Table of Content

28 October 2013, Volume 0 Issue 7

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A NEW NODE CONNECTION OF COMPOSITE MATERIAL LATTICE STRUCTURE

XU Long-xing, ZHAO Qi-lin, CHEN Hao-sen, AI Shi-gang

2013, 0(7):  3-6. 

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There are many node connections of composite material lattice structure, such as mechanical connection, beset in the groove, glue together and molding in one time. And there are many problems generally happened in these connections, the faceplate is easily divided, core members elastic bucking, faceplate is damaged and the strength of glue which needed is dissatisfactory. In order o solve these problems, this paper brings out a new technique connection which called self-balance connection, this connection has many advantages. And the new connection was used in the composite material lattice structure, compared with the lattice structure with traditional node connection, the paper made two specimens and died load tests were conducted. Experimental results show that the lattice structure with the new node connection have characters of high specific stiffness and high specific strength, and the strength of node is high. It solved the problem that the node is weak in lattice structure, and have good potential applications.

RHEOLOGY ANALYSIS OF EPOXY RESIN SYSTEM USED FOR VACUUM INFUSION MOLDING OF CARBON FIBER

JIA Zhi-yuan, SONG Qiu-xiang, WANG Hai-zhen, CHEN Chun

2013, 0(7):  7-10. 

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The rheological behavior of epoxy resin system for vacuum infusion molding of carbon fiber was studied. A viscosity model was established through simulating the obtained rheological data of the epoxy resin system by means of experiments. Compared with the normal epoxy system for glass fiber, this epoxy system has a significantly increased pot life. The predicted viscosity values of the established model are in good agreement with the experimental ones. According to the prediction of the rheological model of the epoxy resin, the optimal temperature for vacuum infusion molding of carbon fiber was in the range of 50 to 70 degrees. The study is important for the vacuum infusion molding of carbon fiber thick parts.

DAMPING PERFORMANCE OF HINDERED PHENOL MODIFIED PU/P(MMA-St) IPN

ZHOU Meng, FANG Zhou, ZHONG Jian-feng, DONG Qing-zhi

2013, 0(7):  11-14. 

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Hindered phenol AO-80-modified polyester/polyether amine type polyurethane/poly(methyl methacrylate- styrene) interpenetrating polymer networks (PU/P(MMA-St) IPN) was prepared by one-step way. Through the thermo-gravimetric analyzer, dynamic mechanics analysis and scanning electron microscope to IPN material, the thermal stability, damping performance and microstructure morphology of this material were characterized. The results of the study show that, AO-80 can improve the compatibility of the PU and P (MMA-St), thus effectively broaden the damping temperature range. When polyester/polyether amine is 80/20, w (AO-80) is 20 phr, PU/P (MMA-St) is 70/30, the damping properties of the IPN material is best.

STUDY ON PROPERTIES OF QUARTZ FIBER REINFORCED POLYTRIAZOLE RESIN COMPOSITES

ZHOU Hao, LI Yu-jing, WAN Li-qiang, E Yan-peng

2013, 0(7):  15-18. 

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Curing behavior, thermal properties, dielectric properties and mechanical properties of quartz fiber reinforced polytriazole resin composites were investigated in this paper. The composites can be cured at 80℃, and Tg of one of the composites reaches 230℃ after the post-processing of 120℃/2h+150℃/2h+180℃/2h+200℃/2h+ 250℃/2h. Dielectric constant of this composite is 3. 8. Mechanical properties of the composites increase by the post-processing temperature. Flexural strength arrives at 795MPa after the post-processing at 250℃, which retention rate at 180℃ is 59%. Interlaminar shear strength is 61MPa at ambient temperature.

STRENGTH ANALYSIS OF CARBON FIBER LAMINATES WITH PRE-EMBEDDED METAL PART UNDER MORMAL LOAD

LIU Feng, ZHANG Zhong-bo, ZHANG Cheng-lei

2013, 0(7):  19-23. 

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The analysis models of carbon fiber reinforced epoxy laminates with cylindrical and step shape preembedded metal part are built based on the application of embedded metal part in composite laminates. The single layer in the laminates is assumed as three dimensional orthotropic material. The stress analysis of the laminates with embedded metal part which is simply supported is carried out by finite element method. The distributions of material principal direction stresses of the damaged single layers and the von mises stress of metal parts are given. The ultimate loads of the composite laminates are determined based on the strength criterion of maximum stress. It is shown that the initial damage of the laminates with cylindrical shape pre-embedded metal part occurs at about two o'clock location near the central hole border in the 45° layer, and the damage mode is matrix crack under shearing. The initial damage of the laminates with step shape pre-embedded metal part occurs at about ten o'clock location near the central hole border in –45° layer. Under normal loading, the ultimate load of the laminates increases by 40. 36% when the cylindrical metal part is replaced by the step metal part, which is due to the increase of the force transfer area and bigger percentage of fibers under desirable tension state.

EXPERIMENTAL MEASUREMENT AND ANALYSIS OF TENSILE PERFORMANCE OF SHCC IN DIFFERENT AGES

HU Chun-hong, GAO Yan-e, WANG Xiao-cheng

2013, 0(7):  24-27. 

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Direct tensile test is feasible to reflect the strain-hardening and multiple micro cracking characteristics of SHCC, it is also the only feasible method to get stress-strain curve of material on uniaxial tensile load. The stress-strain full curves of SHCC at different ages was obtained on the basis of direct tensile test in this paper, and crack development of different specimens was observed in the course of the experiments with three specimens each group. The results show that obvious strain hardening characteristics appears in all specimens, and the ultimate tensile strain can all reach or even exceed 3%, the crack spacing of specimens are various at different ages, the cracking characteristics have differences. With the increase of age, the tensile strength increases and the toughness decreases. The results obtained in this paper can provide theoretical guidance for the popularization and application of SHCC in the practical engineering.

EXPERIMENTAL INVESTIGATION OF DAMAGED COMPOSITE LAMINATES REPAIRED WITH BONDED GFRP OR CFRP PATCHES

QIU Qiu-yuan, FAN Hai-rong, WANG Yue-ran

2013, 0(7):  28-31. 

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The damaged composite laminates were repaired by the composite patching technology in this paper. Effects of some important parameters of the technology, including reinforcements, patch design, cured temperature, on the specimen static mechanic properties have been comprehensively investigated experimentally. And the experimental data results indicate that static mechanic properties of the bonded structures are significantly improved. The failure strength of the bonded structures could reach up to 66.69% of the perfect composite structures', while its static stiffness is almost as the same as the perfect ones. However, the whole curing-time of the repair process is limited to 1 hour and the cured temperature is limited to 66℃.

EFFECT OF ANTIFRICTION FILLER ZrSiO₄ and Al₂O₃ ON FRICTION AND WEAR BEHAVIOR OF BRAKE FRICTION MATERIAL

ZHANG Bao-yu, YAO Guan-xin

2013, 0(7):  32-36. 

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The fiber reinforced organic friction materials are prepared by the way of thermoforming. In order to check the role of antifriction filler ZrSiO₄ and Al₂O₃ in organic friction material, friction and wear performance are tested using MM3000 inertial frame friction and wear tester. The surface morphology of the prepared friction materials was analyzed by scanning electron microscope (SEM). It turns out that antifriction fillers have the significant role in increasing friction coefficient; the hard particles could fill the pits and holes on the surface of the friction material, on which a stable surface film formed, they can also make the surface film fall off from the material surface regularly by stress rupture, which has self-cleaning capacity. The wear mechanism of friction material is abrasive wear and fatigue abrasion, accompanying with thermal abrasion.

ACCELERATING AGING BEHAVIOR OF MODIFIED THERMOSET BUTADIENE-STYRENE COMPOSITE IN SYNTHETIC SEAWATER

YUAN Ming-yue, ZHOU Quan, NI Li-zhong

2013, 0(7):  37-41. 

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Modified thermoset butadiene-styrene (GPSB) composite was accelerating aging tested in artificial seawater. The hygroscopic properties and mechanism of GPSB composite was studied. The changes of chemical structures of GPSB composite before and after test were characterized by FTIR. The changes of static and dynamic mechanical properties were analyzed by electronic universal testing machine and DMA. The results showed that the bending strength's and interlaminar shear strength's retention rates were 66.6% and 55.3% after aging 50 days in artificial seawater, and the storage modulus was significantly reduced. The dielectric property test showed that the change of dielectric properties was tiny after aging. The interface bonding performance was investigated by SEM before and after aging. The results showed that GPSB composite corrosion aging occured mainly in the interface of resin and glass fiber.

DESIGN OF A KA-BAND RADOME

ZHANG Jia-lin, LIN Zhou-jin

2013, 0(7):  42-46. 

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Design and production of Ka-band antenna masks with high size accuracy and high wave transmissivity is crucial to the antenna protection and transmission loss reduction. This paper describes the development process of a Ka-band antenna mask. Through analysis of the basic properties for the antenna mask materials, a preliminary antenna mask structure is derived. By using the ANSYS software, structure analysis of the designed Ka-band antenna mask is made, meanwhile, the development process is simply described. The performance of Ka-band antenna mask manufactured according to the design fulfills the requirements of the user's technology indices.

STUDY PROGRESS OF FATIGUE BEHAVIORS OF CONCRETE BEAMS WITH REINFORCING BARS

DONG Su-ran, YANG Yong-xin, GUAN Zeng-wei

2013, 0(7):  47-52. 

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To summarize the fatigue performance, failure criteria, damage model of concrete, steel bars and FRP tendons in the domestic and foreign countries, the paper discusses the fatigue stress process, failure pattern, stiffness degradation, and deflection growth rule of the beam composed with those materials above, analysises the fatigue performance characteristics of FRP reinforcement instead of reinforced concrete beam, and shows the development space and research value of fatigue property of concrete beam with reinforcing tendons.

RESEARCH PROGRESS OF CONTINUOUS FIBER REINFORCED THERMOPLASTIC PREPREGS

TIAN Zhen-sheng, LIU Da-wei, LI Gang, YANG Xiao-ping

2013, 0(7):  53-58. 

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The development and application of continuous fiber reinforced thermoplastic prepregs were reviewed. The reinforcing fiber and resin matrix used in thermoplastic prepreg preparation were listed, and the progresses of foreign commercial thermoplastic prepregs were summarized. The advantages and shortcomings of preparation method of thermoplastic prepregs were discussed, and the difficulties of melt impregnation technique were stated in detail, which indicated that the combination of melt impregnation and film stacking was the optional molding technique for the fabrication of thermoplastic prepregs.