COMPOSITES SCIENCE AND ENGINEERING

OPTIMIZATION OF LAYUP STACKING SEQUENCE IN COMPOSITE LAMINATE WITH CENTRAL HOLE BASED ON GENETIC ALGORITHM

GUO Yan, HUANG Bin, QIAN Zheng-hua

2018, 0(12): 5-10.

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The Genetic Algorithm (GA) was applied to conduct the optimal design of layup stacking sequence in laminate with central hole, where the maximization of fundamental natural frequency was selected as the objective function. The fundamental frequency was calculated by using the Rayleigh Ritz method based on independent coordinate coupling method. The optimal layup stacking sequence was obtained by the GA for random search of layup stacking sequence. The effects of layer number, hole size, length to width ratio and boundary condition on the optimal layup stacking sequence were investigated. Finally, it is found that the layer number and hole size do not affect the optimal layup stacking sequence, while the length to width ratio has great influence on the optimal layup stacking sequence.

CALCULATION METHOD FOR CRACK WIDTH OF FRP REINFORCED CONCRETE MEMBERS UNDER FATIGUE LOADING

SUN Li-xiang, Li Xing, YANG Zi-jiang

2018, 0(12): 11-15.

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FRP reinforced concrete members have many advantages, such as high bearing capacity, good durability and so on. At present, the bending performance of FRP reinforced concrete members is relatively more. However, in practical engineering applications, the components often work under repeated loads. In order to study the flexural performance of the FRP reinforced concrete members under fatigue load, the bending performance of the reinforced concrete members is studied. In this paper, the crack width of FRP reinforced concrete member under the action of fatigue load is studied. Based on the calculation theory of crack width of FRP reinforced concrete members under static load, the calculation formula of FRP reinforced concrete member under fatigue load is obtained by introducing the relevant parameters, and the modified formula is tested. The study shows that the fatigue damage of the FRP reinforced concrete member under the continuous load of fatigue load will result in the fatigue damage in the member, and the bond performance between the FRP reinforcement and the concrete, which makes the overall stiffness of the component lower, the early initiation of fatigue crack, and the increasing of the load cycle and the number of action times. The crack width will gradually increase, and eventually tend to a stable range of change. By introducing the parameter a of the bond slip of the FRP bar and concrete and the strain increasing coefficient of the concrete in the compression zone, the calculation method of crack width of FRP reinforced concrete members under fatigue loading is obtained.

STUDY ON SIMPLIFIED TRUSS MODEL FOR COATED FABRICS

MA Ben, HAO Sheng-jie, XU Jun-hao, ZHAO Yu-shuai

2018, 0(12): 16-20.

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Based on the unit cell model, a simplified truss model for predicting the mechanical properties of coated fabric membrane materials was proposed. According to the tensile test data of the component materials, the fourth-order polynomial with true strain as the variable is selected to describe the nonlinear behavior of the fiber bundle, the mechanical response of the coating is reflected by the ideal elastoplastic model, the microstructure and the structure size parameter of the film is obtained by scanning electron microscopy. The above model was realized by ABAQUS finite element software and UMAT subroutine to predict the tensile properties of the film. The results show that the overall prediction results are good, and the maximum error is about 20%. The main reason for the error is that the nonlinearity of the contact between the fiber bundles and between the fiber bundle and the coating cannot be reflected in the model.

PREPARATION AND STUDY OF TOUGHENED BISMALEIMIDE RESIN MODIFIED BY BENZOXAZINE

ZHOU Ru-jin, WANG Xiang, WANG Jun, CAI Hao-peng

2018, 0(12): 21-27.

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The unmodified pure bismaleimide resin has the shortcomings of poor solubility, high curing processing temperature and ease of brittleness fracture. 2,2′-Diallylbisphenol A (DABPA) and 3-aminophenylacetylene (m-APA) as chain extender toughening agent, bisphenol A phenylbenzoxazine (BOZ) as toughened agent were adopted to copolymerize with 4,4′-bismaleimidodiphenyl methane (BDM) resin. Then, a kind of resin matrix was prepared, which presented high temperature resistance and high toughness. The curing reaction of BOZ/BAD422 resin system was studied by Fourier transform-infrared spectroscopy and differential scanning calorimetry analyses, respectively. Mechanical measurements, thermal properties analysis, and microanalyses were conducted to assess the toughness and morphology of the cured blends. The research results show that the addition of BOZ resin can effectively increase the BMI resin toughness. In the range of 0~30wt% BOZ resin, the impact performance of the blended resin system is increased with the increase of the quality fraction of BOZ resin. The maximum impact performance reaches up to 18.3 kJ/m², which was 53.8% higher than the BAD422 system. The bending strength is slightly increased and remains at a high level compared with the BAD422 system, reaching at 145.9 MPa. The bending modulus slowly increases with the increase of BOZ content. However, heat resistance and thermal stability are reduced. But glass transition temperature (T_g) can still reach 250.8 ℃ and the initial decomposition temperature (T_5%) is 346.5 ℃ after the addition of 30wt% BOZ, indicating that the thermal performance is still good.

STUDIES ON INTERFACIAL BONDING PROPERTY AND INFLUENCING FACTORS OF PBO FIBER AND EPOXY RESIN

WANG Qian, GU Yi-zhuo, LIU Ning, ZHANG Cheng-shuang

2018, 0(12): 28-35.

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In this study, physical and chemical properties and interfacial adhesion with epoxy of domestic and imported poly-p-phenylene benzobisoxazole (PBO) fibers were studied. Two kinds of epoxy systems were developed. Wettability between these resins and fibers was evaluated using static contact angle method, and interfacial shear strength (IFSS) between PBO fiber and resin was measured by single fiber pull-out test. Unidirectional PBO/epoxy composite laminate was fabricated using wet winding molding process. Then, interlaminar shear strength (ILSS) was tested, and the effects of resin matrix and process conditions on ILSS were analyzed. Experimental results show that physical properties of domestic and imported PBO fiber are similar, but imported PBO fiber has higher content of surface active groups and higher IFSS with epoxy resin. Moreover, adding coupling agent into resin can improve interfacial shear strength. The developed resin systems show good wettability and interfacial adhesion with PBO fiber. Their ILSS can reach 48 MPa, and fiber content and modulus of resin matrix are believed to affect ILSS.

STUDY ON DYNAMICS PERFORMANCE AND INFLUENCE PARAMETERS OF COMPOSITE LAMINATES

WANG Shao-qing, LIU Peng, LIANG Sen

2018, 0(12): 36-40.

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In order to obtain the vibration characteristics of composite laminate structure, the composite laminate is taken as the research object. The kinetic properties of the structure were analyzed by finite element method. The influence of the main elastic modulus ratio, length to width ratio and layup mode on the natural frequency of the structure is obtained. The results show that the initial fourth natural frequencies of the structure increase with the increase of the main elastic modulus ratio and the length to width ratio. As the length to width ratio of the structure increases, the initial fourth natural frequencies of the structure increase with increasing amplitude. The first-order natural frequency and the second-order natural frequency change approximately linearly with an increase in the ratio of the principal elastic modulus. The initial fourth natural frequencies of the symmetric laminate structure, the antisymmetric laminate structure and the asymmetric laminate structure increase with the increase of the layer thickness, compared with the other two laminate methods, the initial fourth natural frequencies of the antisymmetric laminate structure is larger.

TENSILE DEFORMATION AND DAMAGE BEHAVIOR OF CARBON FIBER THREE DIMENSIONAL FOUR DIRECTIONAL BRAIDED COMPOSITES

SHANG Ya-jing, YIN Han-fei, ZHOU Wei, ZHANG Yan-nan

2018, 0(12): 41-46.

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In order to study the tensile deformation, damage and failure behavior of carbon fiber three-dimensional braided composites, the acoustic emission and digital image correlation complementary techniques are applied to the study of carbon fiber three-dimensional and four-directional braided composites. Meanwhile, acoustic attenuation characteristics, tensile deformation and damage destruction processes are monitored simultaneously. Besides, the corresponding speckle images and AE characteristic signals are acquired dynamically. Then the related calculations and AE signal processing are performed. The results show that the attenuation of the composite along the braiding yarn direction is significantly lower than that of other directions, and the farther the distance between the broken lead and the sensor is, the greater the attenuation amplitude is. At the early stage of the specimens loading, AE signal levers are a bit low and the displacement fields as well as strain fields change steadily. In the accumulation phase of damage, the relative energy of AE increases gradually, and the material exhibits obvious elastic deformation characteristics. When the load reaches the maximum value, both the displacement and strain values in the tensile direction and the horizontal direction reach the maximum, and the specimen fails and fractures. The comprehensive monitoring and analysis of AE and DIC can better describe the damage evolution and destruction process of the specimen, and provide reference for the safety evaluation and health monitoring of carbon fiber three-dimensional braided composites.

NUMERICAL ANALYSES ON MODAL SHAPE AND IMPACT PERFORMANCE OF COMPOSITE SOFTBALL BAT

XIE Xin, MAO Jia-jia, CHEN Ji-ye

2018, 0(12): 47-52.

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Comparied with the traditional aluminium alloy softball bat and wooden softball bat, carbon fiber composite softball bat hare some major advantages, such as light in weight, high strength, high impact resistance, and high fatigue life. In this paper, ANSYS/LS-DYNA finite element software was used to establish a composite softball bat model. The experimental results^[6]could be predicted by the proposed numerical model with sufficient accuracy. Moreover, the proposed numerical model was used to simulate three common composite softball bats on modal shapes and softball rebound velocities. The results demonstrated that Demarini softball bat has smaller bending modal shape and hoop modal shape, which resulted in good working performance, and such softball bat also has better batting performance.

INFLUENCE OF THREAD FABRICATION PROCESS ON PROPERTY OF THREAD CONNECTION OF THE HIGH PRESSURE FIBERGLASS TUBING

LI Hou-bu, GAO Long, LIU Lang, LIU Hong-feng

2018, 0(12): 53-56.

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High pressure fiberglass tubing has been an important solution for corrosion of the conventional steel tubing. However, the well depth and application fields of fiberglass tubing had been largely limited due to its lower axial tensile properties caused by the weak thread connection. This paper studied the influence of thread component, thread profile, thread length and thread interface on connection properties of the high pressure fiberglass tubing (2 7/8 in, PN17 MPa) by using the impact test and tensile test. On the basis of thinking about the fabrication of thread, the tensile strength of thread can be highly improved by adding 1.1wt% short carbon fiber and 1wt% coupling agent (K550) with a suitable increased thread length. With the same fabrication process, the maximum failure load of the round thread is increased by 28% relative to that of the buttress thread. The connection property of the thread with the notched interface is not improved obviously. However, the notching process on the thread interface increases the complexity of the thread fabrication. Thus, notching on the thread interface is not recommended.

EFFECT OF THE TACKIFIED PRESSURE ON THE TENSILE PROPERTY OF THE PES FILM MODIFIED COMPOSITES

QU Li, LI Jin, KANG Shao-fu, ZHANG Dian-ping

2018, 0(12): 57-61.

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The composites have widely used in the aerospace and automotive field for the excellent performance. However, the high cost has hindered its further use and production of the high property composites with low cost has obtained the most concerns. In the present study, the hot-press tackified process was provided to improve the disadvantage of the VARTM of low mechanical property by using the PES (Polyethersulfone) film material interval stacked into the fabrics under certain temperature and pressure to get the modified preforms. Finally, the modified composites were obtained with the VARTM on the modified preforms. The pressures of 0.1 MPa, 0.3 MPa and 0.6 MPa were used to study the effect of tackifier pressure on the tensile strength and modulus on the modified composites, as compared to the unmodified composites. The results indicate that the tensile strength of the modified composites for the three tackifier pressures have improved by 16.78%, 41.21% and 29.47% respectively, and the tensile modulus have improved by 2.48%, 19.01% and 13.22%, which provide the guidance to obtain the high performance composites with low cost process of VARTM.

RESEARCH ON CUTTING FORCE AND MACHINING DAMAGE OF CFRP UNIDIRECTIONAL PLATE AT DIFFERENT TEMPERATURES

GE En-de, WANG Dong, LI Ru-peng, CHENG De

2018, 0(12): 62-66.

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Carbon fiber reinforced plastic (CFRP) have shown great advantages in aerospace high-end equipment because of their advantages of light quality and high strength. However, CFRP is difficult to be processed. Its mechanical and thermal properties show obvious anisotropy in different fiber directions. It is easy to cause damage during processing. Meanwhile, temperature changes also greatly affect its process ability and aggravate the degree of damage. Therefore, in order to realize the high quality processing of CFRP, it is very important to clarify the effect of temperature on the cutting performance of CFRP. This paper set up the experimental system to control temperature to obtain the change of cutting force and machining damage on different cutting direction. It is found that not only the change of resin matrix caused by temperature will affect the mechanical properties. With the increase of cutting angle, the fiber reinforce phase in the material also becomes more important. This paper provides new data and theoretical support for the optimization of subsequent process parameters and the development of new technology.

DESIGN AND DEVELOPMENT OF IRREGULAR HEXAGONAL HONEYCOMB ABSORBING MATERIALS

GUO Xue-song, CHEN Le, SUN Hui-min, GU Zhao-zhan

2018, 0(12): 67-71.

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Compared to analogous regular hexagonal honeycombs with the same relative density, the heteromorphic honeycomb has advantages in mechanical properties and has more obvious anisotropy, but its high geometric complexity would bring troubles to the design of radar absorbing materials. Based on the equivalent medium theory, simulation software was used to simulate the electromagnetic parameters of the heterogeneous honeycomb to obtain the equivalent electromagnetic parameters. The complex permittivity and microwave-absorbing properties were investigated in the frequency range of 2 GHz~18 GHz. The calculated data were in good agreement with the experimental results. Based on the model, honeycombs of 15 mm thickness with different draw ratios were optimized in the case of the same absorber increment. The band width can reach nearly 12 GHz as the microwave-absorption reflectivity was below than -10 dB with thickness of 15 mm. The minimum reflectivity of -30 dB, -22 dB were obtained at 4 GHz and 12 GHz, respectively, for the i=0.68 honeycomb with 41.25wt% absorbers. The calculated results have certain practical value and wide applicability for similar honeycomb structure design and absorbing performance optimization.

STUDY ON A MOLDING PROCESS OF THE PUMP INJECTION STATOR PIPE

ZHU Xiu-di, SUN Chao-ming, SONG Zhi-qian, HOU xin

2018, 0(12): 72-77.

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Pump-jet propeller is a kind of water-jet propulsion device of aircraft. It is mainly composed of pump-jet stator duct and rotor. It can greatly improve the cavitation performance and reduce the noise of itself. This paper introduces the development technology of a pump-jet stator duct. As a main component of the pump-jet propeller, the pump-jet stator duct is mainly composed of two parts: the stator and the duct, in which the stator is divided into two parts: the hub stator and the stator blade. According to the structural characteristics and technical requirements of pump-jet stator conduit, through the design of connection structure of stator hub, stator blade, conduit, design of tube skin structure and so on, the design and manufacture of molding technology scheme are studied in this paper. The product of composite pump-jet stator duct has been developed successfully, and the application of composite pump-jet propeller in underwater vehicle in China has been promoted by testing load, model value and hydraulic pressure, which has remarkable social benefit value.

RESEARCH ON CABIN FORMED BY SPLITTING METAL MOLD ASSISTED WINDING PROCESS

YU Yong-hong, YANG Jing-wen, LIU Zhao-peng, LI Ze-ying

2018, 0(12): 78-81.

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In this paper, a splitting metal mold assisted winding process, which could be used for internal grid rib reinforced cylindrical shell composite structure, was developed due to the background of the development of a certain type of composite material cabin. A scaling prototype of carbon fiber composite material was designed and formed by splitting metal mold according to the structural features. The research results show that complete shape and accurate dimension of the scaling cabin can be obtained through the use of splitting metal mold with good dimensional stability and high precision, but high labor intensity. The issues are discussed in the paper. Experiment results show that the internal grid reinforced cylindrical shell composite structure can be integrally formed by the splitting metal mold assisted winding process. Ideas on the future research composite material cabin are proposed in the paper.

STUDY ON PROPERTIES OF PHENOLIC MODIFIED POLYARYLACETYLENE RESIN MATRIX COMPOSITES

MIAO Chun-hui, ZHAI Quan-sheng, YE Hong-jun, ZHAO Yan-wen

2018, 0(12): 82-88.

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Polyarylene acetylene (PAA) resin is an ideal substrate for ablative thermal protection composite materials because of its high carbon residue rate and low water absorbency. The PAA resin was modified by phenolic resin. The curing reaction characteristics and shrinkage characteristics of different resin systems were analyzed before and after the modification. Composite laminates were made with different fiber/resin systems. The bending and interlaminar shear properties of laminates were tested, and the cross section and the fracture appearance of different system laminates were compared. The results show that the mechanical properties of the laminates made of PAA resin modified by phenolic resin are obviously improved, and the defects in the laminates are obviously reduced. After the modification of the phenolic resin, the curing shrinkage of the PAA resin is reduced and the surface tension of the PAA resin is reduced. In the curing process, the phenolic resin and the PAA resin are prepolymerized. These properties and the change of curing properties can reduce the defects of the laminate.

OPTIMIZATION OF HIGH STABLE COMPOSITE FRAME STRUCTURE IN THE SATELLITE

XING Si-yuan, LIU Hong-xin, ZHANG Yu-sheng

2018, 0(12): 89-95.

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With the increasing accuracy of the satellite payload, the thermal deformation of the frame structure as the satellite body and payload transition in the space environment cannot be ignored, and the thermal stability of the structure needs to be investigated at the initial design. In this paper, Hyperworks finite element software is used for satellite high-stability composite frame structure, and the topological optimization of the structure is emphasized. The structural configuration, the thickness of the ply and the angle of the ply are also investigated. The weight, stiffness and heat of the composite frame are also considered. The results show that compared with the original configuration, the optimized frame structure quality is reduced by 25.1%, the fundamental frequency is increased by 48.8%, and the thermal deformation is reduced by 57.1%. The Hyperworks topology optimization method significantly improves the composite frame structure, can guide the design of satellite high stability composite structure.

RESEARCH PROGRESS OF AEROENGINE COMPOSITE STATOR BLADES

WANG Yi-lin, LIU Tian-sheng, LIU Dong, SHI Peng-cheng

2018, 0(12): 96-101.

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As a core component of compressor, the stator blades have decisive influence on the performance of aeroengine. Adopting fiber reinforced plastic composites in lightweight engine fabrication plays a key role in realizing weight reduction, large thrust-to-weight ratio and high fuel efficiency. This paper mainly presents the designing process and technical progress of fiber reinforced resin-based composite blades, and then reviews the related research on the manufacturing process of stator blades from three aspects: pre-forming, forming and cutting. In addition, underlining the importance of prophase design in the integrated development of aero-engine cold-end. Finally, by analyzing the successful foreign application of typical composite blades and according to the development trend of current design technology and molding process, the paper highlights the visible position of 2.5D woven composites in the development of aerospace engine stator blades in the future, and prospects for the future development of aeroengine composite stator blades.

SUMMARIZE FOR TECHNOLOGY OF AUTOMATED FIBER PLACEMENT SOFTWARE AND APPLICATION IN DOMESTIC

HUANG Wei, YAO Feng, ZHENG Guang-qiang

2018, 0(12): 102-106.

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As the automated fiber placement(AFP) technology has been extensively applied in the area of wide plane composite manufacture, AFP software technology in the design and fabrication of composite is becoming increasing significant. CADFiber and Vericut have been purchased in domestic, the key technologies of the commercial AFP software on trajectory planning, post processing, and simulation are introduced and compared, especially the difference of trajectory planning algorithm and post processing are discussed. Furthermore, the development of AFP software and the application of the purchased software in domestic are reported. On account of the gap between the domestic AFP software and commercial software in foreign, beneficial reference for the development of independent intellectual property rights of AFP software through introducing the CADFiber and Vericut system has provided.

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