COMPOSITES SCIENCE AND ENGINEERING

Simulation of temperature field distribution of carbon fiber composites under laser irradiation

WANG Wenqian, FENG Yu, LI Zhe, LIU Songjing, AN Tao, WANG Yitao, LI Yuankai

2024, 0(7): 5-15. DOI: 10.19936/j.cnki.2096-8000.20240728.001

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Based on the theory of laser irradiation of carbon fiber composites, the temperature field of carbon fiber composites was simulated by finite element method. Firstly, the distribution law of laser irradiation temperature field of carbon fiber composites was studied, and the temperature field characterization equation of different position lines was established. The variation law of irradiated surface temperature was quantitatively analyzed, and the validity of finite element model was verified by literature data. Then, based on the model, the temperature field changes of the composite sheet under different layering directions, different spot diameters and different laser power were investigated. The results show that the heat affected zone is elliptical under different layering directions, and the long axis direction of [0]₁₆ and [0/90]_4S plates is the 0° layering direction of carbon fiber, while the long axis direction of [45/90/-45/0]_2S plates is the 45° layering direction of carbon fiber, and the maximum temperature of the three plates is about 1 830 ℃. When the spot diameter is 6 mm, 10 mm and 14 mm, the area of the heat affected zone gradually increases, while the maximum temperature of the center gradually decreases, and the maximum temperature in the whole process is 3 347 ℃, 2 401 ℃ and 1 838 ℃, respectively. At 200 W, 400 W and 600 W laser power, the center temperature of the plate increases with the increase of laser power, and the maximum temperature of the center point is 1 750 ℃, 2 401 ℃ and 2 789 ℃, respectively.

Mechanical behavior investigation of the FGM cantilever beam based on the semi-analytical method

ZHANG Long, LIU Bingbin, FAN Juntao

2024, 0(7): 16-22. DOI: 10.19936/j.cnki.2096-8000.20240728.002

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Functionally graded materials (FGM) possess excellent physical properties and have important applications, thus have received increasing attentions in recent years. In this paper, a semi-analytical method for mechanical behavior analysis of the FGM cantilever beam is developed, which has the same accuracy in contrast to the analytical method, and furthermore can be used for cantilever beam with complex material property gradation. The method is applied to the bending stress analysis of FGM cantilever beams with linear gradation, exponential gradation and complex empirical formula gradation. The computed results are compared with those of analytical method, graded finite element method (FEM) and layered FEM. The study shows that the bending stress distribution calculated by semi-analytical method and graded FEM is basically consistent with analytical solution on the condition that the numbers of integration points in height and longitude direction are respectively 11 and 21, whereas the bending stress distribution calculated by layered FEM deviate a lot from analytical solution up to 10%. For the analysis of deflection value, the calculated results of semi-analytical method, gradient FEM and layered FEM are all very close to analytical solution, with the maximum relative error within 1.0%.

A prediction model for dynamic compressive response of composite materials considering strain rate

WEN Jinjun, QU Meijiao, SHEN Yongao, LI Mengqi, SONG Yuheng, ZHU Hanrui

2024, 0(7): 23-30. DOI: 10.19936/j.cnki.2096-8000.20240728.003

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This article proposes a dynamic compression response prediction model for composite materials considering strain rate effects. Based on neural networks, a high strain rate compression response prediction model is constructed for carbon fiber reinforced composite materials prepared from T300/QY8911 prepreg with material properties as parameter variables. The dynamic compression response of the material at strain rates of 517 s^-1, 721 s^-1, and 1 070 s^-1 is predicted, and experiments are conducted to verify the prediction results. The results indicate that the predicted results are in good agreement with the experimental results, the maximum error of stress is only -1.585 6%, and the maximum error of the strain is only 1.703 7%.

Performance study of functionalised PVC/PET flexible composites

GUO Yichuan, JIANG Yuyang, SHEN Chunhui, GAO Shanjun, LU Hao, JIANG Ying

2024, 0(7): 31-38. DOI: 10.19936/j.cnki.2096-8000.20240728.004

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Polyvinyl chloride (PVC) and polyester fibre (PET) were used as raw materials to form PVC/PET flexible composites by a hot press lamination process. By adding different flame retardants and anti-UV agents to the PVC coated film, it was found that the antimony oxide-zinc borate synergistic flame retardant system exhibited good flame retardant effect, which increased the ultimate oxygen index of the coated fabric to 28.7% when 5 phr was added. In addition, the flame retardant system also had the effect of inhibiting smoke generation, resulting in a 35.2% reduction in smoke density. In terms of UV resistance, UV-531 anti-UV agent is comparable to UV-234, but performs even better in terms of resistance to heat migration. Therefore, UV-531 was chosen as the anti-UV agent for PVC/PET flexible composites. The addition of 3.0 g/m² of adhesive during the lamination of the coated film and the base fabric increases the peel strength of the material to 28.89 N/5 cm without affecting other properties, thus extending the service life of the PVC/PET flexible composite.

Creep properties of injection molded carbon fiber reinforced polypropylene composites

GAO Jiayi, YANG Yang, YANG Yuqiu

2024, 0(7): 39-44. DOI: 10.19936/j.cnki.2096-8000.20240728.005

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The creep behavior of carbon fiber reinforced resin matrix composites under extreme environmental and long-term service conditions can change the shape of structural components, posing a challenge to their performance stability. Therefore, the study of the creep performance of this material is the key to material design and application. The creep behavior of injection molded carbon fiber reinforced polypropylene composites was studied and the theoretical equations of the Burgers model for this material were obtained through uniaxial tensile creep test. Moldex3D was used to simulate the orientation and distribution of carbon fibers inside the injection molded samples, and the simulation results were mapped to ABAQUS to perform finite element analysis on the creep process of a three-dimensional model of this material. It is shown that the fitting curves of the Burgers model are in good agreement with the experimental curves, and can be applied to predict the creep behavior of this material at a wider range of timeand stress levels; the results of mold flow analysis are consistent with the cross-sectional observations of the actual samples; the orientation and distribution of carbon fibers during injection molding can affect the creep behavior of the final formed samples. The combination of mold flow analysis and finite element analysis can better reflect the creep process of the material.

Deicing technology of resin matrix composites by electric heating based on carbon nanotube film

YE Lu, ZHANG Daijun, LI Jun, LI Fuping, CHEN Xiangbao

2024, 0(7): 45-52. DOI: 10.19936/j.cnki.2096-8000.20240728.006

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In this paper, the application of carbon nanotube films to the electrothermal deicing of resin matrix composites was studied. Carbon nanotube films/composites were prepared by an integrated molding process, and their structures were optimized. The electrothermal and deicing properties of carbon nanotube film/composites were investigated. The results show that the obtained carbon nanotube film/composite has good internal quality, excellent electric heating performance, high deicing efficiency and low deicing energy consumption compared with metal electric heating elements.

Study on behavior of GFRP beam-to-column T-joints based on angle steel connection

GU Jing, ZONG Zhongling, XIE Qinghai, LI Keke, LI Meng

2024, 0(7): 53-61. DOI: 10.19936/j.cnki.2096-8000.20240728.007

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Different types of T-joints of GFRP beam-column were designed with the connection form of upper and lower angle steels. The effects of type of angle steel, row distance of bolt, end distance of bolt and row number of bolt on the bearing capacity and deformation properties of T-joints of GFRP beam-column were studied through the monotone loading test of eight node members and combined with the finite element analysis. The results show that, compared with no stiffeners, the addition of stiffeners can significantly reduce the deformation at the angle steel corner, and the installation of triangular stiffeners can improve the bearing capacity and rotational stiffness of T-joints of GFRP beam-column. The ultimate bearing capacity of joints increases with the increase of row spacing of bolt, decreases with the increase of end spacing of bolt, and first increases and then decreases with the increase of row number of bolt. The rotational stiffness increases first and then decreases with the increase of row distance and end distance. In the range of parameters analyzed in this paper, the T-joints of GFRP beam-column can obtain better mechanical properties by angle steel connection with two rows of bolts, and it is reasonable to control the row spacing between 45 mm and 50 mm and the end spacing between 55 mm.

Experimental study on frost resistance and energy dissipation of carbon fiber and carbon fiber cloth concrete

YANG Xiao, GE Yaqiong, JIN Jiasheng

2024, 0(7): 62-69. DOI: 10.19936/j.cnki.2096-8000.20240728.008

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In order to investigate the effect of carbon fiber reinforcement on the frost resistance and energy dissipation of concrete materials, the longitudinal wave velocity and mechanical properties of four kinds of concrete (plain concrete, carbon fiber concrete, carbon fiber concrete, carbon fiber concrete and fiber fabric concrete) after freeze-thaw cycles (0, 25, 50, 75, 100 times) were obtained by using a longitudinal wave tachometer and an electro-hydraulic servo press. The effects of carbon fiber reinforcement method and number of freeze-thaw cycles on relative dynamic elastic modulus, peak stress, energy dissipation and damage degree were analyzed. The results show that: ① Compared with plain concrete with 0 freeze-thaw cycles, the relative dynamic elastic modulus of specimens with 25, 50, 75 and 100 freeze-thaw cycles decreased by 8.21%, 18.33%, 30.44% and 45.89%. The more freeze-thaw cycles occurred, the more significant the relative dynamic elastic modulus of specimens declined. Carbon fiber and carbon fiber cloth could both slow down the relative dynamic elastic modulus of specimens. ② As the number of freeze-thaw cycles increased, the peak stress of the four different concrete specimens showed a decreasing trend. Carbon fiber and carbon fiber cloth could not only enhance the strength of the specimens, but also enhance their freeze-resistance, and the combination of the two had the best lifting effect on the specimens. ③ Compared with the non-freeze-thaw specimens, the elastic deformation energy decreased by 3.87%, 7.63%, 9.67% and 12.70%, and the dissipative energy decreased by 10.42%, 21.97%, 30.16% and 41.60%, respectively, during freeze-thaw cycles of 25, 50, 75 and 100 times. The internal damage of the specimens was caused by freeze-thaw action, reducing the effect of sample energy storage and energy consumption. ④ The corresponding damage value of the three kinds of carbon fiber concrete at the peak stress is significantly higher than that of plain concrete, and the strengthening effect of carbon fiber can effectively improve the energy absorption effect, ductility and frost resistance of concrete materials.

Study on deformation correction technology of forming accuracy of hyperbolic composite components

LIU Baoming, LUO Chen, WANG Xiaokai, HAN Zhiren

2024, 0(7): 70-73. DOI: 10.19936/j.cnki.2096-8000.20240728.009

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Curing deformation of hyperbolic composite components was one of the key issues affecting part quality and geometric accuracy. The deformation correction method based on experimental data was proposed by this paper in order to improve the geometric accuracy of hyperbolic composite components and key issues such as experimental data acquisition, denoising and data alignment, as well as the multi-section experimental data search method and mirror method were elaborated on. A correction module was developed based on CATIA/CAA secondary development technology, which can effectively compensate for the curing deformation of hyperbolic composite components. Experimental verification was conducted using a hyperbolic part on an aircraft, and after correction by the module, the manufacturing error of the part was significantly reduced, demonstrating the effectiveness and feasibility of the method. The results of this study are of great significance for improving the manufacturing accuracy and performance of hyperbolic composite components.

Experimental and numerical simulations of HB-FRP flexural reinforced beam

LI Yan, WEI Qi'an, SHI Nan, GAO Lei, WANG Jiabin, HUANG Yue

2024, 0(7): 74-85. DOI: 10.19936/j.cnki.2096-8000.20240728.010

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In order to study the flexural performance of concrete (RC) beams reinforced with hybrid bond FRP (HB-FRP), three-point bending tests were conducted on eight HB-FRP reinforced beams to investigate the effects of bolt torque, fastener spacing, anchorage distribution pattern and FRP plate bonding method on the damage pattern, load-deflection curve and FRP strain distribution of the specimens. Based on the finite element software ABAQUS, a finite element model of HB-FRP strengthened RC beams was established, and the model was verified by test results and parametric analysis was carried out. The results show that the ultimate load of HB-FRP strengthened beams is increased by 71%~156% compared with unreinforced beams, and the ultimate load and FRP utilization rate increase with the increase of bolt torque and decrease with the increase of fastener spacing; FRP plate peeling damage occurs in all specimens by eliminating the bond between fasteners and FRP plates; the reinforcement effect of span-centered and end-centered anchorage is unstable and prone to early damage occurred; the established calculation model of HB-FRP reinforced RC beams has good accuracy and can be used for the simulation of flexural performance; the increase of fastener width and carbon plate width increased the ultimate load of HB-FRP reinforced beams; the high bolt torque and fastener width will lead to premature concrete damage in the compression zone; the utilization rate of FRP decreases with the increase of FRP width.

Static and fatigue properties of laminate single lap specimens with two thicknesses

ZHANG Ru, CHEN Xiangming, LI Xinxiang, Yuan Fei, CHENG Liping

2024, 0(7): 86-92. DOI: 10.19936/j.cnki.2096-8000.20240728.011

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The mechanical properties and fatigue characteristics of the single lap bonded surface made of two different thicknesses of composite materials were studied through a combination of experimental research and numericalsimulation. Virtual crack closure technique (VCCT) was used to simulate the bond interface, and the crack initiation and propagation principle of single lap specimens under axial tensile load was studied. It was found that at the damage initiation time G_Ⅲ was much smaller than G_Ⅰ and G_Ⅱ, while G_Ⅰ decreased and G_Ⅱ increased with increasing crack length. The out-of-plane peeling stress mainly affected the interface damage initiation, while the sliding shear stress mainly affected the crack propagation. Fatigue tests were designed for the composite single lap specimens of two thicknesses to determine their fatigue life under different fatigue loads. The values of G_Ⅰ/G_ⅠC and G_Ⅱ/G_ⅡC of the corresponding crack tips were given. N-G_Ⅰ/G_ⅠC and G_Ⅱ/G_ⅡC curves are drawn, and it was found that the range of life decrease with the increase of G_Ⅰ/G_ⅠC was much larger than that of G_Ⅱ/G_ⅡC. The failure forms of the adhesive interface were compared, and it was found that the failure forms of the test pieces with thicker adhesive layers were smoother than those with thinner adhesive layers, and the failure area of the adhesive layer accounted for a higher proportion. With an increase in fatigue load value, the proportion of the failure area of the adhesive layer in the lap area decreased, while the tear area of the bonded composite fiber layer increased.

Simulation study on the strength of GFRP jumper protection structure based on DNV specification

GAO Shuang, LI Xiang, WEN Ziyan, LIU Xiaobin, CHU Xingpeng

2024, 0(7): 93-99. DOI: 10.19936/j.cnki.2096-8000.20240728.012

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Glass fiber composites have been widely used in the protection of underwater oil and gas production facilities by overseas oil field companies in the past two decades due to their lightweight, high strength and corrosion-resistant material characteristics, and have achieved mature engineering applications. In this paper, for the domestic fiberglass jumper cover, combined with the function of the cover underwater, the finite element ANSYS software is applied to establish the three-dimensional model of the domestic fiberglass jumper cover, analyze the strength of the cover from the three aspects of the sand slope buildup, the trawl of fishing nets and the impact of the falling objects, and carry out the safety assessment according to the DNV specification. Comparison between simulation and experiment shows that the strength of the protective cover meets the specification requirements and matches the experimental conclusions, which can provide a reference for the future design of domestic fiberglass underwater protective structure.

Research on carbon fiber airflow spreading technology and uniformity analysis

TAN Jing, WAN Kai, WU Xuesong, DING Qisheng, YANG Weimin

2024, 0(7): 100-104. DOI: 10.19936/j.cnki.2096-8000.20240728.013

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To study the fiber spreading process of carbon fiber by airflow, a set of airflow fiber spreading device has been developed. The effects of airflow velocity, support roller span, and fiber overhang on fiber spreading width were studied through multiple orthogonal experiments, and the experimental results were analyzed. The MATLAB digital image processing technology was used to preprocess the unfolded carbon fiber image, including reduction, grayscale, and image enhancement. The coefficient of variation and probability distribution were introduced to characterize the uniformity of the transverse and longitudinal distribution of carbon fibers. The results show that there is a linear positive correlation between the width of air flow fiber expansion and the fiber overhang within a certain range. Choosing the optimal process parameters of air flow velocity of 4 m/s and support roller span of 140 mm has a good fiber spreading effect. The digital image analysis method can better characterize the uniformity of carbon fiber airflow and is consistent with experimental results, which has good industrial application prospects.

Study on preparation of continuous carbon fiber reinforced aluminum matrix composites by twin-roll casting technology

MU Weipeng, ZHU Baoshun, WEI Nana, FENG Ming, LIN Jinbao

2024, 0(7): 105-115. DOI: 10.19936/j.cnki.2096-8000.20240728.014

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Continuous carbon fiber reinforced aluminum matrix composites have many excellent characteristics such as high specific strength, low density, good heat transfer, and low coefficient of thermal expansion, making them have broad application prospects in fields such as aviation materials, automotive manufacturing, electronic equipment, and industrial production. The preparation method of continuous carbon fiber surface coating was discussed. Summarized the main preparation processes, important research achievements and existing problems of CCF/Al composites in recent years. Finally, the article focuses on the research results of our team's use of twin-roll casting technology to prepare CCF/Al composites, including the experimental equipment built, properties of modified carbon fibers, microstructure and strengthening mechanism of the prepared composites. The main problems currently existing were elaborated and the development prospects were discussed.

Advances in pultruded composites for large wind turbine blades

WEI Lijiang, QIU Ruilei, WANG Ganwu, XIE Bowu, LI Mingzhi, FENG Wei

2024, 0(7): 116-121. DOI: 10.19936/j.cnki.2096-8000.20240728.015

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The increasing size of wind turbine blades puts forward higher and higher requirements on the performance of composite materials. In recent years, the successful application of pultruded composite materials has been a milestone in the development of decades-long wind turbine blade manufacturing technology. With higher mechanical properties of end-products, higher production efficiency, and lower manufacturing costs, pultrusion process almost completely replaces the vacuum infusion process that has been used for more than 20 years to manufacture the main bearing spar cap of wind turbine blades. In order to sort out the research advances of pultruded composite materials in wind turbines blades and shed lights on future research for engineers and scholars in the field of composite materials in wind turbine blades, this paper summarizes the technical development and patent application from the aspects of raw materials for pultruded plates, mechanical properties of pultruded plates, pultrusion process parameters for infusion technology and defect detection method of pultruded blade spar caps.

Research progress on construction of stiffened interphase and rigid-soft interphase of carbon fiber composites

LI Baolai, ZHEN Ziting, BU Tongan, YANG Jiale

2024, 0(7): 122-128. DOI: 10.19936/j.cnki.2096-8000.20240728.016

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Carbon fiber reinforced polymer (CFRP) have excellent properties such as light weight, high strength, high modulus, and have wide application prospect in the fields of aerospace. As a bridge connecting the resin matrix and carbon fiber (CF) reinforcement, the interphase is an important factor affecting the mechanical properties of composite. Aiming at the problem that the modulus difference between carbon fiber and resin matrix is too large, it's an effective strategy to improve the interfacial properties by improving the modulus of interphase to make the modulus transition smoothly and improve the stress transfer efficiency. The construction methods of stiffened interphase and rigid-soft interphase in recent years are mainly summarized in the paper. Finally, some issues of the interphase of CFRP are discussed and the future trends of interfacial reinforcement research are prospected.

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