COMPOSITES SCIENCE AND ENGINEERING

STATIC INDENTATION TEST OF COMPOSITE LAMINATE AND THE NUMERICAL ANALYSIS OF ITS WHOLE PROCESS

ZHANG Hai-qing, ZHOU Shi-gang, GONG Zhan-feng, XUE Yuan-de

2014, 0(11): 5-10.

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There are several injury patterns such as delamination, matrix cracking, matrix compression, fiber fracture and fiber crush, when composite laminates are under static indentation force. Based on ABAQUS software, a finite element model is built to simulate the damage evolution in the composite laminates which are under static indentation force. Load-displacement curve, damage evolution process, and dent depth-load of NCF carbon fiber laminates are predicted by the finite element model. Load-displacement curve of composite laminates under the action of static indentation force is made in the quasi-static indentation test and the dent depth of the plate is measured by the dent depth instrument in the test process. The results of numerical simulation and experiment agree well with each other.

STRUCTURE DAMAGE IDENTIFICATION RESEARCH OF WIND TURBINE BLADE BASED ON THE AXIAL MODE SHAPE DIFFERENCE

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

2014, 0(11): 11-15.

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Space structure damage identification is a relatively complex process, it has to consider three dimensional vibrations of the structure. In order to identify the structure damage of wind turbine blade, a new standard which is named the axial mode shape difference is put forward for the complex space structure of wind turbine blade. The wind turbine blade structure models of no damage and damage is established by ANSYS, and the influence disciplines of axial mode shape difference is researched under the different of wind turbine blade damage, the method is applied to recognize the damage location of wind turbine blade model. The result shows that the axial mode shape difference can identify damage location, a feasible method is put forward to identify the wind turbine blade structural damage by axial mode shape difference.

RING STIFFNESS FINITE ELEMENT ANALYSIS AND APPLICATION OF GRP PIPES

WANG Zhun, DENG Jing-lan, WANG Ji-hui, DING An-xin

2014, 0(11): 16-20.

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Ring stiffness is an ability to resist deformation under external loads pipeline. Through understanding the concept about ring stiffness of glass reinforced plastic sand pipe. Ring stiffness related to concepts and basic methods of design and testing were analyzed, and method of calculating FEM ring stiffness was worked out. Using the finite element software ANSYS to model and analysis pipes, we confirmed the feasibility and accuracy of finite element method by comparing the finite element results and experimental data. It provided convenience for engineering design, application and optimization of glass reinforced plastic sand pipes and similar pipeline.

STUDY ON FAILURE MECHANISM OF PVC-FRP CONFINED CONCRETE COLUMN SUBJECTED TO AXIAL COMPRESSION

YU Feng , NIU Di-tao

2014, 0(11): 21-25.

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According to the experimental study on 12 PVC-FRP confined concrete columns subjected to axial compression, the failure mode and failure mechanism of PVC-FRP confined concrete column are analyzed. The loading process of PVC-FRP confined concrete column may be divided into three sections: the elastic, the elastic-plastic and strengthening stage. Based on the material characteristics of PVC tube, core concrete and CFRP strips, the confining procedure of core concrete may be divided into three stages: preceding the crack of concrete, after the crack of concrete and the internal force redistribution. PVC tube includes the elastic and elastic-plastic stage; the stress and strain of CFRP strips are in increasing condition; the stress paths of PVC tube, core concrete and CFRP strips are presented on the basis of experimental study. The simplified calculating method of bearing capacity of PVC-FRP confined concrete column is also proposed by the condition of limit equilibrium.

NUMERICAL SIMULATION FOR AUTOCLAVE CURING DESIGN OF COMPOSITE MATERIALS

LI Cai-lin

2014, 0(11): 26-29.

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Based on PAM-AUTOCLAVE software and autoclave curing design control equations, finite element analysis model was built. Multi physical fields coupling were simulated by numerical method. The simulation results were analyzed by using the visual method. The research demonstrated that the steady or unsteady computation can calculate well-distribution of flow field in autoclave, and that transmission of hot-air influenced distribution of temperature field of tools and parts. The proper position of parts and tools in autoclave were optimized, in order to improve curing mass of parts. The study is not only the trend of technological design but also important route of reducing composite manufacturing cost.

FINITE ELEMENT ANALYSIS OF FULLY WARPPED CARBON FIBER REINFORCED ALUMINUM-LINED CYLINDERS

ZU Lei, WANG Ji-hui, LI Shu-xin, WANG Zhun

2014, 0(11): 30-35.

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In this paper, the structural analysis for carbon fiber fully wrapped aluminum-lined composite pressure vessels was presented using finite element method (FEM). The finite element model of a typical composite pressure vessel was built using ANSYS parametric programming language (APDL), where the element type and its real constants, the mesh density, and the boundary conditions were respectively determined. According to the American standard DOT-CFCC, the numerical solutions for the stresses of the composite overwrap and the aluminum liner were obtained under the service pressure, the test pressure, and the minimum required burst pressure. The actual burst pressure of the composite pressure vessel was also numerically predicted.

THE HYGROTHERMAL AGING BEHAVIOUR OF CARBON FIBER REINFORCED POLYTRIAZOLE RESIN COMPOSITES

LI Yu-ling, WAN Li-qiang, HUANG Fa-rong, DU Lei

2014, 0(11): 36-41.

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The hygrothermal aging properties of the carbon fiber reinforced polytriazole resin composites (T700/PTA) were studied under the condition of 80℃ and 98% (relative humidity). Mechanical properties, moisture absorption characteristics and morphology changes of the composites were investigated by the weighing method, static and dynamic mechanical test as well as the SEM observation. The strength of composites can be fitted by semiempirical mathematical model, which was used to predicte the service lifetime of composites. The results show that the flexural strength and ILSS of composites are significantly affected by the hygrothermal environment, especially in the early aging period. Absorption characteristics of the composites obey Fick's second law in the first aging stage (diffusion coefficient D=1.129×10^-6mm²/s). Two transitions are found on the dynamic mechanical thermographs of the aging composites, while the secondary transition at lower temperature disappears after drying. The interaction at the fiber/resin interface weakens after aging. It is predicted that the lifetime of composites is 33600h when the strength retention remains 50%. The T700/PTA composites have excellent resistance to hygrothermal environment.

RESEARCH ON ADVANCED PULTRUSION EQUIPMENT TECHNOLOGY OF HALF LENTICULAR TUBE

XIAO Jian, QI Jun-wei, XIAO Jun, LI Tao

2014, 0(11): 42-47.

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Aiming at astronautic composite lenticular tubes in this paper, the advanced pultrusion technique was developed. Main modules of half lenticular tube advanced pultrusion equipment, including unreeling device, preformed device, hot pressing device and traction clamping device were designed. After setting up the prototype of advanced pultrusion, half lenticular tubes were manufactured. It is shown that half lenticular tubes cured at 130℃ for 30min under the pressure of 1MPa could meet the quality requests. It provides a new method for the low-cost manufacture technique of composite lenticular tubes.

EXPERIMENTAL RESEARCH ON THE REPAIR OF THE DAMAGE IN HONEYCOMB-CORE T700/BMI COMPOSITE SANDWICH STRUCTURES

LI Cai-yan, XING Su-li, ZHU Bao-jun, XIAO Jia-yu

2014, 0(11): 48-53.

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Honeycomb sandwich structures and three different aperture semi-penetrating damage parts were prepared in this paper. The damage is repaired by patching technology, including high temperature repair (homogeneous repair) and middle temperature repair (heterogeneous repair). The mechanical properties were tested at room temperature and high temperature. The results show that there is little difference on performance recovery of the damaged specimens between homogeneous repair and heterogeneous repair. And due to the poor manufacturability and high cure temperature (>177℃), damages tend to occur on other components. Heterogeneous repair, however, has better manufacturability and lower cure temperature, which can not only recover the properties of the damaged successfully but is suitable for rapid repair.

ANALYSIS VACUUM RESIN INFUSION PROCESS OF WIND TURBINE BLADE ROOT

ZHAI Bao-li, ZHONG Lian-bin, YANG Qing-hai

2014, 0(11): 54-57.

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Using PAM-RTM software numerical simulation for wind turbine blade root vacuum resin infusion process, it is concluded that the different piping layout of the corresponding resin flow form, through a lot of vane vacuum import production simulation results are verified, the verification results show that the VARI simulation result in accordance with wind turbine blade root manufacture. Numerical simulation can well predict blade manufacture risk, timely put forward preventive solution, to avoid blade defects and reduce economic loss.

RESEARCH ON THE MICRO-CRYSTALLIZATION STRUCTURE AND DEFECT STRUCTURE OF DOMESTIC CARBON FIBER

LIU Zhong-ling, LI Guo-ming, TONG Yuan-jian, XU Liang-hua

2014, 0(11): 58-62.

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The micro-crystallization structure and defect structure of domestic commodity carbon fiber and TORAY T300 carbon fiber were studied by XRD, HRTEM, and EDS. The results showed that the distance between graphite sheets (d₀₀₂), micro-crystallization piled thickness (Lc) and width (La) of domestic carbon fiber were same as T300 carbon fiber. And the orientation of crystalline of domestic fiber was higher than T300, but the depth of parallelism of domestic carbon fiber was smaller than T300. There was onion structure and some impurities elements in domestic carbon fiber, such as Ca, Si, and S.

THE MECHANICAL AND ACOUSTIC PROPERTIES OF POLYPROPYLENE COMPOSITES REINFORCED BY VIRGINICA STEM BARK FIBER

ZHANG Sheng-zhong, ZHAO Lei, LIU Hua, HE Yuan-fang

2014, 0(11): 63-66.

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The virginica stem bark fiber was treated by KMnO₄and silane coupling agent KH-570. Then, the polypropylene composites reinforced by untreated and treated virginica stem bark fiber with the content of 30% were prepared. The surface treatment on the microstructure and mechanical properties of the virginica stem bark fiber, and the insulation property and mechanical properties of fiber reinforced polypropylene composite were discussed. The results showed that the microstructure of the fiber was changed after surface treatment, and the mechanical property and acoustic property of the composites were enhanced. The mechanical property and acoustic property of the fiber composite which was treated by the silane coupling agent KH-570 was better than that treated by the KMnO₄.

THE PERFORMANCE ANALYSIS OF CF/GF HYBRID COMPOSITES AND ITS APPLICATION IN WIND TURBINE BLADES

WANG Hai-zhen, YAN Chen, Wang Xing-bo, SONG Qiu-xiang

2014, 0(11): 67-71.

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In this paper, through 11 groups of tensile comparative experimental samples, the tensile properties of C/G hybrid fiber-reinforced composites at different hybrid ratios were analyzed. The results show that with the relative volume percentage of carbon fibers in the C/G hybrid fibers increasing, the tensile strength and modulus of the HFRP increased, and the elongations of the HFRP decreased. By means of theoretical calculations, the economical benefits of the spar cap for 50m long wind turbine blades made of C/G hybrid fiber-reinforced composites were calculated. If the C/G hybrid fiber-reinforced composites were used to made the spar cap, the weight of the spar cap can be reduced by 10%~60% compared with using glass fibers, and the cost of the spar cap will be increased by 150%~310%. However, relative to single wind turbine blade the weight of the blade can be reduced by 4%~22%, the cost of overall wind turbines will equal or even be decreased.

STUDY ON HEAT AGING PROPERTY OF TPU/ATH COMPOSITE MATERIAL

LIU Yun-xue, ZHAO Zhi-bin, YAO Peng-cheng, TANG Yuan-liang

2014, 0(11): 72-76.

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Thermoplastic polyurethane elastomer (TPU) is widely used by human, and obtained a higher rating in the organic field. But, due to the weakness of TPU itself, it often leads to the occurrence of some accident. Human found some inorganic particles, they have stable chemical properties, and the endothermic dehydration progress of them in the thermal decomposition procedure can delay the combustion of the polymer. So we use TPU and ATH as the main crude materials to prepare the TPU/ATH composite, which used by the means of solution blending. The mechanical property and thermal property after TPU/ATH composite aging were studied. The result reveals that with the aging time running, the mechanical property of TPU/ATH composite gradually reduced from the point of mechanical property. Analyzing the FTIR curve, the aging of composite material results in breakage of molecular link of the composite materials, causing the reduce of mechanical property from 0h to 168h. With the aging time 0h~24h, composite crystallinity decreases due to molecular link rupture. Composite material with aging time of 24h is lower than that before aging. The results from XRD are largely in line with those from DSC.

RESEARCH ON MECHANICAL PROPERTIES OF SUPPORT MATERIAL ON SPHERICAL GROUND-BASED INFLATABLE ANTENNA

PAN Qiao-ling, JIANG Jin-hua, TANG Yu-si, ZHUO Dong-fang

2014, 0(11): 77-81.

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To study the mechanical properties of support materials of spherical ground-based inflatable antenna, the properties of tensile, tear, bursting of high-strength polyester yarn plain weave PVC membrane fabric were investigated in a standard laboratory environment. The tensile properties were investigated in varying length of the glued material which adhered by Loctite 401 glue and in different immersion periods of hydrochloric acid and sodium hydroxide. The results showed that the warp tensile strength of support material was greater than that of the weft. The tensile strength increased at first then flattened out with the glued length increases. The tensile strength of the warp and weft both declined as alkaline etching time progresses, but the decline magnitude of weft tensile strength was greater than warp. PVC membrane materials had good resistance properties to hydrochloric acid. The warp tear strength of support material was greater than the weft and bursting specimens showed cracks in the form of weft breakage.

HIGH-TEMPERATURE COMPRESSIVE CREEP PERFORMANCE OF PMI FOAMS

DAI Wen-ping, LI Wen-xiao

2014, 0(11): 82-87.

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High-temperature compressive creep performance of polymer foam core is very important for the co-curing processing of foam-cored sandwich composite structure. This paper introduces the present research status of high-temperature compression creep of polymethacrylimide (PMI) foams, and analyzes the influence of material and environment factors on the high-temperature compressive creep of PMI foams. Finally, several test methods applied in high-temperature compressive creep performance of foams are compared.

THE PROGRESS OF VARIATIONS IN UNSATURATED FLOW WITH FLOW DIRECTION IN RESINTRANSFER MOLDING

LIU Hong-ying

2014, 0(11): 88-90.

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Resin Transfer molding is wildly used. This paper reviews the study of RTM from resin matrix system, reinforcing materials, processing, processing mould and theoretical research. This paper introduces the proposed work of unsaturated flow and the results of variations in unsaturated flow with flow direction.

TOW-SPREADING TECHNOLOGY AND EQUIPMENT

LI Bei-bei, ZHU Jia-qiang, LI Wei

2014, 0(11): 91-95.

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Compared to conventional carbon fabric, fiber tow in the spread tow fabric (STF) is spread before weacing. Advantages of STF such as relatively straighter fibers, less crimp and better surface smoothness were established. Thereby it results in the final composite material product with better mechanical performance. This paper introduces spread tow technology, presents mechanical multi-rollers, acoustic energy, ultrasonic and air flow tow spreading methods and related equipment in detail.

PROGRESS ON THE MODIFICATION OF THERMOSETTING RESINS AND THEIR FIBER COMPOSITES BY USING GRAPHENE

LI Wei, ZHOU Bao-quan, LI Zhong-hui, WANG Ming-yu

2014, 0(11): 96-101.

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Due to its unique two-dimensional monoatomic layer structure and many excellent properties, the graphene has broad application prospects in the field of improving the mechanical properties, thermal properties and electric conductivity of resin matrix composites. In this paper, the primary preparation method and surface functionalization of graphene were introduced. The progress on the modification of thermosetting resins and their fiber composites by using graphene was reviewed. Based on the summary of the achieved modification effects and their influence factors, the future development of graphene modified resin matrix composites was discussed. It was pointed out that the effective way of improving the performance and functional application of traditional fiber composites is to use the graphene modified FRP.

RESEARCH PROGRESS IN HEAT EXCHANGE PRINCIPLE AND THERMAL PERFORMANCE EVALUATION OF THE SHOWERING COOLING TOWER

YANG Jie-biao, ZHANG Lin-wen, ZHANG Li-chen

2014, 0(11): 102-108.

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For the design and engineering application of the spray cooling tower, the heat transfer principle is not clear and the cooling effectiveness evaluation is difficult. This paper introduces the research progress of heat transfer principle of the kinds of shower cooling tower, analyzes and simplifies the heat transfer model based on the previous frameworks, discusses the research progress of thermal performance evaluation method, summarizes the two available thermal performance evaluation methods based on previous literatures and puts forward views to their respective applicability. This has positive significance for the heat exchange theory research and engineering application of the shower cooling tower.

Industry information contents

2014, 0(11): 109-128.

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