COMPOSITES SCIENCE AND ENGINEERING

STUDY OF PERFORMANCE AND ENHANCEMENT MECHANISM OF SILANE COUPLING AGENTMODIFIED BASALT FIBER REINFORCED ASPHALT MUCILAGE

XIANG Yu, LIU Zhao-hui, LIU Li, LI Sheng

2016, 0(5): 5-11.

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Because of the lack of existing studies of silane coupling agent modified basalt fiber reinforced asphalt mucilage, this study used silane coupling agent KH-550 to modify the surface of basalt fiber and then prepared fiber reinforced asphalt mucilage in different powder binder ratios and dosages of fiber. The performance of low temperature, middle temperature and high temperature of these specimens were studied by low temperature ductility test, elastic recovery test, cone penetration test and softening point test and then the enhancement mechanism of modified basalt fiber reinforced asphalt mucilage was analyzed. The results show that modified basalt fiber had good wettability with asphalt mucilage; the adhesion between fiber and asphalt mucilage was strong; fiber′s surface film thickness of asphalt mucilage was large and the mechanical properties of modified fiber was significantly developed. When the powder binder ratio is between 0.8~1.0 and the dosage of modified fiber is between 0.4%~0.6%, the tensile strength, anti-shearing strength, elastic recovery ratio and softening point of asphalt mucilage were significantly enhanced, which indicate the abilities of low temperature anti-cracking, high temperature anti-shearing, fatigue performance and self-healing were improved. This study provides popularization and application of mineral fiber composite in road engineering.

EXPERIMENTAL STUDY ON FLEXURAL PERFORMANCE OFFIBER-METAL HYBRID SANDWICH BEAM

DING Jie-ming, LIU Wei-qing, WAN Li, WANG Lu

2016, 0(5): 12-16.

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In this paper, the fiber-metal hybrid sandwich beam (FMS) was fabricated. From top to bottom, alkali-free glass fiber, the metal sheet with tooth nail, paulownia wood, the metal sheet with tooth nail and alkali-free glass fiber were arranged. Tooth nail was used to connect the metal plate with paulownia and unsaturated polyester resin was used to connect the metal plate with non-alkali fiber glass. According to four-point bending tests, the bending performance and failure modes of FMS with different span-depth ratio were investigated and compared with the ordinary fiber reinforced sandwich beam (FSS). An analytical formula to identify failure modes was also obtained to validate the bearing capacity. The test results show that when span-depth of the beam were 10, 12, 16, 20, 24, the ultimate bearing capacity and bending stiffness of the FMS were increased. The calculated bearing capacity agreed well with the experiment results.

RESEARCH ON TENSION CONTROL OF CARBON FIBERPREPREG CUTTING COILING MACHINE

ZHU Teng-fei, WEN Li-wei, XIAO Jun, CAI Zhi-qiang

2016, 0(5): 17-22.

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On the background of the narrow prepregs used by AFP, combined with 16 tow cutting-coiling machine developed by ourself, we carried out the research on the coiling tension, and briefly analyzed and discussed the influence of the coiling tension on the cutting and coiling quality of the narrow prepregs. To ensure the cutting and coiling quality, being different from the traditional PID algorithm, we focused on the application of the fuzzy-PID on the closed-loop control system, which can achieve an accurate control in low tension applying on the accurate control strategy, the control precision can be achieved to 0.1 N, which meets the cutting requirement of the narrow prepregs, ensures the quality of the cutting and coiling and improves the wire laying quality.

THERMAL RESIDUAL STRESS ANALYSIS OF BONDED COMPOSITE REPAIRSTO CRACKED METALLIC PLATE

NIU Yong, MU Zhi-tao, LI Xu-dong, HAO Jian-bin

2016, 0(5): 23-29.

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The thermal residual stress will increase the stress intensity factor (SIF) of the crack after repair, which may subsequently enhance fatigue crack growth rate, and decrease the fatigue life of repaired structure. In this study, a 3-D finite element method is used to analyse the thermal residual stress of bonded composite repairs to cracked metallic plate and the SIF at the crack front of the repaired structure is computed using the virtual crack closure technique (VCCT). Meanwhile, the SIF at the crack tip is chosen as fracture criterion in order to estimate the influence of composite lay-up direction, curing temperature, and adhesive property to thermal residual stress of repaired structure. The obtained results show that the lay-up direction of [0°/45°/-45°/90°]_s could effectively decrease the thermal SIF. Meanwhile, the variation of the thermal SIF is approximately linear when curing temperature increases. The material property and thickness of adhesive do not show significant influence on the variation of the thermal SIF.

THERMAL BUCKLING FOR LOCAL DELAMINATION NEAR THE SURFACE OFPIEZOELECTRIC COMPOSITE PLATES WITH HONEYCOMB CORE

WANG Yi-chen, WANG Xi

2016, 0(5): 30-35.

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In this paper, an investigation is carried out to understand the thermal buckling behavior of local delamination near the surface of laminated piezoelectric composite plates with honeycomb core. The model of piezoelectric composite plates was built. The critical temperatures of laminated plates in the case of local delamination near the surface by making use of the energy principle was calculated. The effect of different factors on thermal buckling by comparing the critical temperatures under different situation was analyzed. It shows that, the different shape of delamination and stacking sequences have impact on critical temperature of thermal buckling. The elliptic delamination has the best stability. Also the critical temperature has a linear variation with electric-field strength. In real application, applying electrical field can prevent the buckling of piezoelectric plates.

STUDY ON THE CONTROL STRATEGY OF THE GLASS PIPE THREAD GRINDING ROBOT

YOU Bo, MIAO Zhuang, XU Jia-zhong, QIAO Ming

2016, 0(5): 36-40.

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For the requirements of force and position control of the robot in the process of the thread grinding operations, the dynamic constraint model of the robot is established. Through on the modeling and analysis of grinding force, the impedance control method based on the adaptive algorithm is adopted. The method is based on the analysis of the interaction between the robot and the working object. Then, we can correct the reference value of the force in real time and the amount of actual force at the end of the robot arm can be ensured to stabilize the desired grinding force. This method has a good robustness for the disturbances and errors arising from the external environment and other unknown factors, and the amount of computation is small. Based on the above method, the dynamic controller of the manipulator system is established. The simulation results show that the method has good stability, and can meet the requirements of real-time control of the robot.

INVESTIGATION ON LOW CYCLE TENSILE FATIGUE PROPERTIESOF GLASS FIBER MAT REINFORCED COMPOSITES

ZHAO De-fang, YANG Yu-qiu, ZHANG Zhi-yuan, Hiroyuki Hamada

2016, 0(5): 41-47.

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In this paper, glass fiber mat and unsaturated polyester were used to fabricate composite through hand lay-up method. The tensile properties of unnotched and open-hole notched glass fiber mat reinforced composites (GMC) specimens were examined based on the normal and low cycle fatigue (LCF) tensile tests. It was found that both the unnotched strength and notched strength were promoted with increasing volume fraction (V_f). In LCF test, for unnotched and notched specimens, the properties of GMC showed stable in 30 cycles under 55% of max load but degraded much under the cycle load more than 70% of max load. In the investigation on the fracture behavior of specimens, delamination was found in the fracture section of unnotched test specimens. While for notched specimens, two different fracture areas defined as parallel area and fan shape area were found. The values of characteristic distance were calculated by finite element analysis software (MSC-Marc). Furthermore, the characteristic distance was found. It is close to the length of parallel area, decreasing with the increase of the load level in LCF tests, reducing the resistance of GMC to the effect from an open hole. Finally, SEM observation was carried out on the selected specimens to compare the difference between the ones before and after LCF test.

AGING STUDY AND LIFE PREDICTION OF RAMIE/GLASS FIBER HYBRID COMPOSITES

ZHU Kun-kun, NI Ai-qing, WANG Ji-hui

2016, 0(5): 48-54.

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Hybrid fibers consisting of glass fiber and ramie fiber reinforced composites were fabricated. Combined with the actual situation of ship in service, three different accelerated aging, including water, salt fog and ultraviolet, of the hybrid composite materials were tested. The changes of the tensile strength and bending strength of the composites under different aging time and different aging temperature and the trend of performance degradation were investigated. Residual strength model was used to predict the residual strength of composite materials. It shows that the moisture absorption trend of the sample is mainly driven by the concentration gradient of FICK diffusion at the initial phase. The degree of the the material strength degradation changes with different aging environments. The results shows that, the damage of water is greater than salt-fog which is greater than ultraviolet. According to the residual strength model, after 10 years of aging, residual strength of specimens in salt fog environment can maintain 78%, and the residual strength of specimen in ultraviolet environment can maintain 81.89%.

INFLUENCE OF PVA FIBER CONTENT ON FLEXURAL BEHAVIOR OFREINFORCED HPFRCC/CONCRETE COMPOSITE BEAMS

LI Yan, PAN Yan-qiu, CHEN Wei-feng

2016, 0(5): 55-60.

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In order to improve the shortcoming of easy-cracking of reinforced concrete beams, concrete of tension zone can be partly replaced by HPFRCC to make reinforced HPFRCC/concrete composite beam. Based on experiments on normal section flexural behavior of composite beams, the influence of PVA fiber content by volume on flexural performance of composite beams were studied. Experimental results indicate that the HPFRCC layer in tension zone can inhibit and disperse the extension of cracks effectively and the crack distribution of composite beams are similar to root system. With the increase of PVA fiber content by volume, cracks become more fine. After cracking, the strain increases of tension steel and compression concrete slow down owing to the bridging effect of PVA fiber. Compared with ordinary concrete beam, the cracking load, yielding load and ultimate load of composite beams are all increased and the increases of cracking load are more obvious.

PREPARATION AND CONDUCTIVE PROPERTIES OF COPPER COATINGON CARBON FIBER REINFORCED COMPOSITE

LIANG Ke, ZHANG Hua-dong, QIN Wen-feng

2016, 0(5): 61-64.

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Carbon fiber reinforced composites (CFRC) were widely apllied in civil aircraft structure, but it is vulnerable to lightning damage due to its poor electrical conductivity. In this paper,copper coating were prepared on carbon fiber composites by electroless plating with the goal of lightning resistance for aviation composite materials. The surface topography and crystal structure of copper plating were inspected by SEM and EDX. The effect of the concentration of copper sulfate on the deposition rate and conductivity of the metal copper coating was studied. The results show that the deposition rate increases gradually and the resistance value of the coating decreases with the increase of the concentration of copper sulfate. Copper grains on the surface of the carbon fiber composite are uniform and have good crystallinity, while the surface resistance of the coated carbon fiber reinforcement reached 19.8 mΩ/sq when the concentration of copper sulfate is 14 g/L, where good electrical conductivity was obtained.

THE MICROWAVE DIELECTRIC PROPERTIES OF BASALT FIBERS AND CBF-EP COMPOSITES

YAO Yong, HE Yue-chuan, CHEN Zhong-wu

2016, 0(5): 65-67.

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In order to investigate the electrical performance of basalt fiber, some tentative research was made in this paper. The results show that the dielectric constant of basalt fiber is less than other fibers such as E-glass fiber, S-glass fiber, D-glass fiber, quartz fiber and Kevlar fiber, etc. But the dielectric loss is a little bit higher even though the results were of the same order of magnitude. The wave absorption properties of basalt fiber cloth and mat are also measured. According to the results, these basalt fiber fabrics show good wave permeability in frequency range of 2~18 GHz. The CBF-EP composite laminate were prepared through a vacuuming procedure and measured by arch method. The results indicate that the CBF-EP composite laminate exhibits excellent characteristic in wave permeability in frequency range of 2~18 GHz. The reflection losses of all the above basalt fiber products are less than 10 dB, but the absorbing performance is not positively related to the thickness for the reasons of spatial distribution of the material.

INFLUENCE OF THE TYPE AND CONTENT OF SIZING AGENT ONTHE CARBON FIBER SURFACE PROPERTIES

OUYANG Xin-feng, LIU Fang, HUANG Xing, QI Lei

2016, 0(5): 68-73.

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The effect of a single component sizing agent and three kinds of composite sizing agent in different content on carbon fiber surface properties was investigated. The results indicate that the width, hardness, friction coefficient, fuss weight, splitting rate of carbon fiber, and the morphology of the composite interface varied with the content and type of sizing agent, the correlated variable law between surface properties of carbon fiber and the type and content of the sizing agent was disclosed. By combining with TOARYT700SC-12K test result,reference values that are suitable for the industrial production was offered, i.e., the sizing agent content general is 1.0±0.3% in industrial production, carbon fiber T300/700-12K surface properties general is: width is 7±1 mm, hardness is 10±2 cm, the friction coefficient is 0.16±0.05, splitting rate is 2.0±0.3, fuzz weight is less than 3 mg. Furthermore, it suggested that the multi-component composite sizing agent is better than the single component sizing agent in obtaining carbon fiber with controllable surface properties, which provides reference for the controllable method of carbon fiber surface properties.

EVALUATION OF GEOMETRICAL SIZE AND TEMPERATURE EFFECTON THE MECHANICAL BEHAVIOR OF CFRP BARS

FU Cheng-long, CHEN Li, ZHANG Ya-lu

2016, 0(5): 74-79.

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In order to reveal the mechanical behavior of the carbon fiber reinforced polymer (CFRP) at elevated temperatures, different diameter CFRP bars were investigated by the three-point bending test and compression test at a range of temperatures from 25℃ to 150℃. The failure mode and mechanism of CFRP bars were investigated and analyzed to elucidate the effect of diameter and temperature on bending strength and compressive strength. The results show that the influence of the diameter on the bending strength and compressive strength is not obvious. However, the bending strength and compressive strength of the specimen are greatly influenced by temperature. And the strength retention rate of the CFRP is decreased with the increase of temperature.

ANALYSIS OF THE STRESS CHARACTERISTICS OF THE BURIED GLASS FIBER REINFORCED PIPE UNDER LOAD

ZHANG Ji-yuan, ZHENG Yan-jun, SHI Hua-wang, CHEN Zhao-nan

2016, 0(5): 80-84.

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This article carried out the indoor simulation experiments and analysis to study the force issues of the buried FRPM pipe under different loads. The tests acquired stresses and strains of the buried FRPM pipe in different parts, earth pressures and deformation characteristics of the pipe circumference at different locations, summarized the pipe-soil interaction law under different loads, as a basis for judging the force characters of the buried FRPM pipe in key parts, and provided a scientific basis for designing the buried FRPM pipe under loads

EFFECTS OF THE EPOXY-AMINE STOICHIOMETRY RATIO ON THE PROPERTIESOF MWCNTs-NH₂/EPOXY COMPOSITES

TANG Feng, ZHANG Qing-jie, GAO Liang, WU Jian-qiao

2016, 0(5): 85-90.

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By regulating the DDS contents of TDE-85/DDS system, different epoxy-amine stoichiometry ratios, i.e. the excess of epoxy (r=0.8), stoichiometric ratio (r=1) and excess of hardener (r=1.2) were obtained. Amino-functional multi-walled carbon nanotubes (MWCNTs-NH₂) were added into these systems and the effects of the epoxy-amine stoichiometry ratios on the curing kinetic and tensile properties of MWCNTs-NH₂/epoxy composites were compared and evaluated. The results showed that the curing kinetic and tensile properties of MWCNTs-NH₂/epoxy nanocomposites were closely related to the epoxy-amine stoichiometry. When r=0.8, MWCNTs-NH₂ can adequately participate in the crosslinking reaction in the excess of epoxy. Compared with neat epoxy, a significantly catalytic effect of curing reaction can be obtained with addition of MWCNTs-NH₂. As a result, about 17% and 20% increase of tensile strength and modulus, respectively,were observed. When r=1, the curing reaction was changed from chemical control to diffusion control; the tensile strength and the modulus of the MWCNTs-NH₂/epoxy nanocomposites were only increased about 10% and 14%, respectively. When r=1.2, compared with neat epoxy, the addition of MWCNTs-NH₂ resulted in a lower activation energy during the last stage of cure reaction, leading to excessive crosslinking reaction in the local scale. As a result, the tensile strength of the MWCNTs-NH₂/epoxy nanocomposites was reduced about 14%, while the tensile modulus of the composites was only increased about 9%.

STUDY ON MOULD DESIGN AND PROCESS PLAN OF THE VARIABLECROSS SECTION COMPOSITE INLET DUCT

SHI Lei, XU Jin-wei, CHAI Peng-jun

2016, 0(5): 91-93.

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In the paper, the existing metal mould plan and water soluble mould plan was researched. Based on the research, scheme of combined type composite material mould was designed. The process parameters of the composite fragile layer in the scheme was determined. The composite inlet duct had made. The plan gave a reference on composite inlet duct and other complex surface composite product whole forming.

PLASMA TREATMENT TECHNOLOGY ON BONDING SURFACE PREPARATION OF COMPOSITE

YUAN Xie-yao, YANG Yang, CHEN Ping, LIU Wei-ping

2016, 0(5): 94-100.

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The definition of plasma was introduced. The principle and application on fiber surface preparation of plasma technology were briefly introduced. At the same time, the research and development of plasma technology on matrix surface preparation domestic and overseas in the past years were summarized. There were several important factors during the plasma preparation procedure, such as electric power, processing time, gas types and processing pressure. The characterization method, such as mean surface roughness, contact angle (water) and shear strength, fatigue mode after bonding were also introduced in this work. Finally, the potential difficulties of domestic plasma technology were summarized.

THE DESIGN AND PRODUCTION OF CFRP ANTICATHODE

LI Na

2016, 0(5): 101-104.

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The paper introduces the performance requirement of CFRP anticathode used in WESP facility. According to the characteristic of FRP product, the design and processing of CFRP anticathode are analyzed.

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