The advancement and novel technologies in materials science have been steadily growing toward adopting ethical practices.To reduce the stress on the environment the producers integrate novel materials to extend tradit...The advancement and novel technologies in materials science have been steadily growing toward adopting ethical practices.To reduce the stress on the environment the producers integrate novel materials to extend traditional functionality.They develop modern fibers that are eco-friendly,light,resilient,mechanically flexible,and easy to process.Moreover,novel fabrics are acquiring unique properties such as sensory capabilities,electrical conductivity,and data transmission.Cloths with characteristics such as hydrophobic cotton,plant-based textiles,antimicrobial fabrics,and shape memory polymers show versatility in textile innovations.Overall,these textile innovations provide sustainable alternatives,which are commercially viable and suitable for large-scale production.展开更多
Recent decades have seen a substantial increase in interest in research on natural fibres that is aligned with sustainable development goals(SDGs).Due to their renewable resources and biodegradability,natural fiberrei...Recent decades have seen a substantial increase in interest in research on natural fibres that is aligned with sustainable development goals(SDGs).Due to their renewable resources and biodegradability,natural fiberreinforced composites have been investigated as a sustainable alternative to synthetic materials to reduce the usage of hazardous waste and environmental pollution.Among the natural fibre,jute fibre obtained from a bast plant has an increasing trend in the application,especially as a reinforcement material.Numerous research works have been performed on jute fibre with regard to reinforced thermoset and thermoplastic composites.Nevertheless,current demands on sustainable materials have required new developments in thermoplastic composites.In this paper,the author reviews jute plants as reinforcement materials for thermoplastic matrix polymers.This review provides an overview of the sustainability of jute plants as reinforcement material for thermoplastic matrix polymers.The overview on jute based thermoplastic composites focused on the thermal behavior and mechanical properties.Apart from physical,chemical,and mechanical properties,the study also covers the current and perspectives for future research challenges faced by the researchers on jute fibre reinforced thermoplastic composites.展开更多
The poor interfacial stability not only deteriorates fibre lithium-ion batteries(FLBs)performance but also impacts their scalable applications.To efficiently address these challenges,Prof.Huisheng Peng team proposed a...The poor interfacial stability not only deteriorates fibre lithium-ion batteries(FLBs)performance but also impacts their scalable applications.To efficiently address these challenges,Prof.Huisheng Peng team proposed a generalized channel structures strategy with optimized in situ polymerization technology in their recent study.The resultant FLBs can be woven into different-sized powering textiles,providing a high energy density output of 128 Wh kg^(-1) and simultaneously demonstrating good durability even under harsh conditions.Such a promising strategy expands the horizon in developing FLB with particular polymer gel electrolytes,and significantly ever-deepening understanding of the scaled wearable energy textile system toward a sustainable future.展开更多
To solve the problems of a few optical fibre line fault samples and the inefficiency of manual communication optical fibre fault diagnosis,this paper proposes a communication optical fibre fault diagnosis model based ...To solve the problems of a few optical fibre line fault samples and the inefficiency of manual communication optical fibre fault diagnosis,this paper proposes a communication optical fibre fault diagnosis model based on variational modal decomposition(VMD),fuzzy entropy(FE)and fuzzy clustering(FC).Firstly,based on the OTDR curve data collected in the field,VMD is used to extract the different modal components(IMF)of the original signal and calculate the fuzzy entropy(FE)values of different components to characterize the subtle differences between them.The fuzzy entropy of each curve is used as the feature vector,which in turn constructs the communication optical fibre feature vector matrix,and the fuzzy clustering algorithm is used to achieve fault diagnosis of faulty optical fibre.The VMD-FE combination can extract subtle differences in features,and the fuzzy clustering algorithm does not require sample training.The experimental results show that the model in this paper has high accuracy and is relevant to the maintenance of communication optical fibre when compared with existing feature extraction models and traditional machine learning models.展开更多
New fibres continue to be developed for a wide range of technical textile applications.Currently,they include fibres based on organic or recycled feedstocks to meet sustainability targets and others with new functiona...New fibres continue to be developed for a wide range of technical textile applications.Currently,they include fibres based on organic or recycled feedstocks to meet sustainability targets and others with new functional properties for advanced high performance applications.Many of them were showcased at the forthcoming Techtextil 2024 exhibition which takes place in Frankfurt,Germany,from April 23-26.The development of specific multifilaments,monofilaments and nonwovens for niche fibre applications–over 70 to date–is very much the specialist field of BTMA member Fibre Extrusion Technologies(FET),along with designing the bespoke fibre extrusion and spunbond and meltblown nonwoven systems to successfully produce them.展开更多
The yttrium as a sintering aid was introduced into polycarbosilane(PCS) to prepare yttrium-containing PCS(PYCS).Two types of yttrium-containing SiC fibres,the SiC(OY) fibres and the SiC(Y) fibres,were fabricat...The yttrium as a sintering aid was introduced into polycarbosilane(PCS) to prepare yttrium-containing PCS(PYCS).Two types of yttrium-containing SiC fibres,the SiC(OY) fibres and the SiC(Y) fibres,were fabricated with PYCS.The structural evolution and the associated properties on changing from SiC(OY) to SiC(Y) fibres during the sintering process were studied.The chemical composition of the SiC(OY) fibres is SiC1.53O0.22Y0.005 with an amorphous structure.The composition of SiC(Y) fibres is SiC1.23O0.05Y0.005.The fibres are composed of a large number of β-SiC crystallites with a size of 50 nm and a small amount of α-SiC crystalline.The tensile strength and fracture toughness of the SiC(OY) fibres are 2.25 GPa and 2.37 MPa·m1/2,respectively,and 1.61 GPa,1.91 MPa·m1/2,respectively for SiC(Y) fibres.The SiC(Y) fibres have a higher thermal stability than the SiC(OY) fibres.展开更多
The reflected optical caustics method is applied to study dynamic fracture problems in hardened cement paste. First both the unreinforced cement paste and the glass fibres reinforced cement paste specimens were fabric...The reflected optical caustics method is applied to study dynamic fracture problems in hardened cement paste. First both the unreinforced cement paste and the glass fibres reinforced cement paste specimens were fabricated and the reflective coating on the surface of the specimen was prepared. Secondly the crack path and the shadow spot patterns during the crack propagation process for the two specimens were recorded by using a multi-spark high speed camera.Thirdly some dynamic parameters of two cement paste specimens including crack onset time the dynamic stress intensity factor and crack growth velocity were determined and analyzed comparatively.This indicates that the glass fibres can improve the fracture resistance and delay fracture time.These results will play an important role in evaluating the dynamic fracture properties of cement paste.展开更多
Polypropylene fibres and three sizes of steel fibres reinforced concrete are discussed. The total fibres content ranges from 0 4%-0 95% by volume of concrete. A four point bending test is adopted on the notched pris...Polypropylene fibres and three sizes of steel fibres reinforced concrete are discussed. The total fibres content ranges from 0 4%-0 95% by volume of concrete. A four point bending test is adopted on the notched prisms with the size of 100?mm×100?mm×500?mm to investigate the effect of hybrid fibres on crack arresting. The research results show that there is a positive synergy effect between large steel fibres and polypropylene fibres on the load bearing capacity in the small displacement range. But this synergy effect disappears in the large displacement range. The large and strong steel fibre is better than soft polypropylene fibre and small steel fibre in the aspect of energy absorption capacity in the large displacement range. The static usage limitation for the hybrid fibres concrete with “wide peak' or “multi peaks' load CMOD pattern should be carefully selected. The ultimate load bearing capacity and the crack width or CMOD at this load level should be jointly considered.展开更多
BN coated A1203 fibre-reinforced NiAl-alloy composites were fabricated by hot pressing at 1 200-1 400 ℃, and the interracial microstructure and chemical stability of BN coated Al2O3 fibre-reinforced NiAl-alloy compos...BN coated A1203 fibre-reinforced NiAl-alloy composites were fabricated by hot pressing at 1 200-1 400 ℃, and the interracial microstructure and chemical stability of BN coated Al2O3 fibre-reinforced NiAl-alloy composites were investigated by scanning electron microscopy (SEM) and analytical transmission electron microscopy (TEM). It was found that the complicated chemical reactions and diffusion processes happened in the interface area between BN-layer and Ni25.8A19.6Ta8.3 during the hot pressing at 1 200-1 400 ℃. A continuous AlN-layer was formed at the interface due to the reaction between NiAl and BN. At the same time, Cr diffused extensively into the BN-layer and reacted with boron to form Cr boride precipitates (CrsB3). In addition, a few particles of Ta-rich phase were also precipitated in NiAl matrix near the interface.展开更多
The orientation and concentration distributions of fibres in laminar and turbulent channel flows are investigated numerically. The obtained results are in good agreement with the experimental data. In the laminar flow...The orientation and concentration distributions of fibres in laminar and turbulent channel flows are investigated numerically. The obtained results are in good agreement with the experimental data. In the laminar flow regime, more fibres orient to the flow direction as the Reynolds number increases. The shear rate of fluid around a fibre plays an important role in determining the orientation distribution of fibres, while the fibre density and the fibre aspect-ratio have marginal influence on the orientation distribution. In the turbulent regime, the orientation distribution of fibres becomes more homogeneous with the increase of Reynolds number, and the concentration profile is flatter than that in the laminar regime. The fluctuating intensity of fibre velocity in the downstream direction is larger than that in the lateral directions.展开更多
In this paper,the temperature dependence of birefringence in polarization maintaining photonic crystal fibres(PMPCFs) is investigated theoretically and experimentally.Utilizing the structural parameters of the PM-PC...In this paper,the temperature dependence of birefringence in polarization maintaining photonic crystal fibres(PMPCFs) is investigated theoretically and experimentally.Utilizing the structural parameters of the PM-PCF samples in the experiment,two effects leading to the birefringence variation under different temperatures are analysed,which are the thermal expansion of silica material and the refractive index variation due to the temperature variation.The actual birefringence variation of the PM-PCF is the combination of the two effects,which is in the order of 10-9 K-1 for both fibre samples.Calculation results also show that the influence of refractive index variation is the dominant contribution,which determines the tendency of the fibre birefringence variation with varying temperature.Then,the birefringence beat lengths of the two fibre samples are measured under the temperature,which varies from -40℃ to 80℃.A traditional PANDA-type polarization maintaining fibre(PMF) is also measured in the same way for comparison.The experimental results indicate that the birefringence variation of the PM-PCF due to temperature variation is far smaller than that of the traditional PMF,which agrees with the theoretical analysis.The ultra-low temperature dependence of the birefringence in the PM-PCF has great potential applications in temperature-insensitive fibre interferometers,fibre sensors,and fibre gyroscopes.展开更多
Titanium metal matrix composites (TiMMCs) reinforced by continuous silicon carbide fibres are being developed for aerospace applications. TiMMCs manufactured by the consolidation of matrix-coated fibre (MCF) metho...Titanium metal matrix composites (TiMMCs) reinforced by continuous silicon carbide fibres are being developed for aerospace applications. TiMMCs manufactured by the consolidation of matrix-coated fibre (MCF) method offer optimum properties because of the resulting uniform fibre distribution, minimum fibre damage and fibre volume fraction control. In this paper, the consolidation of Ti-6Al-4V matrix-coated SiC fibres during vacuum hot pressing has been investigated. Experiments were carried out on multi-ply MCFs under vacuum hot pressing (VHP). In contrast to most of existing studies, the fibre, arrangement has been carefully controlled either in square or hexagonal arrays throughout the consolidated sample. This has enabled the dynamic consolidation behaviour of MCFs to be demonstrated by eliminating the fibre re-arrangement during the VHP process. The microstructural evolution of the matrix coating was reported and the deformation mechanisms involved were discussed.展开更多
The impact properties of normal concrete (NC) and reinforced concrete (RC) specimens,steel fibre reinforced concrete (SFRC) specimens and RC+SFRC specimens with different steel fibre dosages were investigated with the...The impact properties of normal concrete (NC) and reinforced concrete (RC) specimens,steel fibre reinforced concrete (SFRC) specimens and RC+SFRC specimens with different steel fibre dosages were investigated with the drop-weight impact test recommended by ACI Committee 544.The results indicate that the number of blows to final failure is greatly increased by addition of steel fibres.Moreover,the combination of steel fibres and steel rebars demonstrates a significant positive composite effect on the impact resistance,which results in the improvement in impact toughness of concrete specimens.In the view of variation of impact test results,the two-parameter Weibull distribution was adopted to analyze the experimental data.It is proved that the probabilistic distributions of the blows to first crack and to final failure of six types of samples approximately follow two-parameter Weibull distribution.展开更多
In this paper, the generalized nonlinear Schrodinger equation (GNLSE) is solved by an adaptive split-step Fourier method (ASSFM). It is found that ASSFM must be used to solve GNLSE to ensure precision when the sol...In this paper, the generalized nonlinear Schrodinger equation (GNLSE) is solved by an adaptive split-step Fourier method (ASSFM). It is found that ASSFM must be used to solve GNLSE to ensure precision when the soliton selffrequency shift is remarkable and the photonic crystal fibre (PCF) parameters vary with the frequency considerably. The precision of numerical simulation by using ASSFM is higher than that by using split-step Fourier method in the process of laser pulse propagation in PCFs due to the fact that the variation of fibre parameters with the peak frequency in the pulse spectrum can be taken into account fully.展开更多
To study the adsorption properties of organic functional groups in plant fibres and identify a highly efficient and affordable adsorbent for radioactive wastewater treatment,natural bamboo fibre(NBF)samples were prepa...To study the adsorption properties of organic functional groups in plant fibres and identify a highly efficient and affordable adsorbent for radioactive wastewater treatment,natural bamboo fibre(NBF)samples were prepared,and the adsorption properties of Eu(Ⅲ)on NBFs were studied under given experimental conditions.The effects of the pH,solid-to-liquid ratio,background ions,humic acid,contact time,and temperature on the adsorption behaviour of Eu(Ⅲ)on NBFs were investigated.Adsorption was greatly influenced by pH,and the adsorption curves presented two inflection points at pH≈7 and pH≈11.Moreover,while the ionic strength presented a negative effect at pH<7,the high ionic strength favoured adsorption at pH>7.During adsorption on NBFs,the–OH,C–H,O–H,C–O,and C=O were the main adsorption groups.Hydrolysis occurring on the NBF surface caused the adsorption process to become increasingly difficult at pH>7.The maximum adsorption capacity of NBFs was 147.6 mg/g at 308 K,and the adsorption could be described using the pseudo-second-order kinetic model.The adsorption of Eu(Ⅲ)on NBFs was a spontaneous and endothermic process according to the thermodynamic parameters of the process,and the adsorption thermodynamics could be well described using the Freundlich adsorption model.Therefore,NBFs were determined to be an efficient,inexpensive,and easily disposable sewage treatment material.展开更多
The flexible structure of photonic crystal fibre not only offers novel optical properties but also brings some difficulties in keeping the fibre structure in the fabrication process which inevitably cause the optical ...The flexible structure of photonic crystal fibre not only offers novel optical properties but also brings some difficulties in keeping the fibre structure in the fabrication process which inevitably cause the optical properties of the resulting fibre to deviate from the designed properties. Therefore, a method of evaluating the optical properties of the actual fibre is necessary for the purpose of application. Up to now, the methods employed to measure the properties of the actual photonic crystal fibre often require long fibre samples or complex expensive equipments. To our knowledge, there are few studies of modeling an actual photonic crystal fibre and evaluating its properties rapidly. In this paper, a novel method, based on the combination model of digital image processing and the finite element method, is proposed to rapidly model the optical properties of the actual photonic crystal fibre. Two kinds of photonic crystal fibres made by Crystal Fiber A/S are modeled. It is confirmed from numerical results that the proposed method is simple, rapid and accurate for evaluating the optical properties of the actual photonic crystal fibre without requiring complex equipment.展开更多
This paper theoretically studies the double-pumped fibre-optical parametric amplifiers (FOPAs) in photonic crystal fibres. Two distinct working regimes of FOPAs are researched, which depend on the dispersion at the ...This paper theoretically studies the double-pumped fibre-optical parametric amplifiers (FOPAs) in photonic crystal fibres. Two distinct working regimes of FOPAs are researched, which depend on the dispersion at the central wavelength of the two pumps. Extremely broad tuning range can be obtained when the central pump wavelength is in the normal dispersion regime and is insensitive to the wavelength separation between the two pumps, while the tuning range is narrow in the anomalous dispersion regime and can be significantly enhanced by increasing the wavelength separation. Impacts of higher-order dispersions and temporal walk-off on the gain spectra are also discussed.展开更多
Polylactic acid(PLA)bioplastic is a common material used in Fused Deposition Modeling(FDM)3D printing.It is biodegradable and environmentally friendly biopolymer which made out of corn.However,it exhibits weak mechan...Polylactic acid(PLA)bioplastic is a common material used in Fused Deposition Modeling(FDM)3D printing.It is biodegradable and environmentally friendly biopolymer which made out of corn.However,it exhibits weak mechanical properties which reduced its usability as a functional prototype in a real-world application.In the present study,two PLA composites are created through coextruded with 3K carbon fibres and twisted Kevlar string(as core fibre)to form a fibre reinforced parts(FRP).The mechanical strength of printed parts was examined using ASTM D638 standard with a strain rate of 1 mm/min.It has been demonstrated that the FRPs coextruded with 3K carbon fibres had achieved significant improvement in Young’s modulus(+180.6%,9.205 GPa),ultimate tensile strength(+175.3%,103 MPa)and maximum tensile strain(+21.6%,1.833%).Although the Young’s modulus of Kevlar FRP was found to be similar to as compared to unreinforced PLA(~3.29 GPa),it has gained significant increment in terms of maximum tensile strain(+179.7%,104.64 MPa),and maximum tensile strain(+257%,5.384%).Thus,this study revealed two unique composite materials,in which the 3K carbon FRP can offer stiff and high strength structure while Kevlar FRP offers similar strength but at a higher elasticity.展开更多
To obtain the stable operation of erbium-doped fibre laser, the simple and ideal technology is adopted by use of the erbium doped polarization maintaining fibre (EDPMF). The design criteria of the Panda-type EDPMF a...To obtain the stable operation of erbium-doped fibre laser, the simple and ideal technology is adopted by use of the erbium doped polarization maintaining fibre (EDPMF). The design criteria of the Panda-type EDPMF are presented, which take into account the cutoff wavelength, mode field diameter, modal birefringence and background loss. Four groups of optimum structural paramcter combinations are determined in terms of the design criteria. Two kinds of the Panda-type EDPMFs are selected to be fabricated. The fabrication process and the parameter control of the Panda-type EDPMFs are presented in detail. Their refractive index profiles, birefringence and absorption spectra are experimentally investigated. The absorption coefficient of the EDPMF, whose core is co-doped with Bi, Ga, A1 and Ge, is about 57.9dB/m at 1.53μm. Co-doping Bi, Ga and A1 can greatly increase the erbium concentration in the silica-based fibre. The high birefringence is obtained for the Panda-type EDPMF. The group birefringence of the EDPMF, whose outer cladding diameter is 125 μm, is about 4.8 × 10%^-4.展开更多
The aim of this study is to investigate the effect of chemical extraction method on the properties of doum palm fibres. The method of extraction which is carried out is a soda treatment. First, an investigation of the...The aim of this study is to investigate the effect of chemical extraction method on the properties of doum palm fibres. The method of extraction which is carried out is a soda treatment. First, an investigation of the extraction processes was undertaken. Secondly, the physical properties (surface morphology, density, linear density and diameter), the mechanical properties (tenacity, strain) and chemical properties (FT-IR spectra) of doum palm fibres were inspected. Finally, a comparison between properties of doum palm fibres and other vegetal ones has been included. Results indicates an influence of soda treatment on properties of Doum palm fibers. In fact, there is an improvement on fibers diameter and linear density while increasing soda concentration, temperature and treatment duration. Moreover, the studied fibers have a low density which does not exceed 1. The fibers tenacity achieved the maximum value of 20.86 cN/Tex when precessing in the following combination (0.75 N, 100°C and 180 mn). In the end, the FTIR spectra reveals a change in structure after this alkali treatment while increasing the cellulose amount exposed on the fiber surface and consequently the number of possible reaction sites (OH groups).展开更多
文摘The advancement and novel technologies in materials science have been steadily growing toward adopting ethical practices.To reduce the stress on the environment the producers integrate novel materials to extend traditional functionality.They develop modern fibers that are eco-friendly,light,resilient,mechanically flexible,and easy to process.Moreover,novel fabrics are acquiring unique properties such as sensory capabilities,electrical conductivity,and data transmission.Cloths with characteristics such as hydrophobic cotton,plant-based textiles,antimicrobial fabrics,and shape memory polymers show versatility in textile innovations.Overall,these textile innovations provide sustainable alternatives,which are commercially viable and suitable for large-scale production.
文摘Recent decades have seen a substantial increase in interest in research on natural fibres that is aligned with sustainable development goals(SDGs).Due to their renewable resources and biodegradability,natural fiberreinforced composites have been investigated as a sustainable alternative to synthetic materials to reduce the usage of hazardous waste and environmental pollution.Among the natural fibre,jute fibre obtained from a bast plant has an increasing trend in the application,especially as a reinforcement material.Numerous research works have been performed on jute fibre with regard to reinforced thermoset and thermoplastic composites.Nevertheless,current demands on sustainable materials have required new developments in thermoplastic composites.In this paper,the author reviews jute plants as reinforcement materials for thermoplastic matrix polymers.This review provides an overview of the sustainability of jute plants as reinforcement material for thermoplastic matrix polymers.The overview on jute based thermoplastic composites focused on the thermal behavior and mechanical properties.Apart from physical,chemical,and mechanical properties,the study also covers the current and perspectives for future research challenges faced by the researchers on jute fibre reinforced thermoplastic composites.
基金the National Key R&D Program of China(2022YFA1203304)the Natural Science Foundation of Jiangsu Province(BK20220288)+1 种基金Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences(Start-up grant E1552102)the China Postdoctoral Science Foundation(No.2023M732553).
文摘The poor interfacial stability not only deteriorates fibre lithium-ion batteries(FLBs)performance but also impacts their scalable applications.To efficiently address these challenges,Prof.Huisheng Peng team proposed a generalized channel structures strategy with optimized in situ polymerization technology in their recent study.The resultant FLBs can be woven into different-sized powering textiles,providing a high energy density output of 128 Wh kg^(-1) and simultaneously demonstrating good durability even under harsh conditions.Such a promising strategy expands the horizon in developing FLB with particular polymer gel electrolytes,and significantly ever-deepening understanding of the scaled wearable energy textile system toward a sustainable future.
基金This paper is supported by State Grid Gansu Electric Power Company Science and Technology Project(20220515003).
文摘To solve the problems of a few optical fibre line fault samples and the inefficiency of manual communication optical fibre fault diagnosis,this paper proposes a communication optical fibre fault diagnosis model based on variational modal decomposition(VMD),fuzzy entropy(FE)and fuzzy clustering(FC).Firstly,based on the OTDR curve data collected in the field,VMD is used to extract the different modal components(IMF)of the original signal and calculate the fuzzy entropy(FE)values of different components to characterize the subtle differences between them.The fuzzy entropy of each curve is used as the feature vector,which in turn constructs the communication optical fibre feature vector matrix,and the fuzzy clustering algorithm is used to achieve fault diagnosis of faulty optical fibre.The VMD-FE combination can extract subtle differences in features,and the fuzzy clustering algorithm does not require sample training.The experimental results show that the model in this paper has high accuracy and is relevant to the maintenance of communication optical fibre when compared with existing feature extraction models and traditional machine learning models.
文摘New fibres continue to be developed for a wide range of technical textile applications.Currently,they include fibres based on organic or recycled feedstocks to meet sustainability targets and others with new functional properties for advanced high performance applications.Many of them were showcased at the forthcoming Techtextil 2024 exhibition which takes place in Frankfurt,Germany,from April 23-26.The development of specific multifilaments,monofilaments and nonwovens for niche fibre applications–over 70 to date–is very much the specialist field of BTMA member Fibre Extrusion Technologies(FET),along with designing the bespoke fibre extrusion and spunbond and meltblown nonwoven systems to successfully produce them.
基金Projects (51175444,50532010) supported by the National Natural Science Foundation of ChinaProject (2011121002) supported by the Fundamental Research Funds for the Central Universities, ChinaProject (2009J1009) supported by Scientific and Technological Innovation Platform of Fujian Province,China
文摘The yttrium as a sintering aid was introduced into polycarbosilane(PCS) to prepare yttrium-containing PCS(PYCS).Two types of yttrium-containing SiC fibres,the SiC(OY) fibres and the SiC(Y) fibres,were fabricated with PYCS.The structural evolution and the associated properties on changing from SiC(OY) to SiC(Y) fibres during the sintering process were studied.The chemical composition of the SiC(OY) fibres is SiC1.53O0.22Y0.005 with an amorphous structure.The composition of SiC(Y) fibres is SiC1.23O0.05Y0.005.The fibres are composed of a large number of β-SiC crystallites with a size of 50 nm and a small amount of α-SiC crystalline.The tensile strength and fracture toughness of the SiC(OY) fibres are 2.25 GPa and 2.37 MPa·m1/2,respectively,and 1.61 GPa,1.91 MPa·m1/2,respectively for SiC(Y) fibres.The SiC(Y) fibres have a higher thermal stability than the SiC(OY) fibres.
基金The Ph.D.Programs Foundation of Ministry of Education of China(No.20120023120020)the National Natural Science Foundation of China(No.51404273)
文摘The reflected optical caustics method is applied to study dynamic fracture problems in hardened cement paste. First both the unreinforced cement paste and the glass fibres reinforced cement paste specimens were fabricated and the reflective coating on the surface of the specimen was prepared. Secondly the crack path and the shadow spot patterns during the crack propagation process for the two specimens were recorded by using a multi-spark high speed camera.Thirdly some dynamic parameters of two cement paste specimens including crack onset time the dynamic stress intensity factor and crack growth velocity were determined and analyzed comparatively.This indicates that the glass fibres can improve the fracture resistance and delay fracture time.These results will play an important role in evaluating the dynamic fracture properties of cement paste.
文摘Polypropylene fibres and three sizes of steel fibres reinforced concrete are discussed. The total fibres content ranges from 0 4%-0 95% by volume of concrete. A four point bending test is adopted on the notched prisms with the size of 100?mm×100?mm×500?mm to investigate the effect of hybrid fibres on crack arresting. The research results show that there is a positive synergy effect between large steel fibres and polypropylene fibres on the load bearing capacity in the small displacement range. But this synergy effect disappears in the large displacement range. The large and strong steel fibre is better than soft polypropylene fibre and small steel fibre in the aspect of energy absorption capacity in the large displacement range. The static usage limitation for the hybrid fibres concrete with “wide peak' or “multi peaks' load CMOD pattern should be carefully selected. The ultimate load bearing capacity and the crack width or CMOD at this load level should be jointly considered.
基金Project (10972190) supported by the National Natural Science Foundation of China Projects (09A089, 08C207) supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProject (2010FJ3132) supported by the Planned Science and Technology Project of Hunan Province,China
文摘BN coated A1203 fibre-reinforced NiAl-alloy composites were fabricated by hot pressing at 1 200-1 400 ℃, and the interracial microstructure and chemical stability of BN coated Al2O3 fibre-reinforced NiAl-alloy composites were investigated by scanning electron microscopy (SEM) and analytical transmission electron microscopy (TEM). It was found that the complicated chemical reactions and diffusion processes happened in the interface area between BN-layer and Ni25.8A19.6Ta8.3 during the hot pressing at 1 200-1 400 ℃. A continuous AlN-layer was formed at the interface due to the reaction between NiAl and BN. At the same time, Cr diffused extensively into the BN-layer and reacted with boron to form Cr boride precipitates (CrsB3). In addition, a few particles of Ta-rich phase were also precipitated in NiAl matrix near the interface.
基金Project supported by the National Natural Science Foundation (Grant No 10372090) and the Doctorate Program of Higher Education of China (Grant No 20030335001).
文摘The orientation and concentration distributions of fibres in laminar and turbulent channel flows are investigated numerically. The obtained results are in good agreement with the experimental data. In the laminar flow regime, more fibres orient to the flow direction as the Reynolds number increases. The shear rate of fluid around a fibre plays an important role in determining the orientation distribution of fibres, while the fibre density and the fibre aspect-ratio have marginal influence on the orientation distribution. In the turbulent regime, the orientation distribution of fibres becomes more homogeneous with the increase of Reynolds number, and the concentration profile is flatter than that in the laminar regime. The fluctuating intensity of fibre velocity in the downstream direction is larger than that in the lateral directions.
文摘In this paper,the temperature dependence of birefringence in polarization maintaining photonic crystal fibres(PMPCFs) is investigated theoretically and experimentally.Utilizing the structural parameters of the PM-PCF samples in the experiment,two effects leading to the birefringence variation under different temperatures are analysed,which are the thermal expansion of silica material and the refractive index variation due to the temperature variation.The actual birefringence variation of the PM-PCF is the combination of the two effects,which is in the order of 10-9 K-1 for both fibre samples.Calculation results also show that the influence of refractive index variation is the dominant contribution,which determines the tendency of the fibre birefringence variation with varying temperature.Then,the birefringence beat lengths of the two fibre samples are measured under the temperature,which varies from -40℃ to 80℃.A traditional PANDA-type polarization maintaining fibre(PMF) is also measured in the same way for comparison.The experimental results indicate that the birefringence variation of the PM-PCF due to temperature variation is far smaller than that of the traditional PMF,which agrees with the theoretical analysis.The ultra-low temperature dependence of the birefringence in the PM-PCF has great potential applications in temperature-insensitive fibre interferometers,fibre sensors,and fibre gyroscopes.
文摘Titanium metal matrix composites (TiMMCs) reinforced by continuous silicon carbide fibres are being developed for aerospace applications. TiMMCs manufactured by the consolidation of matrix-coated fibre (MCF) method offer optimum properties because of the resulting uniform fibre distribution, minimum fibre damage and fibre volume fraction control. In this paper, the consolidation of Ti-6Al-4V matrix-coated SiC fibres during vacuum hot pressing has been investigated. Experiments were carried out on multi-ply MCFs under vacuum hot pressing (VHP). In contrast to most of existing studies, the fibre, arrangement has been carefully controlled either in square or hexagonal arrays throughout the consolidated sample. This has enabled the dynamic consolidation behaviour of MCFs to be demonstrated by eliminating the fibre re-arrangement during the VHP process. The microstructural evolution of the matrix coating was reported and the deformation mechanisms involved were discussed.
基金Project(50578026) supported by the National Natural Science Foundation of ChinaProject supported by FCT (SFRH/BPD/22680/2005)and Research Center of Mathematics of the University of Minho through the FCT Pluriannual Funding Program
文摘The impact properties of normal concrete (NC) and reinforced concrete (RC) specimens,steel fibre reinforced concrete (SFRC) specimens and RC+SFRC specimens with different steel fibre dosages were investigated with the drop-weight impact test recommended by ACI Committee 544.The results indicate that the number of blows to final failure is greatly increased by addition of steel fibres.Moreover,the combination of steel fibres and steel rebars demonstrates a significant positive composite effect on the impact resistance,which results in the improvement in impact toughness of concrete specimens.In the view of variation of impact test results,the two-parameter Weibull distribution was adopted to analyze the experimental data.It is proved that the probabilistic distributions of the blows to first crack and to final failure of six types of samples approximately follow two-parameter Weibull distribution.
文摘In this paper, the generalized nonlinear Schrodinger equation (GNLSE) is solved by an adaptive split-step Fourier method (ASSFM). It is found that ASSFM must be used to solve GNLSE to ensure precision when the soliton selffrequency shift is remarkable and the photonic crystal fibre (PCF) parameters vary with the frequency considerably. The precision of numerical simulation by using ASSFM is higher than that by using split-step Fourier method in the process of laser pulse propagation in PCFs due to the fact that the variation of fibre parameters with the peak frequency in the pulse spectrum can be taken into account fully.
基金supported by the National Natural Science Foundation of China(No.21561001)the Natural Science Foundation of Jiangxi Province,China(No.20161BAB203100)
文摘To study the adsorption properties of organic functional groups in plant fibres and identify a highly efficient and affordable adsorbent for radioactive wastewater treatment,natural bamboo fibre(NBF)samples were prepared,and the adsorption properties of Eu(Ⅲ)on NBFs were studied under given experimental conditions.The effects of the pH,solid-to-liquid ratio,background ions,humic acid,contact time,and temperature on the adsorption behaviour of Eu(Ⅲ)on NBFs were investigated.Adsorption was greatly influenced by pH,and the adsorption curves presented two inflection points at pH≈7 and pH≈11.Moreover,while the ionic strength presented a negative effect at pH<7,the high ionic strength favoured adsorption at pH>7.During adsorption on NBFs,the–OH,C–H,O–H,C–O,and C=O were the main adsorption groups.Hydrolysis occurring on the NBF surface caused the adsorption process to become increasingly difficult at pH>7.The maximum adsorption capacity of NBFs was 147.6 mg/g at 308 K,and the adsorption could be described using the pseudo-second-order kinetic model.The adsorption of Eu(Ⅲ)on NBFs was a spontaneous and endothermic process according to the thermodynamic parameters of the process,and the adsorption thermodynamics could be well described using the Freundlich adsorption model.Therefore,NBFs were determined to be an efficient,inexpensive,and easily disposable sewage treatment material.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB328206)the National Natural Science Foundation of China(Grant No.60977033)the Science and Technology Innovation Foundation for Excellent Doctors of Beijing Jiaotong University,China(Grant Nos.141055522 and 141060522)
文摘The flexible structure of photonic crystal fibre not only offers novel optical properties but also brings some difficulties in keeping the fibre structure in the fabrication process which inevitably cause the optical properties of the resulting fibre to deviate from the designed properties. Therefore, a method of evaluating the optical properties of the actual fibre is necessary for the purpose of application. Up to now, the methods employed to measure the properties of the actual photonic crystal fibre often require long fibre samples or complex expensive equipments. To our knowledge, there are few studies of modeling an actual photonic crystal fibre and evaluating its properties rapidly. In this paper, a novel method, based on the combination model of digital image processing and the finite element method, is proposed to rapidly model the optical properties of the actual photonic crystal fibre. Two kinds of photonic crystal fibres made by Crystal Fiber A/S are modeled. It is confirmed from numerical results that the proposed method is simple, rapid and accurate for evaluating the optical properties of the actual photonic crystal fibre without requiring complex equipment.
基金Project partially supported by the Shanghai Committee of Science and Technology, China (Grant Nos 05 SG 02 and 05 JC 14005)the National Natural Science Foundation of China (Grant Nos 60538010 and 10376009)
文摘This paper theoretically studies the double-pumped fibre-optical parametric amplifiers (FOPAs) in photonic crystal fibres. Two distinct working regimes of FOPAs are researched, which depend on the dispersion at the central wavelength of the two pumps. Extremely broad tuning range can be obtained when the central pump wavelength is in the normal dispersion regime and is insensitive to the wavelength separation between the two pumps, while the tuning range is narrow in the anomalous dispersion regime and can be significantly enhanced by increasing the wavelength separation. Impacts of higher-order dispersions and temporal walk-off on the gain spectra are also discussed.
基金This project is funded by Universiti Tunku Abdul Rahman through the grant number IPSR/RMC/UTARRF/2018-C2/T02.
文摘Polylactic acid(PLA)bioplastic is a common material used in Fused Deposition Modeling(FDM)3D printing.It is biodegradable and environmentally friendly biopolymer which made out of corn.However,it exhibits weak mechanical properties which reduced its usability as a functional prototype in a real-world application.In the present study,two PLA composites are created through coextruded with 3K carbon fibres and twisted Kevlar string(as core fibre)to form a fibre reinforced parts(FRP).The mechanical strength of printed parts was examined using ASTM D638 standard with a strain rate of 1 mm/min.It has been demonstrated that the FRPs coextruded with 3K carbon fibres had achieved significant improvement in Young’s modulus(+180.6%,9.205 GPa),ultimate tensile strength(+175.3%,103 MPa)and maximum tensile strain(+21.6%,1.833%).Although the Young’s modulus of Kevlar FRP was found to be similar to as compared to unreinforced PLA(~3.29 GPa),it has gained significant increment in terms of maximum tensile strain(+179.7%,104.64 MPa),and maximum tensile strain(+257%,5.384%).Thus,this study revealed two unique composite materials,in which the 3K carbon FRP can offer stiff and high strength structure while Kevlar FRP offers similar strength but at a higher elasticity.
文摘To obtain the stable operation of erbium-doped fibre laser, the simple and ideal technology is adopted by use of the erbium doped polarization maintaining fibre (EDPMF). The design criteria of the Panda-type EDPMF are presented, which take into account the cutoff wavelength, mode field diameter, modal birefringence and background loss. Four groups of optimum structural paramcter combinations are determined in terms of the design criteria. Two kinds of the Panda-type EDPMFs are selected to be fabricated. The fabrication process and the parameter control of the Panda-type EDPMFs are presented in detail. Their refractive index profiles, birefringence and absorption spectra are experimentally investigated. The absorption coefficient of the EDPMF, whose core is co-doped with Bi, Ga, A1 and Ge, is about 57.9dB/m at 1.53μm. Co-doping Bi, Ga and A1 can greatly increase the erbium concentration in the silica-based fibre. The high birefringence is obtained for the Panda-type EDPMF. The group birefringence of the EDPMF, whose outer cladding diameter is 125 μm, is about 4.8 × 10%^-4.
文摘The aim of this study is to investigate the effect of chemical extraction method on the properties of doum palm fibres. The method of extraction which is carried out is a soda treatment. First, an investigation of the extraction processes was undertaken. Secondly, the physical properties (surface morphology, density, linear density and diameter), the mechanical properties (tenacity, strain) and chemical properties (FT-IR spectra) of doum palm fibres were inspected. Finally, a comparison between properties of doum palm fibres and other vegetal ones has been included. Results indicates an influence of soda treatment on properties of Doum palm fibers. In fact, there is an improvement on fibers diameter and linear density while increasing soda concentration, temperature and treatment duration. Moreover, the studied fibers have a low density which does not exceed 1. The fibers tenacity achieved the maximum value of 20.86 cN/Tex when precessing in the following combination (0.75 N, 100°C and 180 mn). In the end, the FTIR spectra reveals a change in structure after this alkali treatment while increasing the cellulose amount exposed on the fiber surface and consequently the number of possible reaction sites (OH groups).