COMPOSITES SCIENCE AND ENGINEERING

MECHANICAL PROPERTY ANALYSIS OF FILAMENT-WOUND SANDWICH COMPOSITE CYLINDER UNDER AXIAL COMPRESSION

CHEN Yue, ZHU Xi, LI Hua-dong, ZHU Zi-xu

2016, 0(7): 5-8.

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In order to study the mechanical property of filament-wound sandwich composite cylinder, the axial compression test of sandwich composite cylinder was carried out, and the load-displacement curve and the strain regularity were obtained. Then, based on the classical laminated plate theory, the skins of the sandwich composite cylinder were homogenized and equivalented of unidirectional fiber reinforced composite materials. An effective simulation method was established using ABAQUS software to obtain the load-displacement curve and strain distribution rule. Finally, the simulated and experimental results of load-displacement curve and strain were compared. Results show that the calculated results fit well with the experimental results, the axial stiffness error is 10.69%, and the maximum error of strain is 12.88%, which verified the reliability of the FEM method, providing the foundation for optimal design of composite sandwich cylinders.

ACOUSTIC EMISSION MONITORING FOR DAMAGE EVOLUTION OF COMPOSITE BONDING REPAIR INTERFACE

CHEN Wei-ye, HU Jie, LIU Guang-hui, ZHOU Wei

2016, 0(7): 9-13.

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Acoustic emission (AE) testing technology was used to monitor the process of damage evolution of glass fiber reinforced composite specimens with fiber breakage after repaired under four-point bending tests in real time. According to the statistical analysis method of acoustic emission signal, the influences of patch size on the repair effects were investigated. The results show that the failure modes of two kinds of patch specimens are mainly the patch interfacial cracking under bend loading. As the bonding repair area increases, the failure load of specimens increases. Compared with the specimen without defect, double failure load of repaired specimen was obtained when the length of patch is 90 mm. The damage and failure process of adhesive bonded repair specimen shows a good correlation with the corresponding acoustic emission characteristics, and the method of statistical description of acoustic emission signals could be effectively used to evaluate the micro-damage evolution behavior of adhesive bonded composite specimens.

ANALYSIS OF THICKNESS PREDICTION METHOD OF FILAMENT WOUND PRESSURE VESSEL HEAD

XU Jia-zhong, ZHANG Dian-xin, LUAN Sheng-gang, YUAN Ya-nan

2016, 0(7): 14-19.

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For establishing an accurate model for the structure of filament wound pressure vessel, this paper adopt a polynomial approximation algorithm to predict the fiber layer thickness of pressure vessel head on the basis of previous fiber layer thickness prediction method. According to the influencing factors of the changing of fiber winding angle of head part and yarn accumulation near the polar periphery, this paper adopt the polynomial approximation algorithm to predict the fiber layer thickness. Compared with classical method, exact solution, flat solution and actual thickness, it shows that the fiber layer thickness prediction by the method is close to the actual thickness, providing an accurate pressure vessel structure model for the further analysis of the reliability of the pressure vessel.

STUDY ON PERMEABILITY PREDICTING FORMULA OF FIBER BUNDLES AND NON-CRIMPED FABRICS

KANG Ning, LIANG Xuan-yong

2016, 0(7): 20-25.

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The results of CFD (Computational Fluid Dynamics) was applied to modify the Gebart formula to predict the permeability of fiber bundles. The relationship between permeability and structure parameters of non-crimp fabrics (NCF) was inverstigated and the permeability predicting formula of NCF was obtained. The numerical and modified formula′s results of flow parallel to fiber bundles were closer to the experimental results than the Gebart formula′s results, especially at high porosity. The error between the numerical and experimental results of the NCF unit cell is 5%. Orthogonal experimentals were carried out on NCF composed of fiber bundles with 5 different porosities. The permeability predicting formula of NCF was fitted on the basis of the numerical results of orthogonal tests. The average errors between the numerical and predicting formula′s results were 4.60% for quadratic arrangement and 4.57% for hexagonal arrangement, which verified the accuracy of the permeability predicting formula.

THE DEFLECTION TEST STUDY OF THE REINFORCED RECYCLED CONCRETE BEAMS WITH BFRP BARS

WU Qing-feng, LIU Hua-xin

2016, 0(7): 26-31.

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The variation deflection of the reinforced recycled concrete beams with BFRP bars and the reinforced recycled concrete beams with steel bars are compared and analyzed, by making and crushing 4 reinforced recycled concrete beams with BFRP bars and 4 reinforced recycled concrete beams with steel bars. The experiment results indicate that the deflection of the reinforced recycled concrete beams with BFRP bars is larger than that of the reinforced recycled concrete beams with steel bars, and its ductility is worse than the ductility of the reinforced recycled concrete beams with steel bars. With the increase of the section height and the stirrup reinforcement ratio, the deflections of the members are decreasing. The deflection calculation values of the code for design of concrete structures are consistent with the experimental results of the beams in the normal use phase.

COMPARATIVE ANALYSIS OF TESTING FOR POROSITY OF THE CARBON FIBER REINFORCED RESIN MATRIX COMPOSITES

WEN Qiong-hua, MENG Jiang-yan, GONG Chu, WEN You-yi

2016, 0(7): 32-37.

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The pores of the carbon-fiber reinforced polymer composite are formed during preparation. They have crucial influence on mechanical performance of the carbon-fiber reinforced polymer composite. Hence, it is necessary to be calibrated for the porosity. This paper studied the carbon fiber reinforced bismaleide composites. The composites laminations are cured by autoclave or microwave. They are tested by four methods, the density and metallographic method, supersonic scanning and high-precision X-ray micro computed tomography (CT). And the porosity′s content was calculated. The experimental results showed that the porosity calculated by metallographic and micro-CT is close. And the porosity by the density method has large deviation.

STUDY ON PREPARATION AND PROPERTY OF CARBON FIBER REINFORCED LIGHTWEIGHT COMPRESSION-RESISTANCE COMPOSITES

YAN Liu-liu, XU Ren-xin, WANG Jun, YANG Xiao-li

2016, 0(7): 38-41.

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In this paper, a composite consisting of chopped carbon fiber, hollow glass microsphere and epoxy resin was prepared by molding process .The section morphology, density, compression strength, water absorption rate of the composite were studied. The results show that the density of the composite has little change, but its compression strength increased with the increase of carbon fiber percentage. When the carbon fiber content was 4%, the maximum compression strength of the composite with 50 wt%, 55 wt%, 60 wt% glass microsphere were 68.9 MPa, 65.1 MPa, 57.2 MPa, respectively. The saturated water absorption rate decreased as the increase of carbon fiber percentage. When the carbon fiber content was 4%, the composite with 55 wt% and 60 wt% glass microsphere show the minimum saturated water absorption rate of 0.81% and 1.15%, respectively.

NUMERICAL SIMULATION OF SHIP COLLISION AND STRUCTURAL DESIGN ON FRP ANTI-COLLISION FENDER OF HONG KONG-ZHUHAI-MARCO BRIDGE

LIN Ming, WU Sheng-jun, HOU Xue-jie, XIONG Gang

2016, 0(7): 42-47.

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For the project of Hongkong-Zhuhai-Marco bridge construction, this study verified the technical requirements of anti-collision fender system of bridge, and did finite element numerical simulation of ship collision in order to evaluate the safety of anti-collision system and the rationality of structural design, did nonlinear simulation on ship collision to the fender with FEA software ANSYS/LS-DYNA, meanwhile this study also did analysis on structural design of FRP anti-collision fender and the selection of materials.

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF THE BENDING CHARACTERISTICS OF CFRP SQUARE TUBE FILLED WITH ALUMINUM HONEYCOMB

LIU Qiang, MO Zheng-wei

2016, 0(7): 48-52.

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Carbon fiber reinforced plastic (CFRP) has become the very important material for the lightweighting automotive in the future because of its lighter weight, higher strength and better performance compared with metallic materials. Combining the three-point bending experiment and finite element simulation method, the performance and failure mechanisms of CFRP tube filled aluminum honeycomb are carried out. The test results show that the peak load, absorbed energy and specific energy absorption (SEA) of the filled CFRP tube are increased by 17.09%, 32.31% and 0.9%, respectively, compared with the bare CFRP tube, and the failure mode is more stable. In addition, by the finite element simulation using Ls-dyna software, the failure mode and load-displacement curve agreed well with the physical experiments. It indicates that CFRP tube filled with lightweight aluminum honeycomb structure can effectively improve the lateral bending properties of bare CFRP structure, which is useful for the design of lightweight vehicle structure.

EXPERIMENTAL STUDY OF THE INFLUENCE OF COVERED WAYS AND STRIP SPACE ON THE MECHANICS CHARACTER OF THE BFRP-PVC CONFINED SELF-COMPACTING RECYCLED CONCRETE SHORT-COLUMN

REN Li-li , WANG Xue-zhi, ZHANG Hao-feng, ZHANG Yu-mei

2016, 0(7): 53-59.

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A total of 27 BFRP-PVC confined self-compacting recycled concrete short-columns with different wrapped ways and strip interval were tested under axial compression to study the influence of the wrapped ways, strip intervals and failure patterns on carrying capacity and deformation capacity of the BFRP-PVC specimen. The experimental results show that when the whole layers is same, the strength improvement rate and deformation capacity of specimen entirely wrapped at the inner layer along the PVC tube were obviously better than that of specimen wrapped with strip interval way along the PVC tube, and the strength improvement rate of Z1BS series of specimens is better than that of Z2BS series of specimens. The outside strip interval distance has certain influence on the carrying capacity, and the influence degree is related with the wrapped ways. The deformation capacity of BFRP-PVC confined self-compacting recycled concrete short-column is obviously better than PVC confined self-compacting recycled concrete short-column, and the deformation capacity of short-column entirely wrapped at the inner layer is better than that of short-column wrapped with entirely strip interval way. Besides, the deformation capacity of Z2BS series of specimens is better than that of Z1BS series of specimens.

THE EVALUATION OF PET FOAM PROPERTIES AND STUDY ON ITS APPLICATION PROSPECTS IN WIND TURBINE BLADES

WANG Peng, WANG Hai-zhen, LIU Bao-feng, YAO Hui

2016, 0(7): 60-62.

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With the increasing of wind power installed capacity, the demand of wind turbine blades will grow, foam sandwich materials supply falls short of demand. PET foam has irreplaceable advantages compared with PVC ones, now PET foam has caught more attention due to its excellent mechanical performance, high temperature resistant, recyclable, and low cost advantage. The mechanical properties and processing propertpies were evaluated in this article by the parallel contrast with PVC foam. The application prospect of PET foam in the wind turbine blades in the future is also mentioned.

INVESTIGATION OF BLENDING MODIFIED POLY (SILYLENE-ARYLACETYLENE) WITH DIFFERENT GROUPS

JIANG Xiao-jie, DENG Shi-feng, DU Lei

2016, 0(7): 63-68.

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Poly(silylene-arylacetylene) (PSA) resin is a new high-temperature resin. The cured resin exhibits excellent mechanical properties and good wave transmission properties. PSA resin usually prepared by Grignard reagent, and the resin (PSA-G) is brittle because of the high crosslink density after being cured. PSA prepared by catalyst zinc is a new method with high efficiency. PSA prepared by zinc (PSA-Zn) is a kind of PSA resin with terminal olefinic bond. PSA-Zn has low viscosity and the flexural properties of the cured resin are better than PAS-G while the thermal property is a little lower than PSA-G. In this paper, PSA-G was used to blend with PSA-Zn to obtain a modified resin. The curing process, the viscosity and the heat resistance of the modified resin was studied. Quartz fiber reinforced composite and casting of the modified resin (PSA-Zn′s content is 70 wt%) were prepared and the mechanical properties of the composite and the casting were tested. The results show that the modified resin (PSA-Zn′s content is 70 wt%) kept a low viscosity, the T_d5 (temperature that the weight decreases 5%) of the resin reached to 564 ℃, the composite has good mechanical properties and the flexural strength of the casting increased by 11% relative to PSA-G.

THE NONUNIFORM CROSS-SECTION PROPERTY OF BLADE CALCULATION

YU Yong-feng, LIU Wei-sheng, HUANG Hui-xiu

2016, 0(7): 69-73.

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In the bladed software for wind turbine load calculation, calculation of the loads of wind turbine blade is base on the cantilever beam theory, and the blade is treated as a cantilever beam. In the bladed software, it needs input some cross-section property of blade to create the wind turbine blade′s model. To calculate the cross-section property of blade,the basic principle of engineering mechanics was used in this text. Meanwhile, the computer graphics technology and Matlab which is a programming software to develop the calculating software of blade cross-section should be applied. This software can calculate random blade cross-section property by automatically reading the layer-up information of blade. This text compared the results of the engineering theory calculation method and finite element method, and the error can be accepted. This program of cross section property calculation can provide an efficient design method for structural engineer, and it also reduces the design time and improves the work efficiency.

STUDY ON PREPARATION AND MECHANISM OF DOUBLE-LAYER ABSORBING MATERIAL BASED ON FREQUENCY SELECTIVE

HU Xin, XU Ren-xin, WANG Jun, LIU Cheng-guo

2016, 0(7): 74-78.

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In this paper, nickel powder and vinyl ester resin were used to prepare absorbing composite material, and double cylindrical absorbing layer was designed and prepared to compound with the frequency selective surface (FSS) to obtain an absorbing material based on FSS. The microwave reflectivity of the absorbing material was tested between 1 GHz to 18 GHz. It is found that the experimental values of reflectivity for microwave absorbing materials are in agreement with the simulation results. The first absorption peak at 6.2 GHz is -22.3 dB, and the bandwidth under -8 dB is 4.7 GHz when the content of nickel powder is 35 wt% when the content of nickel powder increases to 45 wt%, the bandwidth below -8 dB for second absorption peak is 8.5 GHz.

REVIEW OF FIRE-RESISTANCE BEHAVIOR OF FRP BARS REINFORCED CONCRETE MEMBERS

DU Fan, OUYANG Li-jun , LU Zhou-dao, CHENG You-liang

2016, 0(7): 79-85.

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Corrosion of steel bar is an important factor for durability deterioration of reinforcing concrete structure. Fiber reinforced polymer bar, which is known as high strength to weight ratio, excellent corrosion resistance reinforced material, is expected to be an alternative material of steel rebar in the future. The performance of FRP bar reinforced concrete members under elevated temperature is becoming an important issue for high frequency of building fire. This paper reviews the relevant achievements, including the impact of elevated temperature on the FRP bars′ mechanical properties, bond strength between FRP bars and concrete under elevated temperature, fire-resistance design of FRP bar reinforced concrete members. Experimental data and theoretical models are summarized and analyzed in detail. Remaining problems and key issues, which need to be resolved in future are pointed out.

THE DEVELOPMENT OF COMPOSITE DELAMIANTION FAILURE BASED ON COHESIVE ZONE MODEL (CZM)

LI Fei, MA Ping-ping, WANG Xin-yu-fang

2016, 0(7): 86-91.

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Composite has been widely applied in different fields, and the delamiantion failure is one of the main failure. In this paper, the development of composite delamiantion failure based on the cohesive zone model (CZM) is presented. First, the development history of CZM, the research status of strength parameters and constitutive relation are introduced and the existing problems are analyzed. Second, the application status of CZM in the composite delamiantion failure anlysis is present and the existing problems of this model applied in the finite element method are introduced. The research result shows that although the CZM is the main method to analyze the composite delamiantion failure, the problems of the prediction accuracy of parameters, convergence difficulties and low calculation efficiency should be solved.

PROGRESS IN THE FABRICATION PROCESS OF COMPOSITE JOINT SKIRT FOR SRM

GAO Wei, CHEN Xiao-ping, HAN Jian-ping, LIU Xin-dong

2016, 0(7): 92-95.

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This paper presents the use of solid rocket motor (SRM) case joint skirt. The composite which applied on SRM case joint skirt was reviewed. The composite joint shirt fabrication process of preformation, integration and resin transfer moulding (RTM) were discussed. The joint structure of composite shirt and the development of grid composite skirt were reviewed.

SOME THOUGHTS ON TRAINING COMPOSITE STRUCTURE DESIGN TALENTS

YUAN Guo-qing

2016, 0(7): 96-100.

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Industry experts have deeply realized that one of the main reason, which affects composite materials that are widely used in advanced structure in our country, is the lack of composite material structure design talent. So it has become the key of composite materials′ innovation application development in some important industry that how to train composite material structure design talents. In this paper, some thoughts about the related concept, training methods and training standards are presented. Serving as a modest spur to induce other people to concern it, the paper can promote composite structure design talented person′s raise work.

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