This work aims at designing a set of curing pressure routes to produce laminates with various void contents. The effects of various consolidation pressures resulting in different void contents on mechanical strength o...This work aims at designing a set of curing pressure routes to produce laminates with various void contents. The effects of various consolidation pressures resulting in different void contents on mechanical strength of carbon/epoxy laminates have been examined. Characterization of the voids, in terms of void volume fraction, void distribution, size, and shape, was performed by standard test, ultrasonic inspection and metallographic analysis. The interlaminar shear strength was measured by the short-beam method. An empirical model was used to predict the strength vs porosity. The predicted strengths conform well with the experimental data and voids were found to be uniformly distributed throughout the laminate.展开更多
Three-dimensional finite element(FE)models of carbon/epoxy composite laminates with copper mesh and aluminum mesh protection were established subjected to lightning strike,in which different mesh spacing was selected....Three-dimensional finite element(FE)models of carbon/epoxy composite laminates with copper mesh and aluminum mesh protection were established subjected to lightning strike,in which different mesh spacing was selected.Effectiveness of numerical method was verified and impulse current waveforms with different current peaks were applied according to aircraft lightning zones.Thermal-electrical material parameters varying with temperature were added into numerical models.Element deletion method was used to deal with lightning ablation elements of composite structures.The results show that ablation area and depth of composite laminates with metal mesh protection are significantly smaller,which proves good protection effectiveness of metal meshes on anti-lightning strike.The denser the mesh spacing,the better the anti-lightning strike will be.Protection of composite laminates with copper mesh has better effects than that of aluminum mesh.Considering the effect of mesh spacing variation on composite structural weight and anti-lightning strike,the ideal mesh spacing was obtained.展开更多
Low-velocity impact and in-plane axial compression after impact(CAI)behaviors of carbon-aramid/epoxy hybrid braided composite laminates were investigated experimentally.The following three different types of carbon-ar...Low-velocity impact and in-plane axial compression after impact(CAI)behaviors of carbon-aramid/epoxy hybrid braided composite laminates were investigated experimentally.The following three different types of carbon-aramid/epoxy hybrid braided composite laminates were produced and tested:(a)inter-hybrid laminates,(b)sandwich-like inter-hybrid laminates,and(c)unsymmetric-hybrid laminates.At the same time,carbon/epoxy braided composite laminates were used for comparisons.Impact properties and impact resistance were studied.Internal damages and damage mechanisms of laminates were detected by ultrasonic C-scan and B-scan methods.The results show that the ductility index(DI)values of three kinds of hybrid laminates aforementioned are 37%,4%and 120%higher than those of carbon/epoxy laminates,respectively.The peak load of inter-hybrid laminates is higher than that of sandwich-like inter-hybrid laminates and unsymmetric-hybrid laminates.The average damage area and dent depths of inter-hybrid laminates are 64%and 69%smaller than those of carbon/epoxy laminates.Those results show that carbon-aramid/epoxy hybrid braided composite laminates could significantly improve the impact properties and toughness of non-hybrid braided composite laminates.展开更多
It is known that fiber metal laminates （FML） as one of hybrid materials with thin metal sheets and fiber/epoxy layers have the characteristics of the excellent damage tolerance, fatigue and impact properties with a ...It is known that fiber metal laminates （FML） as one of hybrid materials with thin metal sheets and fiber/epoxy layers have the characteristics of the excellent damage tolerance, fatigue and impact properties with a relatively low density. Therefore, the mechanical components using FML can contribute the enhanced safety level of the sound construction toward the whole body. In this study, the impact performance of carbon reinforced aluminum laminates （CARAL） is investigated by experiments and numerical simulations. Drop weight tests are carried out with the weight of 4.7 kg at the speed of 1 and 2 m/s, respectively. Dynamic non-linear transient analyses are also accomplished using a finite element analysis software, ABAQUS. The experiment results and numerical results are compared with impact load-time histories. Also, energy-time histories are applied to investigate the impact performance of CARAL.展开更多
Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics(CFRP).Owl feathers are kn...Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics(CFRP).Owl feathers are known for their unique compact structure;they are not only lightweight but also strong.In this study,an in-depth look at owl feathers was made and it found that owl feathers not only have the macro branches structure between feather shafts and branches but also have fine feather structures on the branches.The presence of these fine feather structures increases the specific surface area of the plume branches and allows neighboring plume branches to hook up with each other,forming an effective mechanical interlocking structure.These structures bring owl feathers excellent mechanical properties.Inspired by the natural structure of owl feathers,a weaving technique and a sizing process were combined to prepare bionic Carbon Fiber(CF)fabrics and then to fabricate the bionic CFRP with structural characteristics similar to owl feathers.To evaluate the effect of the fine feather structure on the mechanical properties of CFRP,a mechanical property study on CFRP with and without the fine feather imitation structure were conducted.The experimental results show that the introduction of the fine feather branch structure enhance the mechanical properties of CFRP significantly.Specifically,the tensile strength of the composites increased by 6.42%and 13.06%and the flexural strength increased by 8.02%and 16.87%in the 0°and 90°sample directions,respectively.These results provide a new design idea for the improvement of the mechanical properties of the CFRP,promoting the application of CFRP in engineering fields,such as automotive transportation,rail transit,aerospace,and construction.展开更多
Plastic waste recycling is a focal point in today's sustainable development efforts.Improper disposal can lead to secondary pollution,posing threats to the environment and human health.In this study,we aim to recy...Plastic waste recycling is a focal point in today's sustainable development efforts.Improper disposal can lead to secondary pollution,posing threats to the environment and human health.In this study,we aim to recycle waste epoxy resin and glass fiber-reinforced epoxy resin composites via an electroless plating and a carbonization process,to design high-value-added carbon materials for microwave absorption.By pulverizing solid waste and introducing magnetic metal nanoparticles onto its surface,a composite carbon material capable of excellent microwave absorption performance was successfully developed.Specifically,doping nickel particles into carbon materials derived from glass fiber/epoxy resin achieved a wide effective absorption bandwidth(EAB)of 5.9 GHz with a matching thickness of 1.9 mm,covering nearly the entire Ku band,and achieving a minimum reflection loss(RLmin)of−36 dB simultaneously.The superior absorption performance is attributed to multiple reflections or scattering of electromagnetic waves within the material,as well as conduction and magnetic losses,dipole and interfacial polarization effects.These results demonstrate that through rational design and optimization,waste epoxy and waste glass fiber-reinforced epoxy resin-based composite materials can be effectively recycled into high-performance microwave absorbing materials,offering a straightforward and efficient pathway for waste resource utilization.展开更多
Solar-driven thermo-electric generation(STEG)emerges as a promising solution to mitigate the global en-ergy shortage.However,the practical application of conventional photothermal materials equipped with STEG is limit...Solar-driven thermo-electric generation(STEG)emerges as a promising solution to mitigate the global en-ergy shortage.However,the practical application of conventional photothermal materials equipped with STEG is limited due to low solar thermal conversion efficiency.Herein,we fabricated an epoxy resin(EP)nanocomposite,EP/CCA80,with excellent photo-thermal-electric conversion properties by embedding a vertically aligned aerogel consisting of cellulose nanofibers(CNF)and carboxylated multi-walled carbon nanotubes(CMWCNTs)into a transparent EP matrix.EP/CCA80 composites possessed a broad light ab-sorption range from 200 nm to 2500 nm and excellent photothermal properties.Under illumination of 1.0 kW m^(-2),EP/CCA80 achieved a notable stable temperature of 93.2℃ and a photothermal conversion efficiency of up to 54.35%with only 0.65 wt%CMWCNTs inclusion.Additionally,coupled with thermo-electric(TE)devices,the EP/CCA80 composite facilitated a significant temperature difference and voltage output of up to 25.3℃ and 160.29 mV(1.0 kW m^(-2)),respectively,which could power a small fan to rotate at a speed of 193 min^(-1).Such materials are poised to offer viable solutions for enhancing energy accessibility in remote regions,thereby contributing to the reduction of energy shortages and environ-mental degradation.展开更多
GLARE （glass fibre/epoxy reinforced aluminum laminate） is a member of the fiber metal laminate （FML） family, and is built up of alternating metal and fiber layers. About 500 m2 GLARE is employed in each Airbus A38...GLARE （glass fibre/epoxy reinforced aluminum laminate） is a member of the fiber metal laminate （FML） family, and is built up of alternating metal and fiber layers. About 500 m2 GLARE is employed in each Airbus A380 because of the superior mechanical properties over the monolithic Muminum alloys, such as weight reduction, improved damage tolerance and higher ultimate tensile strength. Many tons of new GLARE scraps have been accumulated during the Airbus A380 manufacturing. Moreover, with the increasing plane orders of Airbus A380, more and more end-of-life （EOL） GLARE scrap will be generated after retire of planes within forty years. Thermal processing is a potential method for the material recycling and re-use from GLARE with the aim of environmental protection and economic benefits. The current study indicatdes that thermal delamination is a crucial pre-treatment step for the GLARE recycling. The decomposition behavior of the epoxy resins at elevated temperatures was investigated by using the simultaneous thermal analysis, thermogravimetry analysis （TGA） and differential scanning calorimetry （DSC）. Based on the thermal analysis results, GLARE thermal delamination experiments at refined temperatures were carried out to optimize the treatment temperature and holding time.展开更多
Extensive research has shown that externally bonded carbon fiber reinforced polymer （CFRP） laminates are particularly suitable for improving the fatigue behavior of reinforced concrete （RC） beams. This paper prese...Extensive research has shown that externally bonded carbon fiber reinforced polymer （CFRP） laminates are particularly suitable for improving the fatigue behavior of reinforced concrete （RC） beams. This paper presents the research on flexural ngidity evolvement laws by testing 14 simple-supported RC beams strengthened with carbon fiber laminates （CFL） under cyclic load, and 2 under monotone load as a reference. The cyclic load tests revealed the peak load applied onto the surface of a supported RC beam strengthened with CFL is linear to the logarithm of its fatigue life, and the flexural rigidity evolvement undergoes three distinct phases： a rapid decrease from the start to about 5% of the fatigue life; an even development from .5% to about 99% of the fatigue life; and a succedent rapid decrease to failure. When the ratio of fatigue ＂cycles to the fatigue life is within 0.0.5 to 0.99, the flexural rigidity varies linearly with the ratio. The peak load does not affect the flexural rigidity evolvement if it is not high enough to make the main reinforcements yield. The dependences of the flexural rigidity of specimens formed in the same group upon their fatigue cycles normalized by fatigue life are almost coincident. This implies the flexural rigidity may be a material parameter independent of the stress level. These relationships of flexural rigidity to fatigue cycles, and fatigue life may be able to provide some hints for fatigue design and fatigue life evaluation of RC member strengthened with CFL; nevertheless the findings still need verifying by more experiments.展开更多
The vibration attenuation and damping characteristics of carbon fiber reinforced composite laminates with different thicknesses were investigated by hammering experiments under free boundary constraints in different d...The vibration attenuation and damping characteristics of carbon fiber reinforced composite laminates with different thicknesses were investigated by hammering experiments under free boundary constraints in different directions.The dynamic signal testing and analysis system is applied to collect and analyze the vibration signals of the composite specimens,and combine the self-spectrum analysis and logarithmic decay method to identify the fundamental frequencies of different specimens and calculate the damping ratios of different directions of the specimens.The results showed that the overall stiffness of the specimen increased with the increase of the specimen thickness,and when the thickness of the sample increases from 24mm to 32mm,the fundamental frequency increases by 35.1%,the vibration showed the same vibration attenuation and energy dissipation characteristics in the 0°and 90°directions of the specimen,compared with the specimen in the 45°direction,which was less likely to be excited and had poorer vibration attenuation ability,while the upper and lower surfaces of the same specimen showed slightly different attenuation characteristics to the vibration,the maximum difference of damping capacity between top and bottom surfaces of CFRP plates is about 70%.展开更多
Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&elec...Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&electrically insulating BNN-30@BNNS/Si-GFs/E-44 laminated composites were then fabricated via hot compression.BNN-30@BNNS-Ⅲ(fBNN-30/fBNNS,1/2,wt/wt)fillers presented the optimal synergistic improvement effects on the thermal conductivities of epoxy composites.When the mass fraction of BNN-30@BNNS-Ⅲwas 15 wt%,λvalue of the BNN-30@BNNS-Ⅲ/E-44 composites was up to0.61 W m^(-1)K^(-1),increased by 2.8 times compared with pure E-44(λ=0.22 W m^(-1)K^(-1)),also higher than that of the 15 wt%BNN-30/E-44(0.56 W m^(-1)K^(-1)),15 wt%BNNS/E-44(0.42 W m^(-1)K^(-1)),and 15 wt%(BNN-30/BNNS)/E-44(direct blending BNN-30/BNNS hybrid fillers,1/2,wt/wt,0.49 W m^(-1)K^(-1))composites.Theλin-plane(λ//)andλcross-plane(λ_(⊥))of 15 wt%BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites significantly reached 2.75 W m^(-1)K^(-1)and 1.32 W m^(-1)K^(-1),186.5%and 187.0%higher than those of Si-GFs/E-44 laminated composites(λ//=0.96 W m^(-1)K^(-1)andλ_(⊥)=0.46 W m^(-1)K^(-1)).Established models can well simulate heat transfer efficiency in the BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites.Under the condition of point heat source,the introduction of BNN-30@BNNS-Ⅲfillers were conducive to accelerating heat flow trans fe r.BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites also demonstrated outstanding electrical insulating properties(cross-plane withstanding voltage,breakdown strength,surface&volume resistivity of 51.3 kV,23.8 kV mm^(-1),3.7×10^(14)Ω&3.4×10^(14)Ω·cm,favorable mechanical properties(flexural strength of 401.0 MPa and ILSS of 22.3 MPa),excellent dielectric properties(εof 4.92 and tanδof 0.008)and terrific thermal properties(T_(g)of 167.3℃and T_(HRI)of 199.2℃).展开更多
The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber(CF)composites.To this end,a facile interracial strategy for fabricating flame-retardant carbon fibers decor...The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber(CF)composites.To this end,a facile interracial strategy for fabricating flame-retardant carbon fibers decorated by bio-based polyelectrolyte complexes(PEC)consisting of chitosan(CH)and ammonium polyphosphate(APP)was developed,and its corresponding fire-retarded epoxy resin composites(EP/(PEC@CF))without any other additional flame retardants were prepared.The decorated CFs were characterized by SEM-EDX,XPS and XRD,indicating that the flame-retardant PEC coating was successfully constructed on the surface of CF.Thanks to the nitrogen-and phosphorous-containing PEC,the resulting composites exhibited excellent flame retardancy as the limiting oxygen index(LOI)increased from 31.0%of EP/CF to 40.5%and UL-94 V-0 rating was achieved with only 8.1 wt%PEC.EP/(PEC8.1@CF)also performed well in cone calorimetry with the decrease of peak-heat release rate(PHRR)and smoke production rate(SPR)by 50.0%and 30.4%,respectively,and the value of fire growth rate(FIGRA)was also reduced to 3.41 kW·m-2-s-1 from 4.84 kW·m-2·s-1,suggesting a considerably enhanced fire safety.Furthermore,SEM images of the burning residues revealed that the PEC coating exhibited the dominant flame-retardant activity in condensed phase via the formation of compact phosphorus-rich char.In addition,the impact strength of the composite was improved,together with no obvious deterioration of flexural properties and glass transition temperature.Taking advantage of the features,the PEC-decorated carbon fibers and the relevant composites fabricated by the cost-effective and facile strategy would bring more chances for widespread applications.展开更多
A critical challenge for initiating many applications of the carbon nanotubes(CNTs) is their dispersion in organic solvent or in polymer melt. In the present study, we described a novel strategy for fabricating carbon...A critical challenge for initiating many applications of the carbon nanotubes(CNTs) is their dispersion in organic solvent or in polymer melt. In the present study, we described a novel strategy for fabricating carbon nanotubes(CNTs)-reinforced epoxy nanocomposite by utilizing aniline trimer(AT) as the noncovalent dispersant. Tensile testing showed that the tensile modulus of the CNTs-reinforced epoxy composites was considerably improved by adding a small amount of AT functionalized CNTs. Additionally, the as-prepared CNTs-epoxy nanocomposites exhibited superior tribological properties with much lower frictional coefficients and wear rates compared to those of neat epoxy resin. The well dispersed AT-functionalized CNTs in epoxy matrix played an important role in enhancing the mechanical properties, as well as acting as a solid lubricant for improving the tribological performance of epoxy/CNTs nanocomposite.展开更多
Facile green oxidation methods are always desired to functionalize carbon nanotubes(CNTs)in the production of advanced CNT/epoxy composites.In the present work,an optimized H2O2/H2O/O3 oxidation method was developed,a...Facile green oxidation methods are always desired to functionalize carbon nanotubes(CNTs)in the production of advanced CNT/epoxy composites.In the present work,an optimized H2O2/H2O/O3 oxidation method was developed,and performances of the H2O2/H2O/O3 oxidized CNT in epoxy matrix were tested and compared with that of the H2O/O3 oxidized CNT and the most commonly used concentrated HNO3 oxidized CNT.The physical and chemical characteristics of the obtained oxidized CNTs were systematically characterized via transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)and Raman.Mechanical performances of the obtained composites were explored by tensile tests,impact tests,dynamic mechanical analysis(DMA)and fracture toughness tests.It was found that the H2O2/H2O/O3 oxidized CNT exhibited all-around overwhelming advantages over the concentrated HNO3 oxidized CNT on reinforcing the epoxy matrix,while the H2O/O3 oxidized CNT only improved the material strength.Reinforcing mechanisms for the different methods oxidized CNTs were studied and compared.The optimized H2O2/H2O/O3 oxidation method makes scaled production possible,avoids environment pollutions,and holds great potentials to replace the most commonly used concentrated HNO3 oxidation method to oxidize CNT during the preparation of the advanced CNT/epoxy composite.展开更多
This paper aims to study the effect of processing temperature on interfacial behavior of HKT800 carbon fiber composites with epoxy and Bismaleimide（BMI） matrix.Referring to the processing conditions of the composite...This paper aims to study the effect of processing temperature on interfacial behavior of HKT800 carbon fiber composites with epoxy and Bismaleimide（BMI） matrix.Referring to the processing conditions of the composite, various processing-heat treatments were conducted on HKT800 and the extracted sizing content declines with increasing temperature.Chemical analysis shows that the HKT800 sizing is epoxy-type and reactive at 200 C.The interfacial shear strength（IFSS） of HKT800/epoxy and HKT800/BMI was investigated by micro-droplet method, for which the composites were fabricated with modeling temperature schemes referring to different diffusion, cure and post-cure stages.It shows that diffusion temperature and conversion degree of the resin both enhance the interfacial adhesion of HKT800/epoxy composite.For the HKT800/BMI composite,the diffusion temperature shows a insignificant effect on the IFSS.FTIR analysis indicates that sufficient reactions are achieved between HKT800-sizing and epoxy resin, however only partial reactions are observed between the sizing and BMI.Moreover, the presence of the sizing can evidently improve the wettability of HKT800 with epoxy resin but is unfavorable for HKT800 with BMI.展开更多
To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis（EDX） is used to establish the content chan...To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis（EDX） is used to establish the content change of oxy- gen in the adhesive in adhesive/carbon fther reinforced epoxy resin composite joints. As water is made up of oxygen and hydrogen, the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints can be obtained from the change in the content of oxygen in the adhesive during humidity aging, via EDX analy-sis. The authors have calculated the water diffusion coefficients and dynamics in the adhesive/carbon fiber reinforced epoxy resin composite joints with the aid of beth energy dispersive X-ray spectroscopy and elemental analysis. The de- termined results with EDX analysis are almost the same as those determined with elemental analysis and the results al- so show that the durability of the adhesive/carbon fther reinforced epoxy resin composite joints subjected to silane cou- pling agent treatment is better than those subjected to sand paper burnishing treatment and chemical oxidation treat- ment.展开更多
Fiber metal laminates(FMLs),a kind of lightweight material with excellent comprehensive performance,have been successfully applied in aerospace.FMLs reinforced with carbon fiber have better mechanical properties than ...Fiber metal laminates(FMLs),a kind of lightweight material with excellent comprehensive performance,have been successfully applied in aerospace.FMLs reinforced with carbon fiber have better mechanical properties than those with glass or aramid fiber.However,carbon fiber binding metal may lead to galvanic corrosion which limits its application.In this paper,electrochemical methods,optical microscope and scanning electron microscope were used to analyze the corrosion evolution of carbon fiber reinforced aluminum laminate(CARALL)in corrosive environment and explore anti-corrosion ways to protect CARALL.The results show that the connection between carbon fiber and aluminum alloy changes electric potential,causing galvanic corrosion.The galvanic corrosion will obviously accelerate CARALL corroded in solution,leading to a 72.1%decrease in interlaminar shear strength,and the crevice corrosion has a greater impact on CARALL resulting in delamination.The reduction of interlaminar shear strength has a similar linear relationship with the corrosion time.In addition,the adhesive layers between carbon fiber and aluminum alloy cannot protect CARALL,while side edge protection can effectively slow down corrosion rate.Therefore,the exposed edges should be coated with anti-corrosion painting.CARALL has the potential to be used for aerospace components.展开更多
Microwave processing was used to cure the carbon fiber/epoxy composites and designed for improving the compressive strength of the materials. By controlling the power of microwave heating, vacuum bagged laminates were...Microwave processing was used to cure the carbon fiber/epoxy composites and designed for improving the compressive strength of the materials. By controlling the power of microwave heating, vacuum bagged laminates were fabricated under one atmosphere pressure without arcing. The physical and mechanical properties of composites produced through vacuum bagging using microwave and thermal curing were compared and the multistep （2-step or 3-step） microwave curing process for improved compressive properties was established. The results indicated that microwave cured samples had somewhat differentiated molecular structure and showed slightly higher glass transition temperature. The 2-step process was found to be more conducive to the enhancement of the compressive strength than the 3-step process. A 39% cure cycle time reduction and a 22% compressive strength increment were achieved for the composites manufactured with microwave radiation. The improvement in specific compressive strength was attributed to better interracial bonding between resin matrix and the fibers, which was also demonstrated via scanning electron microscopy analysis.展开更多
文摘This work aims at designing a set of curing pressure routes to produce laminates with various void contents. The effects of various consolidation pressures resulting in different void contents on mechanical strength of carbon/epoxy laminates have been examined. Characterization of the voids, in terms of void volume fraction, void distribution, size, and shape, was performed by standard test, ultrasonic inspection and metallographic analysis. The interlaminar shear strength was measured by the short-beam method. An empirical model was used to predict the strength vs porosity. The predicted strengths conform well with the experimental data and voids were found to be uniformly distributed throughout the laminate.
基金supported financially by the National Natural Science Foundation of China (No.51875463)the Natural Science Basic Research Plan in Shaanxi Province of China (No.2018JM1001)the Seed Foundation of Innovation and Creation for Graduate Students in Northwestern Polytechnical University (No.ZZ2018107)
文摘Three-dimensional finite element(FE)models of carbon/epoxy composite laminates with copper mesh and aluminum mesh protection were established subjected to lightning strike,in which different mesh spacing was selected.Effectiveness of numerical method was verified and impulse current waveforms with different current peaks were applied according to aircraft lightning zones.Thermal-electrical material parameters varying with temperature were added into numerical models.Element deletion method was used to deal with lightning ablation elements of composite structures.The results show that ablation area and depth of composite laminates with metal mesh protection are significantly smaller,which proves good protection effectiveness of metal meshes on anti-lightning strike.The denser the mesh spacing,the better the anti-lightning strike will be.Protection of composite laminates with copper mesh has better effects than that of aluminum mesh.Considering the effect of mesh spacing variation on composite structural weight and anti-lightning strike,the ideal mesh spacing was obtained.
基金National Natural Science Foundation of China(No.11102133)Tianjin National Natural Science Foundation,China(No.19JCYBJC18300)。
文摘Low-velocity impact and in-plane axial compression after impact(CAI)behaviors of carbon-aramid/epoxy hybrid braided composite laminates were investigated experimentally.The following three different types of carbon-aramid/epoxy hybrid braided composite laminates were produced and tested:(a)inter-hybrid laminates,(b)sandwich-like inter-hybrid laminates,and(c)unsymmetric-hybrid laminates.At the same time,carbon/epoxy braided composite laminates were used for comparisons.Impact properties and impact resistance were studied.Internal damages and damage mechanisms of laminates were detected by ultrasonic C-scan and B-scan methods.The results show that the ductility index(DI)values of three kinds of hybrid laminates aforementioned are 37%,4%and 120%higher than those of carbon/epoxy laminates,respectively.The peak load of inter-hybrid laminates is higher than that of sandwich-like inter-hybrid laminates and unsymmetric-hybrid laminates.The average damage area and dent depths of inter-hybrid laminates are 64%and 69%smaller than those of carbon/epoxy laminates.Those results show that carbon-aramid/epoxy hybrid braided composite laminates could significantly improve the impact properties and toughness of non-hybrid braided composite laminates.
基金supported by a grant-in-aid for the Na-tional Core Research Center Program from the Ministry of Education Science & Technology and the Korea Science & Engineering Foundation (No. R15-2006-022-01001-0)support by the Korea Science and Engineering Foundation (KOSEF) NRL Program grant funded by the Korea government (MEST) (No. R0A-2008-000-20017-0)
文摘It is known that fiber metal laminates （FML） as one of hybrid materials with thin metal sheets and fiber/epoxy layers have the characteristics of the excellent damage tolerance, fatigue and impact properties with a relatively low density. Therefore, the mechanical components using FML can contribute the enhanced safety level of the sound construction toward the whole body. In this study, the impact performance of carbon reinforced aluminum laminates （CARAL） is investigated by experiments and numerical simulations. Drop weight tests are carried out with the weight of 4.7 kg at the speed of 1 and 2 m/s, respectively. Dynamic non-linear transient analyses are also accomplished using a finite element analysis software, ABAQUS. The experiment results and numerical results are compared with impact load-time histories. Also, energy-time histories are applied to investigate the impact performance of CARAL.
基金supported by the Science and Technology Development Program of Jilin Province(No.20240101122JC)and(No.20240101143JC)the Key Scientific and Technological Research and Development Projects of Jilin Provincial Science and Technology Department(Grant Number 20230201108GX)。
文摘Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics(CFRP).Owl feathers are known for their unique compact structure;they are not only lightweight but also strong.In this study,an in-depth look at owl feathers was made and it found that owl feathers not only have the macro branches structure between feather shafts and branches but also have fine feather structures on the branches.The presence of these fine feather structures increases the specific surface area of the plume branches and allows neighboring plume branches to hook up with each other,forming an effective mechanical interlocking structure.These structures bring owl feathers excellent mechanical properties.Inspired by the natural structure of owl feathers,a weaving technique and a sizing process were combined to prepare bionic Carbon Fiber(CF)fabrics and then to fabricate the bionic CFRP with structural characteristics similar to owl feathers.To evaluate the effect of the fine feather structure on the mechanical properties of CFRP,a mechanical property study on CFRP with and without the fine feather imitation structure were conducted.The experimental results show that the introduction of the fine feather branch structure enhance the mechanical properties of CFRP significantly.Specifically,the tensile strength of the composites increased by 6.42%and 13.06%and the flexural strength increased by 8.02%and 16.87%in the 0°and 90°sample directions,respectively.These results provide a new design idea for the improvement of the mechanical properties of the CFRP,promoting the application of CFRP in engineering fields,such as automotive transportation,rail transit,aerospace,and construction.
基金supported by the National Natural Science Foundation of China(No.52173264)the Natural Science Foundation Project of Chongqing(No.cstc2024ycjh-bgzxm0005)+1 种基金the Fundamental Research Funds for the Central Universities(No.SWU-XDJH202314)The authors thanks Dr.Xi Tang in Southwest University for the technical support in the use of the vector network analyzer.
文摘Plastic waste recycling is a focal point in today's sustainable development efforts.Improper disposal can lead to secondary pollution,posing threats to the environment and human health.In this study,we aim to recycle waste epoxy resin and glass fiber-reinforced epoxy resin composites via an electroless plating and a carbonization process,to design high-value-added carbon materials for microwave absorption.By pulverizing solid waste and introducing magnetic metal nanoparticles onto its surface,a composite carbon material capable of excellent microwave absorption performance was successfully developed.Specifically,doping nickel particles into carbon materials derived from glass fiber/epoxy resin achieved a wide effective absorption bandwidth(EAB)of 5.9 GHz with a matching thickness of 1.9 mm,covering nearly the entire Ku band,and achieving a minimum reflection loss(RLmin)of−36 dB simultaneously.The superior absorption performance is attributed to multiple reflections or scattering of electromagnetic waves within the material,as well as conduction and magnetic losses,dipole and interfacial polarization effects.These results demonstrate that through rational design and optimization,waste epoxy and waste glass fiber-reinforced epoxy resin-based composite materials can be effectively recycled into high-performance microwave absorbing materials,offering a straightforward and efficient pathway for waste resource utilization.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52073043 and 52173069)the Fundamental Research Funds for the Central Universities(Grant No.2572022CG03)+1 种基金the Key Research and Development Projects in Heilongjiang Province(Grant No.GZ20210089)the Australian Research Council(Grant Nos.LP220100278,DP240102628,and DP240102728).
文摘Solar-driven thermo-electric generation(STEG)emerges as a promising solution to mitigate the global en-ergy shortage.However,the practical application of conventional photothermal materials equipped with STEG is limited due to low solar thermal conversion efficiency.Herein,we fabricated an epoxy resin(EP)nanocomposite,EP/CCA80,with excellent photo-thermal-electric conversion properties by embedding a vertically aligned aerogel consisting of cellulose nanofibers(CNF)and carboxylated multi-walled carbon nanotubes(CMWCNTs)into a transparent EP matrix.EP/CCA80 composites possessed a broad light ab-sorption range from 200 nm to 2500 nm and excellent photothermal properties.Under illumination of 1.0 kW m^(-2),EP/CCA80 achieved a notable stable temperature of 93.2℃ and a photothermal conversion efficiency of up to 54.35%with only 0.65 wt%CMWCNTs inclusion.Additionally,coupled with thermo-electric(TE)devices,the EP/CCA80 composite facilitated a significant temperature difference and voltage output of up to 25.3℃ and 160.29 mV(1.0 kW m^(-2)),respectively,which could power a small fan to rotate at a speed of 193 min^(-1).Such materials are poised to offer viable solutions for enhancing energy accessibility in remote regions,thereby contributing to the reduction of energy shortages and environ-mental degradation.
基金the Royal Netherlands Academy of Science and Arts(KNAW)(No.10CDP026)the National Outstanding Young Scientist Foundation of China (No.50825401)the National Natural Science Foundation of China(No.50821003)
文摘GLARE （glass fibre/epoxy reinforced aluminum laminate） is a member of the fiber metal laminate （FML） family, and is built up of alternating metal and fiber layers. About 500 m2 GLARE is employed in each Airbus A380 because of the superior mechanical properties over the monolithic Muminum alloys, such as weight reduction, improved damage tolerance and higher ultimate tensile strength. Many tons of new GLARE scraps have been accumulated during the Airbus A380 manufacturing. Moreover, with the increasing plane orders of Airbus A380, more and more end-of-life （EOL） GLARE scrap will be generated after retire of planes within forty years. Thermal processing is a potential method for the material recycling and re-use from GLARE with the aim of environmental protection and economic benefits. The current study indicatdes that thermal delamination is a crucial pre-treatment step for the GLARE recycling. The decomposition behavior of the epoxy resins at elevated temperatures was investigated by using the simultaneous thermal analysis, thermogravimetry analysis （TGA） and differential scanning calorimetry （DSC）. Based on the thermal analysis results, GLARE thermal delamination experiments at refined temperatures were carried out to optimize the treatment temperature and holding time.
基金National Natural Science Foundation of China (No.10272047)the Natural Science Foundation of Guangdong Province (No.020856)
文摘Extensive research has shown that externally bonded carbon fiber reinforced polymer （CFRP） laminates are particularly suitable for improving the fatigue behavior of reinforced concrete （RC） beams. This paper presents the research on flexural ngidity evolvement laws by testing 14 simple-supported RC beams strengthened with carbon fiber laminates （CFL） under cyclic load, and 2 under monotone load as a reference. The cyclic load tests revealed the peak load applied onto the surface of a supported RC beam strengthened with CFL is linear to the logarithm of its fatigue life, and the flexural rigidity evolvement undergoes three distinct phases： a rapid decrease from the start to about 5% of the fatigue life; an even development from .5% to about 99% of the fatigue life; and a succedent rapid decrease to failure. When the ratio of fatigue ＂cycles to the fatigue life is within 0.0.5 to 0.99, the flexural rigidity varies linearly with the ratio. The peak load does not affect the flexural rigidity evolvement if it is not high enough to make the main reinforcements yield. The dependences of the flexural rigidity of specimens formed in the same group upon their fatigue cycles normalized by fatigue life are almost coincident. This implies the flexural rigidity may be a material parameter independent of the stress level. These relationships of flexural rigidity to fatigue cycles, and fatigue life may be able to provide some hints for fatigue design and fatigue life evaluation of RC member strengthened with CFL; nevertheless the findings still need verifying by more experiments.
基金supported by the Fundamental Research Funds for the Central Universities [grant nos.DUT21LAB108,DUT22LAB401].
文摘The vibration attenuation and damping characteristics of carbon fiber reinforced composite laminates with different thicknesses were investigated by hammering experiments under free boundary constraints in different directions.The dynamic signal testing and analysis system is applied to collect and analyze the vibration signals of the composite specimens,and combine the self-spectrum analysis and logarithmic decay method to identify the fundamental frequencies of different specimens and calculate the damping ratios of different directions of the specimens.The results showed that the overall stiffness of the specimen increased with the increase of the specimen thickness,and when the thickness of the sample increases from 24mm to 32mm,the fundamental frequency increases by 35.1%,the vibration showed the same vibration attenuation and energy dissipation characteristics in the 0°and 90°directions of the specimen,compared with the specimen in the 45°direction,which was less likely to be excited and had poorer vibration attenuation ability,while the upper and lower surfaces of the same specimen showed slightly different attenuation characteristics to the vibration,the maximum difference of damping capacity between top and bottom surfaces of CFRP plates is about 70%.
基金support and funding from Guangdong Basic and Applied Basic Research Foundation(2019B1515120093)National Natural Science Foundation of China(51773169 and 51973173)+3 种基金Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(2019JC11)Open Fund from Henan University of Science and Technology(2020-RSC02)Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX202055)financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars。
文摘Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&electrically insulating BNN-30@BNNS/Si-GFs/E-44 laminated composites were then fabricated via hot compression.BNN-30@BNNS-Ⅲ(fBNN-30/fBNNS,1/2,wt/wt)fillers presented the optimal synergistic improvement effects on the thermal conductivities of epoxy composites.When the mass fraction of BNN-30@BNNS-Ⅲwas 15 wt%,λvalue of the BNN-30@BNNS-Ⅲ/E-44 composites was up to0.61 W m^(-1)K^(-1),increased by 2.8 times compared with pure E-44(λ=0.22 W m^(-1)K^(-1)),also higher than that of the 15 wt%BNN-30/E-44(0.56 W m^(-1)K^(-1)),15 wt%BNNS/E-44(0.42 W m^(-1)K^(-1)),and 15 wt%(BNN-30/BNNS)/E-44(direct blending BNN-30/BNNS hybrid fillers,1/2,wt/wt,0.49 W m^(-1)K^(-1))composites.Theλin-plane(λ//)andλcross-plane(λ_(⊥))of 15 wt%BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites significantly reached 2.75 W m^(-1)K^(-1)and 1.32 W m^(-1)K^(-1),186.5%and 187.0%higher than those of Si-GFs/E-44 laminated composites(λ//=0.96 W m^(-1)K^(-1)andλ_(⊥)=0.46 W m^(-1)K^(-1)).Established models can well simulate heat transfer efficiency in the BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites.Under the condition of point heat source,the introduction of BNN-30@BNNS-Ⅲfillers were conducive to accelerating heat flow trans fe r.BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites also demonstrated outstanding electrical insulating properties(cross-plane withstanding voltage,breakdown strength,surface&volume resistivity of 51.3 kV,23.8 kV mm^(-1),3.7×10^(14)Ω&3.4×10^(14)Ω·cm,favorable mechanical properties(flexural strength of 401.0 MPa and ILSS of 22.3 MPa),excellent dielectric properties(εof 4.92 and tanδof 0.008)and terrific thermal properties(T_(g)of 167.3℃and T_(HRI)of 199.2℃).
基金Financial supports by the National Natural Science Foundation of China(Nos.51773137 and 51721091)the Sichuan Province Youth Science and Technology Innovation Team(No.2017TD0006)
文摘The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber(CF)composites.To this end,a facile interracial strategy for fabricating flame-retardant carbon fibers decorated by bio-based polyelectrolyte complexes(PEC)consisting of chitosan(CH)and ammonium polyphosphate(APP)was developed,and its corresponding fire-retarded epoxy resin composites(EP/(PEC@CF))without any other additional flame retardants were prepared.The decorated CFs were characterized by SEM-EDX,XPS and XRD,indicating that the flame-retardant PEC coating was successfully constructed on the surface of CF.Thanks to the nitrogen-and phosphorous-containing PEC,the resulting composites exhibited excellent flame retardancy as the limiting oxygen index(LOI)increased from 31.0%of EP/CF to 40.5%and UL-94 V-0 rating was achieved with only 8.1 wt%PEC.EP/(PEC8.1@CF)also performed well in cone calorimetry with the decrease of peak-heat release rate(PHRR)and smoke production rate(SPR)by 50.0%and 30.4%,respectively,and the value of fire growth rate(FIGRA)was also reduced to 3.41 kW·m-2-s-1 from 4.84 kW·m-2·s-1,suggesting a considerably enhanced fire safety.Furthermore,SEM images of the burning residues revealed that the PEC coating exhibited the dominant flame-retardant activity in condensed phase via the formation of compact phosphorus-rich char.In addition,the impact strength of the composite was improved,together with no obvious deterioration of flexural properties and glass transition temperature.Taking advantage of the features,the PEC-decorated carbon fibers and the relevant composites fabricated by the cost-effective and facile strategy would bring more chances for widespread applications.
基金financially supported by “One Hundred Talented People” of the Chinese Academy of Sciences(No.Y60707WR04)National Basic Research Program(973 Program,No.2015CB654705)Natural Science Foundation of Zhejiang Province(No.LY16B040004)
文摘A critical challenge for initiating many applications of the carbon nanotubes(CNTs) is their dispersion in organic solvent or in polymer melt. In the present study, we described a novel strategy for fabricating carbon nanotubes(CNTs)-reinforced epoxy nanocomposite by utilizing aniline trimer(AT) as the noncovalent dispersant. Tensile testing showed that the tensile modulus of the CNTs-reinforced epoxy composites was considerably improved by adding a small amount of AT functionalized CNTs. Additionally, the as-prepared CNTs-epoxy nanocomposites exhibited superior tribological properties with much lower frictional coefficients and wear rates compared to those of neat epoxy resin. The well dispersed AT-functionalized CNTs in epoxy matrix played an important role in enhancing the mechanical properties, as well as acting as a solid lubricant for improving the tribological performance of epoxy/CNTs nanocomposite.
基金supported financially by the China Scholarship Council(No.201706340114).
文摘Facile green oxidation methods are always desired to functionalize carbon nanotubes(CNTs)in the production of advanced CNT/epoxy composites.In the present work,an optimized H2O2/H2O/O3 oxidation method was developed,and performances of the H2O2/H2O/O3 oxidized CNT in epoxy matrix were tested and compared with that of the H2O/O3 oxidized CNT and the most commonly used concentrated HNO3 oxidized CNT.The physical and chemical characteristics of the obtained oxidized CNTs were systematically characterized via transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)and Raman.Mechanical performances of the obtained composites were explored by tensile tests,impact tests,dynamic mechanical analysis(DMA)and fracture toughness tests.It was found that the H2O2/H2O/O3 oxidized CNT exhibited all-around overwhelming advantages over the concentrated HNO3 oxidized CNT on reinforcing the epoxy matrix,while the H2O/O3 oxidized CNT only improved the material strength.Reinforcing mechanisms for the different methods oxidized CNTs were studied and compared.The optimized H2O2/H2O/O3 oxidation method makes scaled production possible,avoids environment pollutions,and holds great potentials to replace the most commonly used concentrated HNO3 oxidation method to oxidize CNT during the preparation of the advanced CNT/epoxy composite.
基金Financial supports from the National Natural Science Foundation of China (No.51273007)the Program for New Century Excellent Talents in University (NCET) of China
文摘This paper aims to study the effect of processing temperature on interfacial behavior of HKT800 carbon fiber composites with epoxy and Bismaleimide（BMI） matrix.Referring to the processing conditions of the composite, various processing-heat treatments were conducted on HKT800 and the extracted sizing content declines with increasing temperature.Chemical analysis shows that the HKT800 sizing is epoxy-type and reactive at 200 C.The interfacial shear strength（IFSS） of HKT800/epoxy and HKT800/BMI was investigated by micro-droplet method, for which the composites were fabricated with modeling temperature schemes referring to different diffusion, cure and post-cure stages.It shows that diffusion temperature and conversion degree of the resin both enhance the interfacial adhesion of HKT800/epoxy composite.For the HKT800/BMI composite,the diffusion temperature shows a insignificant effect on the IFSS.FTIR analysis indicates that sufficient reactions are achieved between HKT800-sizing and epoxy resin, however only partial reactions are observed between the sizing and BMI.Moreover, the presence of the sizing can evidently improve the wettability of HKT800 with epoxy resin but is unfavorable for HKT800 with BMI.
基金Supported by Commission of Science Technology and Industry for National Defense of China(No.JPPT-115-477).
文摘To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis（EDX） is used to establish the content change of oxy- gen in the adhesive in adhesive/carbon fther reinforced epoxy resin composite joints. As water is made up of oxygen and hydrogen, the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints can be obtained from the change in the content of oxygen in the adhesive during humidity aging, via EDX analy-sis. The authors have calculated the water diffusion coefficients and dynamics in the adhesive/carbon fiber reinforced epoxy resin composite joints with the aid of beth energy dispersive X-ray spectroscopy and elemental analysis. The de- termined results with EDX analysis are almost the same as those determined with elemental analysis and the results al- so show that the durability of the adhesive/carbon fther reinforced epoxy resin composite joints subjected to silane cou- pling agent treatment is better than those subjected to sand paper burnishing treatment and chemical oxidation treat- ment.
基金Project(51675538)supported by the National Natural Science Foundation of China。
文摘Fiber metal laminates(FMLs),a kind of lightweight material with excellent comprehensive performance,have been successfully applied in aerospace.FMLs reinforced with carbon fiber have better mechanical properties than those with glass or aramid fiber.However,carbon fiber binding metal may lead to galvanic corrosion which limits its application.In this paper,electrochemical methods,optical microscope and scanning electron microscope were used to analyze the corrosion evolution of carbon fiber reinforced aluminum laminate(CARALL)in corrosive environment and explore anti-corrosion ways to protect CARALL.The results show that the connection between carbon fiber and aluminum alloy changes electric potential,causing galvanic corrosion.The galvanic corrosion will obviously accelerate CARALL corroded in solution,leading to a 72.1%decrease in interlaminar shear strength,and the crevice corrosion has a greater impact on CARALL resulting in delamination.The reduction of interlaminar shear strength has a similar linear relationship with the corrosion time.In addition,the adhesive layers between carbon fiber and aluminum alloy cannot protect CARALL,while side edge protection can effectively slow down corrosion rate.Therefore,the exposed edges should be coated with anti-corrosion painting.CARALL has the potential to be used for aerospace components.
基金the Innovation Funds of China-National Engineering and Research Center for Commercial Aircraft Manufacturing (SAMC12-JS-15-015) for financial support
文摘Microwave processing was used to cure the carbon fiber/epoxy composites and designed for improving the compressive strength of the materials. By controlling the power of microwave heating, vacuum bagged laminates were fabricated under one atmosphere pressure without arcing. The physical and mechanical properties of composites produced through vacuum bagging using microwave and thermal curing were compared and the multistep （2-step or 3-step） microwave curing process for improved compressive properties was established. The results indicated that microwave cured samples had somewhat differentiated molecular structure and showed slightly higher glass transition temperature. The 2-step process was found to be more conducive to the enhancement of the compressive strength than the 3-step process. A 39% cure cycle time reduction and a 22% compressive strength increment were achieved for the composites manufactured with microwave radiation. The improvement in specific compressive strength was attributed to better interracial bonding between resin matrix and the fibers, which was also demonstrated via scanning electron microscopy analysis.
