Additive manufacturing(AM),also known as 3D printing,is a process of creating three-dimensional objects with complex geometries that is utilized in various engineering applications.Continuous carbon fiber(CCF)is a hig...Additive manufacturing(AM),also known as 3D printing,is a process of creating three-dimensional objects with complex geometries that is utilized in various engineering applications.Continuous carbon fiber(CCF)is a high-performance material that offers a range of benefits in terms of strength,weight,and durability.Fused filament fabrication(FFF)is a type of AM that uses a thermoplastic filament as a material with which to create a three-dimensional object,and it has been widely used in various applications,as it enables the faster,cheaper,and more customizable production of parts and products.Lightweight cellular composite structures consists of small,repeating unit cells that are interconnected to form a larger structure,and they are employed in high engineering applications.In this study,cellular composite structures were fabricated using FFF technology,considering two types of infill paths design(grid and triangular)manufactured at three infill density levels(20%,40%,and 60%).After the fabrication process,tensile and flexural properties were experimentally investigated,and the influence of the infill pattern and density on the cellular composite parts were studied.The achieved results demonstrated that the infill design pattern and its density had great influence on the mechanical properties of the cellular structure.The obtained results also showed that the lightweight cellular composite parts had great potential for use in structural applications.展开更多
The additive manufacturing of continuous fiber composites has the advantage of a high-precision and efficient forming process,which can realize the lightweight and integrated manufacturing of complex structures.Howeve...The additive manufacturing of continuous fiber composites has the advantage of a high-precision and efficient forming process,which can realize the lightweight and integrated manufacturing of complex structures.However,many void defects exist between layers in the printing process of additive manufacturing;consequently,the bonding performance between layers is poor.The bonding neck is considered a key parameter for representing the quality of interfacial bonding.In this study,the formation mechanism of the bonding neck was comprehensively analyzed.First,the influence of the nozzle and basement temperatures on the printing performance and bonding neck size was measured.Second,CT scanning was used to realize the quantitative characterization of bonding neck parameters,and the reason behind the deviation of actual measurements from theoretical calculations was analyzed.When the nozzle temperature increased from 180 to 220℃,CT measurement showed that the bonding neck diameter increased from 0.29 to 0.34 mm,and the cross-sectional porosity reduced from 5.48%to 3.22%.Finally,the fracture mechanism was studied,and the influence of the interfacial bonding quality on the destruction process of the materials was determined.In conclusion,this study can assist in optimizing the process parameters,which improves the precision of the printing parts and performance between the layers.展开更多
The fast and high response detection of neurotoxic H_(2)S is of great importance for the environment.In this paper,directly electrospinning technology on the ceramic tube is developed to improve the response of H_(2)S...The fast and high response detection of neurotoxic H_(2)S is of great importance for the environment.In this paper,directly electrospinning technology on the ceramic tube is developed to improve the response of H_(2)S detector based on superlong SnO_(2)fibers.The submillimeter continuous fibers are deposited directly on ceramic tubes by in-situ electrospinning method and can keep morphology of fibers during calcination.By employing this technology,CuO-doped SnO_(2)fiber H_(2)S detectors are fabricated,and 10%atom CuO-doped SnO_(2)H_(2)S detector shows the highest response of 40 toward 1 ppm H_(2)S at 150℃while the response is only 3.6 for the H_(2)S detector prepared in traditional route.In addition,the in-situ electrospinning H_(2)S detectors show faster response and recovery compared to the H_(2)S detectors fabricated by the conventional way.The high and fast response of H_(2)S detectors based on in-situ electrospinning can be ascribed to the continuous fiber structure and CuO modification.The present in-situ electrospinning technology may provide a new strategy for the development of other gasdetectors and bio-detectors with fast and high response.展开更多
A novel metal matrix composite freeform fabrication approach,fiber traction printing(FTP),is demonstrated through controlling the wetting behavior between fibers and the matrix.This process utilizes the fiber bundle t...A novel metal matrix composite freeform fabrication approach,fiber traction printing(FTP),is demonstrated through controlling the wetting behavior between fibers and the matrix.This process utilizes the fiber bundle to control the cross-sectional shape of the liquid metal,shaping it from circular to rectangular which is more precise.The FTP process could resolve manufacturing difficulties in the complex structure of continuous fiber reinforced metal matrix composites.The printing of the first layer monofilament is discussed in detail,and the effects of the fibrous coating thickness on the mechanical properties and microstructures of the composite are also investigated in this paper.The composite material prepared by the FTP process has a tensile strength of 235.2 MPa,which is close to that of composites fabricated by conventional processes.The complex structures are printed to demonstrate the advantages and innovations of this approach.Moreover,the FTP method is suited to other material systems with good wettability,such as modified carbon fiber,surfactants,and aluminum alloys.展开更多
This study focuses on the process validation and performance evaluation of 3D-printed continuous fiber-reinforced thermoplastic composite corrugated sandwich structures.It explores their mechanical behavior under diff...This study focuses on the process validation and performance evaluation of 3D-printed continuous fiber-reinforced thermoplastic composite corrugated sandwich structures.It explores their mechanical behavior under different structural desi gns and manufacturing process characteristics.Through real-time impregnation technology,continuous fibers were combined with thermoplastic resin to print both arc-shaped and trapezoidal corrugated sandwich structures,and their compressive strength was tested and analyzed through experimental testing.The results show that the trapezoidal sandwich structure exhibits higher compressive strength under compression loads,with a peak compressive strength value of 9.11 MPa.In contrast,the arc-shaped sandwich structure has a value of 4.76 MPa.Under the same conditions,the trapezoidal structure demonstrates superior load distribution capability and higher stiffness with lower deformation.The experiment investigated the impact of process parame ters and fiber-resin bonding quality on structural performance in real-time impregnation technology,indicating that this process can effectively optimize material properties and offer good manufacturing flexibility.展开更多
Polyether ether ketone(PEEK)-based continuous glass fiber reinforced thermoplastic composite offers advantages such as high strength,electrical insulation,and heat insulation.Parts manufactured using this composite an...Polyether ether ketone(PEEK)-based continuous glass fiber reinforced thermoplastic composite offers advantages such as high strength,electrical insulation,and heat insulation.Parts manufactured using this composite and 3D printing have promising applications in aerospace,automobile,rail transit,etc.In this paper,a high-temperature melt impregnation method was used to successfully prepare the 3D printing prepreg filaments of the aforementioned composite.In the FDM 3D printing equipment,a nozzle of high thermal conductivity and wear-resistant copper alloy and a PEEK-based carbon fiber thermoplastic composite build plate with uniform temperature control were innovatively introduced to effectively improve the quality of 3D printing.The porosity of the 3D printed samples produced from the composite prepreg filament was analyzed under different printing parameters,and the mechanical properties and fracture mechanism of the printed parts were studied.The results show that the printing layer thickness,printing speed,printing temperature and build plate temperature have varying effects on the porosity of printed parts,which in turn affects tensile strength and the interlaminar shear strength(ILSS).When the printing layer thickness is 0.4 mm,printing speed is 2 mm/s,nozzle temperature is 430℃ and build plate temperature is 150℃,the tensile strength and ILSS of the composite printed parts reach their maximum values of 463.76 and 24.95 MPa,respectively.Microscopic analysis of the fracture morphology of the tensile specimens reveals that the 3D printed CGF/PEEK composite sample has three types of fracture mode,which are single filament bundle fracture,fracture mode of delamination,and fracture failure of the sample at the cross-section.The essence of the above three kinds of fracture mode is the difference of the interface bonding force of 3D printed CGF/PEEK composites.The fracture failure at the cross-section is that the continuous glass fibers in the composite are pulled out until they break,which is the main form of the failure of the composite under tensile load.The interfacial region of the composite is prone to microscopic defects such as voids and delamination during 3D printing,which become the most vulnerable link of the composite.Understanding the relationship between voids and fracture behavior lays a foundation for defect suppression and performance improvement of subsequent printed parts.展开更多
Fiber-reinforced composites are an ideal material for the lightweight design of aerospace structures. Especially in recent years, with the rapid development of composite additive manufacturing technology, the design o...Fiber-reinforced composites are an ideal material for the lightweight design of aerospace structures. Especially in recent years, with the rapid development of composite additive manufacturing technology, the design optimization of variable stiffness of fiber-reinforced composite laminates has attracted widespread attention from scholars and industry. In these aerospace composite structures, numerous cutout panels and shells serve as access points for maintaining electrical, fuel, and hydraulic systems. The traditional fiber-reinforced composite laminate subtractive drilling manufacturing inevitably faces the problems of interlayer delamination, fiber fracture, and burr of the laminate. Continuous fiber additive manufacturing technology offers the potential for integrated design optimization and manufacturing with high structural performance. Considering the integration of design and manufacturability in continuous fiber additive manufacturing, the paper proposes linear and nonlinear filtering strategies based on the Normal Distribution Fiber Optimization (NDFO) material interpolation scheme to overcome the challenge of discrete fiber optimization results, which are difficult to apply directly to continuous fiber additive manufacturing. With minimizing structural compliance as the objective function, the proposed approach provides a strategy to achieve continuity of discrete fiber paths in the variable stiffness design optimization of composite laminates with regular and irregular holes. In the variable stiffness design optimization model, the number of candidate fiber laying angles in the NDFO material interpolation scheme is considered as design variable. The sensitivity information of structural compliance with respect to the number of candidate fiber laying angles is obtained using the analytical sensitivity analysis method. Based on the proposed variable stiffness design optimization method for complex perforated composite laminates, the numerical examples consider the variable stiffness design optimization of typical non-perforated and perforated composite laminates with circular, square, and irregular holes, and systematically discuss the number of candidate discrete fiber laying angles, discrete fiber continuous filtering strategies, and filter radius on structural compliance, continuity, and manufacturability. The optimized discrete fiber angles of variable stiffness laminates are converted into continuous fiber laying paths using a streamlined process for continuous fiber additive manufacturing. Meanwhile, the optimized non-perforated and perforated MBB beams after discrete fiber continuous treatment, are manufactured using continuous fiber co-extrusion additive manufacturing technology to verify the effectiveness of the variable stiffness fiber optimization framework proposed in this paper.展开更多
Continuous fiber reinforced polymer composites(CFRPC)have been widely used in the field of automobile,air-craft,and space due to light weight,high specific strength and modulus in comparison with metal as well as allo...Continuous fiber reinforced polymer composites(CFRPC)have been widely used in the field of automobile,air-craft,and space due to light weight,high specific strength and modulus in comparison with metal as well as alloys.Innovation on 3D printing of CFRPCs opened a new era for the design and fabrication of complicated composite structure with high performance and low cost.3D printing of CFRPCs provided an enabling technol-ogy to bridge the gaps between advanced materials and innovative structures.State-of-art has been reviewed according to the correlations of materials,structure,process,and performance as well as functions in 3D printing of CFRPCs.Typical applications and future perspective for 3D printing of CFRPCs were illustrated in order to grasp the opportunities and face the challenges,which need much more interdisciplinary researches covering the advanced materials,process and equipment,structural design,and final smart performance.展开更多
The application of continuous natural fibers as reinforcement in composite thin-walled structures offers a feasible approach to achieve light weight and high strength while remaining environmentally friendly.In additi...The application of continuous natural fibers as reinforcement in composite thin-walled structures offers a feasible approach to achieve light weight and high strength while remaining environmentally friendly.In addition,additive manufacturing technology provides a favorable process foundation for its realization.In this study,the printability and energy absorption properties of 3D printed continuous fiber reinforced thin-walled structures with different configurations were investigated.The results suggested that a low printing speed and a proper layer thickness would mitigate the printing defects within the structures.The printing geometry accuracy of the structures could be further improved by rounding the sharp corners with appropriate radii.This study successfully fabricated structures with vari-ous configurations characterized by high geometric accuracy through printing parameters optimization and path smoothing.Moreover,the compressive property and energy absorption characteristics of the structures under quasi-static axial compression were evaluated and compared.It was found that all studied thin-walled structures exhibited progressive folding deformation patterns during compression.In particular,energy absorption process was achieved through the combined damage modes of plastic deformation,fiber pullout and delamination.Furthermore,the com-parison results showed that the hexagonal structure exhibited the best energy absorption performance.The study revealed the structure-mechanical property relationship of 3D printed continuous fiber reinforced composite thin-walled structures through the analysis of multiscale failure characteristics and load response,which is valuable for broadening their applications.展开更多
Stretchable strain sensors play a key role in motion detection and human-machine interface functionality,and deformation control.However,their sensitivity is often limited by the Poisson effect of elastic substrates.I...Stretchable strain sensors play a key role in motion detection and human-machine interface functionality,and deformation control.However,their sensitivity is often limited by the Poisson effect of elastic substrates.In this study,a stretchable strain sensor based on a continuous-fiber-reinforced auxetic structure was proposed and fabricated using a direct ink writing(DIW)3D printing process.The application of multi-material DIW greatly simplifies the fabrication process of a sensor with an auxetic structure(auxetic sensor).The auxiliary auxetic struc-ture was innovatively printed using a continuous-fiber-reinforced polydimethylsiloxane composite(Fiber-PDMS)to balance the rigidity and flexibility of the composite.The increase in stiffness enhances the negative Poisson’s ratio effect of the auxetic structure,which can support the carbon nanotube-polydimethylsiloxane composite(CNT-PDMS)stretchable sensor to produce a significant lateral expansion when stretched.It is shown that the structural Poisson’s ratio of the sensor decreased from 0.42 to−0.33 at 20%tensile strain,and the bidirectional tensile strain increases the sensor sensitivity by 2.52 times(gage factor to 18.23).The Fiber-PDMS composite maintains the excellent flexibility of the matrix material.The auxetic sensor exhibited no structural damage af-ter 150 cycles of tension and the signal output exhibited high stability.In addition,this study demonstrates the significant potential of auxetic sensors in the field of deformation control.展开更多
The difficulty of reducing the diameter of lutetium oxide(Lu_(2)O_(3))continuous fibers below 50μm not only limits the flexibility of the sample but also seriously affects their application and development in high-en...The difficulty of reducing the diameter of lutetium oxide(Lu_(2)O_(3))continuous fibers below 50μm not only limits the flexibility of the sample but also seriously affects their application and development in high-energy lasers.In this work,a Lu-containing precursor with high ceramic yield was used as raw material,fiberized into precursor fibers by dry spinning.The pressure-assisted water vapor pretreatment(PAWVT)method was creatively proposed,and the effect of pretreatment temperature on the ceramization behavior of the precursor fibers was studied.By regulating the decomposition behavior of organic components in the precursor,the problem of fiber pulverization during heat treatment was effectively solved,and the Lu_(2)O_(3) continuous fibers with a diameter of 40μm were obtained.Compared with the current reported results,the diameter was reduced by about 50%,successfully breaking through the diameter limitation of Lu_(2)O_(3) continuous fibers.In addition,the tensile strength,elastic modulus,flexibility,and temperature resistance of Lu_(2)O_(3) continuous fibers were researched for the first time.The tensile strength and elastic modulus of Lu_(2)O_(3) continuous fibers were 373.23 MPa and 31.55 GPa,respectively.The as-obtained flexible Lu_(2)O_(3) continuous fibers with a limit radius of curvature of 3.5-4.5 mm had a temperature resistance of not lower than 1300℃,which established a solid foundation for the expansion of their application form in the field of high-energy lasers.展开更多
In recent years,innovations in 3D/4D printing techniques for continuous fiber-reinforced polymer composites(CFRPCs)have opened new perspectives for the integrated design and manufacture of composites with customized f...In recent years,innovations in 3D/4D printing techniques for continuous fiber-reinforced polymer composites(CFRPCs)have opened new perspectives for the integrated design and manufacture of composites with customized functions.This paper reviews the current state of 3D/4D printed functional composites,including the materi-als,shape memory/changing effects,self-monitoring/healing behaviors,and challenges surrounding additive-manufactured functional composites.Specifically,continuous fibers and matrices that provide functional roles are classified and discussed in detail.4D printed shape memory and changing CFRPCs can retain their original shapes from a designed shape upon exposure to different external stimuli,including heat,electricity,humidity,and multi-stimuli activation.Furthermore,self-monitoring of structural health is achieved through the piezore-sistive features of reinforced fibers in 3D printed CFRPCs.Finally,this review concludes with an outlook on the future research opportunities for 3D/4D printed functional CFRPCs.展开更多
Continuous basalt fiber(CBF)is an outstanding inorganic fiber produced from nature,which has a wide range of applications in the field of armor protection of national defense military.However,the mechanical response a...Continuous basalt fiber(CBF)is an outstanding inorganic fiber produced from nature,which has a wide range of applications in the field of armor protection of national defense military.However,the mechanical response and failure mechanism of 3D printed CBF reinforced components are still not well understood.Here,the 3D printing thermoplastic composites with high volume fraction CBF have been successfully prepared by fused deposition modelling(FDM)method.The effects of fiber printing direction and polymer matrix type on the tensile and flexural properties of the 3D printed composites have been explored,and the detailed failure morphology has been characterized using scanning electron microscopy and optical microscopy.It was found that under high fiber volume fraction,3D printed CBF reinforced polyamides(PA)composites have the best ability to maintain material integrity of the composites,followed by acrylonitrile butadiene styrene(ABS)and high impact polystyrene(HIPS).Besides,the results from rule of mixtures can accurately predict the longitudinal Young’s modulus of the 3D printed specimens,but there exists a large discrepancy for the prediction of the tensile strength.The microstructure analysis shows that the failure modes of 3D printed composites mainly include fiber debonding,fiber pull-out,stress whitening and matrix cracking.展开更多
To meet the requirements of spacecraft for the thermal conductivity of resins and solve the problem of low thermal conduction efficiency when 3D printing complex parts,we propose a new type of continuous mesophase-pit...To meet the requirements of spacecraft for the thermal conductivity of resins and solve the problem of low thermal conduction efficiency when 3D printing complex parts,we propose a new type of continuous mesophase-pitch-based carbon fiber/thermoplastic polyurethane/epoxy(CMPCF/TPU/epoxy)composite filament and its preparation process in this study.The composite filament is based on the high thermal conductivity of CMPCF,the high elasticity of TPU,and the high-temperature resistance of epoxy.The tensile strength and thermal conductivity of the CMPCF/TPU/epoxy composite filament were tested.The CMPCF/TPU/epoxy composites are formed by 3D printing technology,and the composite filament is laid according to the direction of heat conduction so that the printed part can meet the needs of directional heat conduction.The experimental results show that the thermal conductivity of the printed sample is 40.549 W/(m·K),which is 160 times that of pure epoxy resin(0.254 W/(m·K)).It is also approximately 13 times better than that of polyacrylonitrile carbon fiber/epoxy(PAN-CF/epoxy)composites.This study breaks through the technical bottleneck of poor printability of CMPCF.It provides a new method for achieving directional thermal conductivity printing,which is important for the development of complex high-performance thermal conductivity products.展开更多
It was found that air dielectric barrier discharge(DBD) plasma contributed to the grafting of epoxy resin onto continuous PBO fiber surface. This air-plasma-grafting-epoxy method yielded a noticeable enhancement in th...It was found that air dielectric barrier discharge(DBD) plasma contributed to the grafting of epoxy resin onto continuous PBO fiber surface. This air-plasma-grafting-epoxy method yielded a noticeable enhancement in the interfacial adhesion between PBO fiber and thermoplastic matrix resin, with the interlaminar shear strength of the resulting composites increased by 66.7%. DSC and FTIR analyses were then used to study the curing behavior of epoxy coating on PBO fiber surface, deduce the possible grafting reactions and investigate the grafting mechanism. More importantly, TGA measurement showed that the grafting of epoxy onto PBO fiber had almost no effect on the composite heat resistance, and there was more thermoplastic matrix resin adhering to the fiber surface; the latter could also be clearly found in the SEM photos. Thereby, the air-plasma-grafting-epoxy treatment was proved to be an effective method for the improvement of continuous PBO fiber surface adhesive properties.展开更多
This study tested an improved fiber tracking algorithm, which was based on fiber assignment using a continuous tracking algorithm and a two-tensor model. Different models and tracking decisions were used by judging th...This study tested an improved fiber tracking algorithm, which was based on fiber assignment using a continuous tracking algorithm and a two-tensor model. Different models and tracking decisions were used by judging the type of estimation of each voxel. Thismethod should solve the cross-track problem. This study included eight healthy subjects, two axonal injury patients and seven demyelinating disease patients. This new algorithm clearly exhibited a difference in nerve fiber direction between axonal injury and demyelinating disease patients and healthy control subjects. Compared with fiber assignment with a continuous tracking algorithm, our novel method can track more and longer nerve fibers, and also can solve the fiber crossing problem.展开更多
Conventional deformable wheel systems in robots and other mechatronic systems face significant challenges in achieving miniaturization,intelligence,and integration.To address these issues,we propose a novel integrated...Conventional deformable wheel systems in robots and other mechatronic systems face significant challenges in achieving miniaturization,intelligence,and integration.To address these issues,we propose a novel integrated structural design method and four-dimensional printing strategy for deformable wheels capable of shaping among multiple programmable direct-driven deformation configurations.The load-bearing capacity of the printed wheel is strengthened by employing deformed components in various locations and actuated states.Additionally,a novel analytical design method is presented to determine the structure,actuation,and deformation parameters of each component under complex coupled deformation.Our findings reveal that the designed wheel can transform into three different configurations,exhibiting desired deformations of 12.5%in the radial direction and 19.6%in the axial direction.It also demonstrates robust deformation behavior and structural stability under multi-directional loads.By integrating a terrain sensing system,the designed wheel exhibits highly adaptive deformation capabilities on various terrains,showing great potential for exploring complex environments.展开更多
Carbon nanotube fibers(CNTFs),which hold a transformative potential across fields from aerospace to wearable electronics,have been reported as superstrong fibers,while the fabrication of continuous fibers with excelle...Carbon nanotube fibers(CNTFs),which hold a transformative potential across fields from aerospace to wearable electronics,have been reported as superstrong fibers,while the fabrication of continuous fibers with excellent strength remains a challenge.Herein,we proposed a mixed carbon-source strategy that engineered carbon nanotube(CNT)aerogels with optimally aligned and controlled-entanglement CNT bundles,ensuring structural uniformity and enabling densification into highly oriented architectures via chlorosulfonic acid-assisted stretching,thus yielding continuous high-performance CNTFs.These continuous CNTFs exhibited superior tensile strength(4.10±0.17 N·tex^(-1),exceeding T1100),modulus(268±16 N·tex^(-1),1.4 times of T1100),thermal conductivity(400 W·m^(-1)·K^(-1),over 30 times of T1100)and electrical conductivity(1480 S·m^(2)·kg^(-1)),along with exceptional flexibility indicated by knot-strength retention exceeding 45%.Comprehensive multi-point assessments confirmed that this method yielded a remarkable uniformity in both structural and functional properties across kilometer-scale lengths.These findings highlight the crucial role of nanotube alignment and interfacial engineering in enabling the scalable industrial implementation of high-performance CNTFs.展开更多
After a half century of development, fiber laser has evolved from a concept to a great family penetrating into various fields of applications. This paper reviews the history and current development of fiber lasers, wi...After a half century of development, fiber laser has evolved from a concept to a great family penetrating into various fields of applications. This paper reviews the history and current development of fiber lasers, with topics covering both continuous wave and short pulse fiber lasers. Important issues such as the major rare earth dopants, fiber laser brightness, polarization effects, clad pumping technology, beam combination, mode locking and pulse shaping are discussed in this paper.展开更多
Through millions of years of evolution,bones have developed a complex and elegant hierarchical structure,utilizing tropocollagen and hydroxyapatite to attain an intricate balance between modulus,strength,and toughness...Through millions of years of evolution,bones have developed a complex and elegant hierarchical structure,utilizing tropocollagen and hydroxyapatite to attain an intricate balance between modulus,strength,and toughness.In this study,continuous fiber silk composites(CFSCs)of large size are prepared to mimic the hi-erarchical structure of natural bones,through the inheritance of the hierarchical structure of fiber silk and the integration with a polyester matrix.Due to the robust interface between the matrix and fiber silk,CFSCs show maintained stable long-term mechanical performance under wet conditions.During in vivo degradation,this material primarily undergoes host cell-mediated surface degradation,rather than bulk hydrolysis.We demon-strate significant capabilities of CFSCs in promoting vascularization and macrophage differentiation toward repair.A bone defect model further indicates the potential of CFSC for bone graft applications.Our belief is that the material family of CFSCs may promise a novel biomaterial strategy for yet to be achieved excellent regen-erative implants.展开更多
文摘Additive manufacturing(AM),also known as 3D printing,is a process of creating three-dimensional objects with complex geometries that is utilized in various engineering applications.Continuous carbon fiber(CCF)is a high-performance material that offers a range of benefits in terms of strength,weight,and durability.Fused filament fabrication(FFF)is a type of AM that uses a thermoplastic filament as a material with which to create a three-dimensional object,and it has been widely used in various applications,as it enables the faster,cheaper,and more customizable production of parts and products.Lightweight cellular composite structures consists of small,repeating unit cells that are interconnected to form a larger structure,and they are employed in high engineering applications.In this study,cellular composite structures were fabricated using FFF technology,considering two types of infill paths design(grid and triangular)manufactured at three infill density levels(20%,40%,and 60%).After the fabrication process,tensile and flexural properties were experimentally investigated,and the influence of the infill pattern and density on the cellular composite parts were studied.The achieved results demonstrated that the infill design pattern and its density had great influence on the mechanical properties of the cellular structure.The obtained results also showed that the lightweight cellular composite parts had great potential for use in structural applications.
基金Supported by National Key R&D Program of China(Grant No.2017YFB1103400).
文摘The additive manufacturing of continuous fiber composites has the advantage of a high-precision and efficient forming process,which can realize the lightweight and integrated manufacturing of complex structures.However,many void defects exist between layers in the printing process of additive manufacturing;consequently,the bonding performance between layers is poor.The bonding neck is considered a key parameter for representing the quality of interfacial bonding.In this study,the formation mechanism of the bonding neck was comprehensively analyzed.First,the influence of the nozzle and basement temperatures on the printing performance and bonding neck size was measured.Second,CT scanning was used to realize the quantitative characterization of bonding neck parameters,and the reason behind the deviation of actual measurements from theoretical calculations was analyzed.When the nozzle temperature increased from 180 to 220℃,CT measurement showed that the bonding neck diameter increased from 0.29 to 0.34 mm,and the cross-sectional porosity reduced from 5.48%to 3.22%.Finally,the fracture mechanism was studied,and the influence of the interfacial bonding quality on the destruction process of the materials was determined.In conclusion,this study can assist in optimizing the process parameters,which improves the precision of the printing parts and performance between the layers.
基金supported by National Natural Science Foundation of China(51772082,51804106,51572078,51772086 and 51872087)。
文摘The fast and high response detection of neurotoxic H_(2)S is of great importance for the environment.In this paper,directly electrospinning technology on the ceramic tube is developed to improve the response of H_(2)S detector based on superlong SnO_(2)fibers.The submillimeter continuous fibers are deposited directly on ceramic tubes by in-situ electrospinning method and can keep morphology of fibers during calcination.By employing this technology,CuO-doped SnO_(2)fiber H_(2)S detectors are fabricated,and 10%atom CuO-doped SnO_(2)H_(2)S detector shows the highest response of 40 toward 1 ppm H_(2)S at 150℃while the response is only 3.6 for the H_(2)S detector prepared in traditional route.In addition,the in-situ electrospinning H_(2)S detectors show faster response and recovery compared to the H_(2)S detectors fabricated by the conventional way.The high and fast response of H_(2)S detectors based on in-situ electrospinning can be ascribed to the continuous fiber structure and CuO modification.The present in-situ electrospinning technology may provide a new strategy for the development of other gasdetectors and bio-detectors with fast and high response.
基金Supported by National Key R&D Program of China(Grant Nos.2017YFB1103400,2016YFB1100902)National Natural Science Foundation of China(Grant No.51575430,51811530107)The Youth Innovation Team of Shaanxi Universities.
文摘A novel metal matrix composite freeform fabrication approach,fiber traction printing(FTP),is demonstrated through controlling the wetting behavior between fibers and the matrix.This process utilizes the fiber bundle to control the cross-sectional shape of the liquid metal,shaping it from circular to rectangular which is more precise.The FTP process could resolve manufacturing difficulties in the complex structure of continuous fiber reinforced metal matrix composites.The printing of the first layer monofilament is discussed in detail,and the effects of the fibrous coating thickness on the mechanical properties and microstructures of the composite are also investigated in this paper.The composite material prepared by the FTP process has a tensile strength of 235.2 MPa,which is close to that of composites fabricated by conventional processes.The complex structures are printed to demonstrate the advantages and innovations of this approach.Moreover,the FTP method is suited to other material systems with good wettability,such as modified carbon fiber,surfactants,and aluminum alloys.
文摘This study focuses on the process validation and performance evaluation of 3D-printed continuous fiber-reinforced thermoplastic composite corrugated sandwich structures.It explores their mechanical behavior under different structural desi gns and manufacturing process characteristics.Through real-time impregnation technology,continuous fibers were combined with thermoplastic resin to print both arc-shaped and trapezoidal corrugated sandwich structures,and their compressive strength was tested and analyzed through experimental testing.The results show that the trapezoidal sandwich structure exhibits higher compressive strength under compression loads,with a peak compressive strength value of 9.11 MPa.In contrast,the arc-shaped sandwich structure has a value of 4.76 MPa.Under the same conditions,the trapezoidal structure demonstrates superior load distribution capability and higher stiffness with lower deformation.The experiment investigated the impact of process parame ters and fiber-resin bonding quality on structural performance in real-time impregnation technology,indicating that this process can effectively optimize material properties and offer good manufacturing flexibility.
基金supported by the National Key Research and Development Program Project of China(Grant No.2018YFB1106700).
文摘Polyether ether ketone(PEEK)-based continuous glass fiber reinforced thermoplastic composite offers advantages such as high strength,electrical insulation,and heat insulation.Parts manufactured using this composite and 3D printing have promising applications in aerospace,automobile,rail transit,etc.In this paper,a high-temperature melt impregnation method was used to successfully prepare the 3D printing prepreg filaments of the aforementioned composite.In the FDM 3D printing equipment,a nozzle of high thermal conductivity and wear-resistant copper alloy and a PEEK-based carbon fiber thermoplastic composite build plate with uniform temperature control were innovatively introduced to effectively improve the quality of 3D printing.The porosity of the 3D printed samples produced from the composite prepreg filament was analyzed under different printing parameters,and the mechanical properties and fracture mechanism of the printed parts were studied.The results show that the printing layer thickness,printing speed,printing temperature and build plate temperature have varying effects on the porosity of printed parts,which in turn affects tensile strength and the interlaminar shear strength(ILSS).When the printing layer thickness is 0.4 mm,printing speed is 2 mm/s,nozzle temperature is 430℃ and build plate temperature is 150℃,the tensile strength and ILSS of the composite printed parts reach their maximum values of 463.76 and 24.95 MPa,respectively.Microscopic analysis of the fracture morphology of the tensile specimens reveals that the 3D printed CGF/PEEK composite sample has three types of fracture mode,which are single filament bundle fracture,fracture mode of delamination,and fracture failure of the sample at the cross-section.The essence of the above three kinds of fracture mode is the difference of the interface bonding force of 3D printed CGF/PEEK composites.The fracture failure at the cross-section is that the continuous glass fibers in the composite are pulled out until they break,which is the main form of the failure of the composite under tensile load.The interfacial region of the composite is prone to microscopic defects such as voids and delamination during 3D printing,which become the most vulnerable link of the composite.Understanding the relationship between voids and fracture behavior lays a foundation for defect suppression and performance improvement of subsequent printed parts.
基金supports for this research were provided by the National Natural Science Foundation of China(No.12272301,12002278,U1906233)the Guangdong Basic and Applied Basic Research Foundation,China(Nos.2023A1515011970,2024A1515010256)+1 种基金the Dalian City Supports Innovation and Entrepreneurship Projects for High-Level Talents,China(2021RD16)the Key R&D Project of CSCEC,China(No.CSCEC-2020-Z-4).
文摘Fiber-reinforced composites are an ideal material for the lightweight design of aerospace structures. Especially in recent years, with the rapid development of composite additive manufacturing technology, the design optimization of variable stiffness of fiber-reinforced composite laminates has attracted widespread attention from scholars and industry. In these aerospace composite structures, numerous cutout panels and shells serve as access points for maintaining electrical, fuel, and hydraulic systems. The traditional fiber-reinforced composite laminate subtractive drilling manufacturing inevitably faces the problems of interlayer delamination, fiber fracture, and burr of the laminate. Continuous fiber additive manufacturing technology offers the potential for integrated design optimization and manufacturing with high structural performance. Considering the integration of design and manufacturability in continuous fiber additive manufacturing, the paper proposes linear and nonlinear filtering strategies based on the Normal Distribution Fiber Optimization (NDFO) material interpolation scheme to overcome the challenge of discrete fiber optimization results, which are difficult to apply directly to continuous fiber additive manufacturing. With minimizing structural compliance as the objective function, the proposed approach provides a strategy to achieve continuity of discrete fiber paths in the variable stiffness design optimization of composite laminates with regular and irregular holes. In the variable stiffness design optimization model, the number of candidate fiber laying angles in the NDFO material interpolation scheme is considered as design variable. The sensitivity information of structural compliance with respect to the number of candidate fiber laying angles is obtained using the analytical sensitivity analysis method. Based on the proposed variable stiffness design optimization method for complex perforated composite laminates, the numerical examples consider the variable stiffness design optimization of typical non-perforated and perforated composite laminates with circular, square, and irregular holes, and systematically discuss the number of candidate discrete fiber laying angles, discrete fiber continuous filtering strategies, and filter radius on structural compliance, continuity, and manufacturability. The optimized discrete fiber angles of variable stiffness laminates are converted into continuous fiber laying paths using a streamlined process for continuous fiber additive manufacturing. Meanwhile, the optimized non-perforated and perforated MBB beams after discrete fiber continuous treatment, are manufactured using continuous fiber co-extrusion additive manufacturing technology to verify the effectiveness of the variable stiffness fiber optimization framework proposed in this paper.
基金supported by National Key R&D Program of China(Grant No.2018YFE0207900)National Natural Science Foundation of China(Grant No.52075422)+1 种基金K C Wong Education FoundationThe Youth Innovation Team of Shaanxi Universities.
文摘Continuous fiber reinforced polymer composites(CFRPC)have been widely used in the field of automobile,air-craft,and space due to light weight,high specific strength and modulus in comparison with metal as well as alloys.Innovation on 3D printing of CFRPCs opened a new era for the design and fabrication of complicated composite structure with high performance and low cost.3D printing of CFRPCs provided an enabling technol-ogy to bridge the gaps between advanced materials and innovative structures.State-of-art has been reviewed according to the correlations of materials,structure,process,and performance as well as functions in 3D printing of CFRPCs.Typical applications and future perspective for 3D printing of CFRPCs were illustrated in order to grasp the opportunities and face the challenges,which need much more interdisciplinary researches covering the advanced materials,process and equipment,structural design,and final smart performance.
基金Supported by National Natural Science Foundation of China(Grant Nos.51905555,52105523)Hu-Xiang Youth Talent Program of China(Grant No.2020RC3009)Innovation-Driven Project of Central South University of China(Grant No.2019CX017).
文摘The application of continuous natural fibers as reinforcement in composite thin-walled structures offers a feasible approach to achieve light weight and high strength while remaining environmentally friendly.In addition,additive manufacturing technology provides a favorable process foundation for its realization.In this study,the printability and energy absorption properties of 3D printed continuous fiber reinforced thin-walled structures with different configurations were investigated.The results suggested that a low printing speed and a proper layer thickness would mitigate the printing defects within the structures.The printing geometry accuracy of the structures could be further improved by rounding the sharp corners with appropriate radii.This study successfully fabricated structures with vari-ous configurations characterized by high geometric accuracy through printing parameters optimization and path smoothing.Moreover,the compressive property and energy absorption characteristics of the structures under quasi-static axial compression were evaluated and compared.It was found that all studied thin-walled structures exhibited progressive folding deformation patterns during compression.In particular,energy absorption process was achieved through the combined damage modes of plastic deformation,fiber pullout and delamination.Furthermore,the com-parison results showed that the hexagonal structure exhibited the best energy absorption performance.The study revealed the structure-mechanical property relationship of 3D printed continuous fiber reinforced composite thin-walled structures through the analysis of multiscale failure characteristics and load response,which is valuable for broadening their applications.
基金This work was supported by National Natural Science Foundation of China(Grant No.52075422)Rapid Manufacturing Engineering Technology Research Center of Shaanxi Province of China(Grant No.2017HBGC-06)Youth Innovation Team of Shaanxi Universities,and K.C.Wong Education Foundation.
文摘Stretchable strain sensors play a key role in motion detection and human-machine interface functionality,and deformation control.However,their sensitivity is often limited by the Poisson effect of elastic substrates.In this study,a stretchable strain sensor based on a continuous-fiber-reinforced auxetic structure was proposed and fabricated using a direct ink writing(DIW)3D printing process.The application of multi-material DIW greatly simplifies the fabrication process of a sensor with an auxetic structure(auxetic sensor).The auxiliary auxetic struc-ture was innovatively printed using a continuous-fiber-reinforced polydimethylsiloxane composite(Fiber-PDMS)to balance the rigidity and flexibility of the composite.The increase in stiffness enhances the negative Poisson’s ratio effect of the auxetic structure,which can support the carbon nanotube-polydimethylsiloxane composite(CNT-PDMS)stretchable sensor to produce a significant lateral expansion when stretched.It is shown that the structural Poisson’s ratio of the sensor decreased from 0.42 to−0.33 at 20%tensile strain,and the bidirectional tensile strain increases the sensor sensitivity by 2.52 times(gage factor to 18.23).The Fiber-PDMS composite maintains the excellent flexibility of the matrix material.The auxetic sensor exhibited no structural damage af-ter 150 cycles of tension and the signal output exhibited high stability.In addition,this study demonstrates the significant potential of auxetic sensors in the field of deformation control.
基金supported by the Key Program of the National Natural Science Foundation of China (No.52032003)the National Natural Science for Youth Foundation of China (Nos.52102093 and 52202090)+3 种基金the Shandong University Young Scholars Program (No.2016WLJH27)the Fundamental Research Funds for the Central Universities (No.2082019014)the China Postdoctoral Science Foundation (No.2021M690817)the Heilongjiang Provincial Postdoctoral Science Foundation (Nos.LBH-Z21050 and LBH-Z20144).
文摘The difficulty of reducing the diameter of lutetium oxide(Lu_(2)O_(3))continuous fibers below 50μm not only limits the flexibility of the sample but also seriously affects their application and development in high-energy lasers.In this work,a Lu-containing precursor with high ceramic yield was used as raw material,fiberized into precursor fibers by dry spinning.The pressure-assisted water vapor pretreatment(PAWVT)method was creatively proposed,and the effect of pretreatment temperature on the ceramization behavior of the precursor fibers was studied.By regulating the decomposition behavior of organic components in the precursor,the problem of fiber pulverization during heat treatment was effectively solved,and the Lu_(2)O_(3) continuous fibers with a diameter of 40μm were obtained.Compared with the current reported results,the diameter was reduced by about 50%,successfully breaking through the diameter limitation of Lu_(2)O_(3) continuous fibers.In addition,the tensile strength,elastic modulus,flexibility,and temperature resistance of Lu_(2)O_(3) continuous fibers were researched for the first time.The tensile strength and elastic modulus of Lu_(2)O_(3) continuous fibers were 373.23 MPa and 31.55 GPa,respectively.The as-obtained flexible Lu_(2)O_(3) continuous fibers with a limit radius of curvature of 3.5-4.5 mm had a temperature resistance of not lower than 1300℃,which established a solid foundation for the expansion of their application form in the field of high-energy lasers.
基金supported by National Natural Science Foundation of China(Grant No.51905555)Hu-Xiang Youth Talent Program of China(Grant No.2020RC3009)+1 种基金Hunan Provincial Science Foundation for Distinguished Young Scholars of China(Grant No.2021JJ10059)The first author gratefully acknowledges the financial support from the China Scholarship Council(Grant No.202206370135).
文摘In recent years,innovations in 3D/4D printing techniques for continuous fiber-reinforced polymer composites(CFRPCs)have opened new perspectives for the integrated design and manufacture of composites with customized functions.This paper reviews the current state of 3D/4D printed functional composites,including the materi-als,shape memory/changing effects,self-monitoring/healing behaviors,and challenges surrounding additive-manufactured functional composites.Specifically,continuous fibers and matrices that provide functional roles are classified and discussed in detail.4D printed shape memory and changing CFRPCs can retain their original shapes from a designed shape upon exposure to different external stimuli,including heat,electricity,humidity,and multi-stimuli activation.Furthermore,self-monitoring of structural health is achieved through the piezore-sistive features of reinforced fibers in 3D printed CFRPCs.Finally,this review concludes with an outlook on the future research opportunities for 3D/4D printed functional CFRPCs.
基金the financial support from the National Key Research and Development Program of China(grant no.2020YFA0711800)National Natural Science Foundation of China(grant no.11802027)+2 种基金State Key Laboratory of Explosion Science and Technology(grant no.YPJH20-6,QNKT20-01,JCRC18-01)BITBRFFR Joint Research Program(BITBLR2020018)Beijing Institute of Technology Research Fund。
文摘Continuous basalt fiber(CBF)is an outstanding inorganic fiber produced from nature,which has a wide range of applications in the field of armor protection of national defense military.However,the mechanical response and failure mechanism of 3D printed CBF reinforced components are still not well understood.Here,the 3D printing thermoplastic composites with high volume fraction CBF have been successfully prepared by fused deposition modelling(FDM)method.The effects of fiber printing direction and polymer matrix type on the tensile and flexural properties of the 3D printed composites have been explored,and the detailed failure morphology has been characterized using scanning electron microscopy and optical microscopy.It was found that under high fiber volume fraction,3D printed CBF reinforced polyamides(PA)composites have the best ability to maintain material integrity of the composites,followed by acrylonitrile butadiene styrene(ABS)and high impact polystyrene(HIPS).Besides,the results from rule of mixtures can accurately predict the longitudinal Young’s modulus of the 3D printed specimens,but there exists a large discrepancy for the prediction of the tensile strength.The microstructure analysis shows that the failure modes of 3D printed composites mainly include fiber debonding,fiber pull-out,stress whitening and matrix cracking.
基金supported by the National Natural Science Foundation of China(Nos.52175474 and 52275498)。
文摘To meet the requirements of spacecraft for the thermal conductivity of resins and solve the problem of low thermal conduction efficiency when 3D printing complex parts,we propose a new type of continuous mesophase-pitch-based carbon fiber/thermoplastic polyurethane/epoxy(CMPCF/TPU/epoxy)composite filament and its preparation process in this study.The composite filament is based on the high thermal conductivity of CMPCF,the high elasticity of TPU,and the high-temperature resistance of epoxy.The tensile strength and thermal conductivity of the CMPCF/TPU/epoxy composite filament were tested.The CMPCF/TPU/epoxy composites are formed by 3D printing technology,and the composite filament is laid according to the direction of heat conduction so that the printed part can meet the needs of directional heat conduction.The experimental results show that the thermal conductivity of the printed sample is 40.549 W/(m·K),which is 160 times that of pure epoxy resin(0.254 W/(m·K)).It is also approximately 13 times better than that of polyacrylonitrile carbon fiber/epoxy(PAN-CF/epoxy)composites.This study breaks through the technical bottleneck of poor printability of CMPCF.It provides a new method for achieving directional thermal conductivity printing,which is important for the development of complex high-performance thermal conductivity products.
基金Project(L2014056)supported by the Liaoning Education Department,ChinaProject(201501089)supported by the Dr.Start-up Fund of Liaoning Province,China
文摘It was found that air dielectric barrier discharge(DBD) plasma contributed to the grafting of epoxy resin onto continuous PBO fiber surface. This air-plasma-grafting-epoxy method yielded a noticeable enhancement in the interfacial adhesion between PBO fiber and thermoplastic matrix resin, with the interlaminar shear strength of the resulting composites increased by 66.7%. DSC and FTIR analyses were then used to study the curing behavior of epoxy coating on PBO fiber surface, deduce the possible grafting reactions and investigate the grafting mechanism. More importantly, TGA measurement showed that the grafting of epoxy onto PBO fiber had almost no effect on the composite heat resistance, and there was more thermoplastic matrix resin adhering to the fiber surface; the latter could also be clearly found in the SEM photos. Thereby, the air-plasma-grafting-epoxy treatment was proved to be an effective method for the improvement of continuous PBO fiber surface adhesive properties.
基金supported by Xiamen Technology Projects Grand (The study of chronic cerebrovascular insufficiently in Magnetic Resonance Imaging), No.3502Z20084028
文摘This study tested an improved fiber tracking algorithm, which was based on fiber assignment using a continuous tracking algorithm and a two-tensor model. Different models and tracking decisions were used by judging the type of estimation of each voxel. Thismethod should solve the cross-track problem. This study included eight healthy subjects, two axonal injury patients and seven demyelinating disease patients. This new algorithm clearly exhibited a difference in nerve fiber direction between axonal injury and demyelinating disease patients and healthy control subjects. Compared with fiber assignment with a continuous tracking algorithm, our novel method can track more and longer nerve fibers, and also can solve the fiber crossing problem.
基金supported by the National Key Research and Development Program of China(Grant No 2022YFB4600102)the National Natural Science Foundation of China(Grant No.U23A20637 and Grant No 52275561)。
文摘Conventional deformable wheel systems in robots and other mechatronic systems face significant challenges in achieving miniaturization,intelligence,and integration.To address these issues,we propose a novel integrated structural design method and four-dimensional printing strategy for deformable wheels capable of shaping among multiple programmable direct-driven deformation configurations.The load-bearing capacity of the printed wheel is strengthened by employing deformed components in various locations and actuated states.Additionally,a novel analytical design method is presented to determine the structure,actuation,and deformation parameters of each component under complex coupled deformation.Our findings reveal that the designed wheel can transform into three different configurations,exhibiting desired deformations of 12.5%in the radial direction and 19.6%in the axial direction.It also demonstrates robust deformation behavior and structural stability under multi-directional loads.By integrating a terrain sensing system,the designed wheel exhibits highly adaptive deformation capabilities on various terrains,showing great potential for exploring complex environments.
基金support from the National Key Research and Development Program of China(No.2022YFA1203304)the National Natural Science Foundation of China(Nos.52272081,52162007,and 52163032)+1 种基金the Jiangxi Provincial Key Laboratory of Carbonene Materials(No.2024SSY05101)Jiangxi Province Talent Team Plan(No.20243BCE51008).
文摘Carbon nanotube fibers(CNTFs),which hold a transformative potential across fields from aerospace to wearable electronics,have been reported as superstrong fibers,while the fabrication of continuous fibers with excellent strength remains a challenge.Herein,we proposed a mixed carbon-source strategy that engineered carbon nanotube(CNT)aerogels with optimally aligned and controlled-entanglement CNT bundles,ensuring structural uniformity and enabling densification into highly oriented architectures via chlorosulfonic acid-assisted stretching,thus yielding continuous high-performance CNTFs.These continuous CNTFs exhibited superior tensile strength(4.10±0.17 N·tex^(-1),exceeding T1100),modulus(268±16 N·tex^(-1),1.4 times of T1100),thermal conductivity(400 W·m^(-1)·K^(-1),over 30 times of T1100)and electrical conductivity(1480 S·m^(2)·kg^(-1)),along with exceptional flexibility indicated by knot-strength retention exceeding 45%.Comprehensive multi-point assessments confirmed that this method yielded a remarkable uniformity in both structural and functional properties across kilometer-scale lengths.These findings highlight the crucial role of nanotube alignment and interfacial engineering in enabling the scalable industrial implementation of high-performance CNTFs.
文摘After a half century of development, fiber laser has evolved from a concept to a great family penetrating into various fields of applications. This paper reviews the history and current development of fiber lasers, with topics covering both continuous wave and short pulse fiber lasers. Important issues such as the major rare earth dopants, fiber laser brightness, polarization effects, clad pumping technology, beam combination, mode locking and pulse shaping are discussed in this paper.
基金funding from the following funders is acknowledged:National Natural Science Foundation of China(No.82203893 and No.52473090)Capital Med-ical University(Clinical and Basic Research on Lumbar Multiple Trajectory Screw Internal Fixation Technology,CYFH202316)the Anhui Provincial Excellent Youth Fund Project(2408085Y025).
文摘Through millions of years of evolution,bones have developed a complex and elegant hierarchical structure,utilizing tropocollagen and hydroxyapatite to attain an intricate balance between modulus,strength,and toughness.In this study,continuous fiber silk composites(CFSCs)of large size are prepared to mimic the hi-erarchical structure of natural bones,through the inheritance of the hierarchical structure of fiber silk and the integration with a polyester matrix.Due to the robust interface between the matrix and fiber silk,CFSCs show maintained stable long-term mechanical performance under wet conditions.During in vivo degradation,this material primarily undergoes host cell-mediated surface degradation,rather than bulk hydrolysis.We demon-strate significant capabilities of CFSCs in promoting vascularization and macrophage differentiation toward repair.A bone defect model further indicates the potential of CFSC for bone graft applications.Our belief is that the material family of CFSCs may promise a novel biomaterial strategy for yet to be achieved excellent regen-erative implants.
