Table of Content

20 December 2017, Volume 0 Issue 12

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BASIC STUDY

FIBER TENSION RESEARCH FOR CARBON-FIBER ROTOR SLEEVE IN HIGH-SPEED PERMANENT MAGNET MACHINE

ZHOU Fan, ZU Lei, LI Shu-xin

2017, 0(12):  5-13. 

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The goal of this paper is to present a novel application of filament winding to surface mounted high speed permanent magnet electrical motors. The surface-mounted magnets cannot support the ultra-high centrifugal force due to the high-speed rotation of the steel shaft of the rotor. The carbon-fiber overwrap wound with ultra-high tension was thus used as a protective sheath for providing the radial compressive stress resultant over the outer surface of magnets. An approach of calculating the residual stress deformation and radial compressive stress resultant according to superposition principle of elastic theory was proposed. The maximum fiber tension was determined due to winding experiments with different winding tension and the analytical algorithm applied to calculate the residual stress distribution with different tension models of filament winding. Then, the analytical solution was compared with the finite-element results. The static test at the radial compressive stress resultant was conducted. The results show that the proposed analytical solution can accurately predict the residual stress distribution of the composite sheath and the radial compressive stress resultant over the outer surface of magnets. The error between the analytical results and the finite-element results is very small, and the error between the analytical results and the test results is completely within the acceptable limits. So carbon fiber overwrap wound by ultra-high tension can satisfy the requirements of high speed permanent magnet rotors.

STUDY ON CALCULATION AND CONTROL ALGORITHM OF WARP TENSION OF MULTI-SHAFT MECHANISM OF CARBON FIBER MULTI-LAYER DIAGONAL LOOM

LU Xu-feng, YANG Jian-cheng

2017, 0(12):  14-18. 

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In order to study the influence of carbon fiber unwinding tension of three-dimensional loom, combined with the requirements of three-dimensional fabric weaving and physical properties of carbon fiber yarns, the warp mechanism is designed and investigated, based on which the mathematical model of carbon fiber warp tension was established. The warp tension is controlled by Fuzzy PID, and the warp tension control curve is obtained by using Matlab/Simulink. The experimental results show that the tension of carbon fiber warp yarns satisfies the special requirements of multi-layer angle loom. In addition, the stability and control accuracy are significantly improved, and there is no obvious fluctuation of warp tension.

EFFECTS OF DIAMETER ITSELF ON WEIBULL MODULUS AND FRACTURE TOUGHNESS OF PAN-BASED CARBON FIBER

WANG Mei-ling, BIAN Wen-feng, JIANG Zhao-chun

2017, 0(12):  19-24. 

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The effect of diameter of carbon fiber on the mechanical properties is dramatic. The diameter of carbon fiber present obvious lateral and vertical in-homogeneity. Conventional testing technique cannot characterize the diameter of carbon fiber accurately and the deviation made by testing technique is often ignored for performance of carbon fibers and composite products. In this study, two conventional and one image processing methods for testing diameter were analyzed in order to evaluate the effect of the testing technique on Weibull modulus and fracture toughness, the effects of irregular shape on the properties of the carbon fiber were studied, and scheme for correction and calibration was given. The results showed that the diameters tested by the three technique were different and in the inverse proportional relationship fracture toughness, Weibull modulus and diameter had not a linear relationship, but could prove that the image processing method could correctly represent the diameter of the carbon fiber and the mechanical properties. The data tested by method of image processing could be considered as realistic values, and the data tested by method of SEM and calculation could be corrected through SPSS statistical software, and improve the accuracy of the carbon fiber mechanical properties effectively.

TRIBOLOGICAL PROPERTIES OF RESIN-BASED FRICTION MATERIALS REINFORCED BY NANOPARTICLES

WU Juan, ZHANG Qi-shun, ZHANG Chao

2017, 0(12):  25-28. 

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By employing phenolic resin modified by NBR as matrix, kevlar and glass fiber as reinforced fibers, different types of nanoparticles were selected to design the formula for the friction material, which was prepared by hot pressing sintering technology. The tribological properties of the materials were tested by the friction and wear testing machine under dry friction conditions, and the surface of friction materials was observed by scanning electron microscopy (SEM), based on which the effect of different nanoparticles on friction material properties was studied. The result shows that under dry friction, the friction material modified by nanoparticles has a higher friction coefficient, hardness and a lower wear rate than the unmodified material. The friction coefficient and wear rate of materials modified by nanoparticles exhibit a trend, which decrease with the increase of test load and the sliding speed. The wear mechanism of modified materials is fatigue wear and abrasive grain wear. However, the wear mechanism of unmodified material is mainly fatigue wear.

PLACEMENT MANUFACTURABILITY OF FIBER STEER TRAJECTORY PLANNING FOR COMPOSITE FLAT

HUANG Wei, WANG Xian-feng, YAO Feng

2017, 0(12):  29-33. 

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In order to explore trajectory planning for flat fiber steer and the placement manufacturability, this paper discussed a numerical method to obtain the path point of placement with straight line instead of curve. By analyzing deformation mechanism of prepreg tow, a new evaluation criterion for placement manufacturability based on the curvature radius of steer trajectory was proposed. And a paramatic study was conducted to investigate the effect of flat length in 90 degree direction, layup angle and angle interval on fiber steer curvature radius. The results show that the trajectory curvature radius of fiber steer is increased with the layup angle when the flat length in 90 degree direction and layup angle interval are fixed. On condition that flat 90 degree direction length is fixed, the trajectory curvature radius of fiber steer is decreased with the layup angle interval. When layup angle interval is fixed, the trajectory curvature radius of fiber steer is increased with the flat 90 degree direction length.

PREPARATION AND MICROWAVE ABSORPTION PROPERTIES OF ABSORBING PATCH BASED ON POLYURETHANE

HE Xiang, LI Yong-qing, ZHU Xi, LI Mao

2017, 0(12):  34-40. 

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In this work, an PU absorbing patch, filled with MZ and carbon black as the absorbent, was prepared by rotational moulding process. The influence of absorbing agent on the electromagnetic and absorbing property of the absorbing patch was analyzed. Furthermore, the microwave absorbing mechanism of the absorbing patch was discussed. Finally, the results show that the increase of absorbing agent content will cause the improvement of attenuation characteristic, and simultaneously, will cut down the impedance matching between absorbing patch and free space. The destructive interference result in the position of absorption peak tends to low frequency direction, with the increase of the absorbing agent content or thickness of the absorbing patch. An PU absorbing patch, with 1.5 mm thickness and filled with 80wt% MZ as the absorbent, has the best absorbing property, whose reflectivity is less than -10 dB between 9.18 GHz and 17.37 GHz, and could basically meet the requirement of warship keeping radar stealth in the X and Ku band.

THERMAL DEFORMATION ANALYSIS OF THE U-SHAPED THIN SHELL STRUCTURES WITH STIFFENERS BASED ON ABAQUS

DING Chang-fang, ZHANG Jing, CHU Hong-jie, YIN Liang

2017, 0(12):  41-44. 

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The U-shaped thin shell structures with stiffeners are widely used in the field of aeronautic and aerospace. However, due to the thermal deformation of the cross section of the structures, the hole-position and drilling are carried out by the special production tools or separate measurement, which lead to the complex procedure and long manufacture cycle. In this study, the finite element analysis of ABAQUS was employed to calculate and predict the sectional dimension of the U-shaped thin shell structure. The results show that the predictive values in the design condition of local modeling with steel tool were consistence with that of the actual products. While the calculating results of the integrated modeling were smaller than that of actual dimension, which could be attributed to the consideration without steel tools in this modeling. It is concluded that the ABAQUS can be used for the thermal analysis and prediction of the U-shaped thin shell structure with stiffeners.

APPLICATION RESEARCH

EXPERIMENT STUDY ON THE FLEXURAL BEHAVIOUR OF BFRP REINFORCED RECYCLED AGGREGATE CONCRETE BEAMS

HAN Fei, KONG Xiang-qing, BAO Cheng-cheng, LIU Hua-xin

2017, 0(12):  45-50. 

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This paper experimentally investigated the flexural behaviour of basalt fiber-reinforced polymer (BFRP) reinforced recycled aggregate concrete (RAC) beams. A total of eight RAC beams, including seven reinforced with BFRP and one reinforced with steel, were fabricated and tested. The paper studied the effect of the different longitudinal reinforcement ratios and replacing rate of recycled aggregate concrete on the flexural behaviour of BFRP reinforced recycled aggregate concrete beams. The flexural capacity, failure mode, flexibility deformation and crack distribution of the test beams were analyzed. The results indicate that the failure mode was under-reinforced failure or over-reinforced failure which was governed by BFRP rupture or concrete crushing, respectively. The BFRP reinforced RAC beams with reasonable reinforcement ratio would produce larger deflection deformation and strain of BFRP tendons than that of steel reinforced RAC beam before the failure. The results indcate that the BFRP reinforced RAC beam could play a good performance of the two materials with a certain degree of ductility. Compared with the replacement rate of recycled aggregates, the reinforcement ratio had a larger influnce on the width and number of cracks in BFRP reinforced RAC beams. Furthermore, it has found that the initial cracking load of BFRP reinforced RAC beams was slightly lower than steel reinforced RAC beam. Whereas, the ultimate load was improved obviously.

OPTIMUM DESIGN OF REINFORCEMENT STIFFNESS OF GLASS FIBER REINFORCED PLASTIC MORTAR SAND PIPE

SHI Hua-wang,GAO Huai-jun, WEI Lian-yu,YIN Hang

2017, 0(12):  51-56. 

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The glass fiber reinforced plastic mortar sand pipe has high performance and is often used as the underground pipe. However, many countries do not adopt the glass fiber reinforced plastic sand pipe because of its higher cost compared to that of the traditional buried pipe. This paper takes the pipe ring stiffness as a reference index to optimize the design of the DN1500 glass fiber reinforced plastic sand pipe, aiming to reduce the piping cost. Firstly, this paper tests the ring stiffness of DN1500 pipe and then simulates the pipe ring stiffness of with ANSYS. The experimental data and simulation data are compared to verify the feasibility of ANSYS in analyzing the pipe ring stiffness. Secondly, ANSYS was used to analyze the relationship between the ring stiffness and the four variables, such as the pipe layer number, the fiber volume fraction, the intercross enwind layer volume fraction and the fiber winding angle, thus obtaining the relationship between the ring stiffness and the four variables. At last, this paper uses the MATLAB and ANSYS joint-analysis and combines with the PSO intelligence algorithm to optimize the pipe structure. The optimized pipe not only meets the requirement of ring stiffness, meanwhile, its volume is 12% less than that of the original pipe.

STUDY ON AXIAL COMPRESSION PERFORMANCE OF 2D BRAIDED COMPOSITES TUBES

TAN Jiang-tao, MA Xiao-hong, QIN Zhi-gang

2017, 0(12):  57-59. 

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By optimizing the composite process of 2D braided composites tubes, the carbon fibre composite tubes containing high carbon fiber content were made. The axial compression performance test of the tubes fittings was carried out, and the influence of braiding parameters on the volume content and axial compressive properties of the composite tubes fittings was analyzed and discussed. The results show that the optimized composite process can keep the volume of the composite tubes fiber between 20%~40%, while the inner diameter of the composite tubes is consistent. In the case of constant braiding speed, with the decrease of braiding pitch, the braiding angle gradually increases and the tubes volume fraction increases gradually. When the braiding pitch reduces to a certain extent, fiber volume content increases slowly, while the compressive strength increases first and then decreases. When it reaches the maximum, the braiding angle is 46 degrees.

PREPARATION AND PROPERTIES OF CARBON FIBER REINFORCED EUCALYPTUS-POPLAR COMPOSITE PLYWOOD

LIU Yuan-song, GUAN Ming-jie, DONG Zhi-yong, ZHAI Tong-jun

2017, 0(12):  60-66. 

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In order to develop carbon fiber reinforced wood-based composites, four kinds of structure with eucalyptus-poplar composite panel were designed with eucalyptus/eucalyptus, poplar/poplar, crossed poplar/eucalyptus and eucalyptus/poplar, and the carbon fiber (CF) was covered on the surface of composite panel to enhance its properties. The physical mechanical properties and thermal insulation properties of CF reinforced eucalyptus-poplar composite panel were analyzed and the performance changes were discussed before and after aging. After the carbon fiber surface enhancement, the physical and mechanical properties of the four kinds of eucalyptus-poplar composite panel have been greatly improved. Among them, the expansion rate of water absorption of eucalyptus/poplar was 2.6%, for which the decrease rate was 44.7%, and the water absorption rate decreased by 46.5%. The delamination properties of the four structures all meet the standard, and the best was poplar/eucalyptus. The longitudinal modulus of rupture of eucalyptus/poplar was 98.5 MPa before aging, and the improvement rate was 107.4%. The longitudinal modulus of elasticity of eucalyptus/poplar was 15810 MPa before aging, for which the improvement rate was 129.8%. The longitudinal modulus of elasticity of the aged poplar/eucalyptus was 10150 MPa, for which the increased rate was 176.3%, and the bonding strength of poplar/eucalyptus was up to 1.74 MPa. Whereas, the transverse modulus of rupture, modulus of elasticity and bonding strength of the composites were smaller than those of the control group. Overall, the structure of poplar/eucalyptus and eucalyptus/poplar by the carbon fiber enhanced surface had better physical and mechanical properties, and the ratio of longitudinal and transverse strength of the eucalyptus-poplar composite panel was quite different. In the practical application, the aspect ratio of longitudinal and transverse strength need to be adjusted according to the demand. After the surface enhancement of the carbon fiber, the average thermal conductivity of eucalyptus-poplar composite panel was 0.44 W/(m·℃). As indicated, and the thermal conductivity was close to the insulation, and the effect of carbon fiber on the thermal insulation properties of eucalyptus-poplar composite panel was not significant.

STUDY ON VINYL ESTER RESIN FOR SMALL DIAMETER PIPES BY CONTINOUS WINDING PROCESS

LIU Shi-qiang, MAO Ling-feng, SHA Yuan

2017, 0(12):  67-71. 

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In order to make up small diameter corrosion-resistance glass fiber rein forced plastics (GFRP) pipeline which was molded by continuous winding, the matrix properties of GFRP between viny ester resin (VE), unsaturated polyester resin (UP) and UP/VE mixture were realized in the present work. Influence factors of gel time is analyzed. The mechanical properties of different resin casting and GFRP are compared. Bending strength retention rate after immersion of corrosion medium is tested. The results show that the process performance of VE (MFE711FW resin), UP (MERICAN9708) and UP/VE mixture (weight ratio 1∶1) is comparable. The resin gel time is affected by the initiator, accelerator, accelerator assist promoter and temperature. The mechanical properties of pure resin and GFRP of VE are the best. The bending strength retention rate after 6 months immersion at 80 ℃ of VE is up to 80%, while the UP retention rate is below 20% after 2 months immersion at 80 ℃. The GFRP is apt to be damaged compared to pure resin. VE is more suitable for small diameter corrosion-resistance continuous winding GFRP pipeline.

VIBRATION RESPONSE ANALYSIS AND TEST VERIFICATION FOR A SHIP RADOME

DING Jun

2017, 0(12):  72-76. 

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In this paper, the modal analysis and vibration response analysis for a ship radome were performed with ANSYS finite element analysis software. The dangerous area of the radome structure was investigated and the time history of stress, displacement and acceleration on the sensitive parts was analyzed. Finally, the simulation analysis was verified through the vibration test.

STUDY ON MACHINING FORCES AND MACHINED SURFACE QUALITY OF PLANE WOVEN-FABRIC CFRP IN ORTHOGONAL CUTTING EXPERIMENT

WANG Dong-yao, HE Xiao-dong, LIU Wen-bo, WANG Rong-guo

2017, 0(12):  77-82. 

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2-D plane woven-fabric carbon fiber reinforced polymer (CFRP) is widely used in manufacturing composite structural parts owing to its excellent mechanical property, fatigue and impact resistance. However, because of the inhomogeneity and the fiber structure, the machinability of woven-fabric CFRP has significant differences from metal, alloy materials and unidirectional CFRP. In order to study the machinability of woven-fabric CFRP and to improve the machining efficiency and surface quality, an orthogonal cutting experiment was carried out to measure the values of cutting forces of the woven-fabric CFRP with varying conditions and a metallographic microscopy and a roughness profiler were utilized to characterize the surface quality of each machined workpiece. The results show that the fiber orientation angle has a huge influence on cutting forces. The increase of the cutting speed and the decrease of the cutting depth can lead to a better machinability and surface quality of the woven-fabric CFRP.

DESIGN AND CONTROL OF ULTRASONIC CUTTING MECHANISM FOR MULTILAYER FIBER PREPREG BASED ON PMAC

SHEN Zu-wu, XU De-fan, TIAN Hui-fang, ZHANG Jun-wei

2017, 0(12):  83-86. 

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In the light of the structural characteristics of carbon fiber prepregs and the problems existing in the traditional cutting process, an ultrasonic cutting device was designed using PC+ motion control card as the ultrasonic cutting mechanism control system and using servo drive to control its knife′s movement on the worktable. This paper focuses on the control of the cutter′s rotary motion in C axis,which will ensure the direction of ultrasonic cutting knife blade following the tangent direction of cutting graphics. Automatic cutting can be achieved by the upper computer programming software making programs and the PMAC motion control card issuing instructions to control servo drive driving feed movement of motor. Compared with the traditional cutting method, the ultrasonic cutting system has higher efficiency and better cutting quality.

INVESTIGATION ON COMPRESSION MOLDING OF A FAN IMPELLER PRODUCT MADE OF GLASS FIBER REINFORCED POLYMER MATRIX COMPOSITE

LUO Zan-cai, JIANG Da-zhi

2017, 0(12):  87-90. 

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This paper conducts research and development on a fan impeller products made of glass fiber reinforced polymer matrix composite by Sheet molding compound (SMC) for weight reduction and operating performance improvement of the fan impeller products of locomotives. By testing the paving method and technological parameters of the impeller, the SMC material impeller has been successfully developed to meet the requirement of the locomotive ventilator. The research is focused on effects of charging pattern, compression molding pressure, compression molding temperature, pressing speed and pressing time of the SMC material on the quality of impeller products. Experimental results show that the distributed paving method is better than the concentrated paving method to obtain high quality products, and the pressing parameters were determined as the temperature of top and bottom mold are 140 ℃ and 145 ℃, respectively, and molding pressure is 8 MPa for 40 min and pressing speed is less than 20 mm/s.

REVIEW

A REVIEW OF REPAIR TECHNIQUES FOR AVIATION COMPOSITE MATERIALS UNDER IMPACT DAMAGE

WANG Chang-yue,XING Su-li

2017, 0(12):  91-98. 

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Advanced composite materials are widely applied in aviation industry, especially in primary aviation structural components, which brings new and urgent requirements for composite structural maintain and repair techniques with high efficiency and reliability. The anisotropy and heterogeneity make composite materials highly susceptible to delamination and inter-laminar fracture, and this form of damage can sharply reduce the strength and property of the structure, which can bring catastrophic consequences to aviation aircrafts. For this type of damage is mainly induced by impact load, impact damage model and repair techniques of composite materials have been the focus of hot research. This article reviewes the main research progress of domestic and foreign. Firstly, impact damage assessment was introduced. Then, several advanced technologies of non-destructive inspection were listed to indicate the trend of intelligent and precise development. Three main repair techniques were enumerated, including bolting or riveting connection repair, adhesive bonding repair and injection repair. Last but not least, the prospects of developing tendency of repair techniques were presented.

APPLICATION OF COMPOSITE MATERIALS IN MARINE ENGINEERING

YAN Kan, HUANG Peng

2017, 0(12):  99-104. 

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Polymer matrix composites have good application prospects in the field of marine engineering due to their characteristics like light weight, high strength and high modulus. Composite materials are mainly used in national defense and marine energy development, such as naval vessels, weapon underwater, offshore drilling platforms, offshore tidal power stations, offshore wind turbine blades, large seawater farms, desalination, etc.This paper introduces the application of polymer matrix composites in offshore drilling platform, and summarizes the application of composite material riser, winding composite pipe and composite cable and other components. Besides, it also points out the future technological development direction of composite materials for offshore drilling platform.