Table of Content

28 December 2013, Volume 0 Issue 9

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MANUFACTURING METHODS OF PREPREG MATERIAL

XU Yan, LI Wei

2013, 0(9):  3-7. 

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Fiber reinforced resin prepreg is the intermediate product of fiber reinforced resin composite, whose performance greatly depends on its raw materials and processing techniques. This paper reviewed the prepreg classification and its preparation in terms of thermosetting prepreg and thermoplastic prepreg, including the choices of reinforcement fiber, resin matrix, and the curing system, as well as the processing methods for different kinds of prepregs. This paper also discussed the pros and cons of the relevant processing methods.

COMPUTATIONAL ANALYSIS ON SHEAR BEARING CAPACITY OF RC SHORT COLUMNS STRENGTHENED WIHT BFRP

OUYANG Li-jun, DING Bin, LU Zhou-dao, YU Jiang-tao

2013, 0(9):  8-12. 

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To analyze shear bearing capacity and failure modes of RC short columns strengthened with BFRP. Low cyclic loading tests were conducted on one comparative short column and two no-destructive RC short columns strengthened with BFRP. The tests show that failure mode, shear strength, ductility are improved and increased for specimens strengthened with BFRP. Shear capacity calculation formula of RC short column strengthened with BFRP has proposed based on test results and current formulae.

THE STABILITY OF CONTINUOUS GLASS FIBER REINFORCED POLYPROPYLENE PULTRUDED RODS

FANG Li, ZHOU Xiao-dong

2013, 0(9):  13-16. 

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In this paper, pultruded rods of continuous glass fiber reinforced polypropylene were prepared by self-design thermoplastic pultrusion equipment. The stability of pultruded rods under different environment conditions were investigated according to the expectant environment during service life, and the influences of high and low temperature, heat treatment and freeze-thaw cycle on the properties of pultruded rods were studied. The results of high and low temperature test showed that the flexural properties decreased with temperature rising, but there was still 40% retention rate of flexural properties at 100℃. And at low temperature, the flexural properties of pultruded rods raised. The flexural properties also raised after heat treatment. Furthemore, the flexural properties and shear strength of pultruded rods decreased through freeze-thaw cycle after heat treatment, but the decline range was small. The above results indicated that the pultruded rods had good stability under different environment conditions.

PROPERTIES AND MANUFACTURE OF GLASS-FIBER REINFORCED PHENOLIC FOAM

GAO Wei-wei, CAO Hai-jian, QIAN Kun

2013, 0(9):  17-20. 

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In order to study the influence of glass-fiber length and content to the properties of phenolic foams, micro glass-fiber powder, 3mm chopped glass-fibers and 6mm chopped glass-fibers were added into phenolic foams in accordance with some proportion in the paper. Compression and tension properties of glass-fiber reinforced phenolic foams were tested by using Instron universal material tester and micromorphology was observed by SEM too. The result shows that compressive properties of phenolic foam were best when the content of glass-fiber is 12%, with a chop length of 3mm, and compression increased 38% than that of pure phenolic foams. Tensile properties of phenolic foam were best when the content of glass-fiber is 8%, with a chop length of 6mm, and tension increased 47% than that of pure phenolic foams. Flame retardant properties of phenolic foam was best when the content of glass-fiber is 12%, with a chop length of 3mm, and the LOI of phenolic foam was 44.1.

PROPERTY PREDICTION AND MULTI-SCALE MODEL OF WIND TURBINE BLADE COMPOSITES REINFORCED BY CARBON NANOTUBES

XIE Gui-lan, GUO Jin, CAO Wei-nan, TIAN Jie

2013, 0(9):  21-25. 

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Homogenization theory combined with finite element method is applied to predict the properties of wind turbine blade composites composed of carbon nanotube/carbon fiber/epoxy resin by vacuum resin transfer molding. According to the experimental analysis, internal structure of carbon nanotube/carbon fiber/epoxy resin composite is described by three levels (macroscopic, mesoscopic and nanoscopic levels). The multi-scale models of wind turbine blade composite reinforced by CNTs are established. MATLAB program is written based on two-level homogenization methods to predict the effect of the material parameters (volume fraction, aspect ratio, elastic modulus) on the properties of CNTs/CF/EP composites. The effective property increases as the elastic modulus, aspect ratio and volume fraction of CNTs increases, respectively. The conclusions have some significance for guiding preparation of wind turbine blade composites.

THE PREPARATION AND PERFORMANCE OF GRAPHENE/THERMOPLASTIC POLYURETHANE NANOCOMPOSITES

HE Zhi-ping, LI Min, GU Yi-zhuo, CHEN Ming-hai

2013, 0(9):  26-29. 

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Graphene oxide (GO) was reduced by a thermal reduction method to prepare reduced graphene oxide (RGO). Nanocomposite films were fabricated for GO/thermoplastic polyurethane (TPU) and RGO/TPU. Furthermore, thermal conductivity, electrical conductivity and mechanical properties of the nanocomposite films were investigated. The results show that GO/TPU nanocomposites have high thermal conductivity and low electrical conductivity, and RGO/TPU nanocomposites have high thermal conductivity and high electrical conductivity as well. Moreover, addition of the GO and RGO can significantly improve the tensile strength and modulus of TPU, respectively.

SIMULATION ANALYSIS AND VERIFICATION OF 1.5MW WIND TURBINE BLADES BY VARI

TANG Yang-ge, ZHOU Hong-li, WANG Hong, LIU Jin-rong

2013, 0(9):  30-34. 

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The runner design of 1.5MW wind turbine blades made by vacuum-assisted resin infusion (VARI) was analyzed. The filling time in different injection ways and space of injection runners were investigated simultaneously. The resin flow form, the pressure in the mould and the location of venting gates were also analyzed. The best injection scheme has been optimized at last. On that basis, the optimal injection position of simulation for mold filling machine forming was decorating two runners in the root and the space was 487 mm, arranged 3 injection runners along the direction of blade length and the best numbers of injection gates and vent gates were 13 and 14 respectively. When used the simulated results for actual blade molding process, it indicated that the practical filling time was 3.63h, which had 0.38h time different compared with simulated results.

STUDY ON DOMESTIC CARBON FIBER AND EPOXY RESIN FOR RESIN TRANSFER MOLDING

SUN Chao-ming, ZHANG Cui-miao, TAN Juan-juan, YANG Kai

2013, 0(9):  35-38. 

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The rheological properties and curing properties of the domestic epoxy resin were studied through the rheometer and differential scanning calorimetric apparatus. The injection process window was determined and the comprehensive performance was charactered through mechanics performance analysis. The microstructure of the domestic carbon fiber monofilament was charactered by SEM and the contact angle of the carbon fiber and epoxy was studied by the surface tension tester. Comparing with the overseas import carbon fiber and epoxy, the paper found the difference in performance of the RTM process.

BENDING PROPERTIES OF THREE-DIMENSIONAL FULL FIVE-DIRECTIONAL BRAIDED COMPOSITES

CAO Hai-jian, WANG Yi-jie, LIU Fei, LU Xue-feng

2013, 0(9):  39-42. 

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High strength alkali-free glass fibers were used as raw materials in the paper, and three-dimensional five-direction and full five-directional braided fabrics were both prepared on full-automatic modular braided machine by using braided craft of four-step rule 1×1. Three-dimensional five-direction and full five-directional braided composites were prepared by combined braided fabrics with resin matrix, which including epoxy resin E51 and firming agent 70# (tetralin phthalic anhydride). Bending properties of above braided composites were tested by using Instron universal testing machine, and influence of structure parameters, like axis yarns, braided angles and fiber volume fraction, on compressive properties was studied too. The results show that bending properties increased with the increase of axis yarns and fiber volume fraction, and decreased with the increase of braided angles. Bending property of three-dimensional full five-directional composites were better than that of three-dimensional five-directional ones.

CARBON FIBER REINFORCED CARBON AEROGELS PREPARED BY AMBIENT PRESSURE DRYING

TAN Juan-juan, SUN Chao-ming, YANG Li-ping, CHEN Feng

2013, 0(9):  43-47. 

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Carbon aerogels (CRFs) and carbon fiber spiked felt reinforced carbon aerogels (CF/CRFs) were successfully prepared by ambient pressure drying instead of supercritical drying based on conventional methods. The internal microstructure of them was characterized by SEM and BET. The CRFspossessed typical three-dimensional continuous network. The amount of catalyst controlled the size of the framework particles and the pore diameters. The carbon fiber and CRFsachieved a fine complex, and the CRFsadhered to the carbon fiber still kept nano-network structure. Whereas, the fiber obviously affected the size of the inner framework particles and pore diameter, while the flexural and compressive properties were greatly enhanced owning to the reinforcement of carbon fiber spiked felt characterized by the mechanical analysis.

STUDY ON SIMULATION TEST RIG OF TOWER OF COMPOSITE MATERIAL

HUANG He, DING Qing-qiang, LI Xue

2013, 0(9):  48-51. 

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The design and evaluation of logging instrument performance and new instruments depend on experiment. The composite simulation test rig of tower cleverly simulated anisotropic on the rock and thin interbed macroscopic uniaxial anisotropy, provides an ideal experimental platform for the research and development of various new type induction well logging instrument.

STUDY OF CARBON FIBER PREPREG MULTI-TOW WINDING SYSTEM

ZOU Cai-yong, YANG Tao, GE Bang

2013, 0(9):  52-54. 

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The process of carbon fiber prepreg multi-tow winding machine was studied. The tension adjustment link based on friction, winding and unwinding link and synchronous motion link had been researched respectively, which have a great influence on the tension in winding process. On this basis, the system control strategy was gain, while the PID tension control system and synchronous motion system with tracking performance were established. Software system and hardware system of the winding machine were implemented. The results show that winding tension reached ±1N and winding accuracy reached ±0.1mm. A strategy using RS-485 bus on the combination of touch screen and remote controlling was provided.

THE RESEARCH OF LARGE CROSS-SECTION FRP PULTRUSION PROFILES STRUCTURAL DESIGN AND TYPE TESTING IN BRIDGE

ZHANG Wei-jun, TIAN Ye, QIN Zhao-ping, FENG Peng

2013, 0(9):  55-60. 

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Because of its advantages of structure designability, light weight, high strength, corrosion resistance and excellent processing property, the FRP material shows broad application prospect in bridge engineering. Though the research of the structural design for a large cross-section FRP pultrusion profiles, combined with the large crosssection FRP pultrusion profiles of the raw materials selection, layer design, forming process parameters and the postprocessing of adhesive process are discussed, the mechanical properties of the same furnace sample material were tested, the feasibility of using large cross-section FRP pultrusion profiles as bridge panel was verifred.