COMPOSITES SCIENCE AND ENGINEERING

A novel approach for impact load identification on composite material structures using truncated vibration response

ZHANG Li, YANG Xiaoming, JIANG Quanxin

2025, 0(11): 1-7. DOI: 10.19936/j.cnki.2096-8000.20251128.001

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Identification of impact load on composite material structures is the second-category inverse problem in structural dynamics, prone to significant deviations due to the influence of measurement noise and modeling errors. To address this issue, this paper proposes a novel method for the precise identification of impact load based on truncated vibration responses. Firstly, the complete vibration response is decomposed into multi-scale intrinsic mode functions using variational mode decomposition (VMD), thereby eliminating high-frequency modes and measurement noise to obtain a truncated vibration response that contains only the low-order principal frequency components of the structure. Subsequently, the truncated singular value based least squares method is employed to extract the truncated modal constant vector of the impact location from the truncated vibration response to realize impact localization. Finally, based on the localization results, the collinearity factor of the modal constant vector is estimated, thus completing the inversion of the impact intensity. Experiments on a real wing show that the proposed method can achieve a localization success rate of up to 86.67% by using the truncated vibration response composed of the first three modal acceleration responses of the wing with merely a single accelerometer, and the average peak relative error index of force reconstruction is only 6.51%.

Research on the strength and damage of bolted joint of thin plate composites

LI Jie, BAO Zuguo, LI Qi, SUN Xiaowang, ZHOU Qiang, WANG Xianhui

2025, 0(11): 8-19. DOI: 10.19936/j.cnki.2096-8000.20251128.002

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In this paper, the strength and damage process of composite thin plate bolted joint structures under tensile loading are investigated by experimental and simulation analysis. Firstly, the basic performance parameters of the composites were obtained by standard mechanical tests, and then tests were carried out on thin-plate composite joints with varying bolt preloads, different layup configurations, and both single and double bolt distributions. Based on the stiffness continuous degradation model and the three-dimensional Hashin failure criterion, the bolt preload was reverse-calculated by testing the friction between the overlap plates, and the preload of the bolt was simulated using an equivalent cooling method. Calibration of the open-hole plate was performed through both experiments and simulations, leading to the development of a three-dimensional finite element model of the bolted composite laminate. Finally, a progressive failure analysis was conducted to understand the strength and damage mechanisms of the composite plate joints. The results indicated that: with the increase of bolt preload, the peak load of the thin plate composite joint increases and the fracture displacement decreases; the damage process of the thin plate composite joints with different layups is related to the proportion of their layups; the ultimate load of transverse double-bolt joints is approximately twice as much as that of the single-bolt joints, and the ultimate limit of longitudinal double-bolt joints is slightly lower.

Influence and optimization of process parameters on bearing strength of composite bolted connection structure

SUN Xinyang, WU Tao, ZHU Zhaoxuan, HUANG Yan

2025, 0(11): 20-29. DOI: 10.19936/j.cnki.2096-8000.20251128.003

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In order to analyze the influence of the parameters of composite connectors, optimize the ratio between conventional parameters, and improve the structural economy and practicability, the influence of tensile str-ength on the significant connection parameters in the three manufacturing and assembly stages of plate thickness, end-diameter ratio and preload was studied. Combined with the UMAT subroutine, the finite element model of CFRP bolted joints was established, and the static tensile failure and SEM damage observation tests were carried out to verify the finite element model. On this basis, based on the Box-Behnken design, combined with the response regression equation, 3D response surface and contour map, the joint response model of bearing strength and influencing factors was established, and the three parameters were analyzed from the aspects of single factor and multi-factor interaction, and the determined coefficient R² of the joint response model was 0.984 7, Adj R² is 0.957 1, Pred R² value is 0.794 4, the model fitting effect and prediction ability are better; the analysis results show that plate thickness is the most significant single factor affecting the bearing strength among the three parameters, and the interaction between plate thickness and end-diameter ratio has the most significant effect, and the model gives an optimization of plate thickness, end-diameter ratio and preload, and the error between the predicted strength and the finite element result is 0.37%, indicating that the established joint response model has a good strength prediction ability.

Study on frequency response of chirp-excited Lamb wave in the localization of delamination damage in CFRP plate

WU Yilun, FENG Bo

2025, 0(11): 30-39. DOI: 10.19936/j.cnki.2096-8000.20251128.004

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Most current Lamb wave testing methods use a windowed narrow-band signal as the excitation signal to suppress the dispersion and facilitate the subsequent signal interpretation. A suitable center frequency should be selected to improve the signal-to-noise ratio during the measurement. However, the optimal detection frequency of the narrow-band signal often needs to be measured by several repeated experiments. A method for detecting delamination defects in carbon fiber reinforced composite plate is proposed, using a chirp signal as the excitation, which contains a broad frequency range, making more information contained in a single inspection. The narrow-band response of a series of frequencies is extracted using inverse convolution, and the optimal test frequency is selected for defect localization. It is verified by finite element simulation and experiment that the decomposed signal and the signal obtained from the direct excitation of the narrow-band signal are basically in agreement. The improved elliptical imaging algorithm is utilized for localization, and the effectiveness of the proposed method is verified experimentally.

Preparation of in-situ polymerized cross-linked porous polyimide composite materials research on electrochemical performance

LUO Farong, ZHANG Zhiming, CHEN Jian

2025, 0(11): 40-47. DOI: 10.19936/j.cnki.2096-8000.20251128.005

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In this paper, cross-linked porous polyimide composites with different MWCNTs contents were prepared by in-situ polymerization using multi-walled carbon nanotubes (MWCNTs) as additive (INCPI@MWCNTs). The group, pore structure and adsorption properties of the cross-linked porous polyimide composites (INCPI@MWCNTs) were studied. The feasibility of using the cross-linked porous polyimide composites as positive electrode materials for lithium-sulfur batteries was discussed. The results show that in-situ polymerization has no effect on the cross-linking reaction and the structure of porous polyimide. Under the condition of nitrogen isothermal adsorption test of different specifications INCPI@MWCNTs, the nitrogen adsorption capacity increased with the increase of relative pressure due to the presence of large pore structure in the material. The BET specific surface area and micropore specific surface area of INCPI@MWCNTs gradually decreased with the increase of the addition of MWCNTs. The volume of micropores increased with the addition of MWCNTs. Using INCPI@MWCNTs as the positive carrier, S/PPI@MWCNTs positive carrier composite material was obtained by diffusion loading with sulfur, and lithium-sulfur battery was assembled for electrochemical performance test. Under the condition of 0.2 C current density, two discharge platforms and one charging platform appear in the charge and discharge curves of three different S/INCPI@MWCNTs positive terminals. The specific initial discharge capacity of the battery corresponding to S/INCPI@MWCNTs-2 is 1 326 mAh·g^-1, and the retention capacity is 855 mAh·g^-1 after 100 cycles, capacity retention rate is 65%. Under the condition that the current density is 1 C, the specific capacity of the first discharge of S/INCPI@MWCNTs-2 battery is 1 035 mAh·g^-1, and after 400 cycles, the retention capacity is 662 mAh·g^-1, and the capacity retention rate is 65%. S/INCPI@MWCNTs-2 as the cathode material can make the battery have better discharge specific capacity, rate performance and cycle stability.

Investigations on large thickness honeycomb with curing pressure through a fine-structure numerical approach

SHU-SHEN Yunhao, LU Honglong, XUAN Lixin

2025, 0(11): 48-54. DOI: 10.19936/j.cnki.2096-8000.20251128.006

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To investigate the issue of lateral deformation and sliding of large thickness Nomex honeycomb in curing process, a fine-structure honeycomb finite element model was established and calculated, and the calculation results were compared with technological test results. The flatwise compression specimens of honeycomb were modeled first, and the calculation results indicated that the loading response is consistent with the experiment with a small error. It can prove the great accuracy of using 2D shell element to model the honeycomb cells. On this basis, a finite element model of the honeycomb forming technological specimens was established. After calculation, the local mechanical response of the honeycomb core in curing process was obtained and the transition from buckling of cells to sliding of specimens’ edges can be simulated. Compared with the technological test results, the deformation trend of honeycomb is basically consistent. Therefore, the fine-structure simulation model can provide a reference for technological test and the selection of honeycomb stabilization methods.

Effect of adhesive layer defect and ambient temperature on mechanical properties of CFRP-steel single lap bonded joints

WANG Jianzhe, WANG Boli, CAO Qiongfang, YU Sai, GENG Furong

2025, 0(11): 55-63. DOI: 10.19936/j.cnki.2096-8000.20251128.007

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In order to study the failure characteristics of dissimilar materials under different damage defects and temperature environment and promote the application of bonding in vehicle engineering, this paper takes carbon fiber reinforced plastics-steel single lap joint as the research object and carries out experimental research on static tensile mechanical properties. In this study, the common damage defects in engineering and the ambient temperature were taken as variables. Firstly, the static tensile test was carried out on the single lap joint without defects at normal temperature to analyze the mechanical properties and failure modes of the joint. Then, five kinds of joints with different crack locations and lengths were tested to study the effects of different adhesive layer defects on the mechanical properties of CFRP-steel bonded joints. Finally, the study was extended to different ambient temperatures. The research results show that the joints without defects at room temperature mainly fail in cohesiveness, and the defects lead to interface failure. The temperature test results show that the ambient temperature not only affects the mechanical properties of adhesive materials, but also affects the properties of the bonding interface between metal and composite substrate. The synergistic effects of various factors lead to changes in structural strength and failure mode. This study provides the design basis and guidance method for the adhesive connection of composite carbon fiber materials and steel in engineering.

Comparative study on digital tap detection of aramid paper honeycomb sandwich structure

HAO Wei, LI Ming, LI Yao, SUN Jiefu, WANG Huidong

2025, 0(11): 64-69. DOI: 10.19936/j.cnki.2096-8000.20251128.008

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Many kinds of defects can be produced in the manufacturing, assembly and service stage of composite aramid paper honeycomb sandwich structure. The ability to identify defects can be affected by part status, material properties, defect types and non-destructive testing methods. According to the requirement of nondestructive testing for composite honeycomb sandwich structure, glass fiber skin honeycomb structure and carbon fiber skin honeycomb structure were tested by digital tap detection. On the basis of the traditional detection of shallow area defects (such as debonding, delamination, inclusion, weak adhesion), the deep buried volume defects (such as core material fracture and collapse) were also detected. The effects of skin type, defect type and defect topography on the contact time were discussed. The advantages and limitations of digital tap detection, ultrasonic pulse echo detection, through-transmission ultrasonic detection and X-ray digital radiography method were analyzed. The experiment proves that the digital tap detection technology can effectively detect the delamination, debonding, core material fracture and collapse defects in composite honeycomb sandwich structure, especial produced after curing.

Simulation analysis of stitched foam sandwich composite by VARTM molding

ZHANG Lianhe, QIN Cheng, CHENG Yanan, REN Hao, LI Yongfeng, ZHANG Hui

2025, 0(11): 70-78. DOI: 10.19936/j.cnki.2096-8000.20251128.009

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In order to investigate the injection process of stitched foam sandwich composites, the permeability of foam sandwich fiber layer and core layer holes were measured based on Darcy’s law, and the equivalent model of foam sandwich was established. Composite materials were prepared by vacuum-assisted resin transfer molding (VARTM) process. The effects of stitch density and injection method on the permeability and filling process of stitched foam sandwich composites were systematically investigated. The results show that compared to the unstitched fabric, when stitched at a density of 8 mm×8 mm, the permeability of the fiber layer stitched fabric along the stitch direction increase by a maximum of 104.9%. When stitched at a density of 4 mm×4 mm, the permeability along the carbon fiber axis reaches its maximum value of 9.6×10^-11m², which increases by 546.0% compared to the unstitched fabric. This indicates that the introduction of stitch can effectively improve the permeability of the fabric. The efficiency of long edge injection is the highest, with a simulated injection time and actual error of 13.4%. With the increase of stitch density, the injection time of stitched foam sandwich composites increases firstly and then decreases, which may be the reason that the injection direction is in the same direction as the carbon fiber axis.

Product performance analysis and process parameter optimization of needle-punched C/C composite material

YANG Guoyong, LIU Zhenyu, ZHANG Nan, KONG Haoqiang

2025, 0(11): 79-85. DOI: 10.19936/j.cnki.2096-8000.20251128.010

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This research focuses on exploring the relationship between process parameters and the performance of carbon/carbon composite materials during the needle-punched process, employing a central composite design method to plan the experimental scheme. Using the response surface method to analyze the experimental data, a quadratic response model was established that correlates the bending strength of the product with needle-punched process parameters, including needling depth, needling density, and carbon fiber surface density. Based on this model, the process parameters were optimized and an analysis was conducted on the influence patterns of individual process parameters and their combined effects on the bending strength. The research findings indicate that the best parameters were a needling depth of 12 mm, a needling density of 17.81 needles/cm², and a carbon fiber surface density of 400 g/m². The study also reveals that the carbon fiber surface density had the most significant impact on bending strength, followed by the needling depth, while the effect of needling density is relatively minor. Furthermore, the study uncovers that the coupling effects between needling depth and carbon fiber surface density, as well as between needling depth and needling density, significantly influenced the bending strength. Through delving into the interactive effects of the process parameters, it is determined that the bending performance of the product is optimal when the needling depth is between 12~16 mm, the needling density is between 15~25 needles/cm², and the carbon fiber surface density is between 380~400 g/m², with the strength exceeding 100 MPa. These findings expand the needle punching forming process window for carbon/carbon composite materials, which helps to improve their forming efficiency and product quality.

Study on the influence of process parameters on fiber reorientation of woven composite during thermoforming

CHEN Pan, ZHONG Yucheng

2025, 0(11): 86-94. DOI: 10.19936/j.cnki.2096-8000.20251128.011

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The formation process of composite materials alters the internal structure, which subsequently impacts the properties of the composite component. This is especially evident when the geometry of the part is complex; the forming of the woven composite may result in alterations in the warp and weft angles. To investigate the fiber reorientation induced by forming processes and to identify the influencing factors, a finite element model (FEM) employing a hypoelastic constitutive law was developed. This model was validated through hemispherical forming experiments, focusing on two primary aspects: fiber reorientation distribution and the boundary profile of the prepreg. Moreover, the paper extends the validation to U-shaped structures, where forming experiments and simulations are conducted to further substantiate the model’s predictive capability regarding fiber reorientation. Additionally, the impact of various factors such as the coefficient of friction, blank holding force (BHF), and blank holding area (BHA) on fiber reorientation is extensively analyzed through the forming simulations of the U-shaped structure. The results show that these process parameters are important factors affecting fiber reorientation and should be optimized during thermoforming.

Research on lightweight design of automotive hybrid B-pillar assembly

XU Liyou, GUO Yongzheng, ZHANG Shuai, LU Dongzhen

2025, 0(11): 95-102. DOI: 10.19936/j.cnki.2096-8000.20251128.012

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To enhance the lightweight quality and crash safety of automobile B-pillar assembly, this paper puts forth a hybrid material B-pillar assembly design scheme comprising a high-strength steel outer plate, a carbon fiber composite inner plate, and a glued connection between the two. A finite element analysis model must be established for a dynamic impact drop hammer collision test of an automobile B-pillar. The validity of the model must then be verified from the hourglass energy test. A finite element model of a carbon fiber composite B-pillar reinforcing plate must be established, along with the layup design of the carbon fiber composite B-pillar reinforcing plate. Finally, the optimal carbon fiber composite layup sequence must be obtained. The carbon fiber composite B-pillar reinforcement plate was affixed to the high-strength steel outer plate via an adhesive bonding process to construct the B-pillar assembly specimen of the hybrid material. The accuracy and validity of the simulation model were further verified by dynamic drop weight tests and impact failure electron microscopy tests. The results demonstrated that the carbon fiber composite material B-pillar reinforcement panel reduced weight by 0.623 kg, and the hybrid material B-pillar assembly reduced the maximum displacement during the collision process by 12.8% in the falling weight impact test. The discrepancy between the simulation optimization and the actual test results did not exceed 5%. This substantiates the accuracy and reliability of this solution, and the lightweight effect and collision safety were markedly enhanced.

Tensile mechanical test and numerical simulation of pin-anchored CFRP laminated strap cable

LEI Jiayan, ZHAO Daohua, KONG Qinghui, ZHANG Longbin, ZHANG Qirui

2025, 0(11): 103-109. DOI: 10.19936/j.cnki.2096-8000.20251128.013

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The pin-anchored carbon fiber reinforced polymers (CFRP) cable member has promising application in structure engineering for its simple structural construction. However, the effective anchorage of cable end would interrupt its full tensile capacity for premature failure in anchorage zone. In this work, tensile mechanical test was conducted with seven pin-anchored CFRP laminated loop straps to investigate the failure mechanism, ultimate tensile capacity and nonuniform stress in pin-anchored zone with the help of the digital image correlation (DIC) technology. The test results show that the fixture is crucial to the development of the tensile properties and failure mode of the strap cables. One no-fixture specimen was subjected to laminar tear; and the rest six strap cables showed nonlinear development in the load-displacement curves during tensile loading process, in which the microdamage of matrix and the adhesion failure of matrix and fiber interface accumulated continuously. Analysis explained the mechanism that the wedge angle θ and transverse binding force provided by the fixture were crucial in two structural failure modes of the cables. Finally, finite element analysis was carried out with quasi-static tensile simulation technique in ABAQUS to monitor the non-uniform stress in lamination layers up to the premature failure in anchor zone.

Research on the impact resistance performance of ECC-BFRP reinforced composite shear wall for civil defense

WANG Chong, LIANG Haizhi, CHEN Wenlong, XIE Jingru, JIN Zuquan, YE Haibin

2025, 0(11): 110-121. DOI: 10.19936/j.cnki.2096-8000.20251128.014

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In order to investigate the impact resistance of shear wall reinforced with engineered cementitious composite (ECC) and basalt fiber reinforced polymer (BFRP) reinforcement, an impact test was carried out on the reinforced human defense wall. The impact test was carried out on the reinforced human defense wall, and the finite element software ABAQUS was used to carry out numerical simulation based on the existing test at the same time. The accuracy of the numerical model was verified by comparing it with experimental results, and the influence of load levels and ECC thickness on the wall’s impact resistance performance was further analyzed. The results show that both the overall flexural stiffness and bearing capacity are significantly improved with the increase in ECC thickness. The concrete cracking is effectively controlled, and the rate of stiffness decline is reduced too. It can be concluded that the reinforcement method using ECC-BFRP can greatly enhance the impact resistance of the air defense walls, which will provide technical support for the structure upgrade of civil air defense projects.

Performance analysis of FRP grid reinforced fiber concrete sandwich composite wall panels

CHENG Nengming, ZHANG Yaolin, CHANG Mingyuan, ZHANG Rong

2025, 0(11): 122-130. DOI: 10.19936/j.cnki.2096-8000.20251128.015

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To explore new wall panel materials and structural systems that are lightweight, high-strength, and have good thermal insulation properties suitable for prefabricated steel structure buildings, a new type of FRP grid reinforced fiber concrete sandwich composite wall panel was proposed in this paper, referred to as an FGRC sandwich composite wall panel. To study the flexural performance and failure modes of the FGRC sandwich composite wall panels, bending performance tests were designed and conducted on two FGRC sandwich composite wall panels with dimensions of 4 m×3 m and thicknesses of 100 mm and 150 mm respectively. The test results show that the main failure mode of the FGRC sandwich composite wall panels is flexural failure, with excellent interface connection performance. The ultimate flexural load capacity can reach up to 3.11 kN/m² and 4.05 kN/m². The ultimate fire resistance times are 1.1 hours and 1.5 hours, and the structural thermal resistances are 1.41 (m²·K)/W and 1.72 (m²·K)/W, respectively. The air-borne sound insulation and frequency correction amounts are 39(-2;-3) dB and 39(0;-2) dB, respectively. Overall, this wall panel shows significant application value.

Optimization design of test tooling for composite sleeper based on multi-objective genetic algorithm

XU Chen, ZHANG Qingkai, QIN Junfei, HUANG Cheng

2025, 0(11): 131-136. DOI: 10.19936/j.cnki.2096-8000.20251128.016

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A composite sleeper’s design load is 1 000 kN, it must meet deformation requirements of sleeper’s bending load. So the test tooling must be designed to meet the requirements of bending load. This paper established the response surface of target parameters to section sizes based on the theory of material mechanics and Kirging model. Based on this, the tooling was obtained by multi-objective genetic algorithm, and finally, was obtained the optimal combination of tooling’s section size. Then bending resistance of the tooling was calculated according to optimized section sizes by FEM. Thereafter, the tooling was manufactured based on the optimized section sizes. The result show that this tooling did not create any plastic deformation with a 1 000 kN load.

Research progress on fiber reinforced polydicyclopentadiene composites

XIAO Jian, LI Pengfei, FU Hongwei, JIA Zhiyuan, CHEN Yong

2025, 0(11): 137-144. DOI: 10.19936/j.cnki.2096-8000.20251128.017

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Polydicyclopentadiene (PDCPD) is a kind of thermosetting polymeric material with excellent mechanical properties, low density and easy processing, which can replace some steel plate, castings and glass steel parts for agricultural vehicles, engineering vehicles, heavy trucks and other applications. Fiber reinforced PDCPD composites can show stronger mechanical properties and may extend to wider application including but not limited to various vehicle parts, rail transit, wind power, photovoltaic parts, hydrogen storage, etc. However, the polarity of PDCPD itself is low, and the interfacial bonding between commercial fabrics and PDCPD is poor, which limits the application of fiber reinforced PDCPD composites. The research progress of fiber-reinforced PDCPD materials in recent years was reviewed. The approaches to improve the interfacial bonding property of the carbon and glass fiber reinforced PDCPD materials were discussed. And future modifications of the fiber-reinforced PDCPD composites were prospected.

Research progress on 3D printing technology of continuous fiber reinforced composites based on FDM

GUAN Bowen, ZHANG Daijun, WANG Chengbo, YANG Fanghong, YE Lu, CHEN Xiangbao

2025, 0(11): 145-152. DOI: 10.19936/j.cnki.2096-8000.20251128.018

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Continuous fiber reinforced composites (CFRCs) are widely recognized in fields like aerospace, automotive manufacturing, and microelectronics due to their advantages of lightweight, high strength, and high design freedom. 3D printing technology is regarded as an effective approach for achieving rapid, customized, and integrated manufacturing of CFRCs with complex structures. This paper, based on the fused deposition modeling process, introduces the factors affecting the performance of CFRC 3D-printed parts, including printing equipment, raw materials, and printing processes. It also summarizes the research progress of CFRCs in structural-functional design and multiscale performance analysis, as well as their current applications in various fields. Furthermore, it analyzes the current challenges in CFRCs research and discusses prospects for future development.

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