016, Volume 44 Issue 4

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Power & Electrical Engineering

Investigation into Co-Combustion Characteristics of Dyeing Sludge and Bituminous Coal Based on TGA-FTIR

LIAO Yan-fen CAO Ya-wen WU Shu-mei MA Xiao-qian

2016, 44(4):  1-9.  doi:10.3969/j.issn.1000-565X.2016.04.001

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This paper deals with the co-combustion of dyeing sludge and bituminous coal by means of TGA-FTIR.The results show that ( 1) the co-combustion process mainly consists of three stages respectively corresponding to the de-volatilization and combustion of fiber materials at 150 ～ 350 ℃,the combustion of high-molecule polymer materials like bacterium protein at 350 ～ 500℃ and the calcining of inorganic mineral substancesin the dyestuff above 500℃; ( 2) the addition of dyeing sludge in bituminous coalpromotes the ignition,and a sludge dosage of 30% may result in an ignition temperature decrement of 20℃as well as a reduced general combustion parameter; ( 3) the apparent activation energy in the initial combustion stage of the sludge is only 70 kJ /mol and then increases to 130 ～ 160 kJ /mol in the later stage; ( 4) with the increase of sludge dosage,the apparent activation energy of the blend decreases in the initial combustion stage while increases in the later stage; and ( 5) comprehensively,the sludge dosage less than 20% only slightly influences the whole combustion process.Moreover,TGA-FTIR results indicate that ( 1) the mineral substances influence the pollutant emission process in blends via multiple reactions; ( 2) the alkali oxides and Fe₂O₃ in the dyeing sludge both benefit the fixation of sulphur in the ash; ( 3) NO_x mainly comes from the fuel; and ( 4) as the sludge is easy to de-volatilize,a reducing atmosphere consisting of smallmolecule combustible gases may form,which helps to suppress the generation of NO_x blends in the initial combustion stage.

Investigation into Parameters Optimization for Reducing Interference of Plasma Lines of Fly Ash

YAO Shun-chun YIN Ke-jing BIAN Jin-tian LU Ji-dong FAN Yi-song XU Jia-long BAI Kai-jie

2016, 44(4):  10-14.  doi:10.3969/j.issn.1000-565X.2016.04.002

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This paper deals with the interference of C and Fe plasma lines existing in the measurement of unburned carbon in fly ash by means of laser-induced breakdown spectroscopy ( LIBS) ,and explores the interference suppression based on the parameter optimization by experiments.In the investigation,first,according to the excitation and time evolution properties of C and Fe lines,the spectral line interference at various pulse energy and time delay are analyzed in a comparison way,and the optimized parameters are obtained.Then,two multiple regression models describing the unburned carbon are constructed respectively by using the peak intensity and the integrated intensity of elemental lines.Analytical results show that the interference between C and Fe lines at about 248nm can effectively be reduced by optimizing the pulse energy and the time delay; and that,in the optimized conditions,the intensity of Fe 247. 98nm line decreases,while C 247. 86nm line with high signal-to-noise ratio is obtained.Moreover,it is found that the multiple regression model constructed by peak intensity is reliable,with a regression coefficient r2 of 0. 999 and an intercept of 0. 005.

Tomographic Image Diagnosis of Intake Airflow Field in Diesel Engine Cylinder

ZHANG Xiao-fan LI Li-fu LIU Feng-lin

2016, 44(4):  15-20,27.  doi:10.3969/j.issn.1000-565X.2016.04.003

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In order to overcome the difficulty in the online and non-destructive measurement of engine cylinder's intake airflow field caused by its invisibility and dynamic characteristics,a tomographic image diagnosis method is proposed.In the investigation,first,the principles of industrial computer tomography ( ICT) for obtaining the tomographic image of diesel engine cylinder's intake airflow field are analyzed.Then,the behaviors of airflow field's trace point,density,velocity and velocity variation in the tomographic image are discussed,and the segmentation pre-treatment methods of the cylinder intake system's tomographic image are explored based on the maximum average mutual information.Moreover,an extraction method of multi-target image features ofthe intake airflow field is presented based on the mutual information of random variables.Finally,the information of the airflow field's trace point,density,flow velocity and velocity variation status inside confined spaces are non-destructively extracted in realtime from the high-energy ICT images of a single-cylinder vertical diesel engine,and the tomographic chain structure and its shape formed by the gas-cylinder and gas-gas interactions in the flow process are discovered.It is found that the proposed tomographic image diagnosis method is more suitable for the nondestructive,online and multi-dimension diagnosis than the existing methods.

Current Sharing and Circulation Technology of High-Power Synchronous Rectification

DU Gui-ping WEN Xian-jia LI Zhi-yong

2016, 44(4):  21-27.  doi:10.3969/j.issn.1000-565X.2016.04.004

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In this paper,first,an optimal control mode is selected from three control modes for synchronous rectification through energy consumption calculation,and the current sharing problem of the multi-tube paralleling in high-power synchronous rectification is investigated to overcome the output power limitation of single device and single circuit.Then,the main sensitive parameters affecting the parallel current sharing are determined,and a solution to the optimization of current sharing is presented.Moreover,the generation mechanism of the circulation caused by multi-circuit parallel connection is discussed,and a coordination control method of the duty cycle for preventing the circulation is finally presented.Experimental results show that the theoretical analysis is correct and that the proposed method helps to successfully implement the high-power output of synchronous rectification.

Position Sensorless Control of Induction Machines Based on Two-Stage Kalman Filtering

ZHANG Jin-liang KANG Long-yun CHEN Ling-yu YAO Yuan

2016, 44(4):  28-33,54.  doi:10.3969/j.issn.1000-565X.2016.04.005

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The conventional extended Kalman filtering ( EKF) algorithm has been widely applied to the position sensorless control of induction machines ( IM) .However,heavy computational burden may accompany with EKF,especiallyfor the IM with a high-order and strong-coupling mathematical model.In order to solve this problem,a novel control algorithm using the two-stage extended Kalman filtering ( TEKF) ,which is mathematically equivalent to the conventional EKF algorithm,is proposed.In this algorithm,the stator current and the rotor flux linkage in the stationary reference frame are taken as the full-order state variables,and the rotor electrical angle and angular speed are used as the augmented system state variables.Experimental results show that the proposed algorithm can effectively save the operation time without degrading the parameter identification performance of the conventional EKF algorithm.

Power Supply Driven by Cuk Constant Current with Active Ｒipple Compensation for LED Headlamp

TANG Zhi-de WANG Ｒui YANG Xi

2016, 44(4):  34-39.  doi:10.3969/j.issn.1000-565X.2016.04.006

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As the lifespan of the output filter's electrolytic capacitor in general lighting LED power supply does not match LED's long lifespan,a LED driving circuit based on Cuk with active ripple compensation is proposed.In this circuit,the active ripple compensation branch is used to replace the output filter's electrolytic capacitor to offset the inductor's ripple current,which provides the LED array with a constant DC and further with ideal driving state.This paper describes the principle and implementation of the active ripple compensation circuit,analyzes the loss and efficiency of LED driving circuit based on the Cuk with active ripple compensation,and designs and fabricates an LED power supply with an output power of 22W based on the Cuk with active ripple compensation and hysteresis current control.Simulated and experimental results indicate that the proposed power supply is feasible.

Analysis Method of Practical Coefficient Based on Fuzzy Clustering

OUYANG Sen WU Yu-sheng Feng Tian-rui

2016, 44(4):  40-46.  doi:10.3969/j.issn.1000-565X.2016.04.007

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Practical coefficient is usually applied to the selection of distribution transformer capacity for the business expending.As the existing practical coefficient selection methods with low flexibility are greatly affected by dataand do not take into consideration the load development feature,a method to analyze the practical coefficient based on fuzzy clustering is proposed.In this method,first,power usersare divided into such three types as business,house and industry,and the corresponding evaluation indexes,namely the load density,the annual growth rate of electricity consumption and the commission time of distribution transformer,are used to describe the power consumption level and its variation as well as the load development feature of power users.Then,a classification method of practical coefficient levels is designed based on the fuzzy clustering,which uses the three above-mentioned evaluation indexes to perform a fuzzy clustering for the coefficient level classification and determines the evaluation index and practical coefficient's central value of each classification.Finally,the level and value of the practical coefficient of a new power user are obtained according to the sum of the weighted distance between the index value and the central value of each classification.In addition,the effectiveness and practicability of the proposed method are verified through a case study.

Coordinated and Progressive Recovery Strategy for Failure at Ｒeceiving End of Multi-Infeed DC Systems

XIA Cheng-jun HUANG Hao-yu TU Liang HONG Chao

2016, 44(4):  47-54.  doi:10.3969/j.issn.1000-565X.2016.04.008

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In multi-infeed DC systems,there exist subsequent commutation failure,excessive reactive power demand and slowDC power recovery after the failure of AC systems,which probably further degrades the stability of the system.In order to solve this problem,the voltage-active power recovery characteristics of both the single-infeed and the multi-infeed DC systems are analyzed,and a progressive staggering recovery index of multi-infeed DC systems is put forward based on the relationship among multi-infeed effective short-circuit ratio，multi-infeed interaction factor and DC power transmission capacity.Afterwards,according to the value of this index,a staggering recovery strategy for the subsystems of multi-infeed DC systems is formulated.The proposed strategy is then realized by setting a first-order lag after the voltage-dependent current order limiter of each DC system and by controlling the time constant.Moreover,by using the dynamic reactive power peak size,the time consumption for 90% of active power recovery and the whole reactive power demand of multi-infeed DC systems,the recovery performance of the multi-infeed DC system is quantized.Finally,a simulation system with seven-infeed DC receiving end is constructed on PSCAD/EMTDC to verify the effectiveness of the proposed multi-infeed DC coordinated and progressive staggering recovery strategy.

Dynamic Ｒeactive Power Optimization Considering DC Power Ｒegulation Limit in AC/DC Power Systems

LI Qing LIU Ming-bo ZHAO Wen-meng

2016, 44(4):  55-62.  doi:10.3969/j.issn.1000-565X.2016.04.009

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In order to avoid frequent power regulation of DC transmission lines,a dynamic reactive power optimization model of AC /DC power systems,which takes into consideration the DC power regulation limits,is established and then solved by using the generalized Benders decomposition.In the decomposition process,the power variables of DC transmission lines are divided in the master problem together with integer variables,so that the sub-problem can be transformed into a set of independent AC /DC optimization problems in single time section.At the same time,a tightened Benders cut is used to transfer the sub-problem information into the master problem.Moreover,in order to obtain the optimal power of DC transmission lines in a successive linear way,a dynamic step adjustment strategy is proposed.The results on a real large-scale AC /DC interconnection power grid demonstrate the correctness and effectiveness of the proposed method in restricting the regulation times of DC power.Finally,the effect of maximum regulation limit on the dynamic reactivepower optimization results is analyzed.

Encryption and Decryption Methods of GOOSE Packets Based on Domain Implication

WANG Zhi-dong WANG Gang XU Zhi-heng TONG Jin-fang SHI Quan ZHU Ge-lan

2016, 44(4):  63-70.  doi:10.3969/j.issn.1000-565X.2016.04.010

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Although IEC62351 suggests no encryption algorithm for GOOSE and other real-time packets due to the huge time consumption of encryption algorithms,many practical power projects still encrypt GOOSE packets to strengthen the security of network information.In this paper,the classical Rijndael symmetric encryption algorithm is adopted as an example to analyze such factors affecting the time consumption of GOOSE packets encryption as the secret key length,the packet length and the packet mode.Then,in order to reduce the time consumption without weakening the packet confidentiality,a GOOSE encryption method based on critical information is proposed with the combination of packet domain implication.Moreover,GOOSE messages such as StNum,SqNum and T,which possess time synchronization functions，are used to prevent replay attacks,and the CRC verification code in GOOSE packets is used to ensure the integrity of the message.Finally,the time-consuming characteristics of the proposed GOOSE encryption and decryption algorithms are tested on an embedded platform,and the results show that the proposed method meets the real-time requirements of power systems well.

Application of Improved Analytic Hierarchy Process on Evaluation of Lightning Protection in Distribution Networks

LIU Gang MA Hao-yu ZHANG Xian

2016, 44(4):  71-76,100.  doi:10.3969/j.issn.1000-565X.2016.04.011

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In order to effectivelyreduce thelightning incidents of power transmission lines and ensure the safety of power systems,some measures should be adopted to improve the lightning withstand level of transmission lines.In this paper,based on an improved analytic hierarchy process ( AHP) with new scale and the fuzzy comprehensive evaluation method ( FCEM) ,a model suitable for evaluating the lightning protection measures of actual lines in power distribution networks is proposed,which comprehensively considerssuch factors as the reduction of trip-out rate,the impact of engineering cost,the effect of the target,the ease of maintenance andthe service life.Then,in accordance with the AHP,all the evaluation weights of lightning protection measures relative to the destination level are obtained,the memberships of the measures are determined via the FECM,and the optimal rehabilitation scheme is thus presented.The results show that the proposed evaluation system helps to effectively assess the power distribution lines and determine the optimal lightning protection measures as well as line rehabilitation scheme.

Calculation of Cable Temperature Based on Support Vector Machine Optimized by Particle Swarm Algorithm

NIU Hai-qing YE Kai-fa XU Jia WU Ju-zhuo LUO Jian-bin LU Guo-jun

2016, 44(4):  77-83.  doi:10.3969/j.issn.1000-565X.2016.04.012

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Cable conductor temperature is a main factor affectingthe life and material utilization of the cable,and is an important parameter reflecting cable's operation state.However,it is difficult to directly measure the conductor temperature of in-use cables,so that a temperature calculation is necessary.In this paper,a model to calculate the transient temperature of cable conductor based on the support vector machine ( SVM) is proposed.In this model,both the load current and the skin temperature are used as the inputs and the conductor temperature is taken as the output.Moreover,in order to improve the calculation accuracy and avoid blind selection of training parameters,the particle swarm optimization ( PSO) algorithmis introduced in the model for optimizing the punishment index C and the core parameter γ.In addition,a comparison between the simulated and the experimental results is made,finding that the proposed PSO-SVM model is superior to the thermal circuit model and the BP neural network because it helps to obtain more accurate transient temperature and possesses good generalization ability.

Influence of Distributed Photovoltaic Power Generation on Harmonic Characteristics of Power Distribution Network

YE Lin-hao HUANG Wei ZHANG Yong-jun

2016, 44(4):  84-90.  doi:10.3969/j.issn.1000-565X.2016.04.013

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In order to investigate the influence of distributed photovoltaic power generation on the harmonic characteristics of power distribution networks,a simplified model for the theoretical analysis of power distribution network is established，which considers the influences of cable capacitance and reactive power compensation device on the system response characteristics.Next,an actual distribution network model based on Digsilent is constructed by using the constant-current source model commonly used in engineering practice as the harmonic source model,and the model is then used to reveal the harmonic characteristics affected by the PV access mode and the system response characteristics of capacitance.Simulated results show that specific grid structure may amplify the harmonic and cause excessive waveform distortion，and that the distortion level can be decreased by optimizing the access location and dispersion of PV and by improving the filtering channels.

Traffic & Transportation Engineering

Fatigue Lifetime Analysis of Modular Expansion Joints of Bridges

HE Zhi-yong WANG Ye YANG Chu

2016, 44(4):  91-100.  doi:10.3969/j.issn.1000-565X.2016.04.014

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Long-term impacts due to traffic loads may result in the fatigue damage of bridge expansion joints that is difficult to repair and replace.However,there are few researches on the fatigue lifetime of modular expansion joints,especially for the middle-steel beam-welded points.In order to solve this problem,the damage and replacement process of the SD-160 modular expansion joints of a bridge is taken as an example and a survey of the bridge traffic load is performed,based on which five different types of simplified vehicle load frequency spectrum are established.Then，the ANSYS finite element software and the Miner fatigue cumulative damage theory are used to estimate the fatigue lifetime of the SD-160 modular expansion joints in the anchorage concrete,the welding points between anchored and pre-embedded bars,as well as the middle welded steel beam.The results show that ( 1) the lifetimes of the anchorage concrete，the middle steel beam only considering the vehicle load and the welding points of embedded bars are respectively 7. 7,29. 3 and 10. 7 years; ( 2) with the increase of the space between two supporting beams,the lifetime of the middle steel beam decreases; ( 3) greater strength of the concrete in the anchorage zone helps to prolong the lifetime of the concrete itself and the welding points between anchored and pre-embedded bars; ( 4) the lifetime of elastic resin concrete is about 2 times that of C50 concrete; and ( 5) according to the replacement program of the SD-160expansion joints,the simulated lifetime of the welded points in the middle steel beam is 6. 2 years，and the service lifetimes of programs Ⅰ and Ⅱ are respectively 7. 7 and 20. 8 years.This research provides a reference for the design and replacement of the expansion joints similar to the investigated one.

Optimal Route Planning Algorithm Considering Movement Type at Signal Intersections

ZHOU Xi-yang YANG Zhao-sheng ZHANG Wei BING Qi-chun SHANG Qiang

2016, 44(4):  101-108.  doi:10.3969/j.issn.1000-565X.2016.04.015

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As the existing optimal route planning algorithms do not fully consider the waiting time of vehicles with different movement types at signal intersections,no satisfactory optimal routes can be obtained.In order to solve this problem,an optimal route planning algorithm considering the movement type at signal intersections is proposed.In this algorithm,first,a waiting time model considering the movement type at signal intersections is established.Then,an improved forward star structure is constructed to optimize the representation and storage of the movement type and information in the road network.Moreover，an extended A* algorithm considering the movement type,namely CMTA* algorithm,is developed,and a case study is carried out.The results show that,as compared with the traditional algorithm and the CWTSI-SP algorithm considering the waiting time at intersections,CMTA* algorithm helps to obtain better routes with lower time cost.

Short-Term Traffic Flow Prediction Based on Phase Space Reconstruction and RELM

SHANG Qiang YANG Zhao-sheng LI Zhi-lin LI Lin QU Xin

2016, 44(4):  109-114.  doi:10.3969/j.issn.1000-565X.2016.04.016

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In order to increase the accuracy of short-time traffic flow prediction,a flow prediction model based on the phase space reconstruction and the regularized extreme learning machine is put forward.In this method，the CC method is used to calculate the best time delay and embedding dimension of traffic flow time series for phase space reconstruction,and the G-P algorithm is used to calculate the correlative dimension of the seriesthat is an important judgment index ofthe chaotic characteristics of traffic flow series,Then,the reconstructed phase point data are taken as the inputs and outputsto trainthe regularized extreme learning machine model,and the main parameters of the model are determined by means of grid searching.Finally,a comparative analysis is carried out based on the actual measured traffic flow data.The results show that the proposed model possesses high performance and is effective in improving the accuracy of short-time traffic flow prediction.

Reliability Prediction of Travel Time Based on Spatio-Temporal Bayesian Model

YANG Qing-fang WEI Xue-wu LIN Ci-yun LI Zhi-lin LIU Xiang-yu

2016, 44(4):  115-122.  doi:10.3969/j.issn.1000-565X.2016.04.017

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In order to fully and accurately analyze the spatio-temporal distribution of link travel time,this paper incorporates the time sequence and the spatial relationship between two links into two adjacent links for travel time reliability prediction.From the temporal dimension,the widely-used Kalman filtering is adopted to predict the travel time; while from the spatial dimension,the correlation model describing the travel time between downstream and upstream links is built based on the discrete Markov chain model.Then,a spatio-temporal Bayesian model ( STBM) is constructed to fuse the temporal and spatial travel time distributions for predicting the travel time reliability of road links.Case study results show that,as compared with the prior distributions,the proposed model decreases the reliability prediction error by 45. 7% and 29. 2% respectively for the two measured adjacent links,which verifies the effectiveness of the ST-BM model.

Effects of Moving Speed of On-Fire Subway Train on Heat Release Rate

XI Yan-hong MAO JunSchool of Civil Engineering and Architecture∥Beijing Key Laboratory of Track Engineering, Beijing Jiaotong University,

2016, 44(4):  123-129.  doi:10.3969/j.issn.1000-565X.2016.04.018

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If a train traveling in the tunnel is on fire,the corresponding emergency plan is usually to make the train continue running to the next station as far as possible，instead of stopping in the tunnel.This paper takes a moving on-fire train in subway tunnels as the research object,and uses the channel Couette flow,the heat and mass transfer and the combustion reaction kinetics to explore the combustion characteristics of the fire affected by such two factors as the air quantity in the annular space between the tunnel and the train and the piston wind in the tunnel,followed with some small-scale model experiments.Then,the return air quantity is derived,and the relationship between the fire heat release rate and the running speed of the train is modeled.Finally,a reasonable speed for the on-fire train,which keeps the fire heat release rate at a relatively low level，namely 48km/h,is suggested.The research achievements and the proposed method provide theoretical guidance for the emergency rescue of the on-fire train in subway tunnels.

Mechanics

Structural Reliability Analysis Based on Taylor-Edgeworth Series

MENG Guang-wei FENG Xin-yu ZHOU Li-ming LI Feng

2016, 44(4):  130-134,142.  doi:10.3969/j.issn.1000-565X.2016.04.019

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In order to overcome the difficulties in structural numerical analysis caused by the high-dimension nonlinearity or the implicit performance functions in engineering practice,a numerical method to directly analyze the structural reliability is proposed.In this method,the n-dimension function is changed into n single-dimension functions via the dimension reduction,and the origin moment and the central moment of each single-dimension function are calculated through the variable transformation of the single-dimension functions and the Gauss-Hermite numerical integration.Then,the moment information is combined with the central moment of the structural performance function obtained by Taylor expansion,the cumulative distribution function of the structural performance function is deduced with the help of Edgeworth series,and the failure probability of the structural performance function is calculated based on the structural reliability theory.The proposed method avoids the multiple integrations for the statistical moment calculation of the performance function.Numerical examples show that this method is correct and feasible.

Analysis of Dynamic Ｒesponses of Curved Laminated Glass Panels Under Blast Loads

ZHANG Hong DENG Han-guo YAO Xiao-hu LONG Qian

2016, 44(4):  135-142.  doi:10.3969/j.issn.1000-565X.2016.04.020

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This paper deals with the calculation of dynamic response of curved laminated glass panels under blast loads by means of theoretical analyses and finite element simulation.In the investigation,first,the theoretical calculation methods of dynamic responses of flat laminated glass panels with clamped boundary are deduced,finding that the PVB elastic modulus greatly influences the accuracy of theoretical calculation.Then,the dynamic responses of curved laminated glass panels under blast loads are discussed,finding that there are two stable coefficients of curved panels ( CCP) ,which may provide a simplified method for the dynamic response calculation of curved laminated glass panels，that is,to obtain the maximum deflection and principal stress of curved laminated glass panels by multiplying the corresponding values of flat laminated glass panels in the same size with some coefficients.Meanwhile,the influences of geometric parameters of the curved laminated glass panels on the CCP are quantitatively analyzed,and reliable empirical formulas are fitted.This research provides a simple and practical calculation method for estimating the dynamic responses of curved laminated glass panels.

Investigation into Fatigue Lifetime and Reinforcement Parameters of Cracked Steel Plate Strengthened by CFRP

WU Xi-zhi CHENG Jun-sheng YANG Yu HUANG Yi

2016, 44(4):  143-148.  doi:10.3969/j.issn.1000-565X.2016.04.021

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After a period of operation,cracks may occur in the material or welding seam of steel structures,so that some repair measures should be adopted to prolong the lifetime of the structure.This paper deals with the fatigue lifetime and reinforcement parameters of cracked steel plates strengthened by carbon fiber-reinforced polymer ( CFRP) .In the investigation,first,a finite element model of the cracked plate strengthened by CFRP is established based on the cohesive force theory,with which the stress intensity factor of the crack is calculated.Then,four groups of fatigue testsare carried out.According to the test data and the Paris formula，the material constants C and n are calculated.Moreover,the calculated stress intensity factor is put in the Paris formula to predict the fatigue lifetime of the specimen.Finally,the stiffness,length and width of CFRP are studied by using the finite element model.The results demonstrate that the stress intensity factor calculated by the finite element model and the Paris formula helps to accurately predict the fatigue lifetime of the cracked plate strengthened by CFRP,and that CFRP is effective in decreasing the stress intensity factor of the crack edge and prolonging the lifetime of steel plates.