COMPOSITES SCIENCE AND ENGINEERING

STUDY ON ELASTIC PROPERTIES PREDICTION METHOD OF CARBON FIBER REINFORCED NYLONCOMPOSITE BASED ON CT-RVE MODEL AND MORI-TANAKA MODEL

LIU Ying, MA Yi-tao, LIU Qiang

2021, 0(6): 5-11. DOI: 10.19936/j.cnki.2096-8000.20210628.001

Asbtract ( 200 )

PDF (6752KB) ( 135 )

References | Related Articles | Metrics

Mechanical properties prediction of short fiber reinforced composites is a difficult point in engineering application. In this paper, the construction method and the performance prediction analysis of representative volume element model based on micro-CT images (CT-RVE) of fiber reinforced composites are studied. The elastic properties of carbon fiber reinforced nylon 66 (PA66CF) were predicted based on the CT-RVE model of four sizes, and the results were compared with those of the Mori-Tanaka model (M-T). The PA66CF tensile specimen with fiber fraction of 10wt% was prepared by injection molding process. The fracture surface of tensile specimen was observed by scanning electron microscope (SEM). X-ray computed tomography (CT) images of CFRP was used to obtain internal microscopic structure information. The four dimensions of CT-RVE model which were established by using ImageJ, Photoshop, Mimics, Cero, HyperMesh and ABAQUS, predicted the elastic performance of PA66CF materials. And the prediction results were compared with the CT-RVE models and M-T models which had the same geometric parameters. The results show that the random distribution of fibers in the RVE model is regular, the number of fibers and the volume of RVE are linearly increasing, the volume fraction of fibers is about 3%~5%, and the orientation of fibers is mainly in the X direction. When the RVE size is 114.4 μm×114.4 μm×77 μm, the prediction results of the CT-RVE model and the M-T model on the elastic performance were similar. When the RVE size is too large or too small, M-T model can give reasonable prediction on the elastic performance, while CT-RVE model has significantly smaller prediction results on the longitudinal elastic performance of fiber. The research results can provide guidance for the accurate prediction of the properties of short fiber reinforced composites.

ANALYSIS ON FORCE TRANSMISSION MECHANISM OF GFRP TUBE STEEL-REINFORCEDCONCRETE COMPOSITE SHORT COLUMN UNDER AXIAL COMPRESSION

YIN Chao-zheng, LI Shun-tao, YANG Wen-wei

2021, 0(6): 12-19. DOI: 10.19936/j.cnki.2096-8000.20210628.002

Asbtract ( 138 )

PDF (5984KB) ( 99 )

References | Related Articles | Metrics

Through the axial compression tests of 6 GFRP tube steel-reinforced concrete composite short columns and 1 GFRP tube confined concrete composite short column and the use of ABAQUS for finite element numerical analysis, the effects of section form, section steel ratio, and concrete strength on the mechanical properties of the composite short column was studied, and the working mechanism of the composite column was explored. The test results show that the built-in steel can significantly improve the ultimate bearing compression capacity and ultimate deformation capacity of short columns compared with specimens without built-in steel. With the increase of the steel content of the section, the ultimate bearing compression capacity and ultimate deformation capacity of the GFRP tube steel reinforced concrete short columns have been obviously improved. Increasing the strength of concrete can improve the ultimate bearing capacity of short columns, but it has little effect on the initial rigidity of short columns. When other conditions are the same, the built-in steel tube short column has higher ultimate bearing capacity and better deformation capacity than the built-in I-steel short column. The restraint effect of GFRP tube on concrete is slightly later than that of steel tube on concrete, showing a certain hysteresis. The results of finite element simulation fit well with the experimental results, which can provide a reference for the nonlinear analysis of such composite short columns.

NUMERICAL ANALYSIS AND EXPERIMENTAL VERIFICATION OF LOW-VELOCITY IMPACT OFCOMPOSITE LAMINATES BASED ON PUCK′S FAILURE CRITERION

LI Lei, SONG Gui-bin, ZHENG Hua-yong, CHENG Peng-fei, ZHAO Jian

2021, 0(6): 20-25. DOI: 10.19936/j.cnki.2096-8000.20210628.003

Asbtract ( 162 )

PDF (6456KB) ( 125 )

References | Related Articles | Metrics

A numerical simulation analysis method for impact damage of composite laminates was developed, and an analysis model for low-velocity impact was established. The failure modes such as fiber damage, matrix damage, and interlayer damage were considered in the model, Puck failure criterion based on physical failure modes was adopted to predict the damage initiation and the stiffness degradation method based on the fracture strain energy was used to predict the damage evolution process. The impact resistance tests of T300, T700 and T800 carbon fiber reinforced laminates were carried out, and the law of the influence of fiber and resin properties on the impact resistance of laminates was obtained. The comparison between simulation results and test results shows that the developed numerical analysis method for low-velocity impact damage analysis of composite laminates has high accuracy.

PRESTRESS LOSS OF SELF-COMPACTING CONCRETE BEAMSREINFORCED WITH EXTERNAL CFRP TENDONS

WU Li-li, GENG Da-lin, YUE Yan-song, YANG Jia-qi

2021, 0(6): 26-33. DOI: 10.19936/j.cnki.2096-8000.20210628.004

Asbtract ( 112 )

PDF (1836KB) ( 115 )

References | Related Articles | Metrics

This study aimed to provide a comprehensive experimental, analytical and numerical investigation of prestress loss of self-compacting concrete (SCC) beams with external CFRP tendons. A total of 6 specimens of SCC beams and 2 specimens of controlling beams were designed and tested to get the laws of prestress loss, including anchorage loss, temperature difference loss, relaxation loss, shrinkage loss and creep loss of CFRP bars, at different prestressing and concrete strength levels. The comparison of prestress loss between self-compacting concrete and controlling beams were also made. The results show that the theoretical value of anchorage loss is larger than actual value. The formulas for controlling beams are also suitable for CFRP tendons, while some parameters in the formulas should be determined by tests. Linear expansion coefficient of CFRP bars and SCC calculated by the temperature difference loss formula was about 500% bigger than the actual value. So the formulas for controlling beams are no longer suitable for FRP-SCC components. The total theoretical loss of relaxation of CFRP bars, shrinkage and creep of concrete were about 20% different from the test results, while the theoretical formula exhibited the larger error for the SCC specimens of concrete with the strength level of C65. The loss of external prestress of CFRP bars decreased with the decrease of prestress level, and the maximum reduction of prestress loss is 15.2%. The prestress loss increased with the increase of concrete strength, with the maximum increase of 10.4%. The prestress loss of controlling concrete specimens is greater than that of SCC specimens, and the maximum difference is 11%.

STUDY ON WIND TURBINE BLADE DYNAMIC DEFORMATION SENSINGALGORITHM BASED ON MULTI-IMU DATA FUSION

LU Yun-fei, ZHANG Hua-qiang, WANG Guo-dong, SU Qing-hua

2021, 0(6): 34-38. DOI: 10.19936/j.cnki.2096-8000.20210628.005

Asbtract ( 193 )

PDF (1505KB) ( 110 )

References | Related Articles | Metrics

To accurately measure the bending attitude and position of wind turbine blades during dynamic deformation, a relative motion sensing algorithm based on multi-inertial measurement unit (IMU) measurement is proposed. The algorithm is based on the improved Kalman filter and uses a feedback distributed structure to perform multi-node data fusion. This method can not only provide redundant blade motion inertial information, but also has strong fault tolerance, that is, when a single IMU node fails, the measurement accuracy of the algorithm is less affected. The simulation results show that the maximum error of the deflection attitude of the child nodes in the direction of motion after single point fusion is 1.068′, and the maximum position error is -59.89 mm; the maximum error of the node after global fusion is 1.004′, 27.71 mm, respectively. This research has strong theoretical research significance and engineering application value in the field of dynamic deformation testing of full-scale wind turbine blades.

STRESS ANALYSIS OF ADHESIVE LAYER OF COMPOSITE REPAIR BASEDON THE P-VERSION ELEMENT METHOD

WANG Zhuan-li, ZHANG Fa, WANG Liang, CHEN Ning

2021, 0(6): 39-44. DOI: 10.19936/j.cnki.2096-8000.20210628.006

Asbtract ( 120 )

PDF (2584KB) ( 120 )

References | Related Articles | Metrics

Bonding repair is a common kind of composite repairing method. Accurate analysis of stress of repair adhesive layer is always a difficult problem for engineers. The traditional finite element method (FEM) based on H element (less than 2 order) for composite laminate bonding repair is faced with the problem of high ratio of length to width. In order to improve the calculation accuracy, great efforts have to be spent on refining mesh. Advanced FEM using P element (up to 8 order) can achieve the element length-width ratio of more than 200∶1, which is very suitable for composite laminate bonding repair analysis. In this paper, a simplified analysis method for the laminate step-step excavation and bonding repair is used. Furthermore,based on the StressCheck software P element,the shear stress and peeling stress of the adhesive layer are analyzed. The comparison results show that the stress results of the adhesive layer based on P element are more realistic, due to the fact that it considers the additional bending moment caused by the eccentricity of each step load. This indicates that this new method can be applied to engineering analysis.

OPTIMIZATION OF LANDING GEAR DOOR BASED ON RIGID-FLEXIBLECOUPLING DYNAMIC SIMULATION

LIANG Li, JI Xiao-fei, MENG Zhao-kang, CHEN Xi-feng

2021, 0(6): 45-51. DOI: 10.19936/j.cnki.2096-8000.20210628.007

Asbtract ( 119 )

PDF (2687KB) ( 126 )

References | Related Articles | Metrics

The optimization design of a foam sandwich composite landing gear door was studied, a composite structure optimization method was proposed based on rigid-flexible coupling dynamic simulation. Rigid-flexible coupling model of composite landing gear door was established using C-B component mode synthesis method, and the dynamic responses of landing gear door was obtained. Orthotropic experimental method was used to select training samples, BP neural network response surfaces of ply parameters and dynamic responses of landing gear door were trained by training samples. The thicknesses of the composite ply were optimized by genetic algorithm to minimize the door mass and suspension joint load considering the deformation constraints. The results show that the proposed composite structure optimization method based on rigid-flexible coupling dynamic simulation can accurately consider the structural deformation and load in the whole motion process of landing gear door to achieve the optimal design of the composite landing gear door.

APPLICATION OF FAILURE CRITERIA IN THE COMPOSITE LAMINATEOPEN HOLE FOR OUT-OF-PLANE LOADS

QIN Jian-bing, ZHAO Xi, LIANG Rong-na

2021, 0(6): 52-57. DOI: 10.19936/j.cnki.2096-8000.20210628.008

Asbtract ( 137 )

PDF (3687KB) ( 115 )

References | Related Articles | Metrics

The failure modes that local matrix cracking, fiber breakage and delamination caused by local high stress which were introduced by hole and bending. Stresses around the hole edge of infinite laminated plate were studied with the method of analytic method and finite element method. Based on the classical laminated plate theory and the theory of complex function the calculation method was developed for the analysis of open holes in composite structures under out-of-plane loads, using conformal representation, and the boundary issue of stress function on the complex aperture was solved. Real stress and strain distribution around the hole were investigated by the introduction of Puck and Yamada-Sun mixture strength failure criterion, through the comparison with the finite element results, and a good agreement can be found. The hole laminated plate failure could be predicted based on the guide of this paper.

ANALYSIS OF CALCULATION METHOD OF CRITICAL LOADS FOR GLOBAL BUCKLING OFAXIALLY LOADED FRP MEMBERS WITH DOUBLY SYMMETRIC CROSS SECTIONS

ZHAN Yang, LI Ben-ben, CUI Jing, YANG Ya-qiang

2021, 0(6): 58-64. DOI: 10.19936/j.cnki.2096-8000.20210628.009

Asbtract ( 171 )

PDF (1207KB) ( 165 )

References | Related Articles | Metrics

This paper presents a test database of concentric compression experiments on fiber-reinforced polymer (FRP) specimens with doubly symmetric cross sections that failed in a global buckling mode published in literature between 1969 and 2020. The prediction accuracies of the five closed-form solutions recommended by Euler, Engesser, Haringx, Strongwell and Fiberline corporations which can be used to predict the global buckling loads of FRP members with doubly symmetric cross sections were evaluated according to the test database. The results show that the classical Euler formula overestimates the experimentally obtained capacity by 16.7%, and the average absolute error (AAE) is approximately 18.1%. Because the effect of shear deformation is considered in Engesser and Haringx shear correction formulae, the two solutions overestimates the capacity by only 8.4% and 9.5%, respectively, and the AAE values are approximately 11.3% and 12.0%, respectively. The formula recommended by Fiberline Composites underestimates the experimentally measured capacity by 12.5%, and the AAE is approximately 14.3%. The formula recommended by Strongwell Corporation significantly overestimates the experimentally obtained capacity by 118.2%, and the AAE is approximately 118.2%. Considering the prediction accuracy, the Engesser shear correction formula is recommended to be used to predict the global buckling loads of FRP members with doubly symmetric cross sections.

STUDY ON THE PERFORMANCE OF STRETCHING MECHANICS OFCARBON FIBER REINFORCED COMPOSITE RING

SONG Jin-peng, WANG Jin-wei, LUO Hao, FAN Xiao-bin, GUI Lin

2021, 0(6): 65-71. DOI: 10.19936/j.cnki.2096-8000.20210628.010

Asbtract ( 154 )

PDF (9724KB) ( 94 )

References | Related Articles | Metrics

Several typical carbon fiber reinforced composite rings were manufactured and their stretching performance were tested. The tension strength and the typical failure mode were obtained. The composite materials can be applied to flywheel, which can reinforce mechanical behavior of energy storage flywheel and increase kinetic energy storage efficiency perunitmass. The mechanical model of composite energy storage flywheel is built based on the orthotropic elastic solid basic theory and the finite element theory. The distribution of radial and circumferential stresses as well as the radial displacement were analyzed, and the curve of the distribution has been drawn out. Also, the tension strength and the failure mode were obtained, which agreed well with the experimental results. Moreover, the distruibution of radial and circular stress, and radial displacement were caculated by the analytical model. The developed method provides a good reference for optimum and design of flywheel structure.

APPLICATION OF X-RAY CT TO CHARACTERIZE THE MICROSTRUCTURESAND DAMAGES IN C/SiC COMPOSITE MATERIAL

WANG Long, LIU Wu-gang, KONG Fan-jin, ZHANG Yue-ping, YUAN Kai

2021, 0(6): 72-76. DOI: 10.19936/j.cnki.2096-8000.20210628.011

Asbtract ( 212 )

PDF (11235KB) ( 106 )

References | Related Articles | Metrics

The microstructures, damages and damage evolutions in the bulk of C/SiC composite material are characterized by using X-ray CT and three-dimensional digital image processing and analysis method. The advantages of X-ray CT to understand the microstructures and damage mechanisms in C/SiC material are highlighted. The three-dimensional morphologies of carbon fiber bundles, SiC matrix and pores in the bulk of C/SiC composite material and their connectivity are revealed in three-dimension qualitatively. The key three-dimensional geometry parameters, such as the volume, surface area, thickness field for each object, are measured quantificationally, and the variations of pores, carbon fiber bundles and SiC matrix along the direction perpendicular to the laminates could also be obtained. The failure analysis could be performed in the case of undestroying the samples. The final fracture is identified accurately, and the microcracks and the oxidation behaviors under high temperature in the bulk samples are also characterized. The mechanical tests with X-ray CT in-situ observations allow characterizing the damage evolutions in the bulk of C/SiC composite material accurately, and thus help to reveal the damage and failure mechanisms.

PARAMETER ANALYSIS OF DYNAMIC CHARACTERISTICS OF SANDWICH COMPOSITE PLATES

MA Jia-xing, FAN Ya-ping

2021, 0(6): 77-81. DOI: 10.19936/j.cnki.2096-8000.20210628.012

Asbtract ( 123 )

PDF (1306KB) ( 86 )

References | Related Articles | Metrics

The dynamical equations of sandwich composite plates were established based on the Kirchhoff assumption and Hamilton′s principle. The example verification was used to prove the correctness of the formula. Next, the effect of material parameters on the dynamic properties, for instance the thickness ratio of sandwich structure and the ratio of shear modulus of sandwich layer, was studied. The inherent frequency and loss factor were ascent with the increase of the ratio of thickness of sandwich layer to total thickness; inherent frequency was almost constant with the increase of the ratio of shear modulus of sandwich layer, and loss factors are descent with the increase of the ratio of shear modulus of sandwich layer. The first three frequencies and loss factors gradually increase with the increasing of elastic modulus ratio.

ANALYSIS OF SPRAYING PROCESS AND STUDY ON TECHNOLOGICAL PARAMETERSDURING SPRAYING ON COMPOSITE SATELLITE REFLECTOR BY ROBOT

XIE Zhong-qing, SHEN Hui, LI Peng-xin, ZHANG Zhi-bin, QIAN Zhi-ying, HAO Xu-feng

2021, 0(6): 82-87. DOI: 10.19936/j.cnki.2096-8000.20210628.013

Asbtract ( 163 )

PDF (6894KB) ( 87 )

References | Related Articles | Metrics

Metallization on the surface of carbon fiber composite reflector can effectively reduce the energy consumption of electromagnetic wave on the surface of reflector, while robot spraying can effectively solve the problem of unstable quality and low efficiency of artificial spraying products. Based on the spraying process of the robot, the influencing factors of the spraying process have been analyzed. The first is the trajectory of the robot, including the walking path pattern of the robot and the distance between adjacent gun paths. The second is the parameters of the gun unit, including the air pressure, the speed of the spraying wire, the walking speed of the gun and the relative height of the gun from the base surface. Based on a reflector, the appropriate parameters of automatic spraying have been determined, and a composite satellite antenna reflector containing metal coating has been prepared. The porosity detection result is 0.162 %, and the roughness result is Ra 1.417 μm, both of which are better than the conventional requirements, laying a foundation for the subsequent optimization.

THERMAL DISTRIBUTION AND DEFORMATION SIMULATION OFTYPICAL FRAME TOOLING IN AUTOCLAVE MOLDING PROCESS

WANG Min, XU Peng, GAO Long-fei, WANG Shi-jie, LUAN Ying-wei, LI Zhen-you

2021, 0(6): 88-93. DOI: 10.19936/j.cnki.2096-8000.20210628.014

Asbtract ( 157 )

PDF (8122KB) ( 152 )

References | Related Articles | Metrics

In this paper, the thermal distribution and deformation simulation of typical frame tooling for composite autoclave molding are carried out. The analysis results show that: Due to the role of circulating gas in the autoclave, there are windward and leeward sides in the autoclave, and the temperature of windward side first rises. During the heating process, the temperature difference of the tooling increases continuously. When the temperature rise stage ends, the temperature difference of the tooling reaches to the maximum state. In order to reduce the temperature difference in the tooling, an insulation platform can be added. For the tooling with complex frame structure, there are differences between the actual heat distribution results and the empirical cognition, the leading and lagging regions are not distributed in the head and tail area of the tank. Taking the temperature results as boundary conditions, it can be obtained that: Due to the existence of temperature gradient in autoclave, the thermal expansion deformation of tooling occurs. The maximum deformation is basically located at four corners, and the maximum deformation is about 0.9 mm, which is mainly due to the small thermal expansion coefficient of Invar steel. In actual manufacturing, it is a good choice to choose Invar steel as the mould material, which can effectively reduce the curing deformation of the composite during the curing process.

PARAMETRIC DESIGN OF SUTURE HEAD OF COMPOSITE MATERIALPREFORM WITH RIGID SANDWICH STRUCTURE

LIN Dong, DONG Jiu-zhi, CHEN Yun-jun, JIANG Xiu-ming

2021, 0(6): 94-101. DOI: 10.19936/j.cnki.2096-8000.20210628.015

Asbtract ( 118 )

PDF (3604KB) ( 122 )

References | Related Articles | Metrics

In order to solve the problem of yam breakage when using Tufting stitching process to stitch hard sandwich composite preforms, the stitching process was improved, and the stitching head was designed parametrically based on the improved Tufting stitching process. Firstly, the suturing mechanism of the suturing head is graphically simplified and analyzed, and the parameters are designed through the given working conditions of the process to obtain the structure of the suturing mechanism, the initial values of the parameters are calculated by the analytical method, and the boundary values of the parameters are calculated. The theoretical simulation analysis of the parameters is performed using Matlab. The results show that the relevant parameters calculated by the analytical method do not meet the design requirements. Based on the problems in the calculation of the parameters by the analytical method, a parametric virtual prototype is established using ADAMS, and the parametric modeling is performed to obtain a better value. Finally, the simulation analysis and verification of the obtained parameter values are carried out, and a virtual prototype and a processing entity prototype are established. The experimental results prove that the parametric design of the suture head runs stably, reduces the yarn breakage of the suture thread, meets the requirements of the work design, and lays a theoretical foundation for the development of subsequent engineering prototypes.

THE INFLUENCE OF THE PROCESSING METHOD OF WIND TURBINEBLADES SHEAR WEBS ON THE DESIGN AND MANUFACTURE

NIE Yi, XIONG Jie, WANG Jian-dong, GAO Shan, LI Xiao-bo

2021, 0(6): 102-105. DOI: 10.19936/j.cnki.2096-8000.20210628.016

Asbtract ( 183 )

PDF (2249KB) ( 124 )

References | Related Articles | Metrics

With the increasing scale of wind turbine blades, wind turbine blade lightweight is also concerned. As the main component of wind turbine blades, the weight control of shear web also has a great influence on the weight of blades. Aiming at the weight problem of shear webs of large wind turbine blades, the influence of different ways of grooved webs on weight and mechanics was studied to carry out process evaluation, mechanical evaluation and product weight evaluation in depth. The results show that the machining methods of sandwich materials with different grooves and holes have less influence on the mechanics of wind turbine blade webs and less influence on the process property, but have greater influence on the weight reduction of wind turbine blades, which is of great significance to the structural design of lightweight wind turbine blades.

EFFECT OF NEEDLE-PUNCHING ON THE IN-PLANE TENSILE MODULUS OF CFRP

YANG Cheng, ZHU Li-ping, LIU Yan-you, CHENG Hai-xia, GUO Ju-shang

2021, 0(6): 106-112. DOI: 10.19936/j.cnki.2096-8000.20210628.017

Asbtract ( 172 )

PDF (3673KB) ( 152 )

References | Related Articles | Metrics

By transferring the in-plane fibers to the out-plane, needle-punching improves delamination resistance capacity of composites and degrades in-plane properties. In this paper, we analyzed the needling process and constructed a type of RVE model to estimate the in-plane modulus of the CFRP. The simulation results of RVE models and the experiment were in well agreement. Effects of needling density, depth and distribution on the in-plane tensile modulus of CFRP were studied. The results show that under the same needled distribution, increasing needling density and depth would lead to the decrease of in-plane tensile modulus of composite materials, and the effect of needling depth is greater than needling density. A random distribution of needling will cause the dispersion of material properties, and the degree of dispersion will rise with the increase of depth and density of needling.

RESEARCH ON MANUFACTURE OF COMPOSITES BY NON-METALLICCOMPONENTS FROM WASTE PRINTED CIRCUIT BOARDS

LI Shuo, YIN Jin, GONG Jia-hao, ZHAO Lei, GAO Ting, LIU Rui-yong

2021, 0(6): 113-118. DOI: 10.19936/j.cnki.2096-8000.20210628.018

Asbtract ( 105 )

PDF (1120KB) ( 122 )

References | Related Articles | Metrics

With the development of information-based society, the number of electric product is increasing explosively, and its twice-born rate is accelerating. Therefore, a large number of electronic waste is produced. As a kind of hazardous waste, waste printed circuit boards has complex composition, and unreasonable disposal is easy to cause environmental pollution. At present, the recycling of metal components from waste printed circuit boards are developed but the treatment of non-metallic components is still in the research phase. The proportion of non-metallic component of waste printed circuit boards can reach about 70%, and it is the key point of recycling non-metallic component in waste printed circuit boards. Glass fiber and resin are the main components of non-metallic, and have high value utilization. The physical disposal methods of nonmetal are reviewed, in order to provide reference and thinking for the high value utilization of non-metal materials in waste printed circuit boards.

DEVELOPMENT REVIEW AND PROSPECT OF INDUSTRIAL COMPOSITES IN CHINA

XUE Zhong-min, WANG Zhan-dong, YIN Zheng

2021, 0(6): 119-128. DOI: 10.19936/j.cnki.2096-8000.20210628.019

Asbtract ( 222 )

PDF (2191KB) ( 249 )

References | Related Articles | Metrics

This paper reviews the development of industrial composites, raw materials and industrial organizations in China, introduces the application of composites in typical industrial fields in detail, and finally prospects the development direction of domestic industrial composites in the future.

Table of Content