COMPOSITES SCIENCE AND ENGINEERING

AN EXPERIMENTAL AND NUMERICAL INVESTIGATION ON THE DELAMINATION IN COMPOSITE LAMINATES WITH EMBEDDED DEVICES

QIAO Wen-jing, XIAO Yi, Fukuda Hiroshi, HATTA Hiroshi

2014, 0(6): 4-11.

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Functional devices integrated within the structural materials are a key way to implement and design the multifunctional materials and structures. However, the embedded device in a composite structure would generally cause a geometric discontinuity that result in a significant effect on the structural integrity. Some of the key issues in affecting the structural integrity have been explored experimentally and numerically in this paper. During static tensile testing, the damage evolution was monitored by acoustic emission measurement, and several specimens were observed through optical micrograph at different load levels to determine the progressive damage development. Testing results show that delamination at the interface between composite and integrated device is a significant damage mechanism in tensile performance degradation, and the delamination propagation depends on the ply angle of SUS/θ interface. A two-dimensional plane strain finite element model using ABAQUS code was developed to study damage initiation using stress analysis and the behavior for delamination propagation using a fracture mechanics approach. Numerical results show that the different effects of "slipping" and "frictional" on crack propagation can be modeled by introducing different critical release rate.

AN ANSYS ANALYSIS OF THE DEFORMATION OF THE FILAMENT WINDING COMPOSITE CASE UNDER INTERNAL PRESSURE

YANG Le, ZHU Tao, YANG Xi-jun, LIU Hong-cheng

2014, 0(6): 12-15.

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A layered solid element in ANSYS was used to simulate the filament winding composite dome with ellipsoidal ration 1.7, and the numerical analysis results of the deformation of the dome agreed with hydrostatic test results. Considering the filament winding composite dome with ellipsoidal ration 2, the research reveals that the law of the strain along the fiber present first increases then decreases from the fore opening to equatorial. Meanwhile, the maximum displacement located in the middle along meridional of fore dome. In addition, ellipsoidal ration 1.7 of the fore dome, the strain subjected to internal pressure with ellipsoidal ration 2 is more uniform, which corresponds to euuilateral stress dome of filament winding composite.

WIND TURBINE BLADE DESIGN AND THREE-DIMENSIONAL ENTITY MODELING STUDY

WANG Zheng, GU Gui-mei, WANG Fang-li

2014, 0(6): 16-19.

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Blade plays a key role in the wind turbines, which determines the performance of the machine to a large extent. This paper studies the Pituitrin-Momentum theory and puts forward the general steps and methods of blade design in order to gain maximum aerodynamic efficiency of wind turbines. To meet the requirements of the blade pneumatic continuity,radiation fitting method is present to realize the smooth transition on the surface of the blade. Then, according to the principle of coordinate change, the coordinates of cross profile are translated from two-dimensional space to three-dimensional space.At last, ANSYS software is carride out on three-dimensional entity modeling through a bottom-up approach. The present paper lays a foundation for further optimization and analysis of the blade.

FIBER PLACEMENT PATH PLANNING FOR OPEN SURFACES BASED ON TRAVERSAL METHOD

HU Bin, XU Dong-liang

2014, 0(6): 20-24.

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Placement path planning is one of the key technologies of automated fiber placement, because its reasonability can mean the difference between success and failure to get a high-quality composite product. So reasonable placement path is the prerequisite of composite material processing. According to the requirements of automated fiber placement against placement path, factors affecting path planning are analyzed. To fully exploit its advantage of making calculation convenient, meshed surface method is applied to principal stress method. The placement paths are generated based on placement angle information of discrete points obtained from layer design. An algorithm that traverse the surface from left to right is proposed and the way to select the planning start-point and obtain the placement paths next to the borderline is also discussed. Overlap ratio is introduced to control the extent of fiber overlapping and separating and make prepreg placed on the surface as required . Its feasibility has been verified on path planning software based on VC++.

STUDY ON A GLASS WOVEN FABRIC PREPREG LAMINATE OF THE EPOXY MATRIX RESIN TOUGHENED WITH CORE-SHELL RUBBER PARTICLE

LI Hong-feng, WANG De-zhi, QU Chun-yan, MAO Yong

2014, 0(6): 25-29.

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A glass woven fabric prepreg of the epoxy matrix resin toughened with core-shell rubber particles was prepared. The results showed that the core-shell rubber will not affect the epoxy resin infiltration capacity of glass fiber and fabric prepreg laminate achieved excellent toughness by using just 5phr core-shell rubber as tougher, impact strength of which reached 278.1kJ/m² and it increased by 20.0% than that before toughening, fracture toughness G_IC of which reached 982.0J/m² and it increased by 35.4% than before toughening; tensile strength of which reached 749.5MPa and it increased by 16.5% than that before toughening, tensile modulus of laminate toughened with core-shell rubber particle is hardly decreased, the surface morphology observed by scanning electron microscope exhibited typical toughness fracture. The resin has good infiltration and adhesion with glass fiber.

THE CORROSION MECHANISM RESEARCH OF GLASS FIBER REINFORCED VINYL ESTER RESIN COMPOSITES IN SULFURIC ACID SOLUTIONS

LI Ya-nan, YU Yun-hua, YANG Xiao-ping

2014, 0(6): 30-34.

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The corrosion mechanism of glass-fiber-reinforced vinyl ester composites was investigated by immersiong composite samples in deionized water and 40wt% sulfuric acid solution at constant temperature of 35℃, 45℃, 55℃, 65℃, and 75℃ for periods up to 1800 hours. Results were characterized through weight gain tests, inductively coupled plasma analysis (ICP), near infrared spectroscopy (NIR), and scanning electron microscopy (SEM). Ion-leaching behaviors show that ion leachability depends on immersion temperature, ion content of fiber, and the character of ions in the sulfuric acid solution. NIR and SEM results show that hydrolysis reaction occurs on resin matrix. The long corrosion data indicate that most of the corrosion mechanisms initiated by sulfuric acid immersion at lower temperature (35℃,45℃,55℃, and 65℃) for 1800 hours are merely at the resin level, and the fiber/resin matrix interface region remains in good condition. Interface corrosion was merely found at the cutting edge of composite immersed in 75℃.

SIZE EFFECT ON STRESS-STRAIN RELATION OF FRP STRENGTHENED RECTANGULAR CONCRETE COLUMNS UNDER MONOTONIC AXIAL LOADING

WANG Zuo-hu, LIU Jing-bo, DU Xiu-li

2014, 0(6): 35-39.

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Due to research limitations, such as the loading capacity of test equipment, the failure mechanism of FRP strengthened concrete structure design is mainly based on small size destructive test, whether it is scientific and rational to be used for large-size component in modern large-scale civil engineering haven′t been verified. Based on the idea of modified size effect law and the model of circular concrete columns, new models for predicting strength of rectangular columns confined with FRP are proposed, which can reflect the effect of different columns sizes on the compressive strength. The comparison with experiment results and existing models shows that the proposed models are more accurate.

DEVELOPMENT OF COMPOSITE PRESSURE VESSEL FOR SPACE APPLICATION

CUI Guang-qun, XIAO Wen-gang, XIAN Bao-jun

2014, 0(6): 40-43.

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This paper discusses the design method,manufacturing process and test of composite ultrahigh pressure vessels.The results show that the composite pressure vessels are suitable for aerospace application.

SYNTHESIS AND PROPERTIES OF SILICA WHITE N-HEXYL CARBAZOLYL FORMIC ACID COMPOSITE MATERIALS

WANG Xu-chun, LI Xiao-chao, ZHANG Xue-mei, CHEN Jun-ming

2014, 0(6): 44-47.

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N-hexyl carbazolyl formic acid was obtained by oxidizing N-hexyl carbazolyl methanol. The composite materials were successfully prepared by 1.4124g hexyl-carbazole carboxylic acid with 1.005g activated nano-SiO₂, and characterized by IR, UV spectrophotometry and fluorescence spectrophotometry. Experimental results show that the composite materials exhibit strong UV absorption and fluorescence spectroscopy.

SKIN AGING PROPERTIES OF COMPOSITE MATERIALS

LU Dong-bin, CHEN Ping, BAI Tian, CHAI Peng-jun

2014, 0(6): 48-51.

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This paper studies the aging properties of composite skins, and predicts skin′s aging properties by accelerated aging test method. The experiments considered the impact of temperature, humidity and sunlight on the skin′s properties. Besides, the changing trends were also studied also.

APPLICATION OF NRF905 WIRELESS TRANSCEIVER MODULE ON WIND-POWER BLADES ACOUSTIC EMISSION TESTING

HU Rang, GU Gui-mei

2014, 0(6): 52-56.

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For kinking problem of testing of running blades with cable equipment, the paper puts forward using wireless technology for running blades' condition monitoring. And design a wireless detection system based on acoustic emission signal using the idea of modular design. Beijing shenghua SR150M was chosen as the acoustic emission sensor to test acoustic emission signal, 12C5A60S2 of STC series single-chip was selected as the microcomputer control unit to store data and control the transceiver, and the chip of NRF905 was used as the wireless data transceiver module. PC design using VB, and the system implements the data receiving process. Testing results show that the system is reliable for data detection and transmission processing, and it can realize condition monitoring of the blades. The system software is portable, and it provides a method to monitor of rotating objects.

RESEARCH ON THE THERMAL HEATING DE-ICING PROPERTIES OF WIND TURBINE BLADE COMPOSITE PLATES BASED ON POLYMER ELECTRIC HEATING FILM

MU Shu-xiang, WU Rui, CHEN Chun, YAN Shao-yi

2014, 0(6): 57-61.

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Glass-fiber-reinforced epoxy resin plates containing sandwich core structure and polymer electric heating film were prepared via vacuum assisted infusion molding process by simulating the skin lay-up structure of wind turbine blade. The heating effects of the plates under different environment temperature and power density were investigated. The relationship between the minimum power density of polymer electric heating film required by de-icing and anti-icing and corresponding environment temperature was fitted out by experimental data. The de-icing performance of the plate containing polymer electric heating film in low temperature environment under different power density was also studied. The results show that, in 200~600W/m² power density range, the de-icing time of the plate with 1cm ice thickness in the -11~-13℃ environment could be controlled in 1~3h.

RESEARCH OF A NEW METHOD ABOUT THE HALF COMPOSITE LENTICULAR TUBE ADVANCED PULTRUSION

YANG Xing-rui, XIAO Jian, QI Jun-wei, XIAO Jun

2014, 0(6): 62-65.

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To improve the straightness of the composite lenticular tube, a solution of "Moving Mold Avanced Pultrusion (MMADP)" was proposed with analyzing shortcomings of the advanced pultrusion technique in manufacturing the lenticular tube. A new advanced pultrusion system for lenticular tube was built up and the pultrusion test was conducted. The test results showed that the straightness of composite lenticular tube were improved from 3mm/m up to 0.5mm/m.

ACOUSTIC PROPERTIES OF POLYPROPYLENE COMPOSITES REINFORCED BY FLAX FIBER

WANG Qian-wen, ZHAO Lei, YAO Gui-xiang, DENG Xian-bao

2014, 0(6): 66-69.

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The polypropylene composites reinforced by flax fiber with the content of 0%, 10%, 20%, 30%, and 40% were prepared. Also the flax fiber modified by alkali and silane coupling agent KH -570 reinforced composites were prepared, and effects of fiber content and surface modification by alkali and silane coupling agent KH-570 on the acoustic properties of composites were studied. The results showed that the acoustic property of composite first increased and then decreased with the trend of increasing audible frequency when the fiber content overpass 10%. When the audible frequency was the same, the lower the content of the flax fiber, the worse the acoustic performance. But, when the content of the flax fiber overpass 30%, the peak voltage attenuation percentage declined. After surface treatment, the acoustic properties of composites were enhanced, and the flax fiber treated with coupling agent reinforced composites was better than that treated with alkali reinforced composites.

MECHANICAL CONSIDERATIONS FOR UNFOLDED HONEYCOMB MILLING

LI Xing-de, ZHOU Chun-ping QIU Jin-hao

2014, 0(6): 70-73.

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In reference [1], honeycomb material with changing thickness is applied to the molds of radome after it is milled. This paper investigates the stress and strains in the honeycomb material in this process and use these stress and strains as criteria to determine proper portions suitable for milling in one process. These methods avoid the complicated finite modeling process and the errors caused by the finite elements. After proper programming to the FEMAP software, the results in this paper can be displayed in FEMAP in the form of stress and strain level contours, which gives a vivid link between the FEM analysis and the results of this paper.

REQUIREMENTS OF FOUNDATIONS FOR FRP TANKS

CHENG Ai-lin, ZHANG Guo-jun, DU Hui-bo

2014, 0(6): 74-75.

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This paper analyzes different types and requirements for FRP tanks.

COMPOSITE POLE&TOWER TECHNOLOGY AND APPLICATION STATUS

LIU Wei-jun, ZHANG Jin-nan, WANG Qiang-hua

2014, 0(6): 76-82.

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In this paper, FRP/Composites application to pole&tower of transmission line and its technical advantages are described. The current R&D of composite pole&tower in domestic and foreign companies and research institutes are presented. The domestic composite poles&towers are under development and pilot production phase, and some of its products have been used in transmission lines on trial. The domestic composite pole&tower products mainly employ the polyurethane and epoxy as their resin matrix and E-glass fiber as their reinforcement, with filament winding process for their production. Performance tests for composite pole&tower include basic material properties, electrical properties, aging performance tests and prototype model test.

ADVANCES OF STUDY WITH MICROMECHANICAL MODELING ON DAMAGE BEHAVIOR AND STRENGTH PREDICATION OF PREDICATION FIBER REINFORCED COMPOSITES

WANG Yan-fei, SUN Yao-ning, SUN Wen-lei, HAI Ji-zhe

2014, 0(6): 83-89.

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The strength of fiber-reinforced composites is determined by the microscal cracking,debonding and interaction between the elements and phases of the composites.The processes of damage of composites is a main factor to influence the disorder of service life in engineering applications.Prediction of strength,stiffness and service life of composites through micromechanical models can complete the integrated macroscopic and microscopic analysis for composite structure.An overview of methods of micromechanical modeling of damage and fracture in fiber-reinforced composites is presented.The models are classified into different groups,including shear lag-based models,fiber bundle model,fracture mechanics based and continuum damage mechanics based models and et al.And different approaches to the simulation of damage and fracture of fiber-reinforced composites are summarized.Finally,further applications of these micromechanical models applications are briefly noted.

Industry information contents

2014, 0(6): 90-126.

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