Table of Content

28 January 2013, Volume 0 Issue 1

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EXPERIMENTAL STUDY OF COMPRESSIVE MEMBRANE ACTION IN THE CONCRETE BRIDGE DECK SLABS REINFORCED WITH GFRP BARS

PAN Yun-feng, ZHENG Yu, ZHONG Yong-gang

2013, 0(1):  3-9. 

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With the consideration of compressive membrane action (CMA) in the structural design of concrete bridge deck slabs reinforced with GFRP bars,the reinforcement percentages and construction costs could be decreased．Therefore,a series of one-third scaled experimental tests of GFRP reinforced concrete bridge deck slabs under static patch loads was carried out． In the experimental study,the influences from some structural variables were investigated,which included widths of supporting beams,reinforcing materials and reinforcement percentages． In this study,some structural parameters,such as loading capacity,stress＆strain relationship,cracking patterns,were measured and observed in the different stages． The structural behaviours of GFRP reinforced concrete bridge deck slabs were discussed,including displacements of supporting beams,cracking patterns and failure mechanism． The results were used to study the effects of CMA and influenced from this structural phenomenon on structures． In this study,it was found that the increase in lateral restraint stiffness could enhance load-carrying capacities significantly． However,the effects of reinforcement percentages were not obvious． Furthermore,current design standards underestimate the load-carrying capacities without consideration of CMA．

THE MULTI-DIRECTIONAL FIBER-REINFORCED COMPOSITE MATERIALS USED FOR PREPARATION OF INTEGRATED POST-AND-CORE PRODUCTS TARGETING FOR RESIDUAL ROOTS AND CROWNS RESTORATION

YANG Yan-yang, CAI Qing, YANG Xiao-ping, HUANG Zhi-xin

2013, 0(1):  10-13. 

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It is important to use post and core restoration techniques to repair the residual tooth crown and root in the treatment of oral rehabilitation． The study on developing a kind of multi-directional fiber-reinforced composite materials used for preparation of integrated post-and-core products was proposed and performed． At first,two kinds of multi-directional fiber reinforcing design were supposed． And finite element analysis was applied to assess stress distribution throughout post-and-core and tooth root with the aid of dental CAD digital model,by which multi-directional fiber reinforcing design was optimized． Secondly,the processing parameters and machines were modified,namely pultrusion-winding technique,to produce the multi-directional FRC materials successfully． At last,basing on an oral CAD/CAM system, integrated FRC post-and-cores were machined． According to macro-and microscopical observation,the final products demonstrated prospective properties and further application in clinic practices．

FINITE ELEMENT ANALYSIS FOR MATERIAL NONLINEARITY OF PMI-FOAM CORED SANDWICH

TANG Chao, QIAO Yu-wei

2013, 0(1):  14-19. 

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Based on the provided mechanical property data of the given foam,the nonlinear elastic constitute for this foam is defined． And it is written into a material user subroutine of MSC． Nastran secondary development by Fortran to form the nonlinear analysis model in FEM． An example of foam-cored sandwich aluminum panel is calculated using this method． Through the comparison with the linear analytical,elastic-plastic analytical and experimental results,it demonstrates the accuracy of this nonlinear elastic material finite element model．

PROPERTIES STUDY OF ULTRAFINE (NANOSCALE) FULL-VULCANIZED POWDERED RUBBER TOUGHEN EPOXY RESIN

DONG Ling, LI Peng, YANG Xiao-ping, ZHANG Xue-mei

2013, 0(1):  20-24. 

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In this paper,it was studied the effect of using ultrafine (nanoscale) full-vulcanized powdered rubber (VP-501) on epoxy resin． Analysis of FT-IR,universal tensile machine,DSC,DMTA and SEM were introduced to compare the mechanical properties of epoxy,curing kinetics,dynamic mechanical properties,tensile fracture surface morphology of epoxy resin with and without VP-501 nanoparticles． Resulting from the homogeneous dispersion of the nanoparticles in epoxy resin,the addition of VP-501 made substantial improvement on the impact properties while the tension properties and the flexural properties were not obviously reduced,increase glass transition temperature (Tg),from 148． 41℃ to 159． 08℃,and changed the tensile fracture morphology from smooth to rough． Consequently,epoxy resin is toughed by VP-501．

BARYCENTRIC INTERPOLATION COLLOCATION METHOD WITH DOMAIN DECOMPOSITION FOR SIMULATING BIMATERIAL MODEL

LI Shu-ping, WANG Zhao-qing, TANG Bing-tao

2013, 0(1):  25-29. 

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The barycentric interpolation collocation method with domain decomposition for simulating mechanical properties of bimaterial model is presented in polar coordinate system． According to the interface of biomaterial model,the physical domain is divided into two subdomains． The formulations of barycentric interpolation collocation method is constructed on the subdomian,respectively． The formulations of subdomain are assembled in a global form． Applying boundary and interface conditions to Solve the system of algebraic equations,the displacement field of bimaterial model is obtained． The numrical results of bimaterial model indicate the validity and accuracy of proposed method．

CARBON FIBERS AND INTERFACIAL PROPERTIES OF THEIR REINFORCED RESIN MATRIX COMPOSITES

HAO Hua, LI Peng, LING Hui, SUN Hong-jie

2013, 0(1):  30-34. 

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Surface properties including surface physical morphology,chemical elements and wetting properties of MT700C-6K-42B-1 (abbr． MT700C) and T700SC-12K-50C (abbr． T700SC) carbon fibers were analyzed by SEM、XPS and contact angle analyzer． The interfacial properties of their reinforced resin matrix composites MT700C /603 and T700SC /603 were also studied at dry / hygrothermal ageing conditions． Results show MT700C carbon fibers present better wetting property and stronger adhesion with resin matrix due to higher O/C ratio and active carbon ratio than T700SC carbon fibers． MT700C /603 composite has higher ILSS than T700SC /603 composite at dry and RT conditions． While,through hygrothermal aging,the T700SC /603 composite has better ILSS retention rate than MT700C /603 composite．

TESTING AND ANALYZING ENGINEERING PARAMETERS OF THE COMPOSITE LAMINATE USING FIBER BRAGG GRATING

WANG Kai-ge, MEI Zhi-yuan

2013, 0(1):  35-39. 

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Effective analysis and evaluation of the composite structural mechanics is based on accurate measurement of the composite engineering parameters． By measuring the strain characteristic of the composite structure using the technology of embedded fiber Bragg grating (FBG),the engineering parameters such as elastic modulus and Poisson ratio are obtained． In this paper,the result of the measurement by FBGs is compared with that of extensometer and electrical strain gauges,proving the reliability and availability of FBG． Then the Poisson ratio of the composite specimen is measured by embedded transverse and longitudinal FBGs,the result is compared with that of strain gauges． The comparisons of the results show that FBGs is more sensitive and steady than strain gauges．

FINITE ELEMENT MODLEING METHOD OF COMPOSITE ROTOR BLADE WITH BALLISTIC PERFORATION

SUN Zhong-tao, WANG Hua-ming

2013, 0(1):  40-43. 

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The military helicopter rotor blade has design requirement of sustaining some kind of ballistic damage． According to the structural properties and operating characteristics of composite blades,this article provides an even cross-section and node removed method to build finite elements model of composite blade with ballistic perforation． This modeling method builds three-dimensional model of blade typical section by even cross-section tension,then nodes around bullet holes are removed to simulate ballistic damage of the blade． The model of ballistic blade built in this article has a high degree of confidence and an acceptable solver scale,it can be used for further research of composite blade’s performance of resisting ballistic damage．

APPLICATION OF ENDOCHRONIC THEORY FOR POLYURETHANE FOMAS

CHU Hong-jie, CUI Guo-qi, WU Hua-jie, GU Fang

2013, 0(1):  44-46. 

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Polyurethane foams are a kind of energy absorbing material,and its mechanical behavior can be modeled by endochronic theory． This paper introduces the endochronic theory into the constitutive models of polyurethane foams and model for the isothermal small strain is derived from Gibbs free energy． Based on these,instructional tendencies of the model are also discussed．

FABRICATION AND MECHANICAL PROPERTIES OF CENTRIFUGAL CAST HIGH SPEED STEEL ROLLER UNDER ELECTROMAGNETIC FIELD

LI Gui-rong, WANG Hong-ming, SHEN Guo-qing, SHAO Li-jun

2013, 0(1):  47-50. 

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Pulse electromagnetic field is imposed during the centrifugal casting high speed steel to solve the segregation of elements and carbide． The main components of elements in high speed steel are designed as 1.5%~2.5% C,4.0~6.0% V,4.0%~6.0% W,1.5%~4.5% Mo,2.0%~4.0% Cr and 0.04%~0.18% Zr． The frequencies of pulse electromagnetic fields were set at 1,2,4,6,8 and 10Hz levels separately． The corresponding magnetic induced intensities of mould center were 0．2~5T． The actual elemental components were analyzed using Atomic Emission Spectrometer． During data processing parameter of variance was used to characterize the fluctuation and segregation of elements and carbides． After heat treatment of quenching and tempering several mechanical properties of materials were tested． The results show that the fluctuation and segregation have been inhibited after using pulse electromagnetic filed． The comprehensive mechanical properties are enhanced obviously,which include hardness,tensile strength,bending strength and impact toughness． The average increase amplification is about 10% compared to that without using pulse electromagnetic field．

TECHNOLOGY AND BENEFIT ANALYSIS OF COOLING TOWER'S ENERGY SAVING AND ENVIRONMENTAL PROTECTION IN CHINA

LIU Jing-nan, ZHANG Li-xin, YIN Zheng, SHEN Yan

2013, 0(1):  51-55. 

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The cooling tower is a kind of large cooling device in thermodynamic cycle and industrial process． Recent years,for the purpose of environmental protection and energy saving,there was a large-scale reconstruction and development occurred in the industry of cooling tower． Then cooling tower industry has made a considerable progress in resource-saving and environment-friendly． In this paper,based on the summaries of the technology in domestic cooling tower industry energy-saving and environmental protection; and estimate the economic and social benefits amount of cooling tower in energy conservation and environmental protection．

DESIGN,MANUFACTURE AND APPLICATION OF HIGH PERFORMANCE RADOME

ZHANG Jia-lin, LV Xue-song

2013, 0(1):  56-59. 

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“Satellite communication in motion (SCM) ”enjoys the advantages of wide coverage area,no topography or region restriction,stable and reliable transmission,and mobile communication,exhibiting wide and promising prospects in both military and civilian fields． Antenna mask is used to protect " SCM" antenna of the necessary equipment． This paper introduces the design,manufacture process,and applications of high performance antenna mask of SCM． Through analyzing the basic properties for high performance antenna mask materials,a lay up design for Ku-band antenna mask is made． Structure optimization is conducted by using the ANSYS software． Also,process and electrical property optimization designs are made for suitable use． Finally,the application prospects of the antenna mask manufactured according to above design are discussed．

SYNTHETIC OPTIMUM DESIGN OF AIRSHIP POD

SHAN Hang-ying, YANG Zhong-qing, SUN Zhong-tao, ZHANG Hai-li

2013, 0(1):  60-64. 

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From out-hung properties of airship pod,the slight weight and the cheap manufacturing expenses as design objective,synthetic optimization design is carried out from material choice,structure arrangement and detail design． The optimized pod structure of static strength and stiffness is verified through finite element analysis and static test． The result shows the strength and stiffness of airship pod meet design demand,actual weight is less 10% than fixed weight,and can add effective assignment load or reduce gasbag volume．

IMPACT RESISTANCE OF FIBER HOOP-WRAPPED COMPOSITE CYLINDERS

ZHANG Yong-ming, LI Pei-ning

2013, 0(1):  65-72. 

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The composite / metal hybrid structure is widely used in composite cylinders of new energy vehicles, which has different impact damage characteristics compared with pure composite structure． This paper,combining both the tests of composite cylinder and test panel,evaluates impact resistance performance with parameters such as: impact energy absorption rate,delamination extension resistance and attenuation factor of the residual strength ratio． The experiments of falling ball impact with various support fixtures and glass fiber /epoxy unidirectional laminates are carried out to simulate how different liner materials of composite cylinders affect the impact damage degree of fiber winding layers． It is found that,under certain impact energy,changing composite / metal hybrid structure leads to the change of impact energy absorption rate and increases critical value of impact damage,namely,bear load impact capacity． The higher impact energy absorption rate will reduce delamination extension resistance,and the residual strength of laminate with impact damage will attenuate faster． As a result,the effect of delamination extension resistance and impact energy absorption rate should be taken into consideration while designing composite cylinders．

THE STUDIES ON THE PROTECTION FUNCTION OF COMPOUND MATERIAL MULTI-FUNCTION BULLET-PROOF PLATE

LI Huan-qiu, OUYANG Ke-feng, ZHANG Shi

2013, 0(1):  73-78. 

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Although the bullet-proof plates made by single armor steel or the armed fiber have good characteristics of anti-penetration to high-speed bullet,but the compound structure can greatly increase bullet-proof properties and reduce its area density． The propertities of penetration of the sandwich structure with foam and armor steel reinforced by the armed fiber under the 56 types with 7.62 mm common steel core bullet are studied by experiments and numerical analysis． The protective ability of anti-bullet and influence factors of the absorbing bullet kinetic energy have been researched through the different compound forms of foam sandwich structure． The concept of the best bullet-proof speed zone and V₅₀ homologous formula in the structure are given． So the bullet-proof plates with the best benefit-cost ratio can be designed．

TENSILE PRORERTY AND PREPARATION OF 2. 5D WOVEN COMPOSITES USING AS AUTOMOBILE INTERIOR

YUAN Shou-ren, CAO Hai-jian, QIAN Kun, XU Wen-xin

2013, 0(1):  79-83. 

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In this work,PP filaments were wrapped in the flax surface to form PP /flax covered yarn． The covered yarns were used to weave three typical 2． 5D woven fabrics(deep crossing linking,straight shallow-crossing linking and the curved one)． Then those woven fabrics were made into PP / flax composites which can be used as car interior by hot pressing． Tensile property was tested by using Instron universal material testing instrument and the damage mechanism was analyzed in the paper． The results showed that warp direction tensile property of deep crossing linking woven fabrics turned out to be best,and those of curved ones were worst． The weft direction tensile property of the three 2．5D woven fabrics just differed little． Warp direction tensile property of straight shallow-crossing linking composites were best,while the deep crossing linking ones were worst． The weft direction tensile property of the three 2．5D woven composites just differed little．

THE STUDY ON THE MODEL OF THE LOOP STRUCTURE OF MULTI-AXIAL WARP KNITTING FARBIC

LU Qian-qian, LI Wei

2013, 0(1):  84-89. 

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Multi-axial warp knitting technology has been widely promotion and application in foreign,but it is in the initial stage at home． The loop structure of multi-axial warp knitting fabric has great effect on the material performance． This paper introduced research history about the model of the structure of knitted fabrics,and analyzed and discussed the loop structure of multi-axial warp knitting fabric in detail,including the geometry model of the single axial warp knitting fabrics,the bi-axial warp knitting fabrics,the unit cell model and the 3D model of the multi-axial warp knitting fabrics．

THE RESEARCH AND PROGRESS OF AMPHIPHILIC POLYMERS PREPARED BY CONTROLLABLE POLYMERIZATION METHOD

SUN Li, ZHANG Ai-bo, LUAN Jing-fan, ZHAO Chun-ying

2013, 0(1):  90-93. 

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The research on amphiphilic polymers has been paid more attention for its unique structure and potential application prospect． In this paper some important methods to synthesize amphiphilic polymers were introduced, which are the atom transfer radical polymerization(ATRP),nitroxide-mediated living free-radical polymerization(NMRP) and reversible addition-fragmentation transfer polymerization(RAFT) ． The application of amphiphilic polymers in drug delivery,surface modification of membrane and immobilized enzyme,also were introduced．

RESEARCH DEVELOPMENT ON THE WEAR-RESISTING PERFORMANCE OF PEEK COMPOSITES

ZHANG Zhi-dan, XU Juan, SUN Ke-yuan, NING Chong-chong

2013, 0(1):  94-98. 

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In recent years,high performance thermoplastic polymer matrix composites have attracted the attention of researchers． Polymer based composites are being more and more used as tribomaterials due to their light weights and good tribological performances especially under dry sliding conditions． Poly (ether ether ketone),which is developed in 80s,is an attractive material for journal bearing and piston rings under various loading conditions as it exhibits a low creep rate at higher temperatures． Also,it has a high glass transition temperature (Tg: about 143℃) and a high melting temperature (Tm: about 343℃) ． In addition,PEEK as a semi-crystalline specialengineering plastic has many performances,for example,excellent chemical resistance,thermal stability,self-lubricating property,fire resistance,stripped resistance and fatigue durability,high strength,modulus and retention of mechanical properties over a wide temperature range and extreme environmental conditions,which is widely used in aircraft structures,space structural components of space research vehicles,automobile,ship,electronic / microelectronics, medical treatment and so on． But the wear resistance of PEEK still cannot meet the conditions in some special area,such as the request of the parts of the fatigue resistance and impact resistance． So,more and more excellent wear-resisting or mechanical properties of PEEK plastic alloy and PEEK composites are obtained by adding fibers,crystal whisker,inorganic,organic fibers and other fillers． The fillers contain carbon fibers,carbon nano fibers, calcium titanate whisker,potassium titanate whisker,SiO₂,ZrO₂,SiC,CuS and so on． The improvement in wear resistance of composites was attributed to the smoothing of the counter surface,the developing of a transfer film,improved handness of modulus． However,the smoothness,hardness,and stiffness are not only the factore controlling the wear behavior,but also the nature and stability of the transfer film ． The abrasion mechanism of PEEK composites and some traditional methods of improving the friction and wear behaviour were reviewed in this study．