COMPOSITES SCIENCE AND ENGINEERING

RESEARCH ON CARBON FIBER COMPOSITE HIGH SPEED FLYWHEEL ROTOR IN LARGE TENSION WINDING

HUI Peng, ZU Lei, LI Shu-xin, WANG Yang

2018, 0(3): 5-12.

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The carbon fiber composite has been widely applied to manufacture high speed flywheel rotor sheath for its high specific strength, specific stiffness, and absence of high frequency eddy current power loss. Moreover, compared with the press-fitted process, the large tension winding process is more suitable for applying the interference fit between the carbon fiber composite sheath and the metal hub. In this paper, the design and forming process of the large tension winding composite sheath of the flywheel rotor was discussed. A three-dimensional finite element model of composite flywheel rotor has been built. The filament winding tension was applied by using temperature difference method. And the winding and curing processes were simulated by the element deletion method. The influence of the winding tension and the interference between the hub and the shaft on the compressive stress at the interface of the rotor was analyzed at the speed of 30000 RPM and the different operating temperature. In addition, the specimens of composite sheath of high speed flywheel rotor were prepared by the large tension winding technology. The radial compressive stress of the sheath on hub and the radial strain of the hub were tested. The results show that the calculated values were in agreement with the measured values of specimens. The optimum geometry and technological parameters of the composite flywheel rotor were obtained. The maximum energy storage density was 44.5 Wh/kg, while the peripheral speed was 697 m/s. The results of this paper are of important significance to the design and manufacture of composite high speed flywheel rotor sheath.

SIMULATION TECHNOLOGY AND HOLE PARAMETERS OPTIMIZATION OF PERFORATED SQUARE CFRP TUBES

LIU Qiang, HE Zhao-heng, XU Xi-yu, CHEN Rui-xiang

2018, 0(3): 13-18.

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This paper aims to optimize the mechanical properties of perforated square CFRP tubes by finite element analysis. The failure mode, which cannot be observed in the experiment exactly, is analyzed by microscopic process. Mixed mesh for perforated tube, which considered as the best partitioning method, got a better computational efficiency and computational accuracy compared to free mesh and radial mesh. A response surface model of two objective functions and hole parameter was built and it is found that the radius of hole has the largest effect on the two responses. Finally, an optimum solution was obtained by multi-objective optimization, where the three design variables, the radius of the hole, height of the hole and the translation of the hole in cross range, are 8.98 mm, 0.80 and 0.43, respectively. And the improvement of 69.5% in SEA and a few sacrifices of 3.6% in peak load are achieved. The simulation model and optimization method in this paper are of guiding significance for designing CFRP perforated structured.

ANALYZING THE STIFFNESS DEGRADATION OF CFRP-PCPS COMPOSITE REINFORCED CONCRETE BEAM UNDER LOW REVERSED CYCLIC LOADING

DENG Yu, GAN De-li, ZHANG Peng, YANG Xi-tao

2018, 0(3): 19-25.

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In this paper, the low cyclic pseudo static test of 6 concrete beams is carried out. By using an ordinary reinforced concrete beam and a common prestressed concrete beam with CFRP reinforcement as the reference, the stiffness and damage degradation of 4 CFRP-PCPs composite beams with different tension control stresses and different sectional sizes are studied. The experimental results show that the CFRP-PCPs composite bars can effectively restrain the stiffness degradation of the structures. Based on the experimental results, the stiffness degradation of the specimens at the crack point, the yield point and the limit point are analyzed. Stiffness degradation calculation method of characteristic points of each specimen is presented. The calculated results are in good agreement with the experimental results. It will provide some reference value for predicting the development of deformation during the use of the structure.

DESIGN AND OPTIMIZATION OF COMPOSITE UAV LANDING GEAR SKIDS

HU Song, ZU Lei, LI Shu-xin, LIU Meng

2018, 0(3): 26-32.

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This paper established finite element model of landing gear skids according to the approximate requirement of a certain Mini-UAV (unmanned aerial vehicle). The airframe was simplified as a mass point. Then, by conducting the dynamic simulation of UAV landing process, from which a series of simulation results such as the attenuated trend of UAV′s velocity, the acceleration of UAV could be calculated. For the sake of lowering the acceleration of UAV whthin a safety range, the sectional dimension of arched beams and filament winding angles were required to optimizate to meet the demands. Then, by using Tsai-Wu failure criterion to check the strength of arched beams, an appropriate arched beams structure and optimal filament winding angles were designed and obtained, which minimize the value of acceleration of UAV without structure failure. Besides, we attempte to use different kinds of fiber composites to further improve the vibration resistance of landing gear skids. Simulation results indicate that reasonable sectional dimension of arched beams could improve vibration resistance of landing gear skids. The optimal filament winding angles were(45°/-45°/90°/-90°/45°/-45°)which lowered Tsai-Wu failure indice. Meanwhile, the landing gear skids made of aramid fiber composites possessed greater vibration resistance than that made of by carbon fiber composites. The research results had a vital directive meanling on the design and manufacture of UAV landing gear skids.

STUDY ON RHEOLOGICAL PROPERTIES AND CURING PERFORMANCE OF PES/EPOXY RESIN MIXTURE SYSTEM

JIANG Min-qiang, CHENG Chao, ZHANG Hui,YU Mu-huo

2018, 0(3): 33-37.

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Epoxy resin is a kind of thermosetting resin with good properties. However, it has the inherent weakness of poor shock resistance. Polyethersulfone (PES) is a kind of thermoplastic resin with good properties which can improve the toughness of epoxy resin by blending with epoxy resin. The rheological properties and curing performance of PES/epoxy resin mixture system with different PES content were studied systematically in this paper. A viscosity model was established according to the obtained rheological data of isothermal viscosity curves, and the mechanism of the effect of PES on the curing of PES/epoxy resin mixture system was analyzed. The influence of PES on the curing performance of PES/epoxy resin mixture system was also studied by DSC test. The results show that the dissolution of PES in epoxy resin could lead to the fluctuation of viscosity of the mixture system. The introduction of PES shortened the gel time of PES/epoxy resin mixture system, and the hydroxyl groups in PES promoted the curing of the epoxy resin.

EFFECT OF FIBER CLUSTERING EFFECT ON THE TENSILE PROPERTIES OF FIBER REINFORCED CONCRETE

HE Jing-jing, SHI Jun-ping, WANG Wei, ZOU Hao-fei

2018, 0(3): 38-44.

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The fiber sharing coefficient is introduced to characterize the fiber clustering effect in concrete. Meanwhile, six kinds of fiber cluster model are established. According to mechanics theory of composite materials, the influence of fiber clustering effect on the tensile properties of fiber reinforced concrete (FRC) is analyzed. The results show that fiber share coefficient is decreased with the increase of fiber number of fiber agglomerates. The existence of fiber clustering effect leads to the increase of the fiber critical volume fraction to a certain degree and the decrease of the tensile strength of FRC in different degrees. The loss of FRC tensile strength by and critical volume fraction are increased with the increase of fiber cluster content. The calculated values of FRC tensile strength by considering fiber clustering effect are close to the experimental results.

STUDY ON INTERFACE COMPATIBILITY OF HIGH-PERFORMANCE FIBER AND EPOXY RESIN BASED ON TEST OF NOL RINGS

LAN Zong-jin, ZU Lei, HUI Peng, HU Lan-xin

2018, 0(3): 45-51.

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The interface of fiber and resin exerts an outstanding influence on the entire mechanical properties of composite. Macromechanics test based on NOL rings is commonly used to reflect interfacial adhesion property of composite, so it applies to evaluate macromechanical compatibility of fiber and resin. The experiment is conducted to probe into macromechanical compatibility of high-performance fibers, such as T700SC, T800HB and high-strength glass fiber, and epoxy resins. The specimens of NOL rings were firstly prepared referrings to national standards GB/T 1458—2008. Then, we analyzed the causes of differences on macromechanical properties of matching combinations of high-performance fibers and epoxy resins by combinations of tensile and interlaminar shear test of NOL rings with observation of its fracture surface by SEM. And the optimal matching combinations were found out. The results suggest that interfacial properties of glass fiber and epoxy resin is superior to that of epoxy with carbon fiber, and the former posseses optimal interfacial adhesion strength, and different adhesion strength leads to different mechanical properties and modes of damages. But poor interface of carbon composite easily arises delamination, which restricts the use of carbon fiber. Macromechanical compatibility of T800HB and epoxy resin is superior to that of T700SC and epoxy, and mechanical proprerties of composites and that of resin matrix are directly related. The properties of resin, surfacial structure and character of fiber and interaction between carbon fiber and resin are the ultimate cause of affecting interfacial properties. The paper plays practical significance in selection and design of materials of composite reinforced by high-performance fibers.

EFFECT OF END ENHANCEMENT ON MECHANICAL PROPERTIES OF CFRP TUBES

ZHAO Zhi-bo, LI Feng, TAO Jie

2018, 0(3): 52-57.

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The CFRP (carbon fiber reinforced polymer) tube is used to control the axial load bearing capacity of the CFRP (carbon fiber reinforced polymer) pipe, and the CFRP laminates are reinforced with the metal reinforcing hoop-metal end cap and the carbon fiber-metal lining reinforcement. The stress test and the failure form of the specimen are obtained by axial compression test. Based on the Hashin failure criterion, the finite element model was used to analyze the failure mode and bearing capacity of the CFRP pipe under the two end enhancement modes, and the enhancement mechanism was explained. The results show that the end enhancement can change the failure mode of the specimen and increase the bearing capacity compared with the specimen with no end reinforcement. When the end is strengthened, the external reinforcement stiffness should not be too large, and the reinforcement and the specimen are larger. The difference in stiffness will lead to inconsistent deformation, easy to occur at the edge of the enhanced edge of the shear damage. The use of carbon fiber-metal as the enhanced way of the end can effectively prevent the end of the "flowering" damage and shear damage. The overall bearing damage and axial load capacity increased by 46.37%.

STUDY ON THE MODIFICATION OF DIALLYL BISPHENOL A TO CYANATE ESTER RESIN WITH LOW VISCOSITY

JIANG Pei-qi, XIAO Jun, LI Jin-huan, HAN Xiao-yan

2018, 0(3): 58-62.

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The modification of dially lbisphenol A (DBA) to low viscosity cyanate ester resin was investigated by the test of viscosity-temperature characteristics, differential scanning calorimetry, mechanical test, thermal gravimetric analysis, dynamic thermomechanical analysis, water absorption and dielectric performance. The results show that the viscosity of CE modified by DBA slightly increased, but it still satisfied the viscosity requirement for hot melt method. DBA can catalyze the curing reaction of CE and increase the conversion ratio. DBA of appropriate amount can toughen the cured resin, the impact strength and flexural toughness of the resin with 10% DBA were 179% and 165% times higher than those of the unmodified resin, respectively. The heat resistance, moisture resistance and dielectric property of CE modified by DBA all decreased slightly compared with the unmodified, but still met the application requirements. It is concluded that the optimum addition of DBA is 5%~10%.

TENSILE PROPERTIES OF TWO-DIMENSIONAL TWO-AXIAL UNIDIRECTIONAL BRAIDED COMPOSITE

SHI Li, YANG Yu-qiu, YAN Jian-hua

2018, 0(3): 63-67.

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A new braided structure named two-dimensional two-axial unidirectional braided structure was proposed in this paper. Different specimens were prepared to study the influence of different braided angle and fiber volume fraction on its tensile properties. Further investigation was made to study how cracks stretch in this composite under tensile loading process. Experimental results reveal that tensile strength of this composite increases with the increase of fiber volume fraction, but small changes of braided angle has little influence on tensile properties of two-dimensional two-axial unidirectional braided composites. With the influence of braided structure, there are two kinds of cracks, in-layer cracks which stretch along the thickness direction of specimens and interlayer cracks which extend along layers’ contact surface. In general, cracks are showing the extending trend from upper or lower layers to the center layer.The study in this paper gives guiding significance for the design and application of this kind of structural material.

DEFORMATION CHARACTERISTIC ANALYSIS OF THE CULVERT OF DOUBLE FRPM PIPES AT INDOOR TEST

WANG Qing-zhou, WANG Yang, WEI Lian-yu, CHEN Zhao-nan

2018, 0(3): 68-73.

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The Large diameter of FRPM pipe is limited due to the problems such as pipe production, transportation and the elevation of highway culvert. In order to explore the feasibility of using small diameter double pipes instead of large diameter FRPM pipe, the physical and mechanical characteristics and change rules of the double pipes under the condition of single pipe under load are analyzed by indoor simulation test. The experimental results show that there is an interaction between the deformation of the double pipes under the condition of loading single pipe, and the deformation of the pipes is imbalance. And, the weak area of the double pipes appears in the roof of loading pipe and the adjacent position of the double pipes. The result can be used as the safety control points and the actual engineering design basis of double pipes.

STUDY ON CURING PROPERTIES OF NON-EXCAVATED OIL TANK LINING BY UV CURING

LIU Shi-qiang, MAO Ling-feng, QIAN Jian-hua,LIU Hua

2018, 0(3): 74-79.

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Non-excavatedoil tank lining by UV curing is a molding process which was used for reforming in-service tank of gas station. Fiber reinforced plastics (FRP) properties were tested, including curing degree, bending strength, hardness and curing time. The results show that curing properties were influenced by photoinitiator (PI), UV power, layer structure, temperature and humidity, UV curing system is more efficient than cobalt/MEKP system. Both C190 and C191 are suitable for this process. With PI dosage, of 5‰, FRP curing depth is up to 12 mm, forming 3 mm FRP in 3 minutes, and curing efficiency can be improved more than ten times, curing degree can be increased 8%, bending strength can be increased by 20%~30%. MERICAN 9505-50 can be used for UV curing technology resin of non-excavatedoil tank lining.

STUDY ON PYROLYSIS AND KINETICS OF POLYBOROSILOXANE RESIN

SONG Jin-mei, WANG Lei, LI Yan-bin, YAO Ya-lin

2018, 0(3): 80-85.

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The pyrolysis characteristic of polyborosiloxane resin has been investigated by means of thermogravimetric analysis and pyrolysis-GCMS analysis. Models of the pyrolysis kinetics were derived using the coats-redfern integral method. The results show that the pyrolysis reactions of phenolic resin have two types: reaction of chain breaking (＜250 ℃ in the low temperature region), reaction of desilicon methylation (250 ℃ to 650 ℃ in the high temperature region) and stable phase (650 ℃ to 800 ℃), Through analysis of component and content of gas and solid during pyrolysis of polyborosiloxane resin, the possible reaction occurring in the is derived. The pyrolysis of borosiloxane resin pyrolysis of polyborosiloxane resin can be described by two thirds-order kinetics equations in main pyrolysis temperature regions. Active energy and pre-exponential factor increased and then decreased with increasing of heating rates.

EFFECT OF SALT SPRAYON MECHANICAL PROPERTIES OF GLASS FIBER-ALUMINUM LAMINATE

CUI Hai-chao, XIONG Lei, MA Hong-yi, ZHAI Quan-sheng

2018, 0(3): 86-90.

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The mechanism of salt spray aging of glass fiber-aluminum laminate was investigated by analyzing their mechanical properties and IR spectra. Under the condition of accelerating the salt spray aging, the inner matrix of the composite material was degraded, and the resin-fiber interface and the surface of the aluminum alloy corrosion damage occurred. With the extension of aging time, the tensile, compression and in-plane shear strength of 0 ° and 90 ° laminates showed a significant decreasing trend,while the laminate interface of 90°specimen suffered more serious damage. The degree of cross-linking of the thermosetting resin matrix inside the composite layer was reduced. Also, the resin-fiber and resin-aluminum interfaces were destroyed, consequently affecting the material internal stress transmission and the mechanical properties.

APPLICATION OF POLYTETRAFLUOROETHYLENE/GLASS FIBER TAPE IN MANUFACTURE OF WIND POWER BLADE

GUAN Xiao-fang, JIA Zhi-yuan,GUO Li-juan

2018, 0(3): 91-95.

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The effect of polytetrafluoroethylene/glass fiber tape as a release medium on the surface of FRP and its influence on the manufacturing cost of wind power blades was studied. In this paper, surface performance of glass fiber reinforced plastic (FRP) obtained from the four methods of polytetrafluoroethylene/glass fiber tape, nylon stripping cloth, smooth and sandpaper grinding were compared with the three aspects of contact angle, tensile shear performance and adhesion to different coatings. The results show that the FBP obtained from polytetrafluoroethylene/glass fiber tapes has ordinary surface wettability. FRP using polytetrafluoroethylene/glass fiber stripping mold can achieve comparable shear performanle with that by the use of stripping cloth. Fiberglass/fiber glass tape obtained from FRP surface coating adhesion flat with other ways. Economic analysis shows that the application of domestic polytetrafluoroethylene/glass fiber tape in the mold is expected to reduce the manufacturing cost of wind power blades.

RESEARCH OF SILICA AEROGEL/POLYURETHANE HEAT INSULATION MATERIAL

TIAN Jun, YE Dan-dan, LUO Mei-jie

2018, 0(3): 96-100.

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The study of ship′s thermal insulation materials has gained extensive attention during the design and construction of ships. The high performance insulation materials can improve the ship′s living environment, and improve the safety and service life of the ship. In order to obtain high performance insulation materials, in this paper, by using polyurethane (PU) as matrix, silica aerogel (SA) as filler, thermal insulation materials was prepared by blending, The properties of the PU insulation materials were characterized by thermal conductivity test, vertical combustion testand other methods. The best prescription of silica aerogel/polyurethane thermal insulation material is 2 g SA-A1/100 g PU insulation materialsby electric blending. The thermal conductivity of the insulation material was 0.091 W/(m·K), and the tensile strength was 3.6 MPa.

RESEARCH STATUS AND DEVELOPMENT TREND OF CFRP DRILLING TECHNOLOGY

LIU Xue-mei, SUN Hui-lai, HE Long-yu , ZHAO Fang-fang

2018, 0(3): 101-106.

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Due to its high specific modulus and strength, carbon fiber composite (CFRP) has attracted more and more attention in the fields of science and industry, and has been widely used in the field of aerospace. Drilling plays an important role in aviation manufacturing industry. However, because of the anisotropy of CFRP, its quality of drilling is more difficult to control .This paper introduces several typical defects of CFRP drilling process, and points out that the reasons causing the defects and the suppression method. The latest progress of CFRP drilling technology is introduced in this paper, including drilling tools, drilling three aspects of cutting motion and special processing drilling. Besides, drilling technology development trend of CFRP is reviewed.

RESEARCH PROGRESS IN BORON MODIFIED PHENOLIC RESIN AND ITS COMPOSITES

ZHANG Li, ZHANG Yi-he, YAO Ya-lin, TIAN Mou-feng

2018, 0(3): 107-116.

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As one of the most successful modified phenolic resin, boron modified phenolic resin has excellent heat-resistance, ablative resistance, good mechanical, wear resistance and flame retardancy. Boron modified phenolic resin and its composites can be widely used in areas such as aerospace, weapons and equipment, automobile brake and fire retardant. In this review, the current development of boron modified phenolic resin and its composites are presented and discussed. After introducing various methods to synthesize boron modified phenolic resin, functionalization of boron modified phenolic resin is briefly summarized. Particular emphasis is placed on general methods used to fabricate boron modified phenolic resin based composites and heat-resistance, ablative resistance, mechanical property, wear resistance, flame retardancy and water resistance of boron modified phenolic resin based composites. At last, the challenge of this research area was summarized and its future outlook was prospected.

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