COMPOSITES SCIENCE AND ENGINEERING

Connection performance and failure mechanisms of three-dimensional woven composites

ZHANG Qian, ZHANG Yifan, ZOU Qi, ZHANG Peng, JIAO Yanan, AN Liuxu, LIU Yanfeng, ZHANG Daijun, HAO Junjie, CHEN Li

2024, 0(9): 5-11. DOI: 10.19936/j.cnki.2096-8000.20240928.001

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In order to study the influence of fabric structures on the connection performance of three-dimensional woven composites, multi-layer multi-directional woven structure and layer-to-layer interlock woven structure composites were designed, and a macro-meso coupling analysis model of the open-hole connection structures was established to reveal the failure mechanism of 3D woven composite connections. The study shows that the proportion of ±45° yarn has an important effect on the extrusion strength of the mechanical connection of the composite material, and the introduction of ±45° yarns can improve the content of load-bearing yarns, which can effectively improve the stress concentration at the hole edge; the multi-layer multi-directional woven composites are mainly subjected to transverse and longitudinal damages of 0° yarn, 90° yarn, and bias yarns; these damages start at the hole edge and progressively spread symmetrically. The transmission direction of load and the propagation direction of damage show angular characteristics.

Effect of ply angle on anti-high speed impact properties of polyimide fiber reinforced composites

YAN Jiqiang, XIE Zongyou, LI Jun, ZOU Qi, LEI Shuai, CAO Tienan, ZHANG Daijun

2024, 0(9): 12-18. DOI: 10.19936/j.cnki.2096-8000.20240928.002

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In order to investigate the effect of ply angle on anti-high speed impact properties of polyimide fiber reinforced composites, a series of polyimide fiber reinforced bismaleate composites laminates with different ply angle were fabricated. The effects of ply angle on the damage morphology, ballistic limit velocity and breakdown energy absorption of composites were studied. The results demonstrate that the greater the fiber anisotropy in laminates with different ply angles, the greater the deformation of the composite laminates; meanwhile, the results also indicate that [0/90] ply has the best high-speed impact resistance. Under non-breakdown condition, the ballistic energy absorption efficiency of [0/90] ply is 61% higher than that of [45/0/-45] ply, and under breakdown condition, the breakdown energy absorption efficiency of [0/90] ply is 68% higher than that of [30/0/-30] ply. Furthermore, the laying angle affects the transmission of impact loads along the fiber axial direction among different layers, [0/90] laying can avoid the transverse shear failure of fibers, so it has the best high-speed impact resistance performance.

Electrospun PPESK fiber mats interlayer toughened carbon fiber/epoxy resin composite

LÜ Xujin, HUO Hongyu, PENG Gongqiu, ZHANG Baoyan, YE Jinqiu, LIU Yong

2024, 0(9): 19-27. DOI: 10.19936/j.cnki.2096-8000.20240928.003

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With the vigorous development of China’s aerospace industry, the demand for high-performance carbon fiber composite materials is increasing. Poly (phthalazine ether sulfone ketone) (PPESK) exhibits good epoxy compatibility, processability, and mechanical properties, showing promising prospects in the field of interlayer toughening of carbon fiber/epoxy resin composite materials. In this study, stable preparation of PPESK ultrafine fiber felts was achieved using electrospinning technology, and through interlayer paving and hot pressing, the composite of PPESK with T800 carbon fiber/high-temperature epoxy resin prepreg was realized. When 17 g/m² of PPESK ultrafine fiber mats were added between the prepregs, the compression after impact of the composite reached 391 MPa, indicating a significant toughening effect for T800 carbon fiber composite materials. Electrospun PPESK fibers have great potential in the toughening carbon fiber composite materials.

The interlayer structures and lightning strike damage behaviors of the conductive particles modified highly tough composites

GUO Miaocai

2024, 0(9): 28-36. DOI: 10.19936/j.cnki.2096-8000.20240928.004

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The goal of developing next generation of multifunctional structural composites for lightning strike protection is to maintain the mechanical properties while possessing good lightning-strike damage resistance. Two micrometer-sized conductive fillers were introduced into the interlayer of an aero-grade highly-tough composite with thick interlayer. Their effect on the short-beam strength (SBS), electrical conductivity, and lightning strike damage behavior were studied. The results show that the rod-like nickel plated carbon fiber powders formed good conductive paths between carbon plies and the conductivity through thickness direction (σ_z) increased by 361 times, reaching 0.622 S/cm, while the SBS slightly decreased. The Ag-plated t-ZnO particles formed a conductive band inside the interlayer with poor contact with the carbon plies, and its σ_z only increased by 39.6 times. A higher decrease of the SBS was found, but its SBS is still significantly higher than that of the composite modified by carbon nanotube coatings. The introduction of conductive fillers significantly reduced the damage areas and depths caused by simulated Zone 2A lightning strikes and improved the retention rates of flexural strengths of the damaged regions. Because of the large interlayer thickness and less electric contact between plies, the lightning strike damage behavior was significantly affected by σ_z. Large area delamination caused by the interlayer resin ablation was their main damage characteristic, which is significantly different from the damage characteristics of the composites with thin interlayer.

Adhesion study of carbon fiber/polyaryletherketone thermoplastic composites with epoxy coatings

LI Moying, ZHENG Linfeng, LIU Gang, LI Mengjiao, YAO Jianan

2024, 0(9): 37-42. DOI: 10.19936/j.cnki.2096-8000.20240928.005

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With the rapid development of continuous fiber reinforced thermoplastic composites in aerospace field, the surface coating for thermoplastic composites has also become particularly important, therefore, a systematic study of the adhesion of conventional epoxy coatings to carbon fiber reinforced polyaryletherketone (CF/PAEK) thermoplastic composites was carried out. The effects of abrasive blasting treatment, plasma treatment and abrasive blasting treatment + plasma treatment on the microscopic morphology, roughness, contact angle and chemical properties of the composite surface, as well as the adhesion strength between the composites and the epoxy coatings, were investigated separately. The results show that those three surface treatments can effectively increase the adhesion strength between the composites and the epoxy coating. Among them, the highest adhesion strength of 26.6 MPa was obtained for the composite surface coating after sandblasting + plasma treatment, which was 23.1% higher than that of untreated. Meanwhile, the heat resistance and hydraulic oil resistance of the composite surface coating adhesion strength after the three surface treatment were good, and the retention rate is higher than 80%.

Study on properties of high heat resistant and flame retardant epoxy resin matrix CFRP

XIE Wenbo

2024, 0(9): 43-47. DOI: 10.19936/j.cnki.2096-8000.20240928.006

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Mechanical, hydrothermal, flame retardant and fire protection performance of high heat resistant and flame retardant epoxy resin matrix CFRP is investigated in this article. The results show that the high heat resistant and flame retardant CFRP has great mechanical and flame retardant performance. The flame retardant epoxy resin matrix CFRP has achieved a flame retardant grade of V-0. Its maximum smoke density (D_m) within 240 seconds is 5.17, and its limiting oxygen index (LOI) is 39.5%. Therefore, this material can basically meet airworthiness standard. Above all, research on properties of structural and functional integrated CFRP lays a foundation for the final engineering application in advance aero-craft and aero-engine.

Research on the effect of residual monomer acrylonitrile on the preparation of PAN-based carbon fiber

HUANG Daming, TANG Lixin, SUN Juntao, WANG Wei

2024, 0(9): 48-51. DOI: 10.19936/j.cnki.2096-8000.20240928.007

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This article detects the content of residual monomer in the PAN spinning solution through gas chromatography, studies the impact of the residual monomer content on the production environment, and analyzes to obtain the minimum standard of the residual monomer content. It studies the effect of the residual monomer on the properties of the spinning solution, and finds that due to the continuous polymerization reaction, the residual monomer acrylonitrile will increase the viscosity and solid content of the spinning solution due to its own reaction. It further studies the impact on the strength and fuzziness of the carbon fiber, and finds that with the reduction of the residual monomer, it will be beneficial to the production of the carbon fiber and the improvement of the performance of the carbon fiber, and analyzes to obtain the requirements for the residual monomer content suitable for the production of carbon fiber. In addition, starting from aspects such as the vacuum degree, temperature, and film surface area in the de-monomerization process, it analyzes the impact of related methods to reduce the residual monomer content, and helps the rationalization of production.

A method for optical fiber impact localization and load history reconstruction of composite laminates

FENG Zhenhui, WANG Zhe, ZENG Jie, CHEN Binbin, FENG Chunle, ZHOU Fan

2024, 0(9): 52-56. DOI: 10.19936/j.cnki.2096-8000.20240928.008

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A method for identifying the impact response characteristics of composite laminates based on fiber Bragg grating sensors is proposed for typical aerospace composite laminates. Based on the discrete strain sensing information of fiber Bragg grating sensors, a composite laminate impact strain response inversion method based on the principle of distance reciprocal multiplication has been developed. Based on the sudden change characteristics of the impact response and combined with the extreme value comparison method, identify the position of the strain response peak corresponding to the impact load. On the basis of identifying the impact position, the Bayesian regularization method is proposed to reconstruct the impact load of composite laminates, effectively solving the ill posed problem caused by the ill posed pulse response matrix in conventional load history reconstruction. The experimental results show that the average error between the coordinates of the impact point and the identification point is about 13.00 mm. The average relative error within the effective action history of the reconstructed impact load is about 4.21%, and the relative error for identifying the peak load is 3.85%.

Shape control of aircraft composite components based on measured data

ZHANG Dewei, WEI Wei, ZHANG Pin, WANG Qi, ZHAO Cong, AN Luling

2024, 0(9): 57-66. DOI: 10.19936/j.cnki.2096-8000.20240928.009

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In the assembly of aircraft composite components, molding errors are often eliminated through rigid constraint methods such as pallets. The constraint profile of the pallets is consistent with the theoretical shape of the component. Since composite materials have uncontrollable molding errors, this rigid constraint the control method may cause composite material damage. This paper obtains the physical shape data of composite material components through digital measurement, reconstructs its shape model, and designs a flexible multi-point force-applying head to control the shape of the component. A solution scheme that combines finite element calculations with genetic algorithms is proposed. The goal is to ensure that the actual shape of the composite material components matches the theoretical shape as closely as possible without causing damage. This method is verified through an example of a certain type of aircraft radome composite material cover. The shape of the cover is constrained according to the original plan of using a constraint card plate. The accuracy between the actual shape and the theoretical shape at a given position is only 66.7%. Through this method, a multi-point pressure head is used to control the shape of the cover. The accuracy between the actual shape and the theoretical shape at a given position reaches 91.7%, which is 25% higher than the original plan.

Curing deformation study of composite cobonding omega stringer stiffened panel

YAN Chao, RONG Xiaoyuan, ZHAO Yueqing, QIAN Zhongjian

2024, 0(9): 67-72. DOI: 10.19936/j.cnki.2096-8000.20240928.010

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The curing deformation of omega stringer stiffened panel was researched with five stringer stiffened panel. The contour of omega stringer was measured by tri-ordinate measuring machine, and finite element simulation was made for curing deformation of omega stringer, there is a spring-in deformation in the cross-section direction, and a torsional deformation in the length direction. The height and width of omega stringer after omega stringer cured and stiffened panel cured were measured, and explain that there is a collapse deformation for omega stringer, reducing 0.5 mm at height and increasing 2 mm at width approximately, the trend of change is the same between experiment and simulation. The contour of stiffened panel was measured by laser tracker, there is an obvious bending deformation perpendicular to the stringer length direction, 12.9 mm at maximum. Finite element simulation was made for curing deformation of the stiffened panel, the simulation result is in agreement with experimental result. After analysis, the curing deformation of omega stringer stiffened panel is resulted from both the torsional deformation and the collapse deformation of omega stringer.

Research on tension-tensile fatigue behavior and life prediction of T700/PPS filament winding thermoplastic composites with NOL rings

YAN Lei, ZHAO Fei, HUAN Dajun, ZHANG Shengyuan, WANG Bin, XIAO Jun

2024, 0(9): 73-81. DOI: 10.19936/j.cnki.2096-8000.20240928.011

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For the application of filament winding carbon fiber reinforced polyphenylene sulfide (T700/PPS) thermoplastic composites, the NOL ring test was used to study the tension-tension fatigue behavior for the first time and a life prediction method was proposed. Based on the self-developed thermoplastic composite filament winding platform with in-situ consolidation, NOL rings were prepared with T700/PPS prepreg by laser-assisted heating. According to the standard NOL ring tensile test, the result of average static tensile strength was 2 438.35 MPa, the dispersion coefficient was 2.0% and the failure mode was brittle fracture. Based on static strength data, the stress level of the fatigue test was determined. Aiming at the characteristics of the ring-shaped test piece, a “split ring” fatigue fixture was designed to carry out the tension-tension fatigue test of the NOL rings under different stress levels, then the thermal behavior during the fatigue cycle was analyzed with the help of infrared thermal imager and the failure modes was captured. In view of the large discreteness of fatigue life data, a convenient and efficient life prediction algorithm was proposed: The fast data screening was realized by K-means clustering, and the grey GM (1,1) model was constructed to predict the fatigue life of NOL rings and draw the S-N curve. It was found that when the stress level is lower than 47% of the static strength, the fatigue life will exceed 10⁷ times and enter the infinite fatigue life stage, which provides support for the life design of high-speed rotating parts and thermoplastic pressure vessels manufactured by filament winding.

Research on microwave curing process for rib composite parts

CHENG Libing, XU Weiwei, LI Bo, WEN Shiqi

2024, 0(9): 82-86. DOI: 10.19936/j.cnki.2096-8000.20240928.012

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Compared with the autoclave curing process, the microwave curing process of composite can reduce the curing time, reduce energy consumption, and have good process controllability. This research proposes a special functional auxiliary structure based on theoretical analysis, which solves the microwave heating problem of multi-directional layered carbon fiber composite. The formation of typical composite rib parts has been achieved through microwave curing technology, further promoting the engineering application of composite microwave curing technology. The research results indicate that the basic mechanical properties of composite rib parts manufactured by microwave curing can meet the requirements of engineering applications. Compared with the autoclave curing process, the microwave curing process can shorten the curing cycle by 59.8% and reduce the energy consumption by 61.5%.

Study on structural stability of high-modulus carbon fiber composite tube in alternating high and low temperature environment

WU Haisheng, LUO Jintao, GU Yizhuo, SUN Tianfeng, LIU Jia, YAO Qi, LI Yu

2024, 0(9): 87-91. DOI: 10.19936/j.cnki.2096-8000.20240928.013

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Aiming at the problem of cross section deformation and delamination of high-modulus carbon fiber composite tubes in alternating high and low temperature cycle environment, a single layer ultra-thin (0.02 mm) alkali-free glass fiber plain cloth is added between its large angle differential layers based on the idea of fiber hybrid. Simulation analysis shows that the glass fiber plain cloth effectively alleviates the thermal expansion mismatch between the large angle differential carbon fiber layers and reduces the inter-layer stress. The correctness of simulation analysis is confirmed by a test of 6 alternating temperature cycles of liquid nitrogen temperature (-196 ℃)~+150 ℃. After the test, the hybrid tube maintains itself intact layer and unchanged dimensional cross section size. Further bending performance comparison test of unidirectional plates shows that the addition of ultra-thin glass plain cloth enhances interlayer toughness of the tube, while has no significant effect on its bending performance, because of its low modulus and little thickness proportion (1.6%).

Prediction and analysis of burst pressure of type Ⅳ composite cylinder based on progressive damage

FU Chengjian, LIN Song, GUO Shufen

2024, 0(9): 92-97. DOI: 10.19936/j.cnki.2096-8000.20240928.014

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In this paper, Hashin failure criterion was introduced, USDFLD subroutine was compiled, and finite element numerical simulation of type Ⅳ composite cylinder based on progressive damage was realized by ABAQUS-WCM software. Finally, the composite cylinders were prepared and verified by blasting experiment. The finite element analysis (FEA) results of progressive damage show that the maximum diameter circle of the metal joint and the transition position between the cylinder and the head of the Ⅳ composite cylinder are easy to cause the stress concentration of the composite layer, which is the first position where the tensile fracture failure of the resin matrix and the fiber occurs, and the failure of the resin matrix is prior to the failure of the fiber, and the failure area is larger. The results of composite cylinder blasting results show that the predicted blasting pressure and failure position are close to the real test results, which verifies the validity of the FEA model.

Application and development trends of composite materials in civil aircraft

XU Lin, LIU Chuanjun, ZHAO Chongshu

2024, 0(9): 98-104. DOI: 10.19936/j.cnki.2096-8000.20240928.015

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“One generation of aircraft, one generation of materials”, materials are the foundation of aircraft manufacturing. In over a hundred years of world aviation history, the speed of aircraft development largely depends on materials. Composite materials have greatly promoted the development of the civil aircraft industry due to their high specific strength and modulus, good fatigue and corrosion resistance, and low density. At present, the amount of high-performance composites has become one of the important indicators to measure the progressiveness of civil aircraft. This article focuses on a series of aviation composite material research plans formulated and implemented by European and American countries, as well as the important achievements made. It introduces the development process of aviation composite materials in China. Summarized the current application status of composite materials in the field of civil aircraft both domestically and internationally. With the support of national policies and based on the future demand for domestic civil aircraft, this paper analyzes the advantages of composite material application in reducing aircraft structural weight, reducing operating costs, and improving economy from the aspects of raw materials, structural component manufacturing, and process equipment. The opportunities and challenges of composite material application in domestic civil aircraft are discussed.

Advances in fatigue performance of fiber reinforced composite-metal hybrid joints

SONG Jianhui, YU Xiaochen, ZHU Yingdan, WU Huaping, ZHANG Xiongjun, CHEN Gang

2024, 0(9): 105-112. DOI: 10.19936/j.cnki.2096-8000.20240928.016

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Fiber-reinforced composites have been widely used in various lightweight applications due to their excellent mechanical properties. In practice, fiber-reinforced composites are required to be connected with other heterogeneous materials such as metals, in which hybrid joints have better mechanical properties than the bonded and traditional mechanical joints. Fatigue life is the key to the service performance of fiber-reinforced composite-metal hybrid joints. This paper studies the fatigue performance of various components of hybrid joints, discusses the fatigue life prediction methods and the important factors affecting the fatigue performance of hybrid joints. Furthermore, the development trend of hybrid joints is summarized and prospected.

Application of robot technology in composite repair process

XUAN Shanyong, ZHANG Laibin, SHAN Yimeng, ZHOU Jian, YAO Xuefeng

2024, 0(9): 113-124. DOI: 10.19936/j.cnki.2096-8000.20240928.017

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Composite repair mainly relies on manual, which has low efficiency, low accuracy, and experience can not be transplanted and other problems. The robot has the characteristics of high freedom, high flexibility and operation standardization. The combination of the repair process and robotic technology can automate the repair process of composite and greatly improve the repair efficiency and standardization. At present, some scholars have developed end-effector and robot automatic repair system suitable for drilling, grinding, automatic tape laying and monitoring in combination with the actual needs of the composite repair process, which to some extent solved the problems of low precision and unstable repair quality existing in the current manual repair, laying a technical foundation for the realization of high-quality repair of composite structures. According to the current research status of robot repair technology for composite, the research status and key technical problems of robotic drilling, robotic grinding, robotic tape laying and robotic inspection for composite material repair at home and abroad are deeply introduced, and the application of robot technology in the field of composite repair is analyzed. Finally, the future development of composite robot repair technology is prospected.

Research status and development trend of Z-pin reinforced anti-heat insulation composites

HU Zehui, LI Yong, HUAN Dajun, HAN Bing, GUO Da

2024, 0(9): 125-132. DOI: 10.19936/j.cnki.2096-8000.20240928.018

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Future new space vehicles, characterized by fast flight speed and long navigation time, have become an important research hotspot for the world’s space powers. In order to guarantee the safe flight of the vehicle under aerodynamic heating conditions for a long time, the application of anti-insulation composite materials plays a crucial role. At present, in view of the weak interlayer performance and low preparation efficiency of heat protection composites for space vehicles, and the weak core material performance of heat protection ceramic-based composite sandwich structure and hand-stitching enhancement, the article analyses and summarizes the current research status of domestic and foreign research on heat protection composites and Z-pin enhancement technology from the aspects of design, preparation and application, and puts forward the development trend of China’s future Z-pin enhancement technology of heat protection composites.

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