COMPOSITES SCIENCE AND ENGINEERING

Preparation and properties of graphene/PCM composites based on Pickering emulsion method

ZHUO Qing, WANG Shiyi, ZHAO Wei, LI Mingpu, WANG Yuqi, LI Yuanyuan, LI Yingru

2025, 0(9): 1-7. DOI: 10.19936/j.cnki.2096-8000.20250928.001

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As a typical phase change material (PCM) for energy storage, paraffin (PA) was found to possess shortcomings such as easy leakage and poor thermal conductivity, which had limited its large-scale market application. To address this issue, solidified paraffin/graphene (PaGr) composites were prepared by a one-step hydrothermal method, in which PA served as the matrix phase change material and reduced graphene oxide (RGO) acted as the confining carrier. During the hydrothermal process, the Pickering emulsion, configured with GO as a stabilizer, facilitated the effective recombination of paraffin and graphene. XPS and Raman spectroscopy were employed to confirm the successful conversion of GO into RGO during the hydrothermal reduction process. The microstructure, thermophysical properties, and structural stability of the PaGr composite PCM were characterized through optical microscopy, DSC, and thermal cycling. The experimental results show that PaGr composites can effectively improve the shape instability and high thermal resistance caused by PA liquid leakage. Compared with pure PA, its thermal conductivity and structural stability are improved, which indicates that PaGr composites have broad application prospects in the field of PCM.

Research on mode Ⅰ interlaminar properties of chopped fiber-interleaved carbon fiber reinforced composites based on DIC

DENG Yu, TU Haoyun

2025, 0(9): 8-15. DOI: 10.19936/j.cnki.2096-8000.20250928.002

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As an efficient and convenient interlaminar toughening method, chopped fiber interleaved composites has been widely used to enhance the interlaminar mechanical properties of composites. Current research lacks a systematic exploration of the three-dimensional image experimental data for the interlaminar cracking process in carbon fiber-reinforced composites with chopped fiber interlayers. In this study, carbon fiber/epoxy composite laminates toughened with chopped aramid fibers and chopped flax fibers were prepared. The toughening effects of chopped fibers were investigated through double cantilever beam (DCB) experiments, and digital image correlation (DIC) was employed to investigate the surface strain field and damage evolution in the chopped fiber interlayer-toughened composites. The interlaminar toughening mechanisms of different chopped fibers were analyzed. The experimental results demonstrated that the interlaminar insertion of chopped aramid fibers and chopped flax fibers significantly enhanced the mode Ⅰ fracture toughness of the composite laminates. During the delamination process in the toughened DCB specimens, fiber bridging and fiber pull-out phenomena were observed. Compared to chopped flax fibers, the chopped aramid fibers exhibited more pronounced fiber bridging and crack deflection, leading to better interlaminar toughening effects. These findings provide an experimental foundation for optimizing the performance of composite.

Semi-analytical simulation method for bi-directional FGM cantilever beam under stochastically distributed load

ZHANG Long, ZHANG Wei, FAN Juntao, LIAO Wenlin

2025, 0(9): 16-26. DOI: 10.19936/j.cnki.2096-8000.20250928.003

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In order to study the mechanical behavior of bi-directional functionally graded material (FGM) cantilever beam under stochastically distributed load, a semi-analytical method of high precision and efficiency is developed in this paper. Firstly, the physical model of the bi-directional FGM cantilever beam is introduced, and then the basic control equations of the cantilever beam subjected to stochastically distributed load are derived. Then, iterative solution of the equations is complemented through MATLAB programming. Based on this, a case study of unidirectional/bi-directional FGM cantilever beams subjected to pure bending load or uniformly distributed load is carried out, where the results are compared with the exact solution, Timoshenko beam theory results and graded finite element method results, indicating that the proposed method has good convergence and high accuracy. Finally, the proposed method is used to simulate and analyze the mechanical behavior of bi-directional FGM cantilever beams under linearly distributed load, sinusoidally distributed load or stochastically distributed load. The results obtained are in good agreement with the simulation results of the gradient finite element method, where the maximum relative errors for deflection and stress are within 2.11% and 3.39%, respectively.

Effect of layering sequence on low velocity impact properties of flax/basalt fiber hybrid reinforced composites

MU Wenlong, CHEN Liangyu, LI Shijie, ZHANG Shikun, JIANG Junwei

2025, 0(9): 27-34. DOI: 10.19936/j.cnki.2096-8000.20250928.004

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This study examines the effects of different layering sequences on the mechanical properties of flax/basalt fiber hybrid reinforced composites. The resin transfer molding process was used to prepare pure flax fiber, pure basalt fiber, and flax/basalt fiber hybrid reinforced composite laminates with two different stacking sequences. Low-velocity impact and post-impact bending tests were performed to reveal the influence of layering sequences on the mechanical properties and failure mechanisms of the hybrid composites. The study found that in the low-velocity impact test, the mechanical properties of the hybrid composites were between pure flax fiber and pure basalt fiber composites. [B₄F₄]_S exhibited a higher peak force than [F₄B₄]_S(where B denotes the basalt fiber layer, F denotes the flax fiber layer), and the energy absorbed by [B₄F₄]_S was higher. In the three-point bending test, the mechanical properties of the undamaged hybrid composites were between pure flax fiber and pure basalt fiber composites. However, after impact damage, the post-impact bending strength retention rates of both hybrid composites were higher than those of pure flax fiber and pure basalt fiber composites, and under the same impact energy, the post-impact bending strength retention rate of [F₄B₄]_S was higher.

Effects of nano calcium carbonate on the properties of frontal-polymerized dicyclopentadiene resin

LI Kehui, ZHANG Yueyao, SONG Longjie, YANG Liling, CHEN Dingding, XING Suli, YIN Changping, TANG Jun

2025, 0(9): 35-41. DOI: 10.19936/j.cnki.2096-8000.20250928.005

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This study was systematically conducted to investigate the effects of nano-CaCO₃ modification on the processing, thermal stability, and mechanical properties of frontal-polymerized dicyclopentadiene (DCPD) resin. The results demonstrate that the incorporation of nano-CaCO₃ significantly optimized the processing window of DCPD resin. Thus, the initial curing temperature and peak curing temperature are decreased by 16.16 ℃ and 13.92 ℃, respectively, while the room-temperature gelation time extends beyond 2.5 h. Furthermore, as nano-CaCO₃ suppressed the mobility of molecular chain, the glass transition temperature (T_g) is elevated to 127.9 ℃, which is a 33.79% increase over that of the pure resin. Mechanically, the flexural strength, tensile modulus, and impact strength are improved to 60.53 MPa, 1.90 GPa and 4.84 kJ/m² with the optimal nano-CaCO₃ content (3wt%~4wt%), representing improvements of 13.27%, 57.02% and 9.09%, respectively. However, due to the stress concentration caused by the agglomeration of nano-CaCO₃ particles at high content (>5wt%), the mechanical properties of the DCPD resin are degraded. This work could provide insights for designing high-performance frontal-polymerized polymer composites with tailored processability and thermal-mechanical properties.

Synthesis and characterization of graft modified high heat-resistant vinyl resin

LIU Hua, TANG Wenjin, LIU Zhengbiao, CHEN Jianhui, SHU Da, LIU Shiqiang

2025, 0(9): 42-46. DOI: 10.19936/j.cnki.2096-8000.20250928.006

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Three acrylate prepolymers were synthesized from hydroxyethyl methacrylate (HEMA), pentaerythritol triacrylate (PETA) or dipentaerythritol pentaacrylate (DPHA) and isophorone diisocyanate, reacting at a molar ratio of 1∶1. Then the prepolymers were grafted to phenolic vinyl ester resins by the catalysis of dibutyltin dilaurate (DBTDL). The heat distortion temperature (HDT), glass transition temperature (T_g), and thermal decomposition temperature of different acrylate grafted vinyl resins were studied. It is revealed that 20wt% DPHA prepolymer graft vinyl resin behaved the best heat resistant property, with HDT of 230 ℃, T_g of 220 ℃ and 5wt% thermal decomposition temperature of about 330 ℃.

Optimization of cure uniformity for thick-section composite materials before and after gelation based on thermo-fluid-solid multi-physics coupling

HUANG Shunfeng, LIU Wenbo, WANG Peipei, YANG Fan, WANG Rongguo, HU Kejun

2025, 0(9): 47-54. DOI: 10.19936/j.cnki.2096-8000.20250928.007

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To address quality defects arising from non-uniform temperature and cure degree fields before and after gelation in the curing process of thick-section composite materials, a multi-objective optimization approach for cure uniformity is developed. This approach utilizes a thermo-fluid-solid multi-physics coupled finite element model in conjunction with optimized Latin hypercube sampling (OLHS) to construct a radial basis function (RBF) surrogate model. The goal is to optimize the uniformity of temperature and cure degree gradients before and after gelation. Compared to the original design, the optimization results demonstrate a decrease in temperature gradients of 51.7% and 66.5% before and after gelation, respectively, and a reduction in cure degree gradients of 33.3% and 63.6%, respectively, with only a 6.7% increase in total curing time. The maximum temperature peak during the entire curing process was reduced by 8.8%. These results indicate that the proposed method can significantly improve the uniformity of curing before and after gelation.

Study on preparation and compression failure behavior of 3D woven honeycomb composite materials

GUO Jing, JIAO Yanan, ZHOU Qing, WAN Xili, CHEN Li

2025, 0(9): 55-64. DOI: 10.19936/j.cnki.2096-8000.20250928.008

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To address the issue of structural failure due to cracking at the adhesive joints of honeycomb walls during use, this paper utilizes 1 000 D aramid fibers as reinforcement and epoxy resin as the matrix. A 2.5D loom and vacuum assisted resin transfer molding (VARTM) process were used to prepare an integrated fiber-reinforced honeycomb three-dimensional woven composite material. The failure modes of the honeycomb three-dimensional woven composite material under out-of-plane loads were analyzed, revealing that the failure modes include fiber breakage, matrix failure, and overall crushing and buckling collapse of the honeycomb structure. To more accurately investigate the mechanical response and damage evolution of the 3D woven honeycomb composite material under out-of-plane compressive loads, a multi-scale damage model of the 3D woven honeycomb composite material was established using numerical simulation. By comparing the model with experimental results, it was found that the two show good agreement. Finally, a structural parameterization discussion of the 3D woven honeycomb composite material was conducted, exploring the influence of honeycomb side length and wall thickness on the out-of-plane compressive performance of the honeycomb.

Influence of chamfering angle on the curing deformation characteristics of L-shaped composite truss

WANG Yan, HUANG Yongyong, LI Yichao

2025, 0(9): 65-74. DOI: 10.19936/j.cnki.2096-8000.20250928.009

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To solve problems of structure assembly difficulty and loading reliability reduction caused by curing deformation of U-shaped composite trusses, this paper established a composite material curing deformation simulation model under the framework of ABAQUS. Based on this model, the effects of structural shape and layup angle on the cure deformation of L-shaped composite truss were investigated. By comparing with the experimental results of the curing deformation of three asymmetric layups of L-shaped composite trusses, it was found that the maximum calculation error of the simulation model was 11%. Based on this model, the curing residual stress field and curing deformation characteristics of L-shaped composite trusses with lay-up angles of [0/0/45/-45]_S, [0/90/45/-45]_S, [90/90/45/-45]_S were investigated under different chamfer radii. The results showed that the chamfer radius and lay-up angle of the composites significantly affected the curing deformation and residual stress of the components. With the increase of chamfering radius, the curing residual stresses and deformations of the three layup specimens showed a decreasing trend. Under the same chamfering radius, the curing deformation and residual stress of the [0/90/45/-45]_S specimen was the smallest among the three ply designs. These results indicated that increasing the chamfering angle of the L-shaped truss and designing a reasonable and uniform layup angle can help to reduce the curing deformation of the L-shaped composite truss.

Effects of weft yarn deflection angle in the thickness direction on the warp-direction tensile mechanical behavior of 2.5D woven composites

JIANG Pengfei, LI Lei, ZHANG Yifan

2025, 0(9): 75-83. DOI: 10.19936/j.cnki.2096-8000.20250928.010

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2.5D woven composites demonstrate promising application prospects in aerospace and other fields due to their excellent integral structural characteristics. However, the deflection characteristics of weft yarns in the thickness direction of preforms lead to more complex mechanical properties and failure mechanisms, significantly limiting their widespread application in engineering fields. This study focuses on typical 2.5D woven T300/QY8911-Ⅳ composites. By establishing unit-cell models with weft yarn deflection angles of 0°, 5° and 20°, and incorporating the 3D Hashin failure criterion and Mises failure criterion, a progressive damage model for 2.5D woven composites was developed to systematically investigate the warp-direction tensile mechanical behavior under different deflection angles. The results indicate that as the weft yarn deflection angle increases, the warp-direction tensile strength of 2.5D woven composites shows a trend of first increasing and then decreasing. This research provides theoretical foundations for the structural design and engineering applications of 2.5D woven composites, holding important practical engineering significance.

Analysis of calculation methods for local buckling critical load of non-uniform cross-section GFRP compression member

KANG Ertao, XIAO Xiao, ZHANG Tieshan

2025, 0(9): 84-92. DOI: 10.19936/j.cnki.2096-8000.20250928.011

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To investigate the impact of asymmetry due to unequal web and flange thickness in box-section GFRP columns on local buckling critical force prediction accuracy, this study established a nonlinear finite element model using ABAQUS. The model was validated through comparison with experimental results, and existing methods for calculating the local buckling critical force were evaluated. Based on these methods, a new optimized equation was proposed. Compared with finite element results, the optimized equation’s critical load predictions are 5% lower, with an average absolute error (AAE) of 6.58% and a standard deviation (SD) of 7.1%, which indicated low dispersion. This demonstrated the optimized equation’s effectiveness in predicting the local buckling critical force of non-uniform thickness GFRP compression members and provided a reliable design choice.

Application and research of finite difference method in static testing of large wind turbine blades

FANG Siming, ZHUANG Lei, ZHOU Xiaoliang, KONG Kui, XU Liqiang, ZHANG Dinghao, LI Yalong

2025, 0(9): 93-97. DOI: 10.19936/j.cnki.2096-8000.20250928.012

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In order to design a full-size static loading scheme for wind turbine blades more quickly and conveniently, this paper proposes a static loading method based on finite difference method for iterative calculation. Firstly, simplify the blade into a cantilever beam model with variable cross-section; secondly, based on the approximate differential equation of the deflection curve of the cantilever beam, the finite difference method is used to iteratively calculate the final deformation of the blade by correcting the cross-sectional bending moment according to the geometric shape of the blade; then, based on the final geometric shape of the blade, the static loading design of the scheme is carried out; finally, the method was applied to the static testing of 100-meter-class blades, and compared and analyzed with the calculation results of ANSYS software and actual test results to verify the effectiveness of the method proposed in this paper. This method can quickly calculate blade deformation, iterate static loading schemes, and improve the design efficiency of static testing loading schemes.

Prediction of axial bearing capacity of GFRP-reinforced concrete columns based on Bayesian-Bagging-XGBoost algorithm

TANG Peigen, LI Xiaoliang, HE Xin, MA Guohui, ZHANG Xiang

2025, 0(9): 98-109. DOI: 10.19936/j.cnki.2096-8000.20250928.013

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Due to the differences in mechanical properties between steel bars and glass fiber reinforced polymer (GFRP) bars, the axial bearing capacity of GFRP bar-reinforced concrete columns cannot be simply calculated using the methods for reinforced concrete columns. To improve the accuracy of the predictive model for the axial bearing capacity of GFRP bar-reinforced concrete columns, this study used 253 sets of experimental data as the basis for modeling with the extreme gradient boosting (XGBoost) algorithm. Bayesian optimization and Bagging algorithms were employed to optimize the XGBoost algorithm to enhance the model’s predictive accuracy, stability, and training efficiency. The model was evaluated using the coefficient of determination (R²), mean absolute error (MAE), and relative root mean square error (RRSE) and compared with existing predictive models. The study found that Bayesian optimization and Bagging algorithms effectively improved the training efficiency and predictive accuracy of the model. The proposed Bayesian-Bagging-XGBoost model achieved R², MAE, and RRSE values of 0.691 6, 418.162 9, and 0.555 3, respectively, which are significantly better than those of existing predictive models. This model provides a more accurate reference for the engineering application of GFRP bar-reinforced concrete columns.

Cars design and analysis of composite rear seat back panel for passenger cars

GUANG Yubo, REN Mingwei, QIU Rui, CAO Qinglin, WANG Yong, WANG Xinyu

2025, 0(9): 110-116. DOI: 10.19936/j.cnki.2096-8000.20250928.014

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In order to reduce the weight of car seat back panels, glass fiber composite materials are used instead of metal materials, and the lightweight effect is verified through simulation and trial production testing. Establish models of metal and glass fiber composite back panel, collision simulation analysis is conducted according to GB 15083—2019 standard, and the results meet the requirements. The glass fiber composite back panel was producted by using integrated injection molding process, weighing 5.04 kg, which achieved a weight reduction of 31.05% compared to metal (iron) back panel weighing 7.31 kg. Through the swing arm collision test, the maximum relative error between the measured deformation and simulated deformation of the glass fiber composite back panel was 3.2%, and the simulation results were reliable. After the collision, the glass fiber composite back panel did not fail and remained in its original locking position, meeting the requirements of the standard luggage impact test. The glass fiber composite back panel achieved the expected lightweight effect.

Prediction of bonding strength between helically wound FRP bars and concrete based on GEP

HU Cong, YANG Lang

2025, 0(9): 117-124. DOI: 10.19936/j.cnki.2096-8000.20250928.015

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Bonding strength is an important index to evaluate the bond performance between fiber-reinforced polymer (FRP) and concrete. Due to too many influencing factors, the prediction accuracy of the bonding strength of the relevant specifications and the mathematical model established by the researchers is low. In order to solve the above problems, a database containing 81 groups of bonding strength between helically wound FRP bar and concrete was established by collecting relevant references, and a mathematical prediction model was established based on gene expression programming (GEP) algorithm. The GEP model was compared with the mathematical formula based on the experimental data. The evaluation indexes included determination coefficient (R²), mean absolute error (MAE) and root mean square error (RMSE). The results show that the R², MAE and RMSE of the bonding strength prediction model based on GEP are 0.867, 1.510 and 1.853, respectively. Compared with the existing prediction models with the highest accuracy, the GEP-based prediction model R² is increased by 39.39%, MAE is decreased by 31.79%, and RMSE is decreased by 27.48%.

Simulation study on grommet hole reinforcement technology for composite structure and its fatigue life prediction

SUN Zhuowei, YUAN Guoqing

2025, 0(9): 125-134. DOI: 10.19936/j.cnki.2096-8000.20250928.016

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Cold expansion technology is a technique widely used to improve the fatigue life of aerostructures. For composite open-hole structures, the grommet can be expanded into the hole to effectively improve the fatigue life of the laminate. Based on the FEA software ABAQUS, this paper simulates the process flow of grommet hole reinforcement technology of composite laminate, predicts the fatigue life of the laminate after hole reinforcement, and studies the influence of different degrees of cold expansion (DCE) on the fatigue life of the laminate. The results show that: grommet hole reinforcement can generate a certain residual stress field on the hole edge of the laminate and the grommet. There are certain differences in the residual stress field of each layer, and the compressive residual stress on the extrusion outlet surface of the grommet is the highest; there is an optimal DCE , under which the reinforcement will not damage the laminate, and can also generate a suitable residual stress field in the structure, which can maximize the fatigue life of the laminate. The optimal DCE is 2% for the research object in this paper; if the DCE is too large, the grommet hole reinforcement will cause damage at the edge of the hole, mainly the matrix compression damage, which will affect or even reduce the fatigue life of the laminate.

Progress in the preparation and application of carbon fiber reinforced polymer mirrors

WU Di, LIU Zhu, BI Tuanli, CHENG Luchao, LIU Zhenyu, ZHANG Jifeng

2025, 0(9): 135-146. DOI: 10.19936/j.cnki.2096-8000.20250928.017

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Carbon fiber reinforced polymer (CFRP) composites have emerged as ideal materials for lightweight mirror design in large-aperture space telescopes and adaptive optical systems due to their high specific stiffness, low areal density, and excellent thermal stability. Systematically review advances in CFRP mirror design, manufacturing processes, environmental adaptability studies, and their applications in large telescopes. Research demonstrates that optimizing layup design, refining curing processes, and enhancing surface treatment techniques effectively suppress fiber print-through (FPT) and curing-induced residual stress, achieving surface accuracy up to λ/10 (root mean square, RMS). However, the hygroscopicity of CFRP and anisotropy in their coefficients of thermal expansion (CTE) remain critical challenges for practical engineering applications. This paper further discussed the combination of active optical control technology with CFRP mirror, which adjusted the surface shape according to the change of force and environment, and verified its potential application in deformable mirror and large aperture splicing mirror. In the future, it is necessary to focus on the development of new matrix materials, multi-field coupling mechanism analysis and long-term service performance evaluation to promote the reliable application of CFRP mirrors in extreme environments.

Research progress on new resin-based ablative thermal protection materials for thermal protection of hypersonic vehicle

LI Zhuangzhuang, LIU Xinhao, MU Xiujuan, WANG Qikun

2025, 0(9): 147-156. DOI: 10.19936/j.cnki.2096-8000.20250928.018

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Efficient and reliable thermal protection materials are the key to the development of hypersonic vehicles. Facing the development needs of new long-term and ultra-high temperature resistant thermal protection materials for hypersonic aircraft in the future, this paper reviews the research status of new resin-based ablative thermal protection materials at home and abroad. The development prospect of gradient design and preparation of low density resin-based ablative thermal protection materials is prospected, and specific suggestions for the future development direction of new resin-based ablative thermal protection materials are put forward.

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