COMPOSITES SCIENCE AND ENGINEERING

GEOMETRIC NONLINEAR BENDING ANALYSIS OF PIEZOELECTRIC FUNCTIONALLY GRADED PLASES BASED ON NEUTRAL SURFACE

LI Shuang-bei, WU Hai, CUI Kai

2016, 0(11): 5-10.

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According to the concept of neutral surface, the basic equation for geometric nonlinear static bending of functionally graded material (FGM) plates was established. By Ritz method, the effects of gradient index and material properties taking into account of the geometric nonlinear on bending deformation of FGM plates were analyzed. Also,the variation of deformation control was explored when FGM plates were subjected to different electric fields.The accuracy of the present equation and method is verified by comparing them with known results. The static deformation of FGM plates was solved by the geometric nonlinear equation. Analysis results show that the difference increases with the increase of neutral axis shift. The neutral surface should be considered when using piezoelectric material to control the deformation of FGM plates.

EFFECT OF CARBON NANO-FIBER ON THE PERMEABILITY OF GLASS FIBER COMPOSITE

DONG Meng-yao, LU Zhi-li, LV Guang-chao, ZHANG Na

2016, 0(11): 11-14.

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Vacuum assistant spray method was used to fabricate the glass fiber composite with 0.5% and 2% CNF. Meanwhile, the saturated permeability and non-saturated permeability of composites were measured and compared. The results show that the saturated permeability and non-saturated permeability of 0.5% and 2% CNF composites were reduced. The saturated permeability of Z direction was 20% compared to Y direction without CNF and reduced to 10% with CNF addition. The permeability of Z direction was almost zero when the porosity was less than 47%. The 0.5% CNF had little influence on the non-saturated permeability of the glass fiber matrix, but the non-saturated permeability of composite with 2% CNF was 20% compared to the glass fiber matrix.

EXPERIMENTAL INVESTIGATION ON TENSILE BEHAVIOR OF BIAXIAL WARP-KNITTED AND 3D ORTHOGONAL WOVEN COMPOSITE MATERIAL

MA Ya-yun, TAO Nan-nan, GAO Xiao-ping

2016, 0(11): 15-19.

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For comparing the tensile behavior of biaxial warp-knitted and 3D orthogonal woven composite along to 0° direction and 90° direction, two kinds of composites which were reinforced with 0°/90° biaxial warp-knitted glass fabric, 3D orthogonal woven fabric and the mixture of epoxy(E-2511)and curing (2511-1BT) were manufactured by means of VARTM (vacuum assisted resin transfer molding), respectively. The mechanical behavior of specimens along to 0° direction and 90° direction were experimentally executed. The result shows that the tensile strength and specific strength of biaxial warp-knitted composite along to 0° direction were a little higher than those of the 3D orthogonal woven composite. However, the elastic modulus and specific modulus were weaker than those of the 3D orthogonal woven composite. These were closely related with the effect of yarn count and weaving density of the reinforcement in composite. The tensile fracture morphologies of composites show that the tensile laminates failure, yarn pull-out and debonding of fibers in cross section of 3D orthogonal woven composite material have been significantly improved compared with the biaxial warp-knitted composite since the role of Z yarn.

RESEARCH ON HOLLOW AND SOLID GLASS FIBERS AND THEIR COMPOSITE MATERIALS

ZHANG Wen-jiao, PENG Chao-yi, YANG Jin-shui, YANG Fu-biao

2016, 0(11): 20-26.

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To study the properties of hollow glass fiber and its composite, in this work, filament and multifilament tensile strength of hollow glass fibers and solid glass fibers were compared and a glass fiber filament strength model was established. Furthermore, hollow/solid glass fiber reinforced polymers (HGFRP/SGFRP) were fabricated by winding process and molding process, and tensile property and bending property of these two composites were tested. The result indicates that the filament tensile strength of hollow/solid glass fiber coincides well with the Weibull distribution model. Tensile strength and bending strength of hollow glass fibers are lower than that of solid glass fibers. It also shows that the specific tensile/bending strength of HGFRP is less than that of SGFRP. However, the specific tensile modulus and the specific bending modulus of HGFRP are higher than that of SGFRP. Consequently, it can be deduced that hollow glass fibers can be served as a promising reinforcement for the next-generation light-weight composites.

COMPRESSIVE PROPERTIES STUDY ON SEMI-CIRCLE AND SINGLE JOINT STRINGER END OF WING

ZHANG Ming-xing

2016, 0(11): 27-31.

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Compression tests were performed on semi-circle and single joint stringer end of wing upper panel samples. Load-strain curves through the strain flowers around the holes under axial compression load were obtained. The results show that breaks mainly appear on the area near the first row fasteners on joint and stringer flange. A finite element analysis model is established, for which the result is slightly higher than the experimental result because the damage and rigidity are not introduced during the finite element analysis.

STUDY ON RHEOLOGICAL PROPERTIES OF EPOXY IN VARI PROCESS

WU Jia-nan, NI Ai-qing, ZHANG Sheng, WANG Ji-hui

2016, 0(11): 32-38.

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A constant temperature viscosity model of 2511-1A epoxy resin system is established in this study based on viscosity experiments. The dual Arrhenius rheological model, the engineering viscosity model and the combined engineering viscosity model are investigated for the application in the resin system, respectively. The results show that the combined engineering viscosity model reflects the dependence of the viscosity on temperature and time better, with the craft time window of resin predicted. According to the relationship between temperature and time, a variant temperature combined engineering viscosity model is established. The change in viscosity is predicted under different heating rates. Good agreement is achieved between the prediction and experimental results, which shows its potential application for the selection of technical parameters of hot pressing process.

RESEARCH ON THE FATIGUE LIFE PREDICTION OF COMPOSITE VESSEL UNDER MULITA-AXIAL LOADING

HUANG Qi-zhong, ZHENG Jin-yang, HU Jun, REN Ming-fa

2016, 0(11): 39-45.

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There are obvious disadvantages in the ASME pressure vessel code, which is used to calculate the fatigue life of cylinders by the adoption of equivalent strain method, because it cannot take account of the multi-axial non-proportional loading effect. This paper studies the multi-axial low-cycle fatigue life of composite cylinders by adopting the corrected Brown-Miller algorithm as well as the effect of autofrettage pressure, metal liner thickness and single layer thickness on the composite cylinders′ fatigue life, and gives a method for increasing the composite cylinders′ fatigue life.

ANALYSIS OF THE CHEMICAL RHEOLOGICAL BEHAVIOR AND MODELING OF THE PHENOLIC RESOL RESIN FOR VARTM PROCESSES

TIAN Mou-feng, TAN Juan-juan, WANG Lei, SUN Yi

2016, 0(11): 46-50.

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A new kind of phenolic resol resin named Z615101, was developed for vacuum assisted resin transfer molding process (VARTM). The resin has the advantages of higher char yield, lower initial viscosity and longer pot life of the process as compared to conventional phenolic resol resin. It is suitable for manufacturing advanced fiber-reinforced composite materials ranging from smallarticles of simple shape, to large articles with complex shape and high structural performance characteristics, especially large complex three-dimensional part of advanced composite materials for aerospace application. The rheological behavior of phenolic resol resin was studied. The curve of dynamic viscosity-temperature for Z615101 was also studied. The Arrhenius viscosity equation was established based on the measured isothermal viscosity curves. Analysis results indicated that the model values were in good agreement with the experimental results. The optimal processing temperature window was between 70~80 ℃ learned from the isothermal viscosity curves, which were established on the basis of model equation and would provide the theoretical foundation for the actual VARTM processing molding.

STUDY ON THE EFFECTS OF HYGROTHERMAL DAMAGE CHARACTERISTICS OF BRAIDED CARBON FIBER COMPOSITE SUBJECTED TO LIGHTNING

HUANG Lai, LI Yi-chao, CHE Hong-wei, ZHOU Ting

2016, 0(11): 51-58.

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In this paper, damage characteristics of two typical ply ([45₂/0₂/-45₂/90₂]s、[30₂/0₂/-30₂/90₂]s) woven carbon fiber composite material samples, which are subjected to different hygrothermal environments (23 ℃ and 60 ℃), were studied. At the same time, the microscopic mechanism characteristics of two kinds of standard sample member ply by lightning strike at 60 ℃ after a hygrothermal environment immersioning conditions were analyzed. The results show that hygrothermal aging significantly increases the lightning strike damage regions. While, the influence of stacking sequence on the damage forms is decreased. SEM results show that the fiber/matrix interfacial bonding is severely degraded by moisture.

EFFECT OF GAP COMPENSATION ON AXIAL STIFFNESS IN SINGLE BOLT FASTENING COMPOSITE LAMINATES

JIANG Qi-lin, AN Lu-ling, YUN Yi-shen, GAO Guo-qiang

2016, 0(11): 59-64.

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The axial stiffness of the part that be connected will directly affect the formation of the clamping force, the maintain and recession of clamping force in the process of bolt fastening under different working conditions. As a result , a significant influence will appear on the reliability and stability of the assembly structure. On account of the material property of composite laminates itself and the limitation of the molding process method, small assembly gaps are difficult to avoid in the composite laminates bolted fastening. Liquid shim is commonly be used to compensate for the small gaps between the laminates parts in aircraft assembly. First, with the single bolt fastening of composite laminates as the object, the finite element model is built by using ABAQUS software. And two cases are considered in the process, that is, with a liquid shim to compensate for the gap and without it. Secondly, the experiment is designed: the effective contact surface dimension of the bolt fastening. The results of the model are in good agreement with the experimental data. Under different liquid shim compensation parameters, the effective contact area of the bolt fastening is studied based on the model. Research results show that with the increase of the gap′s thickness, liquid shim will significantly improve the axial stiffness of laminates relative to the forced assembly. In the thickness range of process specification, the increase of the gap′s thickness plays more obvious role in promoting the laminates axial stiffness. At the same time, the use of high elastic modulus of liquid shim is more beneficial to improve the axial stiffness of laminates. It is suggested that gap compensation process must be carried out when the thickness of gap reached 0.05 mm in aircraft assembly.

THE INFLUENCE RULE ANALYSIS OF INTERFERENCE IN MULTI-RING

ZHUANG Qian-xin, WANG Dong, ZHANG Xian-biao

2016, 0(11): 65-69.

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The multi-ring flywheel rotor can improve the stress level inside the composite material, which can also solve the problem that the radial strength of extension of the composite material is insufficient. The influence of the designation result from the interference and the number of rings is complicated, so it′s important to design it rationally. The multi-ring composite material flywheel rotor was analyzed in different interference conditions to obtain the effect that the interference has on the stress level inside it. From the results, it can be seen that the interference has distinct influence on the adjacent rings. However, it has less influence on the rings that isn′t adjacent to it. The more the rings are, the less the minimum interference needed to guarantee that the rings won′t separate. But, the stress between the hub and the composite material is raised obviously so that it may exceed the maximum compressive strength. Changing the interference that is adjacent to the position where the stress level isn′t satisfied is the most effective way to improve it.

COMPARATIVE ANALYSIS ON TWO KINDS OF VACUUM INFUSION EPOXY RESIN SYSTEMS FOR LARGE-SCALE WIND TURBINE BLADES

DENG Shuang-hui, FENG Yun-long, LI Han, LV Xiao-ping

2016, 0(11): 70-74.

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In this work, two kinds of vacuum infusion epoxy resin systems, i.e. the domestic product MERICAN 3311A/B and the imported product, were comparatively analyzed with each other under the same experimental conditions for large-scale wind turbine blades application. The basic characteristics, viscosity change profiles, exothermal peak, gelation time and mechanical properties of both epoxy resin systems were systematically studied. The results indicated that, the domestic product MERICAN 3311A/B possessed a lot of advantages, such as low viscosity, long pot-life, low exothermal peak, fast curing at medium-high temperature and excellent mechanical properties, which were totally in accordance with the GL certification requirements. Besides, the properties of the domestic product MERICAN 3311A/B already reached or even partially exceeded the level of the imported product. Therefore, it can be concluded that the domestic product MERICAN 3311A/B can meet the requirements for the performances of epoxy resin used in large-scale wind turbine blades.

INVESTIGATION ON WEAR PROPERTY AND THE MECHANISM OF POLYMER MATRIX COMPOSITES PROTECTED BY CERAMIC TILES

ZHANG Lian-wang, ZHONG Xiang-yu, BAO Jian-wen

2016, 0(11): 75-80.

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In order to raise the abrasion resistant level of polymer matrix composites, Al₂O₃ceramic tiles were used as the protection coating. Wear tests of composites and ceramic tile were performed by to-and-fro wear machine. Surface profiles and indent parameters of samples after wearing test were drawn by Phase Shift MicroXAM-3D. The model of data analysis and evaluation was built to analyze the mechanism of wear process. The results demonstrate that the abrasion resistant level of polymer matrix composites is raised obviously by protection of ceramic tiles. The load is increased from 40 N to 100 N for similar abrasion resistant level. The indent depth of polymer matrix composite protected by ceramic tiles increases greatly while the abrasion grade of steel ball decreases rapidly as the load is increased from 100 N to 150 N. The mechanism of wear process is explored to explain the change.

STUDY ON SAFETY AND RELIABILITY OF 10 kV COMPOSITE POLE IN THE STRONG WIND

HE Chang-lin, ZHU Xiao-dong, SHEN Fan, LIU Huan-huan

2016, 0(11): 81-84.

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For 10 kV composite pole in the coastal windbreak reinforcement engineering, this paper analyzed the windproof ability of 10 kV composite pole. The results showed that 10 kV composite pole could resist at least 17 typhoon. The stochastic theory was used to simulate dynamic response of the 10 kV composite pole distribution circuit in the average wind and fluctuating wind by the finite element software ANSYS. The results showed that the bending moment at the bottom of the pole had so big change that the maximum was promoted up to 4 times of the standard bending moment. And, the displacement at the top of the pole became larger, but the distance between wires was within the scope of the security. By comparison, it can be seen that, no matter the carrying capacity and the dynamic characteristic, the composite pole has more advantages than the concrete pole.

STUDY ON THE FORCE ANALYSIS OF THE BURIED COMPOSITE PUMPING WELL

SHI Qiang, WANG Xin-wu, ZHANG Xiao-yu, YANG Nan

2016, 0(11): 85-89.

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This paper introduces a new type of composite pumping station wells, which uses glass fiber reinforced plastic (also called glass steel structure) instead of pumping station with concrete, brick masonry structure. Based on the theoretical analysis, the strength, stiffness and stability of the glass fiber reinforced plastic pump well with 3 meters diameter are analyzed by finite element method. The results show the hoop stress of the buried FRP pumping station analyzed by finite element software fits with the theoretical analysis nicely, which can be used as a basis for thickness design of the wall. The axial stress analysis by finite element software results in big difference from the theoretical analysis for the latter didn′t consider the influence of rib reinforcement. While the value is relatively small, thus it is not considered as the controlling factor for thickness design of the wall. The minimum safety factor of stability is related to the section of rib reinforcement, and enlarging the height of rib reinforcement can improve the global stability of the pumping station effectively.

STUDY ON COMPRESSION PROPERTY OF ARAMID Ⅲ FIBER AND IT’S HYBRID COMPOSITES

YAN Wen-cong, ZENG Jin-fang, LI Chao-yang, LEI Tao

2016, 0(11): 90-93.

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Compression properties of aramid Ⅲ fiber composite, carbon/aramid Ⅲ fiber composite and carbon fiber(CF) composite were studied. The axial compression of ?150 mm shells in these consituations were also tested. The result shows that compression strength and modulus of hybridcomposites are improved with the increase of the CF volume (V_CF). The compression strength and modulus of hybid composite improve in respective by 57% and 20.9% when the relative volume of CF is 28.5%. Compared with the axial compression of aramid Ⅲ fiber shells, the axial compression of 150 mm shells (V_CF=46%) reaches up to 138.6 kN and improves by 18.5%. Nonetheless, it still shows minus effect.

THE ANALYSIS OF MECHANICAL PERFORMANCE OF THE BURIED FRP PIPE FOR TRANSFERRING RAW WATER IN SOFT SOIL FOUNDATION IN THE PIPE EXPLOSION ACCIDENT

LI Bin, JIANG Hao, ZHANG Guo-li, NIE Jin-xu

2016, 0(11): 94-99.

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In the past years, serious tube bursting accidents occurred six times in buried large diameter FRP pipe in the water distribution system from a certain southern city, which threatened the reliability of the water distribution system. In order to study the reasons of tube bursting accidents, in this paper, a series of mechanical properties tests, containing tension, compression and bending tests were carried out on the pipe at the explosion. At the same time, according to the geological conditions of pipe, combining the mechanical performance parameters of the pipe, the mechanical properties of buried FRP pipe were calculated and analyzed theoretically, including the long-term deformation of pipe, the strength and the stability of pipe wall. On the basis of the results of the test and theoretical calculation, it is concluded that the reasons of the explosion are inferred, and the corresponding suggestions are put forward to reduce the frequency of pipe explosion accident.

REVIEW ON COMPRESSIVE BEHAVIOR OF FRP CONFINED CONCRETE COLUMNS UNDER CYCLIC LOADING

CUI Yu-qiang, WANG Zuo-hu, YUAN Fei-fan

2016, 0(11): 100-106.

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As a kind of new and high performance material, FRP is widely used in civial engineering recently, especially for strengthening structures to resist earthquakes, because it could increase the strength and ductility of components. Many researches about reinforcement on the concreted column by use of FRP focus on the function of one-way load, both at home and abroad. However, few studies about the influence of cyclic load have been done. So making an in-depth analysis of comperssive performance of concrete columns reinforced by FRP under the influence of cyclic load is of great value in theory and engineering practice. This paper sums up the researches of comperssive performance of concrete columns reinforced by FRP under the influence of cyclic load from scholars around the world. Therefore, we can draw the following conclusions. ① The stress-strain curve, under the function of one-way load, could be used as an envelope under the function of cyclic load; ② cyclic load and unload will cause stress losses, the uniqueness theory can not stand; ③ when the sectional dimension increases, the reinforcement effect of FRP cloth decreases. In the end, this paper also puts forward some suggestions and looks into the prospects for studies which will be carried out in the near future.

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