Table of Content

28 January 2022, Volume 0 Issue 1

Previous Issue    Next Issue

BASIC STUDY

Research on crack propagation of composite materials based on cohesive zone model

HE Zhen-peng, DENG Dian-kai, LIU Guo-feng, SUN Ai-jun, QIAN Jun-ze, LI Bai-chun, HU Yi-xin, YANG Fan

2022, 0(1):  5-12.  DOI: 10.19936/j.cnki.2096-8000.20220128.001

Asbtract ( 386 )   PDF (5239KB) ( 459 )  

References | Related Articles | Metrics

Based on the cohesive zone model, this paper develops the numerical calculation method of the three-dimensional zero-thickness cohesive element, and combines the finite element theory to derive the finite element format of the bilinear cohesive zone model and the PPR cohesive zone model. By using the ABAQUS-UEL subroutine module, a three-dimensional eight-node cohesive zone element was developed. Compared with the actual composite material layering test results and the simulation results in ABAQUS, it is proved that it can simulate the problem of composite material delamination damage accurately. The numerical program is applied to the study of the delamination damage mechanism of composite materials. The results show that the PPR cohesive zone model based on potential energy has lower computational cost, higher convergence for calculating delamination damage, higher accuracy. What's more, it further clarifies the influence of peak strength, cohesion zone length, and composite layering angle on the numerical convergence and calculation accuracy of the cohesion model.

Finite element analysis of graphene-reinforced functionally graded beams based on layered method

TENG Jing-mei, HUANG Jun, HUANG Li-xin

2022, 0(1):  13-21.  DOI: 10.19936/j.cnki.2096-8000.20220128.002

Asbtract ( 189 )   PDF (1977KB) ( 121 )  

References | Related Articles | Metrics

Based on the idea of layered method, the finite element analysis of graphene-reinforced functionally graded beam is carried out in this paper. In the layered model of finite element calculation, the material parameters of each layer are constant, and the values of those material parameters are calculated according to the modified Halpin Tsai model. Then, the finite element modeling and mechanical analysis of the graphene-reinforced functionally graded beam are completed according to the standardized steps of finite element method. Numerical examples are presented to analyze the influence of the mass content, distribution patterns and size of graphene on the bending properties of the beam. Numerical results show that adding a small amount of graphene can significantly reduce the bending deflection of the beam, and distributing more graphene on the upper and lower surfaces of the beam is the most effective method to reduce the bending deflection. At the same mass content, the square graphene sheet with larger length thickness ratio can improve the bending performance of the beam more.

Effects of different process parameters and interfacial modification on the fracture toughness of type Ⅰ interfacial of carbon fiber reinforced polyphenylene sulfide composites

CHANG Jian, XIAO Hai-gang, XIE Zhong-qing, BI Hua-yang, ZHENG Jin-hua, ZHU Shu, HOU Jin-sen

2022, 0(1):  22-28.  DOI: 10.19936/j.cnki.2096-8000.20220128.003

Asbtract ( 241 )   PDF (8075KB) ( 268 )  

References | Related Articles | Metrics

In this paper,the effects of different temperatures, pressures, cooling rates, and interfacial modification on the fracture toughness of type I interfacial of carbon fiber reinforced polyphenylene sulfide(CF/PPS) aeronautical thermoplastic composites were investigated. At higher molding temperature (340 ℃), fast cooling rate (32 ℃/min), and interfacial modification, CF/PPS composites exhibit higher G_ⅠC value. The higher temperature favors the entanglement of the intermolecular matrix chains. The faster cooling rate suppresses the crystallization and makes the matrix tougher. The CF interfacial modification improves the interfacial interaction between the fiber and the matrix resin, which is beneficial to stress and energy transfer. This paper has reference value for the preparation and application of aeronautical thermoplastic composites. The effect of pressure on the G_ⅠC of CF/PPS is not obvious. Higher molding pressure will cause the resin to impregnate the fibers weakly, and a large amount of resin will overflow from the gap between the mold edges, which is not conducive to the improvement of the toughness of the composite material.

Research on 3D thermal response of glass fiber epoxy based on UMATHT subroutine

FENG Zhen-yu, HAN Xue-fei, YUAN Hao-ran, LI Han, XIE Jiang

2022, 0(1):  29-35.  DOI: 10.19936/j.cnki.2096-8000.20220128.004

Asbtract ( 239 )   PDF (5459KB) ( 177 )  

References | Related Articles | Metrics

Based on the UMATHT and USDFLD subroutines, a thermal response model of composite materials considering material anisotropic heat conduction, matrix pyrolysis, and pyrolysis product diffusion was established, and the thermal response law of glass fiber/epoxy resin in a single-sided heat flow environment and the effect of flame retardants are studied. The results show that the temperature history predicted by the thermal response model is in good agreement with the experimental measured value, which can effectively predict the thermal response of glass fiber/epoxy resin. Under the same working conditions, the flame-retardant modified glass fiber/epoxy resin has a lower temperature rise rate compared with the unmodified material. The results show that the flame retardant can promote the thermal decomposition reaction and rapidly reduce the density of the surface of the material to form coke, and the thermal decomposition rate and thermal decomposition rate are significantly improved. The phenomenon that the intense pyrolysis zone gradually moves to the adiabatic surface with time is more obvious, so as to achieve the flame retardant effect of endothermic retarding surface ignition.

APPLICATION RESEARCH

Study on the properties of carbon fiber surface coatings peeled by CO₂ laser

DU Hong-yu, CHENG Jian, LIU Dun, LI Zi-wen, FENG Kai

2022, 0(1):  36-41.  DOI: 10.19936/j.cnki.2096-8000.20220128.005

Asbtract ( 219 )   PDF (7243KB) ( 89 )  

References | Related Articles | Metrics

Carbon fiber composite material (CFRP) is widely used in the manufacture of aircraft structures and components in the aviation field. Because aircraft often works in some harsh conditions, the surface coating of carbon fiber will age and lose its original performance. The longer the aircraft is in service, the deeper the coating needs to be removed. The coating of CFRP was quantitatively peeled by CO₂ laser instead of the traditional mechanical grinding. The experimental results show that the preset requirements of 5 μm, 10 μm and 20 μm removal can be achieved under the power of 20 W, 25 W and 30 W, within a certain error permissible range. In addition, the mechanical properties of the material are not weakened, which meet the requirements of recoating.

Damping performance of co-cured viscoelastic composite beam structure

ZHU Xiao-li, WANG Shao-qing

2022, 0(1):  42-45.  DOI: 10.19936/j.cnki.2096-8000.20220128.006

Asbtract ( 143 )   PDF (893KB) ( 93 )  

References | Related Articles | Metrics

In order to obtain the damping performance of co-cured viscoelastic composite beam structure, a dynamic analysis model of the structure was established. Based on the complex modulus theory and the Rayleigh-Ritz method, the vibration differential equation was derived, and the equation was solved. The calculation results were compared with data from the published literature. The validated model is used to analyze the influence of the geometric and material parameters of the structure on the dynamic characteristics of viscoelastic composite beam structure. The results show that placing the damping membrane on the midplane of the viscoelastic composite beam structure can obtain ideal damping performance. It is proved that shortening the length of the beam and increasing the thickness of the damping layer can improve the damping performance of the structure.

Factors influencing the accuracy of the reflector based on large spacer for the land-based inflatable deployable antenna

TAO Hong-bing, HAO En-quan, SHAO Hui-qi, SHEN Wei, CHEN Nan-liang, JIANG Jin-hua

2022, 0(1):  46-53.  DOI: 10.19936/j.cnki.2096-8000.20220128.007

Asbtract ( 129 )   PDF (5699KB) ( 86 )  

References | Related Articles | Metrics

In the manufacturing process of land-based inflatable deployable antenna, the main factors affecting the accuracy of reflector include: The spacing of spacer fabric reinforcement composite, air pressure, number of stickers, adhesive material and air pressure action time. In order to explore the influence of these factors on the reflecting surface, different kinds of cube samples with length and width of 40 cm were made by the spacer fabric reinforcement composite. Through experiments under different conditions of air pressure, the changes of deformation in the direction of length, width and thickness of the cube samples were observed. Combined with the mechanical property test of this material, the effect of this material in practical application was analyzed. The results show that the deformation of the samples in different directions is different, which is closely related to the structure of the composites. The composites with different spacing will have different effects on the deformation of the sample. For the samples with the same spacing, the more stickers, the easier the deformation of the sample. To ensure the accuracy of the reflecting surface, it can be control the appropriate number of stickers and select the sticker material with better dimensional stability. For the same sample, with the increase of air pressure, the deformation rate decreases and the total deformation increases. The accuracy of the reflector can be guaranteed by controlling the appropriate air pressure range and selecting the structure with small deformation. When the sample works under 5 psi air pressure for 24 hours, the sample will creep, the creep rate will decrease continuously, and the air pressure will change accordingly. Therefore, to ensure the accuracy of the reflecting surface, the working time of the antenna needs to be considered.

Modal analysis and experimental verification of a large radome

LI Jian-wei, QIN Qiang-qiang, HAN Bing, ZHOU Jin-zhu

2022, 0(1):  54-61.  DOI: 10.19936/j.cnki.2096-8000.20220128.008

Asbtract ( 162 )   PDF (11390KB) ( 141 )  

References | Related Articles | Metrics

As a composite structure to protect the antenna, the honeycomb sandwich radome should not only meet the requirements of structural strength and rigidity, but also meet the requirements of high electromagnetic wave transmission performance. In the finite element simulation of honeycomb sandwich composite structure, it is difficult to model the actual honeycomb structure. This paper used finite element simulation modal analysis and experimental modal analysis methods to study the modal characteristics of large composite radomes. The error between the experimental and simulated natural frequencies was reduced by the model correction method. The first six natural frequencies and mode shapes of the radome were obtained through experimental modal tests, and the natural vibration characteristics of the radome were determined. After the correction, the error of the first-order natural frequency of the experiment and simulation of the radome model decreased from 16% to 2.3%, and the cumulative error of the first five-order natural frequency was reduced by 31.8%, which effectively improved the accuracy of the finite element simulation and verified the finite element mode accuracy of analysis. The error of the maximum deformation of the radome experiment and simulation was 9.6%, which proved the rationality of the model correction method and the credibility of the material parameters after the model correction. Finally, through the developed simulation wind load experimental device, the sand gravity was used to simulate the wind load to verify the credibility of the model correction results.

Calculation method of deflection after cracking of RC beams strengthened with CFRP plates under fatigue load

DENG Lang-ni, LEI Li-zhen, XIE Hong, ZHOU Zheng, LIAO Ling

2022, 0(1):  62-67.  DOI: 10.19936/j.cnki.2096-8000.20220128.009

Asbtract ( 155 )   PDF (1943KB) ( 119 )  

References | Related Articles | Metrics

Based on the test data of five specimen beams, the change of mid-span deflection of reinforced concrete beams strengthened with CFRP plates under fatigue load is analyzed. The test results show that under cyclic loading, the bending stiffness of reinforced concrete beams will produce fatigue attenuation, and the sectional curvature will continue to extend, resulting in the continuous increase. The embedded reinforcement method of CFRP plate bottom layer can effectively restrain the decline rate of flexural rigidity of reinforced concrete beams and relieve curvature extension, thus improving their fatigue flexural deformation performance. Finally, by introducing the method of tensile stiffening effect, the calculation model of deflection of beams strengthened with CFRP plates under fatigue load is derived. The calculation results show that the calculated values of the proposed deflection calculation model are in good agreement with the experimental values.

Simulation on tension winding of the carbon fiber reinforced plastic rotor sheath for high-speed permanent magnet motor

XIAO Jian-xiong, ZHOU Xiang, SHEN Zheng

2022, 0(1):  68-72.  DOI: 10.19936/j.cnki.2096-8000.20220128.010

Asbtract ( 320 )   PDF (3097KB) ( 393 )  

References | Related Articles | Metrics

For the high-speed permanent magnet motor with the surface-mounted structure, the magnet cannot bear the centrifugal force due to the high-speed rotation and is easy to break. Via the tension winding technology, the carbon fiber reinforced plastic (CFRP) rotor sheath can effectively guarantee the safe and steady operation of the rotor. By the ANSYS Workbench software, finite element analysis was conducted on the tension winding of the CFRP rotor sheath for a surface-mounted high-speed permanent magnet motor. The results show that the finite element model can accurately simulate the stress field of the sheath during the winding process. Besides, under the predetermined winding stress on the fiber, the magnet and the shaft can keep the tight contact during the running process of the rotor, with their stress level maintained below the ultimate limit.

The study on the performance and application of Vectran in airship envelope materials

CUI Xin-wen, JIANG Jin-hua, LI Jun

2022, 0(1):  73-78.  DOI: 10.19936/j.cnki.2096-8000.20220128.011

Asbtract ( 230 )   PDF (2237KB) ( 208 )  

References | Related Articles | Metrics

In order to study whether a Vectran fiber can be made into a fabric that meets the performance requirements of airship envelope material, the mechanical properties of the yarn and fabric were tested respectively. Firstly, the effect of twist on mechanical properties of Vectran filament yarn was investigated by breaking strength test and data fitting. The results show that twisting can enhance the breaking strength of Vectran filament yarn, but special twisting technology is needed. As the twist increases, the strength decreases first, then increases and then decreases. Additionally, by comparing the tensile and tearing properties of four different Vectran fabrics, the influence of coating on the mechanical properties of Vectran fabrics was discussed. The results show that the 400D Vectran fabric can meet the mechanical properties of the airship envelope material and has the advantage of lower cost. The tear failure mode of Vectran coated fabrics is different from that of uncoated fabrics.

Research of aluminum conductor composite core crimping with non-concentricity

SONG Ze-ming, WAN Jian-cheng, ZHU Bo, Alan Kin Tak LAU, LUO Hong-jian

2022, 0(1):  79-85.  DOI: 10.19936/j.cnki.2096-8000.20220128.012

Asbtract ( 173 )   PDF (4354KB) ( 113 )  

References | Related Articles | Metrics

In the previous X-ray inspection work during the Aluminum Conductor Composite Core (hereinafter referred to as "ACCC") construction, despect of conventional obvious defects on the carbon fiber composite core (hereinafter referred to as "core"), it is also non-concentric with the wedge holder. Such defects have not been studied, and the long-term impact has not been known. Based on the X-ray inspection image of ACCC crimping, this paper analyzed the crimping non-concentric, defined the core crimping non-concentricity, and proposed the reasons for the core crimping non-concentricity. According to the construction parameters, this paper carried out a numerical simulation model, and the bending deformation effect finite element calculation is built. Then, through the static simulation calculation on the bending deformation mechanics problem of core crimping with non-concentricity, this paper analyzed the static response of the core, and evaluated the safety hazards caused by core crimping non-concentric. The research can provide theoretical support for the improvement of ACCC crimping.

Study on preparation and performance of silica aerogel/EPDM composite thermal insulation material

WANG Zhen-hao, CHEN Bo, GAO Fei, WANG Shu-ping, LI Xiang-mei, LIU Jing-bing

2022, 0(1):  86-90.  DOI: 10.19936/j.cnki.2096-8000.20220128.013

Asbtract ( 147 )   PDF (4284KB) ( 118 )  

References | Related Articles | Metrics

In this paper, SA/EPDM thermal insulation composite materials were synthesized and prepared, and the thermal insulation performance, thermal stability performance and mechanical properties of the composite materials with different SA/EPDM content ratios and the addition of flame retardants were studied. When the fire source temperature is 300 ℃ and 500 ℃, the back surface temperature of the composite material with 70% SA content is maintained at 130 ℃ and 250 ℃, and the thermal conductivity is 0.2253 W/m·K. The thermal weight loss analysis shows that although the increase of SA content does not delay the high-temperature degradation rate of the material, the addition of SA content reduces the heat of glass transition of the composite material, and plays a positive role in promoting the carbon formation of the material. The highest is 50.67%, and the mechanical properties of the composite material are excellent, the tensile strength can reach 22.45 MPa, and the elongation at break can reach 661.90%.

Study on preparation and properties of degradable epoxy composites containing borate ester bond

ZHANG Wen-hua, FANG Chao-yu, LI Xin, YOU Li-wen, QI Yi-qing, ZHOU Quan

2022, 0(1):  91-97.  DOI: 10.19936/j.cnki.2096-8000.20220128.014

Asbtract ( 314 )   PDF (5969KB) ( 215 )  

References | Related Articles | Metrics

The three-dimensional network structure of traditional epoxy resin not only endows it with good properties, but also brings challenges to its reprocessing and recycling. In recent years, the introduction of dynamic covalent bond into thermosetting resin to achieve degradation has been emerging, but it is still an urgent requirement to achieve degradation in a mild and green method. In this paper, phenylboronic acid (PBA) was used to cure bisphenol-A epoxy resin (DGEBA, E44) to form dynamic borate ester bond. The superior heat resistance of cured resin (PBAE) was investigated by Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA). Glass transition temperature (T_g) and 5% weight loss temperature (T_d5) were 147 ℃ and 267 ℃ respectively, while the mass retention rate at 800 ℃ is higher than 25%. Based on this matrix, recyclable glass fiber-reinforced PBAE composite was prepared, which could achieve green and mild degradation in ethanol aqueous solution (volume ratio=2∶1) at room temperature. PBAE composite exhibited comparable mechanical properties, with bending strength of 499 MPa and interlaminar shear strength of 70 MPa. In addition, PBAE composites could facilely achieve self-healing under heating and pressure conditions.

Research on the effects of ultraviolet aging on the properties of carbon fiber reinforced fast curing epoxy composites

JIANG Shi-cai, YAN Hong-chen, SHI Feng-hui, LI Shao-liang, ZHU Wen-kun

2022, 0(1):  98-103.  DOI: 10.19936/j.cnki.2096-8000.20220128.015

Asbtract ( 206 )   PDF (5772KB) ( 139 )  

References | Related Articles | Metrics

In this paper, the effects of long-term ultraviolet aging on the mechanical properties of carbon fiber reinforced epoxy composites were investigated by artificial accelerated aging test under ultraviolet light source. The properties of the composites, including tensile strength, compression strength, bending strength, apparent morphology, infrared spectrum and XPS, were systematically tested. The results show that the mechanical properties of the composites decreased in different degrees and the surface of the composites appeared defects or holes after long-term ultraviolet aging. These experiments indicate that long-term ultraviolet irradiation will break the chemical bonds of epoxy resin matrix and cause partial degradation of epoxy resin matrix, which will destroy the resin/fiber interfaces and eventually lead to material defects and the deterioration of mechanical properties.

Design of substation frame based on composite materials

CAO Ming-yang

2022, 0(1):  104-111.  DOI: 10.19936/j.cnki.2096-8000.20220128.016

Asbtract ( 161 )   PDF (7528KB) ( 92 )  

References | Related Articles | Metrics

Use the composite post insulator to replace the substation frame angle steel lattice, and the electrical insulation path is changed from suspension insulator to horizontal composite post insulator, to reduce the structural height and building area of substation frame. The specific scheme includes butt four composite post insulators with the hanging plate through the flange, and the conductor relates to the substation frame through the hanging plate. Composite post insulator, as a structural load-bearing part and electrical insulation component, reduces the number of steel frame elements compared with the traditional lattice beam. The mechanical analysis of the new frame model is carried out by Workbench. The analysis results show that under the same load cases, the new frame has good mechanical properties, and the composite post insulator has good adaptability in the substation frame. Finally, the feasibility and rationality of the new frame design are verified by mechanical and electrical tests. The research results show that a new substation frame reduces the weight of the substation frame and the height of the conductor hanging point, reduces the substation building area, has obvious promotion benefits and has broad application prospects.

Research on the curing packaging technology of high temperature polyimide composites

LIANG Heng-liang, ZHOU Hong-fei, CHEN Jing

2022, 0(1):  112-116.  DOI: 10.19936/j.cnki.2096-8000.20220128.017

Asbtract ( 181 )   PDF (5751KB) ( 251 )  

References | Related Articles | Metrics

For polyimide resins with a temperature of 375 ℃ for the thermos-pressor tank-vacuum bag molding curing temperature, the single-layer vacuum bag package system is often broken in the curing process because the curing temperature is close to the temperature limit of high temperature vacuum bag and high temperature sealing material. Dual vacuum package cured parts by non-destructive testing, glass transition temperature and with the furnace part bending and layer shear performance test, in line with the standard requirements, indicating that the dual vacuum package is reasonable and feasible.

REVIEW

Research progress on interlaminar toughening technology of fiber reinforced composites

LIU Xiao-jun, ZHAN Li, ZOU Ai-ling, LI Zhi-kun, ZHAO Yan-mei, WANG Shao-zong

2022, 0(1):  117-128.  DOI: 10.19936/j.cnki.2096-8000.20220128.018

Asbtract ( 528 )   PDF (15432KB) ( 490 )  

References | Related Articles | Metrics

Continuous fiber reinforced composite is widely used in aerospace and other fields due to its advantages of light weight and high strength. The main ways to improve the interlaminar strength of composite are improving the performance of resin matrix, increasing the normal material and interlaminar toughening. Interlaminar toughening is a kind of method which embeds fibers, particles and thin films as reinforcing phases into the interlaminar of continuous fiber composite to achieve the interlaminar strengthening effect, it does not need to change the existing process. The process is easy to realize, and the reinforcement effect is obvious. Considering the cost, technical difficulty and other factors, the interlaminar toughening method is a feasible and effective interlaminar strengthening method. In this paper, the latest research progress of interlaminar toughening technology of fiber-reinforced composite is reviewed. The research of interlaminar toughening technology of composite is divided into fiber interlaminar toughening, nano material interlaminar strengthening, particles interlaminar toughening, film interlaminar toughening, etc, which can provide support for improving the interlaminar strength of fiber-reinforced composite and the wider application of fiber-reinforced composite.